LM2759SD/NOPB [TI]

具有 I2C 兼容接口、1A 开关电容器 LED 闪光灯驱动器 | DQB | 12 | -30 to 85;


型号：	LM2759SD/NOPB
厂家：	TEXAS INSTRUMENTS
描述：	具有 I2C 兼容接口、1A 开关电容器 LED 闪光灯驱动器 \| DQB \| 12 \| -30 to 85 开关驱动闪光灯电容器驱动器
文件：	总22页 (文件大小：1706K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LM2759

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SNVS577D –JUNE 2008–REVISED MAY 2013

LM2759 1A Switched Capacitor Flash LED Driver with I²C Compatible Interface

Check for Samples: LM2759

FEATURES

APPLICATIONS

•

Up to 1A Output Current

Solution Area < 22 mm²

No Inductor Required

90% Peak Efficiency

•

Camera Flash in Cellular Phones

•

DESCRIPTION

LM2759 is an integrated low-noise, high-current

switched capacitor DC/DC converter with a regulated

current source. The device requires only four small

ceramic capacitors making the total solution area less

than 22 mm²and the height less than 1 mm. The

LM2759 is capable of driving loads up to 1A from a

single-cell Li-Ion battery. Maximum efficiency is

achieved over the input voltage range by actively

selecting the proper gain based on the LED forward

voltage and current requirements.

Adaptive 1x, 1.5x and 2x Gains for Maximum

Efficiency

•

Load Disconnect in Shutdown

Accurate Input Current Control During Gain

Transitions

•

Flash Time-Out

TX Input Pin Ensures Synchronization with RF

Power Amplifier Pulse

The LED current can be programmed up to 1A via an

I²C-compatible interface, along with eight selectable

Flash Time-Out durations. One high-current Flash

LED can be driven either in a high-power Flash mode

or a low-power Torch mode. The Strobe pin allows

the flash to be toggled via a Flash enable signal from

a camera module. The TX input pin limits the Flash

LED current to the Torch current level during a RF

PA pulse, to reduce high loads on the battery.

Internal soft-start circuitry limits the amount of inrush

current during start-up.

•

Torch, Flash, and Indicator Modes

External Flash Enable via Strobe Input Pin

Strobe Input Disable via I²C

Programmable Flash Pulse Duration, and

Torch and Flash Currents via I²C-Compatible

Interface

•

1MHz Constant Frequency Operation

Low Profile 12–Pin WSON (3mm x 3mm x

0.8mm)

LM2759 is offered in a small 12-pin thermally

enhanced WSON package.

Typical Application Circuit

= Up to 1A

LED

= 3.0V - 5.5V

OUT

C +

2.2 µF

4.7 µF

OUT

2.2 µF

C -

SINK

C +

LM2759

C -

Strobe

SDA

SCL

GND

TDK: 2.2 µF œ C1608X5R1C225

4.7 µF œ C2012X5R1C475

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

LM2759

SNVS577D –JUNE 2008–REVISED MAY 2013

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Connection Diagram

Die-Attach Pad: GND

Top View

Bottom View

Figure 1. 12-Pin WSON Package

3mm x 3mm x 0.8mm

Package Number DQB0012A

PIN DESCRIPTIONS

Name

V_IN

Description

Input voltage connection.

V_OUT

C1−

Charge pump regulated output.

C1+

Flying capacitor connections.

C2+

C2−

GND

I_SINK

SDA

Strobe

Ground connection.

Regulated current sink input.

Serial data I/O pin.

Manual flash enable pin. Flash will remain on for the duration that the Strobe pin is held high or

when the Flash Timeout occurs, whichever comes first.

Transmission pulse Flash interrupt pin. High = RF PA pulse active, LED current reduced to Torch

level, Low = RF PA pulse off, LED at full programmed current level.

SCL

Serial clock pin.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

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Absolute Maximum Ratings^(1)(2)(3)

V_INpin: Voltage to GND

-0.3V to 6.0V

Strobe, TX, SDA, SCL, I_SINKpins: Voltage to GND

-0.3V to (V_IN+ 0.3V)

w/ 6.0V max

Continuous Power Dissipation⁽⁴⁾

Internally Limited

150°C

Junction Temperature (T_J-MAX

Storage Temperature Range

)

-65°C to 150°C

(5)

Maximum Lead Temp. (Soldering)

ESD Rating

Human Body Model⁽⁶⁾

2.5KV

(1) Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under

which operation of the device is ensured. Operating Ratings do not imply ensured performance limits. For ensured performance limits

and associated test conditions, see the Electrical Characteristics tables.

(2) All voltages are with respect to the potential to the GND pin.

(3) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and

specifications.

(4) Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at T_J=150°C (typ.) and

disengages at T_J= 120°C (typ.).

(5) For detailed soldering specifications and information, please refer to Texas Instruments Application Note AN-1187 (SNOA401).

(6) The Human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. (MIL-STD-883 3015.7)

Operating Ratings⁽¹⁾⁽²⁾

Input Voltage Range

2.7V to 5.5V

2.0V to 4.0V

LED Voltage Range

Junction Temperature Range (T_J)

Ambient Temperature Range (T_A)⁽³⁾

-30°C to +125°C

-30°C to +85°C

(1) Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under

which operation of the device is ensured. Operating Ratings do not imply ensured performance limits. For ensured performance limits

and associated test conditions, see the Electrical Characteristics tables.

(2) All voltages are with respect to the potential to the GND pin.

(3) In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may

have to be derated. Maximum ambient temperature (T_A-MAX) is dependent on the maximum operation junction temperature (T_J-MAX-OP

125ºC), the maximum power dissipation of the device in the application (P_D-MAX), and the junction-to ambient thermal resistance of the

part/package in the application (θ_JA), as given by the following equation: T_A-MAX= T_J-MAX-OP- (θ_JA× P_D-MAX).

Thermal Information

Junction-to-Ambient Thermal Resistance, (θ_JA),

(1)

36.7°C/W

(1) Junction-to-ambient thermal resistance (θ_JA) is taken from a thermal modeling result, performed under the conditions and guidelines set

forth in the JEDEC standard JESD51-7. The test board is a 4–layer FR-4 board measuring 102 mm x 76 mm x 1.6 mm with a 2x1 array

of thermal vias. The ground plane on the board is 50 mm x 50 mm. Thickness of copper layers are 53µm/35µm/35µm/53µm

(1.5oz/1oz/1oz/1.5oz). Ambient temperature in simulation is 22°C, still air. Power dissipation is 1W.The value of θ_JAof this product in the

WSON package could fall in a range as wide as 30ºC/W to 150ºC/W (if not wider), depending on PWB material, layout, and

environmental conditions. In applications where high maximum power dissipation exists (high V_IN, high I_OUT), special care must be paid

to thermal dissipation issues. For more information on these topics, please refer to Application Note AN-1187 (SNOA401): and the

Power Efficiency and Power Dissipation section of this datasheet.

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Electrical Characteristics⁽¹⁾⁽²⁾

Limits in standard typeface are for T_J= 25°C. Limits in boldface type apply over the full operating junction temperature range

(-30°C ≤ T_J≤ +125 °C). Unless otherwise noted, specifications apply to the LM2759 Typical Application Circuit (pg.1) with V_IN

= 3.6V, V_TX= 0V, V_STROBE= 0V, C_IN= C₁= C₂= 2.2 µF, C_OUT= 4.7 µF.⁽³⁾

Symbol

I_LED

Parameter

Conditions

Min

Typ

Max

Units

LED Current Sink Accuracy Flash Mode

198

220

242

ADDR xB0 = 0x02

−10%

+10%

I_FLASH

V_GDX

V_OUT

Max Flash Output Current

Flash Mode

ADDR xB0 = 0x0F

Gain Transition Voltage

Threshold on I_SINK

I_LED= 500mA

(V_ISINKfalling)

350

(4)

Output Voltage

1x Mode, I_OUT= 0 mA (V_IN>V_OUT

1.5x Mode, I_OUT= 0 mA

)

4.7

4.9

5.4

2x Mode, I_OUT= 0 mA

5.1

R_OUT

x1 Mode Output Impedance I_OUT= 200mA, V_IN= 3.3V

0.33

1.9

Ω

1.5x Mode Output

Impedance

I_OUT= 500mA, V_IN= 3.3V

x2 Mode Output Impedance

Switching Frequency

Input Logic High

2.25

F_SW

V_IH

V_IL

2.7V ≤ V_IN≤ 5.5V

0.7

1.3

MHz

Pins: TX, Strobe

1.26

Input Logic Low

Pins: TX, Strobe

0.7

0.9

4.0

7.0

9.7

I_OUT= 0 mA, 1x Mode

I_OUT= 0 mA, 1.5x Mode

I_OUT= 0 mA, 2x Mode

0.6

3.4

5.9

5.8

I_Q

Quiescent Current

Shutdown Current

µA

I_SD

Device Disabled

2.7V ≤ V_IN≤ 5.5V

I²C Compatible Interface Voltage Specifications (SCL, SDA)

V_IL

Input Logic Low “0”

Input Logic High “1'

Output Logic Low “0”

2.7V ≤ V_IN≤ 5.5V

I_LOAD= 3 mA

0.72

300

V_IH

V_OL

1.25

I²C Compatible Interface Timing Voltage Specifications (SCL, SDA)⁽⁵⁾

t₁

t₂

SCL (Clock Period)

2.5

µs

Data in Setup Time to SCL

High

100

t₃

t₄

t₅

Data Out Stable After SCL

Low

SDA Low Setup Time to

SCL Low (Start)

100

SDA High Hold Time After

SCL High (Stop)

(1) All voltages are with respect to the potential to the GND pin.

(2) Min and Max limits are specified by design, test, or statistical analysis. Typical (Typ) numbers are not ensured, but do represent the

most likely norm. Unless otherwise specified, conditions for Typ specifications are: V_IN= 3.6V and T_A= 25°C.

(3) C_IN, C_OUT, C₁, C₂: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics.

(4) For input voltage below the regulation target during the gain of 1x, the output voltage will typically be equal to the input voltage.

(5) SCL and SDA should be glitch-free in order for proper brightness control to be realized.

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Block Diagram

4.7 µF

OUT

FLASH

LED

MODULE

OUT

Gain

Control

Thermal

Shutdown

REF

2.2 µF

FLASH

Timeout

C₁+

REG

OUT

GND

Current

Control

2.2 µF

C₁-

STROBE

1x,1.5x,

Charge

Pump

C₂+

2.2 µF

Power

on Reset

I C Control

Logic

C₂-

LM2759

SDA

SCL

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Typical Performance Characteristics

Unless otherwise specified: T_A= 25°C, V_IN= 3.6V, C_IN= C₁= C₂= 2.2µF, C_OUT= 4.7µF. Capacitors are low-ESR multi-layer

ceramic capacitors (MLCC's). Luxeon PWF3 Flash LED.

Efficiency

Input Current

V_IN

Figure 2.

Figure 3.

Quiescent Current

V_IN, Gain = 1X

Quiescent Current

V_IN, Gain = 2X

Figure 4.

Figure 5.

I_LED

V_ISINK

Shutdown Current

V_IN

Figure 6.

Figure 7.

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Typical Performance Characteristics (continued)

Unless otherwise specified: T_A= 25°C, V_IN= 3.6V, C_IN= C₁= C₂= 2.2µF, C_OUT= 4.7µF. Capacitors are low-ESR multi-layer

ceramic capacitors (MLCC's). Luxeon PWF3 Flash LED.

Oscillator Frequency

V_IN

Torch Code Levels

Figure 8.

Figure 9.

Flash Code Levels

Shutdown to Torch Mode, 100mA

CH1: SDA; Scale: 2V/Div, DC Coupled

CH2: V_OUT; Scale: 2V/Div, DC Coupled

CH3: I_IN; Scale: 100mA/Div, DC Coupled

CH4: I_LED; Scale: 100mA/Div, DC Coupled

Time scale: 400µs/Div

Figure 10.

Figure 11.

Shutdown to Flash Mode, 1A

Torch to Flash Mode, 100mA to 1A

CH1: SDA; Scale: 2V/Div, DC Coupled

CH2: V_OUT; Scale: 2V/Div, DC Coupled

CH3: I_IN; Scale: 1A/Div, DC Coupled

CH4: I_LED; Scale: 1A/Div, DC Coupled

CH1: SDA; Scale: 2V/Div, DC Coupled

CH2: V_OUT; Scale: 2V/Div, DC Coupled

CH3: I_IN; Scale: 1A/Div, DC Coupled

CH4: I_LED; Scale: 1A/Div, DC Coupled

Time scale: 1ms/Div

Figure 12.

Figure 13.

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Typical Performance Characteristics (continued)

Unless otherwise specified: T_A= 25°C, V_IN= 3.6V, C_IN= C₁= C₂= 2.2µF, C_OUT= 4.7µF. Capacitors are low-ESR multi-layer

ceramic capacitors (MLCC's). Luxeon PWF3 Flash LED.

Flash Timeout, Timeout Code (x03) = 325ms

Torch Level (x0F) = 180mA, Flash Level (x05) = 410mA

CH1(bottom): I_IN; Scale: 200mA/Div, DC Coupled

CH2(middle): SDA; Scale: 2V/Div, DC Coupled

CH3(top): V_OUT; Scale: 2V/Div, DC Coupled

Time scale: 100ms/Div

Figure 14.

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APPLICATION INFORMATION

CIRCUIT DESCRIPTION

The LM2759 is an adaptive CMOS charge pump with gains of 1x, 1.5x, and 2x, optimized for driving Flash LEDs

in camera phones and other portable applications. It provides a constant current of up to 1A (typ.) for Flash mode

and 180 mA (typ.) for Torch mode.

The LM2759 has selectable modes including Flash, Torch, Indicator and Shutdown. Flash mode for the LM2759

can also be enabled via the Strobe input pin. The LED is driven from V_OUTand connected to the current sink.

The LED drive current and operating modes are programmed via an I²C compatible interface. The LM2759

adaptively selects the next highest gain mode when needed to maintain the programmed LED current level.

To prevent a high battery load condition during a simultaneous RF PA transmission and Flash event, LM2759

has a Flash interrupt pin (TX) to reduce the LED current to the programmed Torch current level for the duration

of the RF PA transmission pulse.

CHARGE PUMP AND GAIN TRANSITIONS

The input to the 1x, 1.5x, 2x charge pump is connected to the V_INpin, and the loosely regulated output of the

charge pump is connected to the V_OUTpin. In 1x mode, as long as the input voltage is less than 4.7V (typ.), the

output voltage is approximately equal to the input voltage. When the input voltage is over 4.7V (typ.) the output

voltage is regulated to 4.7V (typ.). In 1.5x mode, the output voltage is regulated to 4.7V (typ.) over entire input

voltage range. For the gain of 2x, the output voltage is regulated to 5.1V (typ.). When under load, the voltage at

V_OUTcan be less than the target regulation voltage while the charge pump is still in closed loop operation. This is

due to the load regulation topology of the LM2759.

The charge pump’s gain is selected according to the headroom voltage across the current sink of LM2759. When

the headroom voltage V_GDX(at the LED cathode) drops below 350 mV (typ.) the charge pump gain transitions to

the next available higher gain mode. Once the charge pump transitions to a higher gain, it will remain at that gain

for as long as the device remains enabled. Shutting down and then re-enabling the device resets the gain mode

to the minimum gain required to maintain the load.

SOFT START

The LM2759 contains internal soft-start circuitry to limit inrush currents when the part is enabled. Soft start is

implemented internally with a controlled turn-on of the internal voltage reference.

CURRENT LIMIT PROTECTION

The LM2759 charge pump contains current limit protection circuitry that protects the device during V_OUTfault

conditions where excessive current is drawn. Output current is limited to 1.4A typically.

LOGIC CONTROL PINS

LM2759 has two asynchronous logic pins, Strobe and TX. These logic inputs function according to the table

below:

STROBE

FUNCTION

Current I²C programmed state (Off, Torch,

Flash, Indicator)

Current I²C programmed state (Off, Torch,

Flash, Indicator). If Flash is enabled via I²C

and TX is logic High, the LED current will be

at the programmed Torch level.

Flash Mode (Total LED "ON" Duration limited

by Flash Timeout)

Torch Mode (Total LED "ON" Duration limited

by Flash Timeout)

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I²C COMPATIBLE INTERFACE

START AND STOP CONDITIONS

START and STOP conditions classify the beginning and the end of the I²C session. A START condition is

defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. A STOP condition is defined as

the SDA transitioning from LOW to HIGH while SCL is HIGH. The I²C master always generates START and

STOP conditions. The I²C bus is considered to be busy after a START condition and free after a STOP condition.

During data transmission, the I²C master can generate repeated START conditions. First START and repeated

START conditions are equivalent, function-wise.

SDA

SCL

STOP condition

TART condition

Figure 15. Start and Stop Conditions

DATA VALIDITY

The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, state of

the data line can only be changed when SCL is LOW.

SCL

SDA

data

change

allowed

data

change

allowed

data

valid

data

change

allowed

data

valid

Figure 16. Data Validity Diagram

A pull-up resistor between the controller's VIO line and SDA must be greater than [(VIO-V_OL) / 3.5mA] to meet

the V_OLrequirement on SDA. Using a larger pull-up resistor results in lower switching current with slower edges,

while using a smaller pull-up results in higher switching currents with faster edges.

TRANSFERING DATA

Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) transferred first. Each

byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated by the

master. The master releases the SDA line (HIGH) during the acknowledge clock pulse. The LM2759 pulls down

the SDA line during the 9th clock pulse, signifying an acknowledge. The LM2759 generates an acknowledge

after each byte is received.

After the START condition, the I²C master sends a chip address. This address is seven bits long followed by an

eighth bit which is a data direction bit (R/W). The LM2759 address is 53h. For the eighth bit, a “0” indicates a

WRITE and a “1” indicates a READ. The second byte selects the register to which the data will be written. The

third byte contains data to write to the selected register.

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ack from slave

start msb Chip Address lsb

ack

msb Register Add lsb

ack

msb DATA lsb

ack stop

SCL

SDA

start

Id = 53h

ack

addr = 10h

ack

data h‘03 (Flash)

ack stop

w = write (SDA = "0")

r = read (SDA = "1")

ack = acknowledge (SDA pulled down by either master or slave)

id = chip address, 53h for LM2759

Figure 17. Write Cycle

I²C COMPATIBLE CHIP ADDRESS

The chip address for LM2759 is 1010011, or 53h.

MSB

LSB

ADR5

bit6

ADR6

bit7

ADR4

bit5

ADR3

bit4

ADR2

bit3

ADR1

bit2

ADR0

bit1

R/W

bit0

I C SLAVE address (chip address)

INTERNAL REGISTERS

General Purpose

MSB

LSB

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

Torch Current

MSB

LSB

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

Flash Current

MSB

LSB

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

Flash Timeout Duration

MSB

LSB

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

Power On Value

(lowest 4 bits)

Internal Hex Address

General Purpose Register

Flash Current Register

Torch Current Register

10h

B0h

A0h

0000

1010

0111

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Power On Value

(lowest 4 bits)

Internal Hex Address

Flash Timeout Duration Register

C0h

1011

GENERAL PURPOSE REGISTER AND STROBE INHIBIT FUNCTION

The general purpose register (x10) is used set the mode of operation for the LM2759. The selectable operating

modes using the lower 4 bits in the general purpose register are listed in the table below.

The Strobe Input Pin can be disabled via I²C to ignore external signals into this pin when desired. This function is

implemented through bit 3 of the General Purpose Register (See table below). In the default state, input signals

on the Strobe Input are enabled. (Bit3 = “0”, inputs into the Strobe Pin are not inhibited).

Table 1. General Purpose Register (Reg x10)

Bit3

Bit2

Bit1

Bit0

Mode

Shutdown

Torch

Flash

Indicator (Lowest Torch Level)

Inhibit Inputs into the Strobe Pin

SETTING LED CURRENT

The current through the LED is set by programming the appropriate register with the desired current level code

for Flash and Torch. The time that Flash mode is active is dependent on the lesser of the duration that it is set to

"ON" (via I²C or the Strobe pin), or the duration of the Flash Timeout. Use the tables below to select the desired

current level.

Using the part in conditions where the junction temperature might rise above the rated maximum requires that

the operating ranges and/or conditions be de-rated. The printed circuit board also must be carefully laid out to

account for high thermal dissipation in the part.

Table 2. Flash Current Table (Reg xB0)

CODE (Hex)

FLASH CURRENT (mA)

150

220

280

350

410

470

530

590

650

710

770

830

890

950

1010

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Table 3. Torch Current Table (Reg xA0)

CODE (Hex)

TORCH CURRENT (mA)

100

110

120

130

140

150

160

170

180

FLASH TIME-OUT FEATURE

Time-out Protection Circuitry disables the current sink when either the Strobe pin is held at logic high or the

Flash mode is enabled via the I²C compatible interface longer than the programmed timeout duration. This

prevents the device from self-heating due to the high power dissipation during Flash conditions. During the time-

out condition, voltage will still be present on V_OUTbut the current sink will be shut off, resulting in no current

through the Flash LED. When the device goes into a time-out condition, disabling and then re-enabling the

device will reset the time-out. Use the table below to set the desired Flash timeout duration.

Table 4. Flash Timeout Duration (Reg xC0)

CODE (Hex)

TIME (ms)

125

250

375

500

625

750

1100

CAPACITOR SELECTION

The LM2759 requires 4 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors

are recommended. These capacitors are small, inexpensive and have very low equivalent series resistance (ESR

<20 mΩ typ.). Tantalum capacitors, OS-CON capacitors, and aluminum electrolytic capacitors are not

recommended for use with the LM2759 due to their high ESR, as compared to ceramic capacitors. For most

applications, ceramic capacitors with X7R or X5R temperature characteristic are preferred for use with the

LM2759. These capacitors have tight capacitance tolerance (as good as ±10%) and hold their value over

temperature (X7R: ±15% over -55°C to 125°C; X5R: ±15% over -55°C to 85°C). Capacitors with Y5V or Z5U

temperature characteristic are generally not recommended for use with the LM2759. Capacitors with these

temperature characteristics typically have wide capacitance tolerance (+80%, -20%) and vary significantly over

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temperature (Y5V: +22%, -82% over -30°C to +85°C range; Z5U: +22%, -56% over +10°C to +85°C range).

Under some conditions, a nominal 1 μF Y5V or Z5U capacitor could have a capacitance of only 0.1 μF. Such

detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum capacitance

requirements of the LM2759. The voltage rating of the output capacitor should be 6.3V or more. For example, a

6.3V 0603 4.7 μF output capacitor (TDK C1608X5R0J475) is acceptable for use with the LM2759, as long as the

capacitance on the output does not fall below a minimum of 3μF in the intended application. All other capacitors

should have a voltage rating at or above the maximum input voltage of the application and should have a

minimum capacitance of 1 μF.

Table 5. Suggested Capacitors and Suppliers

MFG Part No.

4.7 µF for C_OUT

Type

MFG

Voltage Rating

Case Size Inch (mm)

C1608X5R0J475

JMK107BJ475

Ceramic X5R

TDK

6.3V

0603 (1608)

Taiyo-Yuden

2.2 µF for C1, C2, C_IN

C1608X5R0J225

JMK107BJ225

Ceramic X5R

TDK

6.3V

0603 (1608)

Taiyo-Yuden

POWER EFFICIENCY

Efficiency of LED drivers is commonly taken to be the ratio of power consumed by the LED (P_LED) to the power

drawn at the input of the part (P_IN). With a 1x, 1.5x, 2x charge pump, the input current is equal to the charge

pump gain times the output current (total LED current). The efficiency of the LM2759 can be predicted as follows:

P_LED= V_LED× I_LED

P_IN= V_IN× I_IN

(1)

(2)

(3)

(4)

P_IN= V_IN× (Gain × I_LED+ I_Q)

E = (P_LED÷ P_IN)

For a simple approximation, the current consumed by internal circuitry (I_Q) can be neglected, and the resulting

efficiency will become:

E = V_LED÷ (V_IN× Gain)

(5)

Neglecting I_Qwill result in a slightly higher efficiency prediction, but this impact will be negligible due to the value

of I_Qbeing very low compared to the typical Torch and Flash current levels (100mA - 1A). It is also worth noting

that efficiency as defined here is in part dependent on LED voltage. Variation in LED voltage does not affect

power consumed by the circuit and typically does not relate to the brightness of the LED. For an advanced

analysis, it is recommended that power consumed by the circuit (V_INx I_IN) be evaluated rather than power

efficiency.

THERMAL PROTECTION

Internal thermal protection circuitry disables the LM2759 when the junction temperature exceeds 150°C (typ.).

This feature protects the device from being damaged by high die temperatures that might otherwise result from

excessive power dissipation. The device will recover and operate normally when the junction temperature falls

below 120°C (typ.). It is important that the board layout provide good thermal conduction to keep the junction

temperature within the specified operating ratings.

POWER DISSIPATION

The power dissipation (P_DISSIPATION) and junction temperature (T_J) can be approximated with the equations

below. P_INis the power generated by the 1x, 1.5x, 2x charge pump, P_LEDis the power consumed by the LED, T_A

is the ambient temperature, and θ_JAis the junction-to-ambient thermal resistance for the 12 pin WSON package.

V_INis the input voltage to the LM2759, V_LEDis the nominal LED forward voltage, and I_LEDis the programmed

LED current.

P_DISSIPATION= P_IN- P_LED

(6)

(7)

(8)

= (Gain × V_IN× I_LED) − (V_LED× I_LED

)

T_J= T_A+ (P_DISSIPATION× θ_JA)

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LM2759

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SNVS577D –JUNE 2008–REVISED MAY 2013

The junction temperature rating takes precedence over the ambient temperature rating. The LM2759 may be

operated outside the ambient temperature rating, so long as the junction temperature of the device does not

exceed the maximum operating rating of 105°C. The maximum ambient temperature rating must be derated in

applications where high power dissipation and/or poor thermal resistance causes the junction temperature to

exceed 105°C.

MAXIMUM OUTPUT CURRENT

The maximum LED current that can be used for a particular application depends on the rated forward voltage of

the LED used, the input voltage range of the application, and the Gain mode of the LM2759’s charge pump. The

following equation can be used to approximate the relationship between the maximum LED current, the LED

forward voltage, the minimum input voltage, and the charge pump gain:

(V_{IN_MIN}x Gain) > (V_F+ V_HR) + (I_LEDx R_{OUT_GAIN}

)

(9)

V_HRor the voltage required across the current sink to remain in regulation can be approximated by (I_LEDx K_HR),

where K_HRis 0.8 mV/mA (typ). R_{OUT_GAIN}is the output impedance of the charge pump according to its gain

mode. When using the equation above, keep in mind that the (V_F+ V_HR) portion of the equation can not be

greater than the nominal output regulation voltage for a particular gain. In other words, when making calculations

for an application where the term (V_F+ V_HR) is higher than a particular gain’s regulation voltage, the next higher

gain level must be used for the calculation.

Example: V_F= 4V @ 1A, Charge Pump in the Gain of 2x with a R_OUTof 2.25Ω (typ.)

V_{IN_MIN}> [(4V + 0.8V) + (1A x 2.25Ω) ] ÷ 2

V_{IN_MIN}> 3.53V (typ.)

The maximum power dissipation in the LM2759 must also be taken into account when selecting the conditions

for an application, such that the junction temperature of the device never exceeds its rated maximum. The input

voltage range, operating temperature range, and/or current level of the application may have to be adjusted to

keep the LM2759 within normal operating ratings.

BOARD LAYOUT CONSIDERATIONS

PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance

of a DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce, and resistive voltage loss

in the traces. These can send erroneous signals to the DC-DC converter IC, resulting in poor regulation or

instability. Poor layout can also result in re-flow problems leading to poor solder joints between the WSON

package and board pads. Poor solder joints can result in erratic or degraded performance.

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Product Folder Links: LM2759

LM2759

SNVS577D –JUNE 2008–REVISED MAY 2013

www.ti.com

REVISION HISTORY

Changes from Revision C (May 2013) to Revision D

Page

•

Changed layout of National Data Sheet to TI format .......................................................................................................... 15

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Product Folder Links: LM2759

PACKAGE OPTION ADDENDUM

www.ti.com

10-Dec-2020

PACKAGING INFORMATION

Orderable Device

Status Package Type Package Pins Package

Eco Plan

Lead finish/

Ball material

MSL Peak Temp

Op Temp (°C)

Device Marking

Samples

Drawing

Qty

(1)

(2)

(3)

(4/5)

(6)

LM2759SD/NOPB

LM2759SDX/NOPB

ACTIVE

WSON

DQB

1000 RoHS & Green

4500 RoHS & Green

Level-3-260C-168 HR

-30 to 85

L2759

⁽¹⁾The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

⁽²⁾RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

⁽³⁾MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

⁽⁴⁾There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

⁽⁵⁾Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6)

Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two

lines if the finish value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

Addendum-Page 1

PACKAGE OPTION ADDENDUM

www.ti.com

10-Dec-2020

Addendum-Page 2

PACKAGE MATERIALS INFORMATION

www.ti.com

9-Aug-2022

TAPE AND REEL INFORMATION

REEL DIMENSIONS

TAPE DIMENSIONS

Reel

Diameter

Cavity

A0 Dimension designed to accommodate the component width

B0 Dimension designed to accommodate the component length

K0 Dimension designed to accommodate the component thickness

Overall width of the carrier tape

P1 Pitch between successive cavity centers

Reel Width (W1)

QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE

Sprocket Holes

Q1 Q2

Q3 Q4

Q1 Q2

Q3 Q4

User Direction of Feed

Pocket Quadrants

*All dimensions are nominal

Device

Package Package Pins

Type Drawing

SPQ

Reel

Pin1

Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant

(mm) W1 (mm)

LM2759SD/NOPB

LM2759SDX/NOPB

WSON

DQB

1000

4500

178.0

330.0

12.4

3.3

1.0

8.0

12.0

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com

9-Aug-2022

TAPE AND REEL BOX DIMENSIONS

Width (mm)

*All dimensions are nominal

Device

Package Type Package Drawing Pins

SPQ

Length (mm) Width (mm) Height (mm)

LM2759SD/NOPB

LM2759SDX/NOPB

WSON

DQB

1000

4500

208.0

356.0

191.0

356.0

35.0

Pack Materials-Page 2

MECHANICAL DATA

DQB0012A

SDF12A (Rev B)

www.ti.com

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LM2759SD/NOPB [TI]

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