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Preliminary Datasheet

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

Mar. 2013 Rev. 1.0 BCD Semiconductor Manufacturing Limited

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 pr o du c t implement a ti ons.

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

when input voltage

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.

Features

• High Efficiency Buck Power Converter

• Output Current: 1.0A

• Low R

DS(ON)

Internal Switches:200mΩ (V

=5V)

• 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

Applications

• Post DC-DC Voltage Regulation

• PDA and Notebook Computer

Figure 1. Package Type of AP3427M

DFN-3×3-10

Summary of content (11 pages)

PAGE 1
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M General Description Features 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.
PAGE 2
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 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.
PAGE 3
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Functional Block Diagram VIN1/ VIN2 EN1/EN2 1/6 8/3 Saw-tooth Generator Bias Generator Over Current Comparator Oscillator Current Sensing + Buffer & Dead Time Control Logic Soft Start FB1/ FB2 2/7 + - - + Error Amplifier Control Logic Bandgap Reference LX1/ LX2 Modulator - + 10/5 Reverse Inductor Current Comparator Over Voltage Comparator + Thermal Shutdown 4/9 GND Figure 3.
PAGE 4
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit VIN1, VIN2 0 to 6.5 V VLX1, VLX2 -0.3 to VIN+0.3 V VEN1 , VEN2 -0.3 to VIN+0.3 V ILX1, ILX2 1.8 A PD 2.44 W θJA 41 °C/W θJC 4.
PAGE 5
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Electrical Characteristics TA=25°C, VIN=VIN1=VIN2=5V, VEN1=VEN2=5V, VFB1=VFB2=0.6V, L1=L2=2.2μH, CIN1=CIN2=4.7μF, COUT1=COUT2=10μF, IMAX=1A per Channel, unless otherwise specified. Parameter Symbol Conditions Input Voltage Range VIN VIN=VIN1=VIN2 Shutdown Current IOFF Active Current ION VEN1=VEN2=0 VFB1=VFB2=0.7V, IOUT1=IOUT2=0A For Adjustable Output Voltage VIN=2.5V to 5.
PAGE 6
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M 100 100 90 90 80 80 70 70 60 Efficiency (%) Efficiency (%) Typical Performance Characteristics VIN = 5.0V VOUT = 1.0V 50 VOUT = 1.2V 40 VOUT = 1.8V 60 VOUT = 1.0V 40 VOUT = 1.2V 30 VOUT = 2.5V 30 20 VOUT = 3.3V 20 10 VIN = 3.3V 50 VOUT = 1.
PAGE 7
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Typical Performance Characteristics (Continued) VOUT_AC 10mV/div VOUT_AC 10mV/div VSW 2V/div VSW 2V/div IL 1A/div IL 1A/div Time (400ns/div) Time (400ns/div) Figure 8. Output Ripple (VOUT=1.2V , IOUT=1A) VEN 5V/div VEN 5V/div VSW 5V/div VOUT 1V/div VSW 5V/div VOUT 1V/div IL 1A/div IL 1A/div Mar. 2013 Figure 9. Output Ripple (VOUT=3.3V , IOUT=1A) Time (400μs/div) Time (200μs/div) Figure 10.
PAGE 8
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Typical Performance Characteristics (Continued) VOUT 1V/div VOUT 1V/div VSW 5V/div VSW 5V/div IL 2A/div IL 2A/div Time (400μs/div) Time (400μs/div) Figure 12. Short Circuit Protection (IOUT=1A) Mar. 2013 Figure 13. Short Circuit Protection Recovery (IOUT=1A) Rev. 1.
PAGE 9
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Typical Application COUT1 10 µF VOUT1 L 1 2.2µH R2 R1 1 2 3 Connected to VIN 4 CIN2 4.7µF 5 EN1 FB1 VIN2 GND LX1 AP3427M C1 option GND VIN1 FB2 LX2 EN2 10 CIN1 4.7µF 9 8 VIN = 2.5 V to 5.5V 7 6 R4 R3 C2 option VOUT2 L 2 2.2µH COUT2 10µF Note 2: VOUT1=VFB1×(1+R1/R2) ; VOUT2 =VFB2×(1+R3/R4), and R2=R4=10kΩ is recommended. Figure 14. Typical Application of AP3427M (Note 2) Mar. 2013 Rev. 1.
PAGE 10
Preliminary Datasheet Dual 1A, 1.5MHZ Synchronous Step-down DC-DC Converter AP3427M Mechanical Dimensions DFN-3×3-10 Unit: mm(inch) 1.600(0. 063) 0.300(0. 012) 1.800(0. 071) 0.500(0. 020) 0.500(0. 020) 2.900(0. 114) TYP 3.100(0.122) N6 N10 2.300(0. 090) 2.500(0. 098) 2.900(0. 114) PIN #1 IDENTIFICATION See DETAIL A 3.100(0. 122) Pin 1 Mark N5 N1 0.200(0. 008) 0.700(0.028) 0.800(0. 031) 0.000(0. 000) 0.300(0. 012) DETAIL A 0.050(0. 002) 0.153(0. 006) 0.253(0.
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BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifications herein.