Diodes AP3431 User Manual

1.0MHz, 2.0A, Synchronous Step Down DC-DC Converter AP3431

Data Sheet

General Description

The AP3431 is a high efficiency step-down DC-DC
voltage converter. The chip operation is optimized
by peak-current mode architecture with built-in
synchronous power MOS switchers. The oscillator
and timing capacitors are all built-in providing an
internal switching frequency of 1MHz that allows
the use of small surface mount inductors and
capacitors for portable product implementations.

Integrated Soft Start (SS), Under Voltage Lock Out
(UVLO), Thermal Shutdown Detection (TSD) and
short circuit protection are designed to provide
reliable product applications.

The device is available in adjustable output voltage
versions ranging from 0.8V to 0.9
voltage range is from 2.7V to 5.5V , and is able to
deliver up to 2.0A.

The AP3431 is available in SOIC-8 package.

×

VIN when input

Features

• High Efficiency Buck Power Converter

• Output Current: 2A

• Low R

• Adjustable Output Voltage from 0.8V to 0.9×V

• Wide Operating Voltage Range: 2.7V to 5.5V

•

Built-in Power Switches for Synchronous

Rectification with High Efficiency

• Feedback Voltage: 800mV

• Switching Frequency: 1.0MHz

• Thermal Shutdown Protection

• Internal Soft Start

Internal Switches : 120mΩ(VIN=5V)

DS(ON)

IN

Applications

• LCD TV

• Set Top Box

• Post DC-DC Voltage Regulation

• PDA and Notebook Computer

Figure 1. Package Type of AP3431

SOIC-8

Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Data Sheet

1.0MHz, 2.0A, Synchronous Step Down DC-DC Converter AP3431

Pin Configuration

M Package

(SOIC-8)

1

2

3

4

Figure 2. Pin Configuration of AP3431 (Top View)

8

7

6

5

Pin Description

Pin Number Pin Name Function

1 VCC Supply input for the analog circuit

2 NC No connection

3 GND Ground pin

4 FB

5 EN

6 PGND Power switch ground pin

7 SW Switch output pin

8 VIN

Feedback pin. Receives the feedback voltage from a resistive

divider connected across the output

Chip enable pin. Active high, internal pull-high with

200kΩ resistor

Power supply input for the MOSFET switch

Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Data Sheet

1.0MHz, 2.0A, Synchronous Step Down DC-DC Converter AP3431

Functional Block Diagram

Figure 3. Functional Block Diagram of AP3431

Ordering Information

AP3431 A -

Circuit Type

Package
M: SOIC-8

Package

Temperature

Range

Part Number Marking ID Packing Type

AP3431M-G1 3431M-G1

SOIC-8 -40 to 80°C

AP3431MTR-G1 3431M-G1

BCD Semiconductor's Pb-free products, as designated with "G1" in the part number, are RoHS compliant and
green.

Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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G1:Green

Blank: Tube
TR: Tape & Reel

Tube

Tape & Reel

Data Sheet

1.0MHz, 2.0A, Synchronous Step Down DC-DC Converter AP3431

Absolute Maximum Ratings (Note 1)

Parameter Symbol Value Unit

Supply Input for the Analog Circuit VCC

Power Supply Input for the MOSFET Switch VIN

SW Pin Switch Voltage VSW

Enable Voltage VEN -0.3 to VIN+0.3 V

SW Pin Switch Current ISW 2.9 A

Power Dissipation (on PCB, TA=25°C) PD 1.45 W

Thermal Resistance (Junction to Ambient, Simulation) θJA 68.63 °C/W

Junction Temperature TJ 160 °C

Operating Temperature TOP -40 to 85 °C

Storage temperature T

ESD (Human Body Model) V

ESD (Machine Model) VMM

Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to
the device. These are stress ratings only, and functional operation of the device at these or any other conditions
beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute
Maximum Ratings” for extended periods may affect device reliability.

-55 to 150 °C

STG

HBM

0 to 6.0

0 to 6.0

-0.3 to V

2000

200

IN

+0.3

V

V

V

V

V

Recommended Operating Conditions

Parameter Symbol Min Max Unit

Supply Input Voltage VIN 2.7 5.5 V

Junction Temperature Range TJ -40 125 °C

Ambient Temperature Range TA -40 80 °C

Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Data Sheet

1.0MHz, 2.0A, Synchronous Step Down DC-DC Converter AP3431

Electrical Characteristics

VIN=VCC=VEN=5V, V

specified.

Parameter Symbol Conditions Min Typ Max Unit

Input Voltage Range VIN 2.7 5.5 V

=1.2V, VFB=0.8V, L=2.2µH, CIN=10µF, C

OUT

=22µF, TA=25°C, unless otherwise

OUT

Shutdown Current I

Active Current ION V
Regulated1Feedback

Voltage
Regulated Output
Voltage Accuracy

∆V

Peak Inductor
Current

Oscillator Frequency f

PMOSFET RON R

NMOSFET RON R
EN High-level Input

Voltage
EN Low-level Input
Voltage

V

OFF

For Adjustable Output Voltage 0.784 0.8 0.816 V

V

FB

OUT/VOUT

I

PK

OSC

ON(P)

ON(N)

V

EN_H

V

EN_L

2.9 A

V

VIN = 5V 120 mΩ

VIN = 5V 120 mΩ

1.5 V

0.4 V

=0V 4 µA

EN

= 0.95V 460 µA

FB

=2.7V to 5.5V,

V

IN

=0 to 2.0A

I

OUT

= 2.7V to 5.5V 1.0 MHz

IN

-3 3 %

EN Input Current IEN 2 µA

Soft-start Time tSS 450 µs

Maximum Duty

Cycle

90 %

D

MAX

Rising 2.4 V

Under Voltage Lock

Out Threshold

Falling 2.3 V

Hysteresis 0.1 V

Thermal Shutdown TSD Hysteresis=30°C 160 °C

Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Data Sheet

1.0MHz, 2.0A, Synchronous Step Down DC-DC Converter AP3431

Typical Performance Characteristics

Figure 4. Efficiency vs. Output Current Figure 5. Efficiency vs. Output Current

Figure 6. 2.5V Load Regulation Figure 7. 1.8V Load Regulation

Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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