Rainbow Electronics MAX8848Z - Manual (Page 8)

High-Performance Negative Charge Pump
for 7 White LEDs in 3mm x 3mm Thin QFN
MAX8848Y/MAX8848Z
8 ______________________________________________________________________________________
Pin Description (continued)
PIN
NAME FUNCTION
MAX8848Y MAX8848Z
8–14 8–14 LED1–LED7
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 imped-
ance during shutdown. Short any unused LED_ to IN prior to power-up to disable
the corresponding current regulator.
15 — ENB
Enable and Serial-Pulse Dimming Control Input B for the MAX8848Y. ENB con-
trols LED6 and LED7. Drive ENB high to turn on the LED6 and LED7 current
regulators at 24mA. Drive ENB low for greater than 8ms to turn off the current
regulators or drive both ENA and ENB low to place the IC in shutdown. In addi-
tion to the enable function, ENB can also be used to control the LED6 and LED7
serial-pulse dimming.
— 15 CPWM
Filter Capacitor Connection for PWM Dimming for the MAX8848Z. Connect a
capacitor from CPWM to GND to form a filter with the internal 360kI resistor. The
recommended capacitor for a 2Hz corner frequency is 0.22FF.
16 16 ENA
Enable and PWM/Serial-Pulse Dimming Control Input A. ENA controls LED1–
LED5 for the MAX8848Y, and LED1–LED7 for MAX8848Z. Drive ENA high to turn
on all the controlled LED current regulators at 24mA. Drive ENA low for greater
than 8ms to turn off the current regulators or drive both ENA and ENB low to
place the IC in shutdown. Drive ENA with a PWM signal from 200Hz to 200kHz to
dim LED1–LED7 for the MAX8848Z. See the PWM Dimming Control (MAX8848Z)
section. For the MAX8848Y, ENA controls the LED1–LED5 serial-pulse dimming.
— — EP Exposed Paddle. Connect EP to NEG directly under the IC.