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MAX8847Z

High-Performance Negative Charge Pump for 6 White LEDs in 3mm x 3mm Thin QFN

Maxim Integrated 

MAX8847Y/MAX8847Z

High-Performance Negative Charge Pump

for 6 White LEDs in 3mm x 3mm Thin QFN

Pin Configuration

TOP VIEW

12 11 10 9

LED6 13

ENB 14

CPWM 15

MAX8847Y

MAX8847Z

ENA 16

+

EP

1

2

3

4

THIN QFN

8 LED1

7 NEG

6 C1N

5 C2N

PIN

1

2

3

4

5

6

7

8–13

14

Pin Description

NAME

IN

GND

C1P

C2P

C2N

C1N

NEG

LED1–LED6

ENB

FUNCTION

Supply Voltage Input. The input voltage range is 2.7V to 5.5V. Bypass IN to GND with a 1FF ceramic

capacitor as close as possible to the IC. IN is high impedance during shutdown. Connect IN to the

anodes of all the LEDs.

Ground. Connect GND to system ground and the input bypass capacitor as close as possible to the IC.

Transfer Capacitor 1 Positive Connection. Connect a 1FF ceramic capacitor from C1P to C1N.

Transfer Capacitor 2 Positive Connection. Connect a 1FF ceramic capacitor from C2P to C2N.

Transfer Capacitor 2 Negative Connection. Connect a 1FF ceramic capacitor from C2P to C2N. An

internal 10kI resistor pulls C2N to GND during shutdown.

Transfer Capacitor 1 Negative Connection. Connect a 1FF ceramic capacitor from C1P to C1N.

Charge-Pump Negative Output. Connect a 1FF ceramic capacitor from NEG to GND. In shutdown, an

internal 10kI resistor pulls NEG to GND. Connect the exposed pad to NEG directly under the IC.

LED Current Regulators. Current flowing into LED_ is based on the ENA/ENB input. Connect LED_ to

the cathodes of the external LEDs. LED_ is high impedance during shutdown. Short any unused LED_

to IN prior to power-up to disable the corresponding current regulator.

Enable or Serial-Pulse Dimming Control Input B. ENB controls LED5 and LED6. For the MAX8847Z,

ENB functions as on/off control for LED5 and LED6. For the MAX8847Y, except on/off control func-

tion, ENB can also be used to control the LED5 and LED6 serial-pulse dimming. Drive ENB high to

turn on the LED5 and LED6 current regulators at 24mA. Drive ENB low for greater than 8ms to turn off

the LED5 and LED6 current regulators or drive both ENA and ENB low to place the IC in shutdown.

For the MAX8847Y LED5 and LED6 serial-pulse diming control, see the Serial-Pulse Dimming Control

(MAX8847Y) section for details.

Maxim Integrated

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