APW7108 Datasheet, PDF (1/28 Pages) Anpec Electronics Coropration – Dual Mobile-Friendly PWM Controller

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)
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 V_CC 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
Applications
• Note Book Computers
- Chipset/RAM Supplies as low as 0.9V
- 1.8V and 2.5V Supplies
• Step-Down Converters Requiring High Efficiency
SSOP-28
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