MAX8822 Datasheet, PDF (1/15 Pages) Maxim Integrated Products – Ultra-Efficient Negative Charge-Pump LED Driver with Dual LDOs in 3mm x 3mm Thin QFN

19-0847; Rev 0; 11/07
EVAALVUAAILTAIOBNLEKIT
Ultra-Efficient Negative Charge-Pump LED
Driver with Dual LDOs in 3mm x 3mm Thin QFN
General Description
The MAX8822 drives up to four white light-emitting
diodes (LEDs) with regulated constant current for dis-
play backlighting in cell phones, digital cameras, PDAs,
and other handheld devices. By utilizing a proprietary
negative 0.5x inverting charge pump and innovative
independent low-dropout (LDO) adaptive current regu-
lators, very high efficiency is achieved over the full
1-cell Li+ battery voltage range, even with large LED V_F
mismatch. The 1MHz fixed-frequency switching allows
for tiny external components. The regulation scheme is
optimized to ensure low EMI and low input ripple. Two
200mA, low-noise, high power-supply-rejection-ratio
(PSRR) LDOs with programmable output voltages are
included on-chip to provide power to camera modules
or other devices.
The MAX8822 features a single-wire, serial-pulse control-
logic interface that programs LED current and the output
voltages of the LDOs. The LED dimming range is pseu-
do-logarithmic from 24mA to 0.1mA in 31 steps. LDO
output voltages are programmable in 16 different combi-
nations to meet various camera module requirements.
The MAX8822 includes soft-start, thermal shutdown,
open- and short-circuit protection.
Applications
White LED Backlighting
Cell Phones and Smartphones
Typical Operating Circuit
INPUT
2.7V TO 5.5V
1μF
1μF
C1P
C1N C2P
C2N
Features
♦ High-Efficiency Charge Pump for Up to Four
White LEDs
Independent Adaptive Voltage Supply for Each
LED
24mA to 0.1mA Dimming Range
1% (typ) Current Accuracy and 0.3% Current
Matching
Low 65µA (typ) Quiescent Current
♦ Dual 200mA Low-Noise, High PSRR LDOs
16 Different Output Voltage Combinations Up to
3.3V
High 60dB PSRR at 10kHz
♦ Flexible Single-Wire Control for Dimming and
LDO Output Voltage
♦ Low 0.5µA (typ) Shutdown Mode
♦ Soft-Start Limits Inrush Current
♦ Thermal Shutdown and Open- and Short-Circuit
Protection
♦ Tiny 16-Pin, 3mm x 3mm Thin QFN Package
(0.8mm max Height) with Exposed Paddle
Ordering Information
PART
PIN-PACKAGE
TOP MARK
PKG
CODE
MAX8822ETE+
16 Thin QFN-EP*
(3mm x 3mm)
AFW
T1633-5
Note: The device is specified over the -40°C to +85°C extend-
ed temperature range.
+Denotes a lead-free package.
*EP = Exposed paddle.
Pin Configuration
4.7μF
SERIAL-
PULSE
CONTROL
INTERFACE
0.1μF
IN
MAX8822
GND
ENLED
ENLDO
REF
EP
LED1
LED2
LED3
LED4
UP TO 24mA/LED
NEG
2.2μF
LDO1
LDO2
VLDO1
VLDO2
1μF
1μF
TOP VIEW
12 11 10 9
LDO2 13
8 LED4
ENLED 14
ENLDO 15
MAX8822
7 NEG
6 C1N
REF 16
5 C2N
+1
2
3
4
THIN QFN
(3mm x 3mm)
________________________________________________________________ Maxim Integrated Products 1
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or visit Maxim's website at www.maxim-ic.com.