Diodes AP3427M User Manual

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Preliminary Datasheet

General Description

The AP3427M is a high efficiency step-down dual
channel DC-DC voltage converter. The chip
operation is optimized by peak-current mode
architecture with built-in synchronous power
MOSFET switchers. The oscillator and timing
capacitors are all built-in providing an internal
switching frequency of 1.5MHz 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
ranging from 0.6V to 0.9×V
range is from 2.5V to 5.5V, and is able to deliver up
to 1A.

The AP3427M is available in standard DFN-3×3-10
package.

when input voltage

IN

Features

• High Efficiency Buck Power Converter

• Output Current: 1.0A

• Low R

• Adjustable Output Voltage from 0.6V to 0.9×V

• Wide Operating Voltage Range: 2.5V to 5.5V

• Built-in Power Switches for Synchronous
Rectification with High Efficiency

• Feedback Voltage: 600mV

• 1.5MHz Constant Frequency Operation

• Thermal Shutdown Protection

• Low Drop-out Operation at 100% Duty Cycle

• Input Over Voltage Protection

• No Schottky Diode Required

Internal Switches:200mΩ (VIN=5V)

DS(ON)

Applications

• Post DC-DC Voltage Regulation

• PDA and Notebook Computer

DFN-3×3-10

Figure 1. Package Type of AP3427M

IN

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Pin Configuration

DN Package

（DFN-3×3-10）

Figure 2. Pin Configuration of AP3427M (Top View)

Pin Description

Pin Number Pin Name Function

1 EN1 Enable signal input of channel 1, active high
2 FB1 Feedback voltage of channel 1
3 VIN2 Power supply input of channel 2

4, 9, Exposed Pad GND GND. It should be connected to system ground

5 LX2 Connected from channel 2’s Power MOSFET to inductor
6 EN2 Enable signal input of channel 2, active high
7 FB2 Feedback voltage of channel 2
8 VIN1 Power supply input of channel 1

10 LX1 Connected from channel 1’s Power MOSFET to inductor

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Functional Block Diagram

FB1/
FB2

2/7

EN 1/EN2

1/6 8/3

Over Current

Comparator

Control

Logic

Reverse Inductor

Current Comparator

Thermal

Shutdown

Current

Sensing

Buffer &

Dead Time

Control

Logic

Bias

Generator

Soft

Start

Bandgap

Reference

Saw-tooth
Generator

-

+

Error

Amplifier

-

+

Oscillator

+

+

-

Modulator

Over Voltage

Comparator

VIN1/VIN2

-

+

4/9

10/5

LX1/
LX2

GND

Figure 3. Functional Block Diagram of AP3427M

Ordering Information

AP3427M -

Circuit Type G1: Green

Package
DN: DFN-3×3-10

Package

DFN-3×3-10

Temperature

Range

-40 to 80°C

Part Number Marking ID

AP3427MDNTR-G1 BFE Tape & Reel

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

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TR: Tape & Reel

Packing

Type

Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Absolute Maximum Ratings (Note 1)

Parameter Symbol Value Unit

Supply Input Voltage for the
MOSFET Switch

LX Pin Switch Voltage V
Enable Input Voltage V
LX Pin Switch Current I

Power Dissipation (on PCB,

=25°C)

T

A

Thermal Resistance (Junction to
Ambient, Simulation)
Thermal Resistance (Junction to
Case, Simulation)

Operating Junction Temperature TJ 155

, V

V

IN1

LX1

EN1

LX1

0 to 6.5 V

IN2

, V

-0.3 to VIN+0.3 V

LX2

, V

-0.3 to VIN+0.3 V

EN2

, I

1.8 A

LX2

2.44 W

P

D

θ

JA

θ

JC

41

4.2

°C/W

°C/W

°C

Operating Temperature TOP -40 to 85
Storage Temperature Range T
ESD (Human Body Model) V

ESD (Machine Model)

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

STG

2000 V

HBM

200 V

V

MM

°C
°C

Recommended Operating Conditions

Parameter Symbol Min Max Unit

Supply Input Voltage VIN 2.5 5.5 V
Operating Junction Temperature TJ -40 125
Ambient Temperature TA -40 80

°C
°C

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Electrical Characteristics

TA=25°C, VIN=V
C

OUT1=COUT2

IN1=VIN2

=10μF, I

Parameter Symbol Conditions Min Typ Max Units

=5V, V

=1A per Channel, unless otherwise specified.

MAX

EN1=VEN2

=5V, V

FB1=VFB2

=0.6V, L1=L2=2.2μH, C

IN1=CIN2

=4.7μF,

Input Voltage Range VIN
Shutdown Current I

OFF

Active Current ION
Regulated Feedback

Voltage
Regulated Output
Voltage Accuracy

ΔV

OUT/VOUT

V

FB

V

IN=VIN1=VIN2

V

EN1=VEN2

V

FB1=VFB2

I

OUT1=IOUT2

For Adjustable Output
Voltage

=0

=0.7V,

=0A

VIN=2.5V to 5.5V,
I

OUT1

or I

OUT2

=0 to 1A

2.5 5.5 V

0.1 1
220

μA
μA

0.588 0.6 0.612 V

-3 3 %

Peak Inductor Current IPK 1.5 A
Oscillator Frequency f
PMOSFET R

NMOSFET R

R

DS(ON)

R

DS(ON)

EN High-level Input
Voltage
EN Low-level Input
Voltage

EN Input Current IEN 0.1
Soft Start Time tSS 400
Maximum Duty Cycle D

Input Over Voltage
Protection

V

OSC

VIN=5V 200

DS(ON)P

VIN=5V 200

DS(ON)N

1.5 V

V

EN_H

0.4 V

V

EN_L

100 %

MAX

6.2 V

V

IOVP

=2.5V to 5.5V 1.2 1.5 1.8 MHz

IN

mΩ
mΩ

μA

μs

Rising 2.3

Under Voltage Lock
Out Threshold

V

UVLO

V Falling 2.1

Hysteresis 0.2

Thermal Shutdown TSD Hysteresis=30°C 155 °C

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Typical Performance Characteristics

100

90

80

70

60

50

40

Efficiency (%)

30

20

10

0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200

Output Current (mA)

VIN = 5.0V

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

= 1.0V
= 1.2V
= 1.8V
= 2.5V
= 3.3V

100

90

80

70

60

50

40

Efficiency (%)

30

20

10

0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200

Output Current (mA)

V

= 3.3V

IN

V

= 1.0V

OUT

V

= 1.2V

OUT

V

= 1.8V

OUT

Figure 4. Efficiency vs. Output Current (VIN=5V) Figure 5. Efficiency vs. Output Current (VIN=3.3V)

0.610

0.608

0.606

0.604

0.602

0.600

0.598

0.596

0.594

Regulated Feedback Voltage (V)

0.592

0.590

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110120130

Temperature (oC)

1.54

1.52

1.50

1.48

1.46

1.44

1.42

1.40

1.38

1.36

Oscillator Frequency (MHz)

1.34

1.32

1.30

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110120 130

Temperature (oC)

Figure 6. Regulated Feedback Voltage vs. Temperature

Figure 7. Oscillator Frequency vs. Temperature

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Typical Performance Characteristics (Continued)

V

V

OUT_AC

10mV/div

V

SW

2V/div

I

L

1A/div

OUT_AC

10mV/div

VSW

IL

1A/div

Time (400ns/div)

Figure 8. Output Ripple (V

=1.2V , I

OUT

=1A) Figure 9. Output Ripple (V

OUT

VEN

5V/div

VSW

5V/div

V

OUT

1V/div

IL

1A/div

VEN

5V/div

V

SW

5V/div

V

OUT

1V/div

I

1A/div

Time (400ns/div)

=3.3V , I

OUT

L

OUT

=1A)

Figure 10. Enable Turn On (I

Time (400μs/div) Time (200μs/div)

=1A) Figure 11. Enable Turn Off (I

OUT

OUT

=1A)

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v

Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Typical Performance Characteristics (Continued)

V

OUT

1V/div

VSW

5V/div

V

OUT

1V/div

VSW

5V/div

I

2A/div

L

Time (400μs/div)

Figure 12. Short Circuit Protection (I

I

L

2A/di

Time (400μs/div)

=1A) Figure 13. Short Circuit Protection Recovery (I

OUT

OUT

=1A)

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Typical Application

C

OUT1

10 µF

V

OUT1

L1 2.2µH

Connected

to V

IN

C

IN2

4.7µF

C1

option

R2

R1

110
2

FB1

3

VIN2
GND

56

LX2 EN2

AP3427M

LX1EN1
GND
VIN1

FB2

9
8
74

R3

R4

C2

option

C

IN1

4.7µF

VIN= 2.5V to 5.5V

Note 2: V

OUT1=VFB1

×(1+R1/R2) ; V

L2 2.2µH

=V

OUT2

Figure 14. Typical Application of AP3427M (Note 2)

×(1+R3/R4), and R2=R4=10kΩ is recommended.

FB2

C

OUT2

10µF

V

OUT2

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Preliminary Datasheet

Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M

Mechanical Dimensions

DFN-3×3-10 Unit: mm(inch)

0.700(0.028)

0.800(0.031)

2.900(0.114)

3.100(0.122)

Pin 1 Mark

0.000(0.000)

0.050(0.002)

2.900(0.114)

3.100(0.122)

1.600(0.063)

1.800(0.071)

0.200(0.008)

0.300(0.012)

0.500(0.020)
TYP

N6 N10

2.300(0.090)

2.500(0.098)

N5

0.300(0.012)

0.500(0.020)

PIN #1 IDENTIFICATION

See DETAIL A

N1

DETAIL A

0.153(0.006)

0.253(0.010)

12

12

Pin 1 options

12

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BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifi-

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