Rainbow Electronics MAX5439 - Manual (Page 9)

MAX5436–MAX5439
±15V, 128-Tap, Low-Drift Digital Potentiometers
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CONTROL
V BATT
V OUT
(LCD BIAS)
MICROCONTROLLER/MICROPROCESSOR
FIXED ±28V IN
LCD
PANEL
±16V TO ±26V CONTRAST ADJUST
DC/DC CONVERTER
(SIMPLIFIED)
MAX5436–
MAX5439 MAX629
Figure 5a. Simplified LCD Contrast Control Circuit
H L
R1
R2
+15V
-15V
V S
V O
V O /V S = 1 + R 2 /R 1
W
MAX5436–
MAX5439
MAX427
Figure 4. Noninverting Amplifier
CONTROL
V BATT
V OUT
(LCD BIAS)
MICROCONTROLLER/MICROPROCESSOR
FIXED ±28V IN
LCD
PANEL
±16V TO ±26V CONTRAST ADJUST
DC/DC CONVERTER
(SIMPLIFIED)
MAX5437/
MAX5439 MAX629
Figure 5b. Simplified LCD Contrast Control Circuit with Buffer