AP1601
Step-Up 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. 1.1 Apr. 14, 2005
1/9

„ Features

-A Guaranteed Start-Up from less than 0.9 V.
-High Efficiency.
-Low Quiescent Current.
-Less Number of External Components needed.
-Low Ripple and Low Noise.
-Space Saving Packages: MSOP-8L and
MSOP-10L.


„ Applications

-Pagers.
-Cameras.
-Wireless Microphones.
-Pocket Organizers.
-Battery Backup Suppliers.
-Portable Instruments.


„ General Description

The AP1601 is a high efficiency step-up DC/DC
converter for applications using 1 to 4 NiMH battery
cells. Only three external components are required
to deliver a fixed output voltage of 3.3V or 5V. The
AP1601 starts up from less than 0.9V input with
1mA load. Pulse Frequency Modulation scheme
brings optimized performance for applications with
light output loading and low input voltages. The
output ripple and noise are lower compared with the
circuits operating in PSM mode.
The PFM control circuit operating in 100KHz (max.)
switching rate results in smaller passive
components. The space saving MSOP packages
make the AP1601 an ideal choice of DC/DC
converter for space conscious applications, like
pagers, electronic cameras, and wireless
microphones.
„ Pin Assignments


1
3
2
4
8
6
7
5
MSOP-8L
FB
LBI
REF
OUT
LX
GND
LBO
SHDN



1
3
2
10
8
9
MSOP-10L
FB
LBI
OUT
LX
GND
47CLSEL
56
REF
BATT
SHDN
LBO





„ Pin Descriptions

Name Description
FB
Use a resistor network to set the output
voltage from +2.0V to +5.5V.
If FB=Vout, Vout=3.3V fix voltage
FB=GND, Vout=5V fix voltage
LBI
Low-Battery Comparator Input. Internally set
to trip at +1.30V.
LBO
Open-Drain Low-Battery Comparator Output.
Connect LBO to OUT through a 100kΩ
resistor. Output is low when V
LBI
is <1.2V.
LBO is high impedance during shutdown.
REF
1.2V Reference Voltage. Bypass with a 0.1µF
capacitor.
OUT
Power Output. OUT provides bootstrap power
to the IC.
LX
N-Channel and P-Channel Power MOSFET
Drain
GND Ground
SHDN
Shutdown Input. Drive high (>80% of V
OUT
) for
operating mode. Drive low (<20% of V
OUT
) for
shutdown mode. Connect to OUT for normal
operation.
CLSEL
Current-Limit Select Input. CLSEL = OUT sets
the current limit to 0.8A. CLSEL = GND sets
the current limit to 0.4A.
BATT
Battery Input and Damping Switch
Connection. If damping switch is unused,
leave BATT unconnected.