Diodes ZXSC410/ZXSC420/ZXSC440 - Manual (Page 12)

ZXSC410/ZXSC420/ZXSC440
Document number: DS33618 Rev. 5 - 2
12 of 17
www.diodes.com
March 2013
© Diodes Incorporated
ZXSC410/ZXSC420/ZXSC440
Application Examples
(cont.)
Triple Output TFT Bias Generator
ZXSC410 as Triple Output TFT Bias
Sequencing A
VDD
and V
ON
By adding the circuit below to the LCD bias output (V
ON
) of
the converter a 10ms delay can be achieved between A
VDD
power up and V
ON
power up. The circuit operates by a delay
in turning the PMOS transistor on, which transfers to a 10ms
delay between input and output of the circuit.
The delay is set by the RC time constant of R1 and C1. The
diode, D1, discharges the gate of the PMOS when the main
system supply is turned off, guaranteeing a delay every turn
on cycle.
System
Voltage
A
VDD
C1
0.1µF
R1
470k
LCD Bias
Voltage
V
ON
Q1
ZXMP3A13F
Sequenced Output
10ms Delay
ZXSC410
Q1 ZXTN
25012EFH
C1
10µF
C5
1µF
C2
47µF
R1
22mΩ
R2
30kΩ
R3
1kΩ
L1
22µH
U1
D1
BAT54
V
CC
STDN
GND
V
DRIVE
I
SENSE
V
FB
C7
1µF
C6
1µF
C8
1µF
C4
1µF
V
ON
27V, 10mA
A
VDD
9V, 180mA
V
OFF
-9V, 10mA
C3
1µF
V
IN
4.2V ~ 3V
BAT54S
BAT54S
BAT54S