MAX1570 Datasheet, PDF (1/11 Pages) Maxim Integrated Products – White LED Current Regulator with 1x/1.5x High-Efficiency Charge Pump

19-2526; Rev 0; 7/02
White LED Current Regulator with 1x/1.5x
High-Efficiency Charge Pump
General Description
The MAX1570 fractional charge pump drives up to five
white LEDs with regulated constant current for uniform
intensity. The MAX1570 maintains the highest possible
efficiency over the full 1-cell lithium-ion (Li+) battery
input voltage range by utilizing a 1x/1.5x fractional
charge pump and very-low-dropout current regulators.
The MAX1570 operates with 1MHz fixed-frequency
switching, allowing for tiny external components. The
regulation scheme is optimized to ensure low EMI and
low input ripple.
An external resistor sets the full-scale LED current,
while two digital inputs control on/off and select
between three levels of brightness. A pulse-width mod-
ulation (PWM) signal can also be used to modulate LED
brightness.
The MAX1570 is available in 16-pin 4mm ✕ 4mm Thin
QFN packaging (0.8mm max height).
Applications
White LED Backlighting
Cell Phones and Smart Phones
PDA and Palmtop Computers
Portable MP3 Players
Digital Cameras and Camcorders
Features
o Excellent 0.3% LED-to-LED Current Matching
o 30mA/LED Drive Capability
o Proprietary 1x/1.5x Modes for Ultra-High
Efficiency
o Low Input Ripple and EMI
o Eliminates Ballast Resistors
o Digital or PWM LED Dimming Control
o 0.1µA Shutdown Current
o 2.7V to 5.5V Supply Voltage Range
o Soft-Start Limits Inrush Current
o Thermal-Shutdown Protection
o No External Inductor, Schottky, or Zener Diode
Required
o Tiny 16-Pin 4mm ✕ 4mm Thin QFN Package
PART
MAX1570ETE
Ordering Information
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
16 Thin QFN
Pin Configuration
C2N OUT C2P IN
16 15 14 13
C1P 1
EN2 2
GND 3
LED5 4
MAX1570
12 C1N
11 PGND
10 EN1
9 SET
5678
LED4 LED3 LED2 LED1
THIN QFN
(4mm x 4mm)
Typical Operating Circuit
1µF
1µF
C1P C1N C2P C2N
2.7V TO 5.5V _IN
1µF
1x/1.5x
REGULATING CHARGE PUMP
OUT
4.7µF
ON/OFF ^EN1
AND EN2
DIMMING _SET
RSET
MAX1570
LED1
REFERENCE
AND
CONTROL
LED2
LOW-DROPOUT _LED3
CURRENT
REGULATORS ^LED4
LED5
GND
PGND
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.