Rainbow Electronics MAX1574 - Manual

General Description
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.
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.
The MAX1574 is available in a 10-pin 3mm x 3mm TDFN
package (0.8mm max height).
Applications
LCD Backlighting
Camera Strobes/Flashes and Movie Lights
Cell Phones/Smart Phones
PDAs, Digital Cameras, and Camcorders
Features
♦ Up to 180mA (60mA/LED) Drive Capability
♦ 83% Average Efficiency (P LED / P BATT ) Over Li+
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
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
MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
________________________________________________________________ Maxim Integrated Products 1
TOP VIEW
MAX1574
TDFN
3mm × 3mm
10 9 8 7
OUT GND LED1 LED2
6
LED3
1 2 3 4
IN EN CP CN
4 5
SET
Pin Configuration
Ordering Information
1µF
1µF
MAX1574
LED3
LED2
LED1
OUT
SET
EN
GND
IN
0.22µF
CP CN
2.7V TO 5.5V
ON/OFF AND
DIMMING
UP TO 180mA
Typical Operating Circuit
19-3117; Rev 0; 12/03
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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE
PIN-
PACKAGE TOP
MARK
MAX1574ETB -40°C to +85°C
10 TDFN
3mm x 3mm
ABB