max8879etg Maxim Integrated Products, Inc., max8879etg Datasheet - Page 7

• Manufacturer Part Number: max8879etg
• Description: Charge Pump For Backlight/flash/rgb Leds With Safety Timer
• Manufacturer: Maxim Integrated Products, Inc.

PIN
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
—
1
2
3
4
5
6
7
8
9
Charge Pump for Backlight/Flash/RGB LEDs
NAME
PGND
GND
OUT
SCK
SDA
C1N
C2N
V
FSH
C1P
C2P
PIN
M4
M3
M2
M1
_______________________________________________________________________________________
F4
F3
F2
F1
S3
S2
S1
EP
IN
DD
Power-Supply Voltage Input. Connect PIN to IN. Connect a 4.7µF ceramic capacitor from PIN to
PGND. The input voltage range is 2.7V to 5.5V. PIN is high impedance during shutdown.
Analog Supply Voltage Input. Connect IN to PIN. The input voltage range is 2.7V to 5.5V. IN is high
impedance during shutdown.
Ground. Connect GND to system ground and the ground side of the input bypass capacitor as close
to the IC as possible.
Logic-Input Supply Voltage. Connect V
ceramic capacitor from V
LED Cathode Connections. Current flowing into these pins is based on the internal I
registers. The charge pump regulates the lowest LED cathode voltage to 0.15V. Grounding any of
these pins forces output overvoltage protection mode causing OUT to pulse on and off at
approximately 5V. To avoid constantly operating in overvoltage protection mode, any unused LED
cathode connection (M_, S_, or F_) must be connected to OUT. This disables the corresponding
current regulator. These pins are high impedance in shutdown.
M1 through M4 are for main display backlights.
S1 through S3 are for subdisplay backlights or one RGB LED indicator.
F1 through F4 are for LED flash.
Any combination of M_, S_, and F_ can be connected together to drive higher current LEDs.
Flash Logic Input. Drive FSH low to turn on the flash LEDs (F1–F4) at the current specified in the
internal flash register. The built-in flash timer is activated by synchronizing with the active-low falling
edge on the pin. Drive FSH high to turn off the flash LEDs. This logic-high/low signal is only dedicated
for enabling or deactivating flash LEDs. If the embedded flash timer expires in a certain time, it is not
reactivated unless a falling edge is monitored again.
I
I
Transfer Capacitor 1 Negative Connection. Connect a 1µF ceramic capacitor from C1N to C1P. C1N
is shorted to IN during shutdown.
Transfer Capacitor 1 Positive Connection. Connect a 1µF ceramic capacitor from C1N to C1P. During
shutdown, if V
Power Ground. Charge-pump switching ground. Connect to GND and EP as close to the IC as
possible.
Output. Connect a 10µF ceramic capacitor from OUT to PGND. The anodes of all the LEDs connect
to OUT. OUT is pulled to ground through an internal 5kΩ resistor in shutdown.
Transfer Capacitor 2 Positive Connection. Connect a 1µF ceramic capacitor from C2N to C2P. During
shutdown, if V
Transfer Capacitor 2 Negative Connection. Connect a 1µF ceramic capacitor from C2N to C2P. C2N
is shorted to IN during shutdown.
Exposed Paddle. Connect to GND and PGND directly under the IC.
2
2
C Clock Input. Data is read on the rising edge of SCK.
C Data Input. Data is read on the rising edge of SCK.
OUT
OUT
> V
> V
IN
IN
, C1P is shorted to OUT. If V
, C2P is shorted to OUT. If V
DD
to GND.
DD
to the logic supply driving SDA and SCK. Connect a 0.1µF
FUNCTION
OUT
OUT
with Safety Timer
< V
< V
IN
IN
, C1P is shorted to IN.
, C2P is shorted to IN.
Pin Description
2
C dimming
7