AP1551
150KHz, Dual Channel 2A PWM Buck DC/DC Converter


This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of
this product. No rights under any patent accompany the sale of the product.
Rev. 1.0 Nov 17, 2004
1/8


„ Features

- Dual adjustable output channel
- Adjustable output voltage range, 1.23V to
18V+4%
- 150KHz +15% fixed switching frequency
- Voltage mode non-synchronous PWM control
- Thermal-shutdown and current-limit protection
- ON/OFF shutdown control input
- Operating voltage can be up to 22V
- Output load current: 2A
- SOP-16L Pb-Free packages
- Low power standby mode
- Built-in switching transistor on chip

„ Applications

- Simple High-efficiency step-down regulator
- On-card switching regulators
- Positive to negative converter







„ General Description

The AP1551 is monolithic IC designed for dual
channel step-down DC/DC converters, and own the
ability of driving a 2A load each channel without
additional transistor component. Due to reducing
the number of external component, the board
space can be saved easily. The external shutdown
function can be controlled by logic level and then
come into standby mode. The internal
compensation makes feedback control have good
line and load regulation without external design.
Regarding protected function, thermal shutdown is
to prevent over temperature operating from damage,
and current limit is against over current operating of
the output switch. If current limit function occurred
and V
FB
is down to 0.5V below, the switching
frequency will be reduced. The AP1551 operates
at a switching frequency of 150KHz thus allowing
smaller sized filter components than what would be
needed with lower frequency switching regulators.
Other features include a guaranteed +4% tolerance
on output voltage under specified input voltage and
output load conditions, and +15% on the oscillator
frequency. The packages are available in a
standard 16-lead SOP-16 package.


„ Pin Assignments


1
2
3
15
14
13
12
11
10
98
7
6
5
4
16
( Top View )
SOP-16L
GND2
GND2
FB2
V
OUT2
FB1
V
OUT1
GND1
GND1
GND2
GND2
SD2
V
IN2
SD1
V
IN1
GND1
GND1



„ Pin Descriptions



Name Description
V
IN1/2
Operating voltage input
V
OUT1/2
Switching output
GND1/2 Ground
FB1/2 Output voltage feedback control
SD1/2 ON/OFF Shutdown