1 General Description
The AS3688 is a highly-integrated CMOS Power
and Lighting Management Unit to supply power to
LCD-and cameramodules in mobile telephones, and
other 1-cell Li+ or 3-cell NiMH powered devices.
The AS3688 incorporates one low-power, lowdropout
regulator (LDO), one Step Up DC/DC
Converter for white backlight LEDs, one high-power
Charge Pump for camera flash LEDs, one Analogto-
Digital Converter, support for up to 11 current
sinks, a two wire serial interface, and control logic
all onto a single device. Fully programmable.
The AS3688 is a successor to the
austrimicrosystems AS3681 with several additional
features (Charge Pump Automatic Up Switching,
Extended timer features, autonomous logarithmic
PWM dimming, LED pattern generator, DCDC step
up overvoltage protection, improved Charge Pump
and a fourth high current sink).
2 Key Features
New features of the AS3688 compared to the
AS3681 are written in boldface italics.

Programmable High-Performance Regulator
− Low-Noise LDO (1.85 to 3.4V, 150mA)
− Default off after Power-up
− 3μA Quiescent Current in Standby
− Programmable via Serial Interface

High-Efficiency Step Up DC/DC Converter
− Up to 25V/50mA for White LEDs
− Programmable Output Voltage with
External Resistors and Serial Interface
− Overvoltage Protection
− 0.1Ohm Shunt Resistor

High-Efficiency High-Power Charge Pump
− 1:1, 1:1.5, and 1:2 Mode
− Automatic Up Switching (can be
disabled and 1:2 mode can be blocked)
− Output Current up to 400mA / 900mA
pulsed
− Efficiency up to 95%
− Very Low effective Resistance (0.5W typ.
1W max. in 1:1 mode, 1.4W typ. 2W max.
in 1:1.5)
− Only 4 External Capacitors Required:
2 x 1μF Flying Capacitors, 2 x 2.2μF
− Supports LCD White Backlight LEDs,
− Camera Flash White LEDs, and Keypad
Backlight LEDs

Supports up to 12 Current Sinks
− Four Programmable (8+1Bit) from: 0.6mA
to 300mA
− Two High Voltage Programmable (8-bit)
from: 0.15mA to 38.25mA
− Three Programmable (8-bit) from: 0.15mA
to 38.25mA for RGB LEDs
− Three (AS3688B only; AS3688: One)
Programmable (8-bit) from: 0.15mA to
38.25mA for General Purpose
− Programmable Hardware Control (Strobe,
and Preview or PWM)
− Selectively Enable/Disable Current Sinks
Internal PWM Generation
− 8 Bit resolution
− Logarithmic up/down dimming
Led Pattern Generator
− Autonomous driving for any LED
10-bit Successive Approximation ADC
− 27μs Conversion Time
− Four Selectable Inputs: GPIO0-3
− Internal Temp. Measurement
− Support for Light Sensor, inluding a
adjustable current source (0-15uA)
Support for automatic LED function testing
(open and shorted LEDs can be identified)
Support for external Temperature Sensor
for high current LED protection (CURR3x)
Strobe Timeout protection
− Up to 1600ms
− Three different timing modes
TXMask function (reduce current during
Strobe) selectable on pin GPIO1
Four General Purpose Inputs/Outputs
− GPIO0-2 Input/Output, GPI only Input
− Digital Input, Digital Output, and Tristate
− Programmable Pull-Up, and Pull-Down
− GPI can be used as Flash Strobe
− GPIO2 can be used for Preview Mode
− GPIO0/2 can used for PWM input
Negative or High-Voltage Charge Pump
− Regulated Output Voltage, Programmable
by Dual Resistors e.g. -6V, 10mA for
OLED or ±15V, 5mA for TFT
− ±5% Accuracy
Standby LDO always on
− Regulated 2.5V max. output 10mA
− 3μA Quiescent Current
Wide Battery Supply Range: 3.0 to 5.5V
Two Wire Serial Interface Control
Overcurrent and Thermal Protection
Package QFN32 5x5mm
3 Application
Power- and lighting-management for mobile
telephones and other 1-cell Li+ or 3-cell NiMH
powered devices.