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APW7108

Dual Mobile-Friendly PWM Controller

Anpec Electronics 

APW7108

Dual Mobile-Friendly PWM Controller

Features

• Adjustable Output Voltage up to 5.5V

- 0.9V Reference Voltage

- ±1% Accuracy Over Temperature

• Operates from an Input Battery Voltage Range of

5V to 24V or from 3.3V/5V System Rail

• Power-On-Reset Monitoring on VCC Pin

• Selectable Forced PWM or Automatic PFM/PWM

Mode

• Constant-On-Time Control Scheme

- Switching Frequency Compensation for PWM

Mode

- Constant Switching Frequency (CH1: 345kHz,

CH2: 255KHz) in PWM Mode with DC Output Current

• Excellent Line and Load Transient Responses

• Adjustable Soft-Start and Soft-Stop

• Power-Good Outputs for both Channels

• Adjustable Current-Limit Protection

- Using Sense Resistor or MOSFET’s R

DS(ON)

• 115% Over-Voltage Protection

- No Negative Output Voltage Occurred

• 70% Under-Voltage Protection

• Adaptive Dead-Time Control

- Sensing G-to-S Voltage of Power MOSFETs

• Shutdown Control for both Channels

• 28-pin SSOP (SSOP-28) and 4mmx4mm 24-lead

QFN (QFN4x4-24) Packages

• Lead Free and Green Devices Available

(RoHS Compliant)

Applications

• Note Book Computers

- Chipset/RAM Supplies as low as 0.9V

- 1.8V and 2.5V Supplies

• Step-Down Converters Requiring High Efficiency

General Description

The APW7108 is a dual-channel, constant on-time, and

synchronous PWM controller which drives dual N-

channel MOSFETs for each channel. The APW7108 steps

down high voltage of a battery to generate low-voltage

chipset or RAM supplies in notebook computers.

The APW7108 provides excellent transient response and

accurate DC voltage output in either PFM or PWM

mode. In PFM mode, the APW7108 provides very high

efficiency over light to heavy loads with loading-modu-

lated switching frequencies. The Forced-PWM mode

works nearly at constant frequency for low-noise

requirements.

The APW7108 is equipped with accurate current-limit,

output under-voltag, and output over-voltage protections,

perfect for NB applications. A Power-On-Reset function

monitors the voltage on VCC to prevent wrong opera-

tion during power on. A soft-start ramps up the output

voltage with programmable slew rate to reduce the

start-up current. A soft-stop function actively discharges

the output capacitors with controlled reverse inductor

current. At the end of the soft-stop, the APW7108 forces

LGATE high to prevent over-voltage in shutdown. The

APW7108 has individual enable controls for each

channel. Pulling both EN pin low shuts down the whole

chip with low quiescent current close to zero.

The APW7108 is available in SSOP-28 and QFN4x4-24

packages.

Simplified Application Circuit

VIN

+5V~24V

Q1

VOUT1

Q2

EN1 VCC=5V EN2

SSOP-28

PWM1 PWM2

Q3

VOUT2

Q4

ROCSET1

ROCSET2

ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and

advise customers to obtain the latest version of relevant information to verify before placing orders.

Copyright © ANPEC Electronics Corp.

1

Rev. A.4 - Jan., 2009

www.anpec.com.tw

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