19-3117; Rev 0; 12/03
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
General Description
Features
The MAX1574 charge pump drives up to three white
LEDs with regulated constant current for uniform intensity.
By utilizing adaptive 1x/2x charge-pump modes and
very-low-dropout current regulators, it achieves 180mA
output drive capability and high efficiency over the 1-cell
lithium-battery input voltage range. Fixed-frequency
(1MHz) switching allows for tiny external components,
and the regulation scheme is optimized to ensure low EMI
and low input ripple.
♦ Up to 180mA (60mA/LED) Drive Capability
♦ 83% Average Efficiency (P
/ P
) Over Li+
LED
BATT
Battery Discharge
♦ 0.5% (typ) LED Current Matching
♦ Adaptive 1x/2x Mode Switchover
♦ Low Input Ripple and EMI
♦ 5% to 100% Dimming Through Single-Wire Serial
The MAX1574 uses an external resistor to set the full-
scale 100% LED current. An enable input (EN) is used for
simple on/off control or can be pulsed repeatedly to set
lower LED current in multiple steps down to 5%. Once the
desired brightness is set, the MAX1574 maintains con-
stant LED current as long as EN is kept high. If EN is kept
low for more than 2ms, the MAX1574 enters shutdown.
Pulse Interface
♦ Low 0.1µA Shutdown Current
♦ 2.7V to 5.5V Supply Voltage Range
♦ Soft-Start Limits Inrush Current
♦ Output Overvoltage Protection
♦ Thermal-Shutdown Protection
♦ 10-Pin 3mm x 3mm TDFN Package
The MAX1574 is available in a 10-pin 3mm x 3mm TDFN
package (0.8mm max height).
Applications
Ordering Information
LCD Backlighting
PIN-
PACKAGE
TOP
MARK
PART
TEMP RANGE
Camera Strobes/Flashes and Movie Lights
Cell Phones/Smart Phones
10 TDFN
3mm x 3mm
MAX1574ETB
-40°C to +85°C
ABB
PDAs, Digital Cameras, and Camcorders
Typical Operating Circuit
Pin Configuration
0.22µF
TOP VIEW
CP
CN
10
9
8
7
6
2.7V TO 5.5V
UP TO 180mA
IN
OUT
1µF
1µF
MAX1574
GND
EN
MAX1574
LED1
LED2
LED3
ON/OFF AND
DIMMING
4
1
2
3
5
SET
TDFN
3mm × 3mm
________________________________________________________________ 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.