APW7057

Features:

• Operates from +5V Input
• 0.8V Internal Reference Voltage- ±1.5% Accuracy Over Line, Load and Temp.
• 0.8V to V_CC Output Range
• Full Duty Cycle Range- 0% to 100%
• Internal Loop Compensation
• Internal Soft Start- Typical 2ms
• Programmable Over-Current Protection- Lossless Sensing Using MOSFET R_{DS (ON)}
• Under-Voltage Protection
• Drives External N-Channel MOSFETs
• Shutdown Control
• Small SOP-8 Package




Application

• Motherboard
• Graphics Cards
• Cable or DSL Modems, Set Top Boxes
• DSP Supplies
• Memory Supplies
• 5V Input DC-DC Regulators
• Distributed Power Supplies




Pinout






Specifications

Symbol	Parameter	Rating	Unit
VCC	VCC Supply Voltage (VCC to GND)	-0.3 ~ 7	V
VBOT	BOOT Supply Voltage (BOOT to GND)	-0.3 ~ 15	V
	PHASE, OCSET to GND Input Voltage	-0.3 ~ 12	V
	FB to GND Input Voltage	-0.3 ~ VCC+0.3	V
	Maximum Junction Temperature	125
TSTG	Storage Temperature	-65 ~ 150
TSDR	Maximum Soldering Temperature, 10 Seconds	300
VESD	Minimum ESD Rating (Human body model)	±2	KV

Description

The APW7057 is a 300kHz constant frequency voltagemode synchronous switching controller that drivesexternal N-channel MOSFETs. When the input supplydrops close to output, the upper MOSFET remainson, achieving 100% duty cycle. Internal loop compensationis optimized for fast transient response, eliminatingexternal compensation network. The precision
0.8V reference makes this part suitable for a wide varietyof low voltage applications. Soft start is internallyset to 2ms, limiting the input in-rush current and preventingthe output from overshoot during powering up.The APW7057 has over current and short circuitprotections. Over current protection is achieved bymonitoring the voltage drop across the high side
MOSFET, eliminating the need for a current sensingresistor and short circuit condition is detectedthrough the FB pin. If either fault conditions occur,the APW7057 would initiate the soft start cycle. Afterthree cycles and if the fault condition persists, thecontroller will be shut down. To restart the controller,either recycle the V_CC supply or momentarily pull theOSCSET pin below 1.25V.The APW7057 can be shutdown by pulling the OCSETpin below 1.25V. In shutdown, both gate drive signalswill be low. The controller is available in a small SOP-8 package.