AN137_技术文档

AN137

LITHIUM ION BATTERY CHARGER USING C8051F300

Relevant Devices

Key Points

•

On-chip high-speed, 8-bit ADC provides supe-

rior accuracy in monitoring charge voltage

(critical to prevent overcharging in Li-Ion

applications), maximizing charge effectiveness

and battery life.

This application note applies to the following devices:

C8051F300

Introduction

Driven by the need for untethered mobility and

ease of use, many systems rely on rechargable bat-

teries as their primary power source. The battery

charging circuitry for these systems is typically

implemented using a fixed-function IC to control

the charging current/voltage profile.

•

On-chip PWM provides means to implement

buck converter with a very small external

inductor.

On-chip Temp sensor provides an accurate and

stable drive voltage for determining battery

temperature. An external RTD (resistive tem-

perature device) can also be used via the flexi-

ble analog input AMUX.

The C8051F30x family provides a flexible alterna-

tive to fixed-function battery chargers. This appli-

cation note discusses how to use the C8051F30x

family in Li-Ion battery charger applications. The

Li-Ion charging algorithms can be easily adapted to

other battery chemistries, but an understanding of

other battery chemistries is required to ensure

proper charging for those chemistries.

•

A single C8051F30x platform provides full

product range for multi-chemistry chargers,

expediting time to market and reducing inven-

tory.

Figure 1. Lithium Ion Battery Charge Block Diagram.

V Pos (+)

LDO

Buck

Converter

PWM Out

8051F30x

AIN

Resistor

Divider

LED

Li-Ion

Cells

Cygnal

Integrated

Products

8k FLASH, PWM,

Temp Sensor,

Precision Time Base

V Neg (-)

Sense Resistor

Rev. 1.2 12/03

AN137-DS12

AN137

batteries use a rate of change in voltage or tempera-

ture to determine when to terminate.

Charging Basics

Batteries are exhaustively characterized to deter-

mine safe yet time-efficient charging profiles. The

optimum charging method for a battery is depen-

dent on the battery’s chemistry (Li-Ion, NiMH,

NiCd, SLA, etc.). However, most charging strate-

gies implement a 3-phase scheme:

Note that while charging a battery, most of the elec-

trical energy is stored in a chemical process, but not

all as no system is 100 percent efficient. Some of

the electrical energy is converter to thermal energy,

heating up the battery. This is fine until the battery

reaches full charge at which time all the electrical

energy is converted to thermal energy. In this case,

if charging isn’t terminated, the battery can be

damaged or destroyed. Fast chargers (chargers that

charge batteries fully in less than a couple hours)

compound this issue, as these chargers use a high

charge current to minimize charge time. As one can

see, monitoring a battery’s temperature is critical

(especially for Li-Ion as they explode if over-

charged). Therefore, the temperature is monitored

during all phases. Charge is terminated immedi-

ately if the temperature rises out of range.

1. Low-current conditioning phase

2. Constant-current phase

3. Constant-voltage phase/charge termination

All batteries are charged by transferring electrical

energy into them (refer to the references at the end

of this note for a battery primer). The maximum

charge current for a battery is dependent on the bat-

tery’s rated capacity (C). For example, a battery

with a cell capacity of 1000mAh is referred to as

being charged at 1C (1 times the battery capacity) if

the charge current is 1000mA. A battery can be

charged at 1/50C (20 mA) or lower if desired.

However, this is a common trickle-charge rate and

is not practical in fast charge schemes where short

charge-time is desired.

Li-Ion Battery Charger -

Hardware

Currently, Li-Ion batteries are the battery chemistry

of choice for most applications due to their high

energy/space and energy/weight characteristics

when compared to other chemistries. Most modern

Li-Ion chargers use the tapered charge termination,

minimum current (see Figure 2), method to ensure

the battery is fully charged as does the example

code provided at the end of this note.

Most modern chargers utilize both trickle-charge

and rated charge (also referred to as bulk charge)

while charging a battery. The trickle-charge current

is usually used in the initial phases of charging to

minimize early self heating which can lead to pre-

mature charge termination. The bulk charge is usu-

ally used in the middle phase where the most of the

battery’s energy is restored.

Buck Converter

The most economical way to create a tapered ter-

mination charger is to use a buck converter. A buck

converter is a switching regulator that uses an

inductor and/or a transformer (if isolation is

desired), as an energy storage element to transfer

energy from the input to the output in discrete

packets (for our example we use an inductor; the

capacitor in Figure 3 is used for ripple reduction).

Feedback circuitry regulates the energy transfer via

the transistor, also referred to as the pass switch, to

maintain a constant voltage or constant current

During the final phase of battery charge, which

generally takes the majority of the charge time,

either the current or voltage or a combination of

both are monitored to determine when charging is

complete. Again, the termination scheme depends

on the battery’s chemistry. For instance, most Lith-

ium Ion battery chargers hold the battery voltage

constant, and monitor for minimum current. NiCd

2

Rev. 1.2

AN137

Figure 2. Lithium Ion Charge Profile.

Charge Voltage

Charge Current

Conditioning

Phase

Current regulation

Voltage regulation

Time

within the load limits of the circuit. See Figure 3 voltage decreases and vice versa. Therefore, con-

for details.

trolling the duty cycles allows one to regulate the

voltage or the current to within desired limits.

Tapered Charger Using the F30x

Figure 3 illustrates an example buck converter

Selecting the Buck Converter Inductor

using the ‘F30x. The pass switch is controlled via To size the inductor in the buck converter, one first

the on-chip 8-bit PWM (Pulse Width Modulator) assumes a 50 percent duty cycle, as this is where

output of the PCA. When the switch is on, current the converter operates most efficiently.

will flow like in Figure 3A. The capacitor is

charged from the input through the inductor. The Duty cycle is given by Equation 1, where T is the

inductor is also charged. When the switch is period of the PWM (in our example T = 10.5µS).

opened (Figure 3B), the inductor will try to main-

ton

tain its current flow by inducing a voltage as the

current through an inductor can’t change instanta-

neously. The current then flows through the diode

and the inductor charges the capacitor. Then the

cycle repeats itself. On a larger scale, if the duty

cycle is decreased (shorter “on” time), the average

DutyCycle = --------

T

Equation 1. Duty Cycle.

Figure 3. Buck Converter.

(A)

(B)

Inductor

Pass Switch On

Pass Switch Off

Shottky

Diode

Power

Source

Power

Shottky

Diode

Capacitor

Battery

Source

Rev. 1.2

3

AN137

With this established, select a PWM switching fre- To ensure accurate voltage and current measure-

quency. As Equation 2

ments, the algorithms use a two-point system cali-

bration scheme. In this scheme, the user is expected

to apply two known voltages and two known cur-

rents, preferable, one point near ground and the

other point near full-scale. The algorithm then

takes these two points, calculates a slope and an

offset for both the current and voltage channels,

and stores the results in FLASH. All future conver-

sions are scaled relative to these slope and offset

calculations. Note that if an external amplifier is

used for the current channel, it will need to be cali-

brated with a similar two-point calibration scheme

to ensure maximum accuracy.

(Vi – Vsat – Vo)ton

L = ----------------------------------------------------

2Iomax

Equation 2. Inductor Size.

shows, the larger the PWM switching frequency,

the smaller (and more cost effective) the inductor.

Our example code configures the ‘F30x’s 8-bit

hardware PWM to use the internal master clock of

24.5MHz divided by 256 to generate a 95.7kHz

switch rate.

Temperature

Now we can calculate the inductor’s size. Assum-

ing V , the charging voltage, is 15V, V , the satu-

i

sat

To monitor the temperature, the algorithms use the

on-chip temperature sensor. The sensor is left

uncalibrated, but still provides a sufficiently accu-

rate temperature measurement. For more accurate

temperature measurement, one or two-point tem-

perature calibration is required.

ration voltage, is 0.5V, the desired output voltage,

V is 4.2V, and I

, the maximum output cur-

0MAX

o,

rent, is 1500 mA, the inductor should be at least

18µH.

Note that the capacitor in this circuit is simply a

ripple reducer. The larger it is the better as ripple is

inversely proportional to the size of the cap. For

more details on buck converters, refer to the refer-

ences listed at the end of this note.

An external temperature sensor can be used if

desired. The AMUX can to be reconfigured to

accommodate this additional input voltage.

Current

Li-Ion Battery Charger -

Software

The charge-current to the battery cells is monitored

by taking a differential voltage reading across a

The software example that follows demonstrates a small but accurate sense resistor. The current is

Li-Ion battery charger using the C8051F300. The amplified through the on-chip PGA, digitized by

F300 is designed for high-level languages like “C” the on-chip 8-bit ADC, and scaled accordingly via

and includes an 8-bit 8051 based micro-controller, the slope and offset calibration coefficients. An

an 8-bit 500 ksps ADC, 8k FLASH, an 8-bit and external gain stage may be necessary if more reso-

16-bit PWM, and a 2% accurate oscillator all on- lution is desired for the current measurement.

chip. The algorithms discussed are written entirely

in “C” making them easily portable. Refer to the Voltage

F300’s datasheet for a full description of the

device.

The battery’s voltages are divided down and moni-

tored via external resistors. Note that this example

uses the supply voltage as the ADC voltage refer-

ence. Any monitored voltage above the reference

voltage must be divided down for accurate moni-

Calibration

4

Rev. 1.2

AN137

toring. If a more accurate reference is required, an battery’s current condition and starts charging from

external voltage reference can be used. Adjustment that point.

to the divide resistors must be made accordingly.

Conclusion

Charging - Phase1

The C8051F300’s high level of analog integration,

small form-factor, integrated FLASH memory, and

In phase 1, (for description purposes, we assume

low power consumption makes it ideal for flexible

the battery is initially discharged), the ‘F30x regu-

next generation battery charging applications. This

lates the battery’s current to I

(typi-

LOWCURRENT

application note discussed how to use the

C8051F30x family in Lithium Ion battery charger

applications. Example code is provided as well.

cally 1/50 C) until the battery’s voltage reaches

V

. Note that the battery’s charge cur-

MINVOLTBULK

rent is current limited to I

to ensure

LOWCURRENT

safe initial charge and to minimize battery self-

heating. If at any time the temperature increases out

of limit, charging is halted.

References

Maxim Integrated Product, “DC-DC Converter

Tutorial”.

Charging - Phase 2

Martinez, Carlos and Drori, Yossi and Ciancio,

Joe, “AN126 Smart Battery Primer”, Xicor, Octo-

ber 1999.

Once the battery reaches V

the

MINVOLTBULK

charger enters phase 2, where the battery’s algo-

rithm controls the PWM pass switch to ensure the

output voltage provides a constant charge-current

I

to the battery (rate or bulk current is usually

BULK

1C and is definable in the header file as is

I

and V ).

LOWCURRENT

MINVOLTBULK

Charging - Phase 3

After the battery reaches V

(typically 4.2 V in

Top

single cell charger), the charger algorithm enters

phase 3, where the PWM feeds back and regulates

the battery’s voltage. In phase 3, the battery contin-

ues to charge until the battery’s charge current

reaches I

, after which, the battery is

MINIBULKl

charged for an additional 30 minutes and then

charge terminates. Phase 3 typically takes the

majority of the charging time.

Note that in most practical applications, such as a

portable PC, the batteries may be in any of the three

phases when charging is activated. This doesn’t

really affect the charger as it simply monitor’s the

Rev. 1.2

5

AN137

Appendix

Figure 4. 1 Cell Battery Charger Schematic.

6

Rev. 1.2

AN137

Figure 5. 1 Cell Buck Converter Schematic.

Rev. 1.2

7

AN137

Figure 6. main() Flow Chart.

main()

Config_F300()

CalibrateADCfor

Measurement()

Enable Interrupts

Infinite

Loop

Yes/No

Clear Termination Flags

Clear Charge Status Flags

No

SW0

Pressed?

?

Yes

No

Error

Detected

?

No

Status = BULK

?

Error

Detected

?

Yes

Turn on LED0

Turn off LED0, Error

BULK_charge()

Infinite Loop

Yes/No

No

Status =

LOWCURRENT

?

Yes

LOWCURRENT_charge()

8

Rev. 1.2

AN137

Figure 7. CalibrateADCforMeasurement() Flow Chart.

CalibrateADCforMearurement()

SW0

No

Pushed

?

Yes

SW0

Pushed

?

Setup ADC0's AMUX,

Throughput, Gain, for near

zero-scale voltage cal point

Yes

Setup ADC0's AMUX,

Throughput, Gain, for near

zero-scale Current cal point

Acquire 16-bit

Measurement

Setup ADC0's AMUX,

Throughput, Gain, for near

full-scale voltage cal point

Acquire 16-bit

Measurement

Setup ADC0's AMUX,

Throughput, Gain, for near

full-scale Current cal point

Acquire16-bit

Measurement

Calculate Voltage Slope

Coefficient

Acquire16-bit

Measurement

Calculate Voltage Offset

Coefficient

Calculate Current Slope

Coefficient

Erase Memory Page

0x1A00

Calculate Current Offset

Coefficient

Store Voltage Offset and

Slope Coefficients in

FLASH Memory

Store Current Offset and

Slope Coefficients in

FLASH Memory

END

Rev. 1.2

9

AN137

Figure 8. Monitor_Battery() Flow Chart.

Monitor_Battery()

Measurement

Type

?

Temperature

Stop PWM

Current

Charge Voltage

AMUX = Volt

Battery Voltage

Stop PWM

AMUX = Current

AMUX = Temperature

AMUX = Volt

AV = 0

I = 0

No

I≤10

?

Voltage w/ or w/out PWM

Current

Temperature

Calculate Voltage w/

Calculate Current w/

Calibration Coefficients

Calculate Temperature w/

Calibration Coefficients

Yes

Calibration Coefficients

Start ADC0

No

ADC0 Done?

Yes

AV = AV + ADC0

Turn PWM on

Return Desired Parameter

END

AV = AV/10

10

Rev. 1.2

AN137

Figure 9. Bulk_Charge() Flow Chart (Part 1).

Bulk_Charge()

Start PWM w/ Zero Output

Status = const_C

T

No

Within Limits

?

Yes

V

<max_V &

> min_Bulk

?

Yes

Set Appropriate Flags

Calculate bulk_finish_time

Green LED On

Status =

BULK & No

Error?

No

Yes

Status =

const_c

?

Yes

Regulate Battery Current

Read Charge Voltage

Charge

Yes

Voltage Within

Limits

?

Change Status from

const_C to const_V

No

B

C

A

D

Rev. 1.2

11

AN137

Figure 10. BULKCurrent() Flow Chart (Part 2).

B

C

A

D

No

Status =

const_V

?

Yes

Regulate Voltage()

Time

Overflow

?

Yes

Stop PWM

& Flag Error

No

Yes

Temp.

Overflow

?

Stop PWM

No

& Flag Error

No

60 Sec.

Over

?

Yes

const_V,

NOT Delay & Current

Below Threshold

?

No

Yes

Calculate bulk_finish_time

Status = Delay

Delay

No

Time

Over

?

Yes

Stop PWM

Status = const_C

Status = LOWCURRENT

Green LED Off

END

12

Rev. 1.2

AN137

Figure 11. LowCurrent_Charge() Flow Chart.

LOWCURRENT_charge()

No

V

<BulkThreshold

?

ResetTimeBase()

Yes

Prepare Flags to enter

Bulk Mode

Calculate Finish_time

No

Charge

Voltage

Within Limits

?

No ERROR &

LOWCURRENT =1

?

Yes

Change Status

from const_C to

const_V

Yes

No

Temp

within Limits

?

Regulate Current

Yes

No

V

<max_V

?

Status = const_V

Yes

Green LED Blinking

Regulate Voltage

Status = Delay

Lowcurrent

Finish Time

reached?

Yes

Green LED Off

END

Stop PWM

No

and flag error

Rev. 1.2

13

AN137

Figure 12. Turn_PWM_Off() Flow Chart.

Turn_PWM_Off()

CEX0

Counter

<0x0F?

No

Yes

Increment CEX0

Counter

CEX0

Counter

<0x0F?

Yes

No

Disable PWM Mode

END

14

Rev. 1.2

AN137

Figure 13. Measure() Flow Chart.

measure()

Set accumulator and

counter i variables to zero

Clear End of Conversion

Flag

Start New Conversion

Conversion

Complete

?

No

Yes

accumulator =

accumulator + ADC0

Increment i

No

i = 0

?

Yes

Return 16-bit

Measurement

END

Rev. 1.2

15

AN137

Figure 14. Regulate_Voltage() Flow Chart.

Regulate_Voltage()

Measure Battery's

voltage

Voltage <

VOLT_BULK &

PCA not max

?

No

Yes

No

Voltage >

VOLT_BULK &

PCA not 0

Make Duty Cycle Larger

Yes

Make Duty Cycle Smaller

Voltage

< VOLT_BULK + Tolerence

& > VOLT_BULK

?

No

Yes

END

16

Rev. 1.2

AN137

Figure 15. Regulate_Current() Flow Chart.

Regulate_Current()

Measure Current

Current <

No

passed current &

PCA not max

?

Yes

No

Current >

passed current &

PCA not 0

Make Duty Cycle Larger

Yes

Make Duty Cycle Smaller

No

Current =

passed value

?

Yes

Monitor Voltage

w/ PWM off

No

Voltage <

VOLT_LOWCURRENT

± Tolerence

?

Yes

CHARGE_STATUS =

const_V

END

Rev. 1.2

17

AN137

Figure 16. PCA_OVERFLOW_ISR() Flow Chart.

PCA_OVERFLOW_ISR()

Reset PCA Counter and

PCA Interrupts

Decrement time.count

No

0 = time.count

Yes

Reset time.count to

overflow value

Increment time.sec

No

60 = time.sec

?

Yes

Reset time.sec

Increment time.min

LOW

CURRENT

charge &

no errors

?

No

60 = time.min

?

Yes

Increment time.hour

Yes

odd

second

?

No

Reset time.min

24 = time.hour

Yes

No

Turn on LED

Yes

Turn Off LED

Reset time.hour

END

18

Rev. 1.2

AN137

//-----------------------------------------------------------------------------

//

// Filename:

LIION_BC_MAIN.h

// Target Device: 8051F300

// Created:

// Created By:

11 SEP 2002

DKC

// Tool chain: KEIL Eval C51

//

// This header file is used to define all preprocessor directives, prototypes,

// and global variable for LIION_BC_MAIN.c.

//

// The user should modify this header file before proceeding as key

//

battery parameter limits are set here.

//-----------------------------------------------------------------------------

// Function Prototypes

//-----------------------------------------------------------------------------

void Config_F300(void);

void Reset_Time_Base(void);

void CalibrateADCforMeasurement(void);

void Regulate_Current(int);

void Regulate_Voltage(void);

void Turn_PWM_Off(void);

int Monitor_Battery(unsigned char);

void Bulk_Charge(void);

void Lowcurrent_Charge(void);

unsigned int Measure(void);

void Delay_Loop(void);

//-----------------------------------------------------------------------------

// UNIONs, STRUCTUREs, and ENUMs

//-----------------------------------------------------------------------------

typedef union LONG {

long l;

// byte-addressable LONG

unsigned char b[4];

} LONG;

typedef union INT {

int i;

// byte-addressable INT

unsigned char b[2];

} INT;

typedef struct

{

unsigned long int t_count;

int sec;

int min;

// global seconds

// global minutes

// global hour

int hour;

}time_struct;

//-----------------------------------------------------------------------------

// Global Variable Definitions

Rev. 1.2

19

AN137

//-----------------------------------------------------------------------------

time_struct TIME;

// Global Struct to Track Time

// Global Variable to Track Termination

// Global Variable to Track Charging

// 0x0A0A Default value, for later use

// Volt Slope Register

char bdata TERMINATION;

char bdata CHARGE_STATUS;

INT code CHECK_BYTE

LONG code VOLT_SLOPE

LONG code VOLT_OFFSET

_at_ 0x1A00;

_at_ 0x1A60;

_at_ 0x1A64;

// Volt Offset Register

LONG code I_NOAMP_SLOPE _at_ 0x1A70;

LONG code I_NOAMP_OFFSET _at_ 0x1A74;

LONG temp_LONG_1,temp_LONG_2;

// Current Slope Register,ext. amp off

// Current Offset Register,ext. amp.off

// Temporary Storage Variables

INT temp_INT_1,temp_INT_2;

//-----------------------------------------------------------------------------

// Bit maskable CHARGE STATUS Register Definition

//-----------------------------------------------------------------------------

sbit BULK

= CHARGE_STATUS^0;

// bit 0 : BULK charge status bit

sbit LOWCURRENT = CHARGE_STATUS^1;

// bit 1 : LOWCURRENT charge status bit

// bit 2 : ERROR before/during charging

// bit 3 : charged w/ constant VOLTAGE

// bit 4 : charged w/ constant CURRENT

// bit 5 : BULK charge DELAY for LiIon

sbit ERROR

sbit CONST_V

sbit CONST_C

sbit DELAY

= CHARGE_STATUS^2;

= CHARGE_STATUS^3;

= CHARGE_STATUS^4;

= CHARGE_STATUS^5;

//

// bit 6 : Lowcurrent charge is

// terminated; battery is charged

// bit 7 : Not Currently used

after CURRENT threshold detection

sbit READY

sbit FREE1

= CHARGE_STATUS^6;

= CHARGE_STATUS^7;

//-----------------------------------------------------------------------------

// Bit Maskable TERMINATION Register Definition

//-----------------------------------------------------------------------------

sbit TEMP_MIN = TERMINATION^0;

sbit TEMP_MAX = TERMINATION^1;

// bit 0 : minimum TEMPERATURE overflow

// bit 1 : maximum TEMPERATURE overflow

// bit 2 : minimum CURRENT overflow

// bit 3 : maximum CURRENT overflow

// bit 4 : maximum time overflow

// bit 5 : maximum VOLTAGE overflow

// bit 6 : minimum VOLTAGE overflow

// bit 7 : Not Currently used

sbit I_MIN

sbit I_MAX

= TERMINATION^2;

= TERMINATION^3;

sbit TIME_MAX = TERMINATION^4;

sbit VOLT_MAX = TERMINATION^5;

sbit VOLT_MIN = TERMINATION^6;

sbit FREE2

= TERMINATION^7;

//-----------------------------------------------------------------------------

// Bit maskable PORT Definitions

//-----------------------------------------------------------------------------

sbit SDA

sbit SCL

sbit CEX0

sbit LED0

sbit SW0

= P0 ^ 0;

= P0 ^ 1;

= P0 ^ 2;

= P0 ^ 3;

= P0 ^ 7;

// bit 0 : SDA In/Output, Pin P0.

// bit 1 : SCL Output, Pin P1.

// bit 2 : PWM Output, Pin P2.

// bit 3 : LED0, Pin P0.3

// bit 7 : Switch0, Pin P0.7

// AMUX Selections; Analog Inputs

#define TBAT

#define IBAT

#define VBAT

0xF8;

0x65;

0xF6;

// bit 4 : Temp.

// bit 5 : Current Ch.; Analog In

// bit 6 : Voltage Ch.; Analog In

Ch.; Analog In

//-----------------------------------------------------------------------------

// 8051F300 PARAMETERS

//-----------------------------------------------------------------------------

#define SYSCLK

24500000

// System clock frequency

20

Rev. 1.2

AN137

#define TEMP_SENSOR_GAIN

#define TEMP_GAIN

#define CURRENT_GAIN

#define VREF

#define SCRATCH_PAGE

#define PWM_CLOCK

3300

2

4

3200

0x1C00

SYSCLK/255

// Temp Sensor Gain in (uV / degC)

// PGA gain setting

// ADC Voltage Reference (mV)

// FLASH page used for temp storage

// PWM frequency is 96 kHz

//-----------------------------------------------------------------------------

// Calibration/Calculation PARAMETERS

//-----------------------------------------------------------------------------

#define V1_CAL

#define V2_CAL

#define I1_CAL

#define I2_CAL

#define RSENSE

#define RESB

67

2800

67

133

1

20

// 1st cal point for 2 point cal.

// 2nd cal point for 2 point cal.

// 1st cal point for 2 point cal.

// 2nd cal point for 2 point cal.

// RSENSE is assumed to be 1/2 ohm

// 10k Ohms, Voltage Divide Resistor

// 20k Ohms, Voltage Divide Resistor

#define RESAB

30

#define TEMP_SLOPE ((long) TEMP_GAIN * TEMP_SENSOR_GAIN * 65536 / 100 / VREF)

// An estimate of the Temperature<SLOPE>

// in [tenth codes / K]

// The temperature measurement is

// within 3 degrees of accuracy.

//-----------------------------------------------------------------------------

// Monitor_Battyer Switch PARAMETERS

//-----------------------------------------------------------------------------

#define TEMPERATURE

#define VOLTAGE

#define VOLTAGE_PWM_OFF

#define CURRENT

7

5

3

1

// Value for Switch Statement

//-----------------------------------------------------------------------------

// Battery/Pack Parameters

//-----------------------------------------------------------------------------

#define CELLS

1

150

4200

// Number of cells in the battery pack

// mAh, Battery Capacity (LiIon)

// mV, Nominal Charge Voltage

#define CAPACITY

#define LiIon_CELL_VOLT

#define I_BULK

(unsigned int)(CAPACITY)

#define I_LOWCURRENT

#define VOLT_BULK

(unsigned int)(CAPACITY/4)

(unsigned int)(LiIon_CELL_VOLT)

#define VOLT_LOWCURRENT

#define VOLT_TOLERANCE

(unsigned int)(LiIon_CELL_VOLT)

(unsigned int)(LiIon_CELL_VOLT/100)// 1 Percent Acc

#define CURRENT_TOLERENCE (unsigned int)(CAPACITY/10)

// 10 Percent Acc

//-----------------------------------------------------------------------------

// Battery Characteristics: Charge TERMINATION Limits

//-----------------------------------------------------------------------------

#define MIN_TEMP_ABS

#define MAX_TEMP_ABS

26300

32300

// Abs. min. TEMPERATURE = -10 C, 263K

// Abs. max. TEMPERATURE = 50C, 323K:

Rev. 1.2

21

AN137

#define MIN_VOLT_BULK

#define MAX_VOLT_ABS

#define MIN_I_BULK

3000

// Minimum BULK Voltage

(unsigned int)(CELLS * LiIon_CELL_VOLT)

(unsigned int)(CAPACITY/4)

#define MAX_TIME_LOWCURRENT 30

// Max Lowcurrent Charge Time = 90min

// Maximum BULK Charge Time = 90 min

#define MAX_TIME_BULK

#define BULK_TIME_DELAY

// END OF FILE

90

//

at 1C CURRENT

30

// DELAY = 30min after “MIN_I_BULK”

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//-----------------------------------------------------------------------------

//

// Filename:

LIION_BC_MAIN.c

// Target Device: 8051F300

// Created:

// Created By:

// Tool chain:

//

11 SEP 2002

DKC

KEIL Eval C51

// This is a stand alone battery charger for a Lithium ION battery.

// It utilizes a buck converter, controlled by the on-chip 8-bit PWM,

// to provide constant current followed by constant voltage battery charge.

//

//-----------------------------------------------------------------------------

// Includes

//-----------------------------------------------------------------------------

#include <c8051f300.h>

#include “LIION_BC_MAIN.h”

// Battery Hearder File

//-----------------------------------------------------------------------------

// Functions

//-----------------------------------------------------------------------------

void Config_F300(void)

{ RSTSRC

XBR0

= 0x02;

= 0x70;

= 0x44;

= 0x40;

// Enable VDD Monitor

// Skip P0.4,5,6; they’re analog In

// Enable SMBus on P0.0, P0.1, and CEX0

// as PWM at P0.2

XBR1

XBR2

// Enable crossbar and weak pull-ups

P0MDOUT = 0x0C;

// Set P0.2 & P0.3 output to push-pull

// Configure P0.4,5,6 as Analog Inputs

P0MDIN

OSCICN

ADC0CN

= 0x8F;

= 0x07;

= 0xC0;

// Set SYSCLK to 24.5MHz, internal osc.

// Turn on the ADC Module;

//

enable low power mode for settling

REF0CN

= 0x0C;

// Configure ADC’s to use VDD for

//

Voltage Reference,

Enable On-chip Temperature Sensor

//-----------------------------------------------------------------------------

// PCA Configuration

//-----------------------------------------------------------------------------

PCA0MD

= 0x00;

= 0x08;

// Disable WDT

// Set PWM Time base = SYSCLK

PCA0L

PCA0H

= 0x00;

// Initialize PCA Counter to Zero

PCA0CN

= 0x40;

// Enable PCA Counter

// Clear PCA Counter Overflow flag

//Module 0

PCA0CPM0 = 0x00;

PCA0CPL0 = 0xF0;

PCA0CPH0 = 0xF0;

// Configure CCM0 to 8-bit PWM mode

// Initialize PCA PWM to small duty cycle

// 0xF0 Ensures a Soft Initial Charge

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AN137

//Module 1

PCA0CPM1 = 0x49;

PCA0CPL1 = 0xFF;

// Configure Module 1 as software timer

// Initialize to 255 so that Interrupt

//

is generated when PCA ends

// 8-bit PWM Cycle

PCA0CPH1 = 0x00;

// PCA0CPH is the high byte of the

//

Output Compare Module

EIE1

= 0x08;

// Enable PCA Overflow Interrupt

}

//-----------------------------------------------------------------------------

// Reset_Time_Base - Resets all Time Counting Values

//-----------------------------------------------------------------------------

void Reset_Time_Base()

{

TIME.sec

TIME.min

TIME.hour

= 0x00;

TIME.t_count = PWM_CLOCK;

}

//-----------------------------------------------------------------------------

// Delay - This is a Delay to permit time for Switches to Debounce

//-----------------------------------------------------------------------------

void Delay_Loop (void)

{

long i=0;

for (i=0;i<100000;i++);

}

//-----------------------------------------------------------------------------

// Initialize CalibrateADCforVoltageMeasurement

//-----------------------------------------------------------------------------

// This function calibrates the voltage channel and stores the calibration

// coefficients in the parameters volt_slope and volt_offset.

//

void CalibrateADCforMeasurement()

// This calibration routine uses a 2 point cal.

{ unsigned char xdata *pwrite;

EA = 0;

// FLASH write pointer

// Disable All Interrupts

// Wait until 1st calibration voltage is ready for cal

while (SW0 == 1);

Delay_Loop();

// Wait until SW0 pushed

// Wait for Switch Bounce

// Once ready, Get the first calibration voltage

AMX0SL = VBAT;

// Select appropriate input for AMUX

ADC0CF = (SYSCLK/5000000) << 3;

ADC0CF &=0xF8;

ADC0CF |= 0x01;

// ADC conversion clock = 5.0MHz

// Clear any Previous Gain Settings

// PGA gain = 1

temp_INT_1.i = Measure();

// Wait until 2nd calibration voltage is ready for cal

while (SW0 == 1);

Delay_Loop();

// Wait until SW0 pushed

// Wait for Switch Bounce

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// Once ready, Get the 2nd calibration voltage

AMX0SL = VBAT;

//

Change Mux for second point

temp_INT_2.i = Measure();

// Calculate the SLOPE

// V1 and V2 are in tenth of a degree

temp_LONG_1.l = (unsigned)(temp_INT_2.i-temp_INT_1.i);

temp_LONG_1.l *= (unsigned)100;

// Account for Math Truncation Error

temp_LONG_1.l /= (unsigned)(V2_CAL - V1_CAL);

// Calculate the OFFSET

temp_LONG_2.l = (unsigned)temp_INT_1.i;

temp_LONG_2.l -= (signed)(temp_LONG_1.l * V1_CAL/100);

temp_LONG_1.l = 2050;

temp_LONG_2.l = 0;

// If no cal. use these

// as default values

// Erased memory at page 0x1A00

pwrite = (char xdata *)&(CHECK_BYTE.b[0]);

PSCTL = 0x03;

// MOVX writes target FLASH memory;

// FLASH erase operations enabled

FLKEY = 0xA5;

FLKEY = 0xF1;

*pwrite = 0x00;

// FLASH key sequence #1

// FLASH key sequence #2

// initiate PAGE erase

// Write the Volt SLOPE and OFFSET to Flash

PSCTL = 1;

// MOVX writes to Flash

pwrite = (char xdata *)&(VOLT_SLOPE.b[0]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[0];

pwrite = (char xdata *)&(VOLT_SLOPE.b[1]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[1];

pwrite = (char xdata *)&(VOLT_SLOPE.b[2]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[2];

pwrite = (char xdata *)&(VOLT_SLOPE.b[3]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[3];

pwrite = (char xdata *)&(VOLT_OFFSET.b[0]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[0];

pwrite = (char xdata *)&(VOLT_OFFSET.b[1]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[1];

pwrite = (char xdata *)&(VOLT_OFFSET.b[2]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[2];

Rev. 1.2

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AN137

pwrite = (char xdata *)&(VOLT_OFFSET.b[3]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[3];

PSCTL = 0;

// MOVX writes target XRAM

//-----------------------------------------------------------------------------

// Initialize CalibrateADCforCurrentMeasurement_NOAMP

//-----------------------------------------------------------------------------

// This function calibrates the current channel with no external amp

// and stores the calibration coefficients in the

// parameters i_noamp_slope and i_noamp__offset.

//

// This calibration routine uses a 2 point cal.

// Wait until calibration voltage is ready for cal

while (SW0 == 1);

Delay_Loop();

// Wait until SW0 pushed

// Wait for Switch Bounce

// Once ready, Get the first calibration voltage

AMX0SL = IBAT;

// Select appropriate input for AMUX

ADC0CF = (SYSCLK/5000000) << 3;

ADC0CF &=0xF8;

ADC0CF |= 0x03;

// ADC conversion clock = 5.0MHz

// Clear any Previous Gain Settings

// Set PGA gain = 4

temp_INT_1.i = Measure();

temp_INT_1.i *= 2;

// Acquire 16-bit Conversion

// Account for Differential Mode

// Wait until 2nd calibration voltage is ready for cal

while (SW0 == 1);

Delay_Loop();

// Wait until SW0 pushed

// Wait for Switch Bounce

// Once ready, Get the 2nd calibration voltage

temp_INT_2.i = Measure();

temp_INT_2.i *=2;

// Acquire 16-bit Conversion

// Account for Differential Mode

// Calculate the SLOPE

temp_LONG_1.l = (unsigned)(temp_INT_2.i - temp_INT_1.i);

temp_LONG_1.l *= (unsigned)100;

// Account for Math Truncation Error

temp_LONG_1.l /= (unsigned)(I2_CAL - I1_CAL);

temp_LONG_1.l /= (unsigned)CURRENT_GAIN;// Account for Gain

// Calculate the OFFSET

temp_LONG_2.l = (signed)(temp_INT_1.i/CURRENT_GAIN);

temp_LONG_2.l -= (signed)(temp_LONG_1.l * V1_CAL/100);

temp_LONG_1.l = 2050;

temp_LONG_2.l = 0;

// If no cal. use these

// as default values

// Memory at 0x1A00 is already erased

// Write the Volt SLOPE and OFFSET to Flash

PSCTL = 1;

// MOVX writes to Flash

pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[0]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[0];

pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[1]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[1];

pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[2]);

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Rev. 1.2

AN137

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[2];

pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[3]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_1.b[3];

pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[0]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[0];

pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[1]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[1];

pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[2]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[2];

pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[3]);

FLKEY = 0xA5;

FLKEY = 0xF1;

// enable flash write

*pwrite = temp_LONG_2.b[3];

PSCTL = 0;

// MOVX writes target XRAM

}

//-----------------------------------------------------------------------------

// Measure

//-----------------------------------------------------------------------------

//

// This routine averages 65536 ADC samples and returns a 16-bit unsigned

// result.

//

unsigned int Measure (void)

{

unsigned i;

// sample counter

unsigned long accumulator=0L;

// here’s where we integrate the

// ADC samples

// read the ADC value and add to running total

i = 0;

do {

AD0INT = 0;

// clear end-of-conversion indicator

AD0BUSY = 1;

// initiate conversion

while(!AD0INT);

accumulator += ADC0;

i++;

// wait for conversion to complete

// read adc value and accumulate

// update counter

} while (i != 0x0000);

// the accumulator now contains 16 added bits of which 8 are usable

return (unsigned int) (accumulator >> 8);

}

//-----------------------------------------------------------------------------

// Regulate_Current

//-----------------------------------------------------------------------------

// This routine monitors the battery’s current and adjusts

// the PWM (i.e. duty cycle) to keep the current at a known value

Rev. 1.2

27

AN137

//

void Regulate_Current(int passed_current)

{ unsigned int temp = 0;

do{

temp = Monitor_Battery(CURRENT);

// Measure Current

if (temp < passed_current)

PCA0CPH0--;

if (temp > passed_current)

PCA0CPH0++;

}while ((temp < (passed_current - CURRENT_TOLERENCE)) ||

(temp > (passed_current + CURRENT_TOLERENCE)));

// I_BULK or I_LOWCURRENT is set now

temp = Monitor_Battery(VOLTAGE_PWM_OFF);

// If VOLTAGE within range,

// change from constant CURRENT charge

// mode to constant VOLTAGE charge mode

if ((temp >= (VOLT_LOWCURRENT - VOLT_TOLERANCE)) &&

(temp <= (VOLT_LOWCURRENT + VOLT_TOLERANCE)))

{

CONST_C = 0;

CONST_V = 1;

}

//-----------------------------------------------------------------------------

// Regulate_Voltage

//-----------------------------------------------------------------------------

// This routine monitors the battery’s voltage and adjusts

// the PWM (i.e. duty cycle) to keep the voltage at a known value

//

void Regulate_Voltage(void)

{ unsigned int temp = 0;

// set VOLT_BULK (with “soft start”)

do{

temp = Monitor_Battery(VOLTAGE);

if (temp < VOLT_BULK)

PCA0CPH0--;

if (temp > VOLT_BULK)

PCA0CPH0++;

}while ((temp < (VOLT_BULK - VOLT_TOLERANCE)) ||

(temp > (VOLT_BULK + VOLT_TOLERANCE)));

// VOLTAGE is set now

}

//-----------------------------------------------------------------------------

// Turn_PWM_Off

//-----------------------------------------------------------------------------

// This routine peforms a soft charge turn off by taking the PWM’s

// duty cycle slowly to zero.

//

void Turn_PWM_Off(void)

{

28

Rev. 1.2

AN137

do{

if (PCA0CPH0 < 0xF0)

PCA0CPH0++;

}while (PCA0CPH0 < 0xF0);

// Duty Cycle is now small and safe to turn off.

PCA0CPM0 = 0x00;

// Disable PWM

}

//-----------------------------------------------------------------------------

// Monitor_Battery

//-----------------------------------------------------------------------------

// This routine acts as a switch when gathering different conversion types.

// It adjusts the throughput, adjust the AMUX and returns the current in mA,

// voltage in mV, and temperature in C, 2% accurate.

//

int Monitor_Battery(unsigned char value)

{

char i;

unsigned long av =0;

long signed result;

ADC0CF = (SYSCLK/5000000) << 3;

ADC0CF &= 0xF8;

// ADC conversion clock = 5.0MHz

// Clear any Previous Gain Settings

switch (value)

{

case TEMPERATURE:

Turn_PWM_Off();

AMX0SL = TBAT;

ADC0CF |= 0x02;

break;

// Turn PWM Off

// Select appropriate input for AMUX

// Set PGA gain = 2

case VOLTAGE:

AMX0SL = VBAT;

ADC0CF |= 0x01;

break;

// Select appropriate input for AMUX

// Set PGA gain = 1

case VOLTAGE_PWM_OFF:

Turn_PWM_Off();

AMX0SL = VBAT;

ADC0CF |= 0x01;

break;

// Turn PWM Off

// Select appropriate input for AMUX

// Set PGA gain = 1

case CURRENT:

AMX0SL = IBAT;

ADC0CF |= 0x03;

break;

// Select appropriate input for AMUX

// Set PGA gain = 4

}

//Compute average of next 10 A/D conversions

for(av=0,i=10;i;--i){

AD0INT = 0;

// clear end-of-conversion indicator

AD0BUSY = 1;

while(!AD0INT);

av = av+ADC0;

// initiate conversion

// wait for conversion to complete

}

Rev. 1.2

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AN137

av = av/10;

av = av<<8;

// Compute the average

// Convert to 16-bit conversion

// ...to account for 16-bit cal.

//

coefficients

PCA0CPM0 = 0x42;

// Turn on PWM

switch (value)

{ case TEMPERATURE:

result = (long) av * 1000/TEMP_SLOPE;

break;

case VOLTAGE:

case VOLTAGE_PWM_OFF:

result = (av - VOLT_OFFSET.l);

result /= VOLT_SLOPE.l;

result *= 100;

result *= RESAB;

result /= RESB;

// Account for System Errors

// Convert to Voltage in Millivolts

// Account for Math Truncation Error

// Account for Divide Resistors

break;

case CURRENT:

result = av*2;

// Account for Differential Mode

// Account for System Errors

// Convert to Milliamps

// Account for Math Truncation Error

// Account for Sense Resistor

// Account for Divide Resistors

result -= I_NOAMP_OFFSET.l;

result /= I_NOAMP_SLOPE.l;

result *= 100;

result /= RSENSE;

result *= RESAB;

result /= RESB;

result /= CURRENT_GAIN;

break;

}

return (int) result;

}

//-----------------------------------------------------------------------------

// Bulk_Charge Function

//-----------------------------------------------------------------------------

void Bulk_Charge(void)

{

unsigned int temp = 0;

unsigned int bulk_finish_hour = 0;

unsigned int bulk_finish_min = 0;

unsigned int delay_hour = 0;

unsigned int delay_min = 0;

unsigned int last_min = 0;

Reset_Time_Base();

// Reset Time Base to zero

// Calculate BULK charge finish time

bulk_finish_min = (TIME.min + MAX_TIME_BULK);

bulk_finish_hour = TIME.hour;

while (bulk_finish_min > 60)

{

bulk_finish_min = bulk_finish_min - 60;

bulk_finish_hour++;

}

30

Rev. 1.2

AN137

CONST_C = 1;

DELAY = 0;

// Start in constant current charge mode

// Reset timer DELAY

temp = Monitor_Battery(TEMPERATURE); // Monitor Temperature

// Is temperature within range?

if ((temp > MIN_TEMP_ABS) && (temp < MAX_TEMP_ABS))

{

temp = Monitor_Battery(VOLTAGE);

// Monitor Voltage

// Is Voltage within range?

if ((temp <= (MAX_VOLT_ABS + VOLT_TOLERANCE)) && temp > MIN_VOLT_BULK)

{

PCA0CPM0 = 0x42;

// Configure CCM0 to 8-bit PWM mode

// Enter main loop in Bulk_Charge()

while ((BULK == 1) && (ERROR == 0))

{

if (CONST_C == 1)

Regulate_Current(I_BULK);

// Charge with Constant Current

// Charge with Constant Voltage

else if (CONST_V == 1)

Regulate_Voltage();

// Now, Check for error and charge termination conditions

// If above max charge time, flag error

// Test for BULK Charge Time Out

// Monitor Time

if ((TIME.hour == bulk_finish_hour) && (TIME.min == bulk_finish_min)

&& (DELAY == 0))

{

Turn_PWM_Off();

TIME_MAX = 1;

// Turn Off PWM

// Set Time max error flag

// Set general error flag

ERROR

= 1;

}

// Monitor Temperature

temp = Monitor_Battery(TEMPERATURE);

if ((temp < MIN_TEMP_ABS) && (temp > MAX_TEMP_ABS))

{

Turn_PWM_Off();

// Turn Off PWM

if (temp < MIN_TEMP_ABS)

TEMP_MIN = 1;

else

// Set Temperature below minimum flag

// Set Temperature exceeds maximum flag

// Set general error flag

TEMP_MAX = 1;

ERROR

= 1;

}

// Minute elapsed?

// Check for minimum current

// if reached, enter last DELAY charge

if (TIME.min != last_min)

{

last_min = TIME.min;

if ((CONST_V == 1) && (DELAY == 0) && (Monitor_Battery(CURRENT)

<= MIN_I_BULK))

Rev. 1.2

31

AN137

{

// Calculate TOP OFF Battery Time finish time

delay_min = (TIME.min + BULK_TIME_DELAY);

delay_hour = TIME.hour;

while (delay_min > 60)

{

delay_min = delay_min - 60;

delay_hour++;

}

DELAY = 1;

// Set Delay Flag

}

// Monitor Delay time, time up?

if ((TIME.hour == delay_hour)&&(TIME.min == delay_min) &&

(DELAY == 1))

{

Turn_PWM_Off();

CONST_V = 0;

CONST_C = 1;

BULK = 0;

// Turn Off PWM

// Exit CONST_V

// Prepare to enter CONST_C

// Prepare to exit BULK mode

// Prepare to enter LOWCURRENT Mode

LOWCURRENT = 1;

}

// End Main While loop

}

else if(ERROR == 0)

{

if (temp > (MAX_VOLT_ABS + VOLT_TOLERANCE))

{ VOLT_MAX = 1; // Set Max Voltage error flag

ERROR = 1;

// Set general error flag

}

else if(temp < MIN_VOLT_BULK)

{ VOLT_MIN = 1;

LOWCURRENT = 1;

BULK = 0;

// Set Minimum bulk voltage error flag

// Switch to LOWCURRENT mode

// Exit Bulk Charge mode

}

// battery’s voltage very low

}

else if(ERROR == 0)

{

// Absolute temperature out of range?

if (temp < MIN_TEMP_ABS)

TEMP_MIN = 1;

else

// Set Temperature below minimum flag

// Set Temperature exceeds maximum flag

// Set general error flag

TEMP_MAX = 1;

ERROR = 1;

}

//-----------------------------------------------------------------------------

// Lowcurrent_Charge

//-----------------------------------------------------------------------------

void Lowcurrent_Charge(void)

{

unsigned int temp = 0;

unsigned int lowcurrent_finish_min = 0;

32

Rev. 1.2

AN137

unsigned int lowcurrent_finish_hour = 0;

Reset_Time_Base(); // Reset Time base to zero

// Calculate LOWCURRENT finish time

lowcurrent_finish_min = (TIME.min + MAX_TIME_LOWCURRENT);

lowcurrent_finish_hour = TIME.hour;

while (lowcurrent_finish_min > 60)

{

lowcurrent_finish_min = lowcurrent_finish_min - 60;

lowcurrent_finish_hour++;

}

// Enter Main Lowcurrent Loop.

// Only exits are upon error and full charge

while ((LOWCURRENT == 1) && (ERROR == 0))

{

temp = Monitor_Battery(TEMPERATURE);// Get Temperature Reading

// Is TEMPERATURE within limits

if ((temp > MIN_TEMP_ABS) && (temp < MAX_TEMP_ABS))

{

// Is Battery’s Charge Voltage below max charge voltage

temp = Monitor_Battery(VOLTAGE); // Get Voltage Reading

if (temp <= (VOLT_LOWCURRENT + VOLT_TOLERANCE))

{

if (CONST_C == 1)

// CONST_C ?, charge w/ constant current

Regulate_Current(I_LOWCURRENT);

if (CONST_V == 1)

// CONST_V?, charge w/ constant voltage

Regulate_Voltage();

if ((temp >= MIN_VOLT_BULK) && (DELAY == 0))// Bulk Threshold voltage met?

{ LOWCURRENT = 0;

// Exit LOWCURRENT mode

BULK = 1;

}

// Switch to Bulk Charge mode

// Check elapsed time

if ((TIME.hour == lowcurrent_finish_hour) &&

( TIME.min == lowcurrent_finish_min))

{

TIME_MAX = 1;

ERROR = 1;

// Set Time MAX error flag

// Set general error flag

}

else if(ERROR == 0)

// Voltage to high?

{

VOLT_MAX = 1;

// Set Max voltage error flag

// Set general error flag

ERROR

= 1;

}

else if(ERROR == 0)

{

// Absolute temperature out of range?

if (temp < MIN_TEMP_ABS)

TEMP_MIN = 1;

else

// Set Temperature below minimum flag

// Set Temperature exceeds maximum flag

// Set general error flag

TEMP_MAX = 1;

ERROR = 1;

}

Rev. 1.2

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AN137

}

//-----------------------------------------------------------------------------

// Main Function

//-----------------------------------------------------------------------------

void main(void)

{

EA = 0;

// Disable All Interrupts

Reset_Time_Base();

Config_F300();

// Config F300

CalibrateADCforMeasurement();

// Calibrate F300

EA = 1;

// Enable All Active Interrupts

// Turn LED0 off

while(1)

{

LED0 = 0;

TERMINATION = 0x00;

CHARGE_STATUS = 0x00;

BULK = 1;

// Reset Termination Flags

// Reset Charge Status Flags

// Start in LOWCURRENT Charge mode

CONST_C = 1;

while (SW0 == 1);

Delay_Loop();

// Wait until SW0 pushed

// Wait for Switch Bounce

while (ERROR == 0)

{

if (BULK == 1)

{

LED0 = 1;

Bulk_Charge();

}

// Turn LED0,indicates Bulk Mode

// Enter Bulk Charge Mode

if (LOWCURRENT == 1)

Lowcurrent_Charge();

// Enter Lowcurrent_Charge function

// Toggle LED0 at 1 Hz rate via ISR

}

if (ERROR == 1)

{

Turn_PWM_Off();;

LED0 = 0;

EA = 0;

// Turn PWM Off

// Turn OFF LED0 to indicate “ERROR”.

// Disable All Interrupts

// Enter a eternal loop

while (1);

// No recovery except “reset-button”

}

//-----------------------------------------------------------------------------

// PCA_ISR

//-----------------------------------------------------------------------------

// This routine counts the elapsed time in seconds, minutes, hours.

// It also toggles LED0 every second when in Lowcurrent Charge Mode.

// This routine interrupts every time the PCA counter overflows, every 256

// SYSCLK cycles. After SYSCLK/256 interrupts, one second has elapsed.

//

void PCA_OVERFLOW_ISR (void) interrupt 9

{

34

Rev. 1.2

AN137

PCA0CN = 0x40;

PCA0H = 0x00;

// Reset all PCA Interrupt Flags

// Reset High Byte of PCA Counter

//

of 8-bit PWM we are using Module1

if (0x0000 == --TIME.t_count)

{

TIME.t_count = PWM_CLOCK;

// Reset 1 Second Clock

if ( 60 == ++TIME.sec )

{

// Account for elapsed seconds

// Reset second counter every minute

TIME.sec = 0x00;

if ( 60 == ++TIME.min )

// Account for elapsed minutes

{

// Reset minute counter every hour

TIME.min = 0x00;

if ( 24 == ++TIME.hour )

// Account for elapsed hours

TIME.hour = 0x00;

// Reset hour counter every day

}

if ((LOWCURRENT == 1) && (ERROR == 0))

{

// Blink LED0 at 1 Hz if in Lowcurrent

if (TIME.sec % 2)

LED0 = 0;

else

// Turn on LED every odd second

// Turn on LED every even second

LED0 = 1;

}

// END OF FILE

Rev. 1.2

35

AN137

Contact Information

Silicon Laboratories Inc.

4635 Boston Lane

Austin, TX 78735

Tel: 1+(512) 416-8500

Fax: 1+(512) 416-9669

Toll Free: 1+(877) 444-3032

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36

Rev. 1.2


型号：	AN137
厂家：	SILICON
描述：	LITHIUM ION BATTERY CHARGER USING C8051F300 锂离子电池充电器使用C8051F300 电池
文件：	总36页 (文件大小：381K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

AN137 [SILICON]

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