A8435 Datasheet, PDF (1/9 Pages) Allegro MicroSystems – High Efficiency Charge Pump White LED Driver

A8435
High Efficiency Charge Pump White LED Driver
Features and Benefits
▪ Proprietary adaptive control scheme (1×, 1.5×)
▪ Maximum efficiency, over 92%
▪ 0.5% LED current matching
▪ 1 MHz operating frequency
▪ Flexible dimming control:
▫ Serial 11-level dimming, down to 5%
▫ PWM
▫ 2-bit parallel
▪ Drives up to 4 white LEDs
▪ 30 mA per LED
▪ 120 mA total continuous output
▪ Low input ripple and EMI
▪ Soft-start limits inrush current
▪ Short circuit protection
▪ Overvoltage protection
▪ Thermal shutdown protection
▪ Space-saving MLP-16 package: 3 × 3 mm footprint
▪ Very thin 0.75 mm nominal height package
Package: 16 pin QFN/MLP (suffix ES)
Approximate Scale
Description
The A8435 high efficiency charge pump IC offers a simple,
low-cost white LED driver solution for portable electronics
display applications. Using a proprietary control scheme (1×,
1.5×), the A8435 can output well-matched currents for up to
4 LEDs, while maintaining the highest efficiency over most
of the Li-ion battery lifetime.
The A8435 accepts an input range of 2.7 to 5.5 V and delivers
up to 30 mA for each of the four regulated current sources. The
A8435 can deliver a total continuous output current of 120 mA,
meeting the requirements of most Li-ion battery-powered white
LED backlight applications. Outputs can also be tied together
for WLED flash/torch applications.
The A8435 offers flexible options for LED current driving.
The LED current can be set by any of the following methods:
(a) choosing an appropriate value for RSET, (b) 2-bit
parallel control with 3 levels, (c) PWM control, or (d) serial
programming
The A8435 is available in a very thin profile 0.75 mm (nominal
height) 3 × 3 mm QFN/MLP-16 package (ES), fitting the needs
of space-conscious applications.
Applications include:
▪ White LED backlights for cellular phones, PDAs
▪ Digital cameras, camcorders
▪ Portable audio devices
▪ Other portable device white LED backlighting
▪ 120 mA WLED flash/torch
Typical Applications
CIN
1 µF
VBATT
2.7 to 5.5 V
VIN
C1
C1+
1 µF
C1–
C2
C2+
1 µF
C2–
EN1
EN2
On/Off and
NC CTRL
Dimming Control
VOUT
LED1
A8435 ^LED2
LED3
GND
LED4
ISET
COUT
1 µF
RSET
Figure 1. Typical Circuit. Dual wire control configuration: 2-bit
parallel or PWM dimming.
VBATT
2.7 to 5.5 V
CIN
1 µF
C1
1 µF
C2
1 µF
Single-Wire On/Off and
Dimming Control
VIN
C1+
C1-
C2+
C2-
EN1
EN2
CTRL
VOUT
LED1
A8435 ^LED2
LED3
GND
LED4
ISET
COUT
1 µF
RSET
Figure 2. Typical Circuit. Single wire control configuration.
A8435-DS, Rev. 1