Rainbow Electronics MAX758A - Manual (Page 9)

saturation region. When shut down, the input voltage
exceeds the emitter voltage so the inactive transistor
provides high-impedance isolation between the input
and output. Efficiency will be slightly degraded due to
the PNP transistor saturation voltage and base current.
V
IN
=
0.8V TO
V
OUT
V NEG
-19V
V CC =
2.4V TO
5.5V
D3**
D2*
D1*
R1
240k
R2
16.5k
ON
OFF SHDN
V CC
LIM
GND
LX
FB
MAX1605
L1
10 µH
C3
0.1 µF
C6
0.1 µF
C4
0.01 µF
C1
1000pF
C2
1 µF
R3
1 Ω
C5
1 µF
*D1, D2 = CENTRAL SEMICONDUCTOR
CMPD7000 DUAL
**D3 = CENTRAL SEMICONDUCTOR
CMSD4448 (1N4148)
Figure 4. Negative Voltage for LCD Bias
MAX1605
28V Internal Switch LCD Bias Supply
in SOT23
_______________________________________________________________________________________ 9
V IN = 0.8V TO V OUT
R3 = 180k
V CC = 2.4V TO 5.5V
V OUT = 18V
ON
OFF
R1
R2
SHDN
V CC
2N2907A
V SET = 18.3V
(V OUT +0.3V)
LIM
GND
LX
FB
MAX1605
L1
10 µH
Figure 5. Output Disconnected in Shutdown
Chip Information
TRANSISTOR COUNT: 2329