MAX8847Y Datasheet, PDF (1/13 Pages) Maxim Integrated Products – High-Performance Negative Charge Pump for 6 White LEDs in 3mm x 3mm Thin QFN

19-5196; Rev 0; 4/10
EVAALVUAAILTAIOBNLEKIT
High-Performance Negative Charge Pump
for 6 White LEDs in 3mm x 3mm Thin QFN
General Description
The MAX8847Y/MAX8847Z negative charge pumps
drive up to 6 white LEDs with regulated constant current
for display backlight applications. By utilizing an invert-
ing charge pump and extremely low-dropout adaptive
current regulators, these ICs achieve very high efficiency
over the full 1-cell Li+ battery voltage range even with
large LED forward voltage mismatch. The 1MHz fixed-
frequency switching allows for tiny external components.
The regulation scheme is optimized to ensure low EMI
and low input ripple. The MAX8847Y/MAX8847Z include
thermal shutdown, open- and short-circuit protection.
The MAX8847Y/MAX8847Z support independent LED
on/off and dimming control. The MAX8847Z has PWM
dimming control for LED1–LED6. The MAX8847Y has
PWM dimming control for LED1–LED4 and serial-pulse
dimming control for LED5 and LED6. The serial-pulse
dimming ranges are pseudo-logarithmic from 24mA to
0.1mA and off in 32 steps. All devices include a tempera-
ture derating function to safely allow bright 24mA full-
scale output current while automatically reducing current
gradually to protect LEDs at high ambient temperatures
above +60°C.
The MAX8847Y/MAX8847Z are available in 16-pin,
3mm x 3mm thin QFN packages.
Applications
White LED Backlighting
Cellular Phones
PDAs, Digital Cameras, and Camcorders
Ordering Information
PART
DIMMING
PIN-PACKAGE
TOP
MARK
MAX8847YETE+T
Serial pulse/
PWM
16 Thin QFN-EP*
AHQ
MAX8847ZETE+T PWM
16 Thin QFN-EP* AHP
Note: All devices are specified over the -40°C to +85°C
extended temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Features
S Negative 1x/1.5x Charge Pump
S Adaptive Current Regulators
S Independent Voltage Supply for Each LED
S 24mA to 0.1mA Serial-Pulse Dimming (MAX8847Y)
S 24mA to 0mA PWM Dimming (MAX8847Z)
S 2% (max) LED Current Accuracy, 1% (typ) Matching
S Low 120µA Quiescent Current
S Low 0.4µA Shutdown Current
S Inrush Current Limit
S Temperature Derating Function
S 16-Pin, 3mm x 3mm Thin QFN Packages
Typical Operating Circuit
1µF
1µF
INPUT
2.7V TO 5.5V
1µF
LED ENABLE
AND
DIMMING
CONTROL
0.22µF
C1P
IN
GND
C1N C2P
C2N
NEG
EP
MAX8847Y ^LED1
MAX8847Z
ENA
LED2
ENB
LED3
CPWM
LED4
LED5
LED6
1µF
D1
D2
D3
D4
D5
D6
________________________________________________________________ Maxim Integrated Products   1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.