MP3212DQ [MPS]

1.3A, 1MHz Step-up Regulator with Integrated Input Disconnect Switch;


型号：	MP3212DQ
厂家：	MONOLITHIC POWER SYSTEMS
描述：	1.3A, 1MHz Step-up Regulator with Integrated Input Disconnect Switch 开关光电二极管
文件：	总11页 (文件大小：563K)
中文：	中文翻译
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MP3212

1.3A, 1MHz Step-up Regulator

with Integrated Input Disconnect Switch

DESCRIPTION

FEATURES

The MP3212 is a high efficiency, fixed frequency,

current-mode boost converter with input

disconnect, inrush current limiting, internal soft-

start and compensation.



Up to 88% Efficiency

2.3V to 5.5V Input Voltage

Up to 28V Output

1 MHz Fixed Switching Frequency

Integrated Power MOSFET

Integrated Input Disconnect Switch

Zero Current Shutdown Mode

Internal Soft-Start

Internal Compensation

Automatic Pulse Frequency Modulation

Mode at Light Load

Inrush Current Limiting

1.3A Typical Switch Current Limit

Under voltage lockout

The 1MHz switching frequency allows for smaller

external components producing a compact

solution for a wide range of load currents. The

input disconnect feature provides complete

isolation from output to input when the device is in

either shutdown mode or fault condition. The

internal compensation minimizes the external

component count and soft-start limits the



current during startup.

The MP3212

automatically transitions into pulse-frequency

modulation mode to achieve better efficiency at

light load. The input voltage range of 2.3V to

5.5V can generate 28V at up to 100mA.

Over Voltage Protection

Thermal Shutdown

10-Pin QFN (3x3mm) Package

The MP3212 includes under-voltage lockout,

current limit, over voltage protection and

thermal shutdown. In addition to cycle by cycle

current limit at power switch, the average

current is also monitored at disconnect switch

to prevent damage in the event of output

overload.

APPLICATIONS



Low Noise Power Supply

Wimax RF Amp Power Supply

GPRS/GSM RF Amp Power Supply

All MPS parts are lead-free and adhere to the RoHS directive. For MPS green

status, please visit MPS website under Quality Assurance. “MPS” and “The

Future of Analog IC Technology” are Registered Trademarks of Monolithic

Power Systems, Inc.

The MP3212 is offered in a compact 10-pin

QFN (3x3mm) package.

TYPICAL APPLICATION

MP3212 Rev. 1.0

7/17/2013

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

ORDERING INFORMATION

Part Number*

Package

Top Marking

Temperature

QFN10 (3mm x 3mm)

MP3212DQ

–40C to +85C

* For Tape & Reel, add suffix –Z (e.g. MP3212DQ–Z). For RoHS Compliant Packaging, add suffix –LF (e.g.

MP3212DQ–LF–Z)

PACKAGE REFERENCE

ABSOLUTE MAXIMUM RATINGS ⁽¹⁾

VDD to GND................................. –0.3V to +6V

VOUT to GND............................. –0.3V to +35V

VSW to GND .............................. –0.5V to +36V

All Other Pins................................ –0.3V to +6V

Continuous Power Dissipation (T_A= +25°C) ⁽²⁾

………………………………………………....2.5W

Junction Temperature..............................150C

Lead Temperature ...................................260C

Storage Temperature.............. –65C to +150C

Recommended Operating Conditions ⁽³⁾

Supply Voltage V_IN..........................2.3V to 5.5V

Output Voltage V_OUT............................. 28Vmax

Operating Temperature ............ –40C to +85C

Thermal Resistance ⁽⁴⁾

θ_JAθ_JC

QFN10 (3×3mm) ....................50 ......12 ...C/W

Notes:

1) Exceeding these ratings may damage the device.

2) The maximum allowable power dissipation is a function of the

maximum junction temperature T_J(MAX), the junction-to-

ambient thermal resistance θ_JA, and the ambient temperature

T_A. The maximum allowable continuous power dissipation at

any ambient temperature is calculated by P_D(MAX) = (T_J

(MAX)-T_A)/θ_JA. Exceeding the maximum allowable power

dissipation will cause excessive die temperature, and the

regulator will go into thermal shutdown. Internal thermal

shutdown circuitry protects the device from permanent

damage.

3) The device is not guaranteed to function outside of its

operating conditions.

4) Measured on JESD51-7, 4-layer PCB.

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

ELECTRICAL CHARACTERISTICS

V_DD= 3.6V, V_GND= V_SHDN= 0V, T_A= 25C. C_IN=10F, C_OUT=3.3F, L=10H, R1=10k, R2=133k,

unless otherwise noted

Parameter

Symbol

Condition

Min Typ Max Units

Supply Operating Voltage ⁽¹⁾

V_DD

2.3

5.5

Under Voltage Lockout High

Threshold

V_UVLO,HI

V_UVLO,LO

V_DDrising

V_DDfalling

2.2 2.3

Under Voltage Lockout Low

Threshold

1.8

Shutdown Current

Supply Current (PFM)

Supply Current (PWM)

Switching Frequency

Minimum On time

Maximum Duty Cycle

SW On-Resistance

SW Leakage

I_Q,SHDN

I_Q(PFM)

I_Q(PWM)

F_SW

V_SHDN= V_DD

Not switching

180

A

400

0.85

1.15 MHz

t_{ON, MIN}

D_MAX

R_{DS (ON)}

I_SW



V_FB= 0V

I(SW) = 100mA

V_SHDN= V_DD, V_SW= 30V

0.4

A

SW Current Limit

I_LIM

1.3

0.2

I_OUT= 50mA, t>2.048ms(2)

SHDN = 0V

Input Disconnect On-Resistance

Input Disconnect Leakage Current

R_{DS (ON)_VDDOUT}

I_{SW_VDDOUT}



V_DDOUT= 0V

A

Soft Inrush Current Source at

V_DDOUT

V_DD–V_DDOUT= 0.5V, t_ON

<2.048ms(2)

I_{SS_VDDOUT}

120

Logic High Voltage

V_HI

V_LO

Logic Low Voltage

0.7

Pull-up Resistor

R_UP

Enabled, Input at GND

M

FB Voltage

V_FB

1.2 1.23 1.26

FB Input Bias Current

Leakage Current when Disabled

Thermal Shutdown

I_FB

V_FB= 1.23V

-0.1

0.1

A

C

I_LEAKAGE

T_{SHDN_TH}

T_{SHDN_HYS}

V_OV

Disabled, Input at GND

150

Thermal Shutdown Hysteresis

Over-voltage Thershold

Over-current Thershold

Load Regulation

FB=GND

I_OI

t>2.048ms(2), DC current

I_OUT= 50mA to 100mA

1.7

0.1

ΔV_OUT/ ΔI_OUT

V_DD= 3.6V to 2.6V, I_OUT

50mA

Line Regulation

ΔV_OUT/ ΔV_DD

0.1

%/V

Notes:

1) Minimum supply operating voltage needs to be above 2.5V at -40C.

2) Timer is around 2ms-4ms.

3) Guaranteed by design, not tested.

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

PIN FUNCTIONS

QFN10

Pin #

Name Description

PGND Power Ground. The ground return for C_OUTand internal switch

VDDOUT Input voltage after passing through the input isolation FET

VDD

Actual input voltage before the isolation FET

No Connect

Feedback voltage.

No Connect

AGND Analog ground

SHDN Shutdown. Active high

VOUT Output Voltage

Switch node.

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

TYPICAL PERFORMANCE CURVES

V_IN= 3.3V, V_OUT= 18V, T_A= +25ºC, unless otherwise noted.

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

TYPICAL PERFORMANCE CURVES (continued)

V_IN= 3.3V, V_OUT= 18V, T_A= +25ºC, unless otherwise noted.

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

BLOCK DIAGRAM

Figure 1—Functional Block Diagram

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

OPERATION

The MP3212 uses a constant frequency, peak

current mode boost regulation architecture to

regulate the feedback voltage. The operation of

the MP3212 can be understood by referring to

the block diagram of Figure 1.

The MP3212 has internal soft start control and

internal loop compensation to save external

components.

The MP3212 monitors input under voltage

conditions, output over voltage conditions, and

over temperature events for input under voltage

lockout, output over voltage protection and over

temperature protection.

At the beginning of each cycle, the power

MOSFET-M1 turns on, to prevent sub-harmonic

oscillations at duty cycles greater than 50%, a

stabilizing ramp is added to the output of the

current sense amplifier. When the output voltage

of current sense amplifier equals to the output

voltage of error amplifier, the power MOSFET-M1

turns off.

Start-Up Sequence

After SHDN pin is pulled low, or a restart is

triggered by the fault condition, MP3212 will go

through a start up sequence described as below.

At the beginning of start up, the VDDOUT switch

is configured as the current source to regulate

the inrush current, and pre-charge the capacitor

at Vout. There is 2ms timer to make sure the

capacitor at Vout is charged up close to Vin

minus a diode drop. However, if Vout is still not

charged up after timeout, MP3212 will stay in this

mode.

The voltage at the output of the error amplifier is

an amplified version of the difference between

the 1.23V reference voltage and the feedback

voltage. The peak inductor current is

corresponded to the error amplifier output. If the

feedback voltage starts to drop, the output of

error amplifier increases, which results in more

current flowing through the power MOSFET-M1

and thus increases the power delivered to the

output. The use of current mode control improves

transient response.

After 2ms timeout, if Vout is charged up close to

Vin minus a diode drop, then the VDDOUT

switch will be fully turned on and connect the

inductor to VDD. MP3212 will enter soft start.

To prevent the battery from discharging, when

MP3212 is disabled, the inductor is automatically

disconnected from the input supply.

The error amplifier voltage is increased slowly

during soft start to prevent overshoot. When VFB

approaches the internal band-gap voltage, the

MP3212 starts normal operation.

Fault Control

FAULT DESCRIPTION

FAULT CONDITION

V(VDD) < V_UVLO,LO

FAULT REACTION

Disables I/Os and waits until V(VDD)

reaches V_UVLO,HIon to begin with the

start-up sequence

Under-voltage at VDD

Disables VDDOUT switch and SW switch

and immediately restarts the start-up

sequence

Disables VDDOUT switch and SW switch

and waits until output voltage V(VOUT)

drops to V_OV- V_{OV_Hys}to restart the start-

up sequence

Over-current drawn from VDDOUT

Over-voltage at VOUT

I(VDDOUT) > I_OI

V(VOUT) > V_OV

Disables VDDOUT switch and SW switch

and waits until junction temp drops to

T_{SHDN_TH-}T_{SHDN_HYS}to restart the start-up

sequence

Over Temperature on chip

Tj > T_{SHDN_TH}

MP3212 Rev. 1.0

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

required to keep the noise at the IC to a

Maximum Duty Cycle

minimum. Ceramic capacitors are preferred, but

tantalum or low-ESR electrolytic capacitors may

also suffice.

The maximum duty cycle Dmax will determine

the maximum output voltage that the MP3212

can provide. The maximum duty cycle is defined

by the minimum off time of the switch.

Use an input capacitor value greater than 4.7μF.

The capacitor can be electrolytic, tantalum or

ceramic. However since it absorbs the input

switching current it requires an adequate ripple

current rating. Use a capacitor with RMS current

rating greater than the inductor ripple current

(see Selecting The Inductor to determine the

inductor ripple current).

DMAX = 1 – to_FF*Fosc

PFM Mode

During the light load condition, the MP3212

automatically enters pulse frequency modulation

(PFM) mode. In PFM mode, most of the internal

circuitry is turned off, only keeping alive the

active circuitry required to regulate the output

voltage.

To ensure stable operation, place the input

capacitor as close to the IC as possible.

Alternately a smaller high quality ceramic 0.1μF

capacitor may be placed closer to the IC with the

larger capacitor placed further away. If using this

technique, the larger capacitor can be a tantalum

or electrolytic type. All ceramic capacitors should

be placed close to the MP3212.

Isolation From V_IN(SHDN=High)

To prevent the battery from discharging the

MP3212 is automatically disconnected from the

battery when put in shutdown mode. The

MP3212 has an internal, low resistance isolation

FET that opens when the SHDN pin is pulled

high.

Selecting the Output Capacitor

Average Current Monitor at the Disconnect

Switch

If the average current is above the over current

set value VOI, the isolation switch is open, the

boost switch is opened, MP3212 then

immediately goes into start-up mode.

The output capacitor is required to maintain the

DC output voltage. Low ESR capacitors are

preferred to keep the output voltage ripple to a

minimum. The characteristic of the output

capacitor also affects the stability of the

regulation control system. Ceramic, tantalum, or

low

ESR

electrolytic

capacitors

are

recommended. In the case of ceramic capacitors,

the impedance of the capacitor at the switching

frequency is dominated by the capacitance, and

so the output voltage ripple is mostly independent

of the ESR. The output voltage ripple is

estimated to be:

APPLICATION INFORMATION

Components referenced below apply to

Typical Application Circuit on page 1.

Setting the Output Voltage

Set the output voltage by selecting the resistive

voltage divider ratio. Use 10kΩ for the low-side

resistor R2 of the voltage divider. Determine the

high-side resistor R1 by the equation:









 I_LOAD

V_OUT





V_RIPPLE



COUT  f_SW

R2(V_OUTV_FB)

R1 

V_FB

Where V_RIPPLEis the output ripple voltage, V_INand

V_OUTare the DC input and output voltages

respectively, I_LOADis the load current, f_SWis the

switching frequency, and C_OUTis the capacitance

of the output capacitor.

where V_OUTis the output voltage.

For R2 = 10kΩ and V_FB= 1.23V, then

R1 (kΩ) = 8.13 x (V_OUT– 1.23) kΩ.

In the case of tantalum or low-ESR electrolytic

capacitors, the ESR dominates the impedance at

the switching frequency, and so the output ripple

is calculated as:

Selecting the Input Capacitor

An input capacitor is required to supply the AC

ripple current to the inductor, while limiting noise

at the input source. A low ESR capacitor is

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MP3212–PRODUCT DESCRIPTION IN A PINCOUNT PACKAGE TYPE

should be rated for a reverse voltage greater than

the output voltage used. The average current

rating must be greater than the maximum load

current expected, and the peak current rating

must be greater than the peak inductor current.

V_IN

(1

) I_LOAD

V_OUT

I_LOAD R_ESRV_OUT

V_RIPPLE





COUT  f_SW

V_IN

Where R_ESRis the equivalent series resistance of

the output capacitors.

Layout Consideration

High frequency switching regulators require very

careful layout for stable operation and low noise. All

components must be placed as close to the IC as

possible. Keep the path between the SW pin,

output diode, output capacitor and GND pin

extremely short for minimal noise and ringing. The

input capacitor must be placed close to the IN pin

for best decoupling. All feedback components must

be kept close to the FB pin to prevent noise

injection on the FB pin trace. The ground return of

the input and output capacitors should be tied close

to the GND pin. See the MP3212 demo board

layout for reference.

Choose an output capacitor to satisfy the output

ripple and load transient requirements of the

design. A 3.3μF ceramic capacitor is suitable for

most applications.

Selecting the Inductor

The inductor is required to force the higher output

voltage while being driven by the input voltage. A

larger value inductor results in less ripple current

that results in lower peak inductor current,

reducing stress on the internal N•Channel.switch.

However, the larger value inductor has a larger

physical size, higher series resistance, and/or

lower saturation current.

A 10µH inductor is recommended for most

applications. However, a more exact inductance

value can be calculated. A good rule of thumb is

to allow the peak-to-peak ripple current to be

approximately 30-50% of the maximum input

current. Make sure that the peak inductor current

is below 75% of the current limit at the operating

duty cycle to prevent loss of regulation due to the

current limit. Also make sure that the inductor

does not saturate under the worst-case load

transient and startup conditions. Calculate the

required inductance value by the equation:

V_IN(V_OUT- V )

L 

V_OUT f_SW I

V_OUTI_LOAD

(MAX)

I_IN(MAX)

I 



V 



30% 50% _IN(MAX)

Where I_{LOAD (MAX)}is the maximum load current, ΔI is

the peak-to-peak inductor ripple current, and η is

efficiency.

Selecting the Diode

The output rectifier diode supplies current to output

when the internal MOSFET is off. To reduce losses

due to diode forward voltage and recovery time,

use a Schottky diode with the MP3212. The diode

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MP3212–1.3A, 1MHz, STEP-UPREGULATORWITHINTEGRATEDINPUTDISCONNECTSWITHCH

PACKAGE INFORMATION

3mm x 3mm QFN10

NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third

party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not

assume any legal responsibility for any said applications.

MP3212 Rev. 1.0

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MP3212DQ [MPS]

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