Rainbow Electronics MAX1621 - Manual (Page 19)

MAX1620/MAX1621
Digitally Adjustable LCD Bias Supplies
______________________________________________________________________________________ 19
___________________Chip Information
TRANSISTOR COUNT: 341
SUBSTRATE CONNECTED TO AGND
R1
360k
2V
TO
12V
BATT
POK
D1
MBRS0540+
Q1
MMBT4401LT1 Q1
MMBT2907
V DD
POL
SHDN (SUS)
DN (SDA)
UP (SCL)
REF
AGND
3
5
11
7
4
1
2
6
12
( ) ARE FOR MAX1621.
NOTE: CONNECTIONS TO DIGITAL INPUTS NOT SHOWN.
14
16
15
13
R3
300k
RS
470 Ω
R4
300k
R5
2.2M
C6
100pF
10
9
8
LX
DHI
DLO
PGND
DOUT
FB
LCDON
3V
TO
5.5V
C1
0.1
µ F
C2
0.1
µ F
R2
100k
C3
10
µ F
C5
10
µ F
12.5V
TO
23.5V OUT
VOUTSW
OPTIONAL
R6
150k
R7
150k
L1
220
µ H
MAX1620
MAX1621
U1
R8
10k
TO REF
D3 1N6263 (ANY SCHOTTKY)
Figure 10. Positive Output with Bipolar Switching Transistor
___________________________________________________Simplified Block Diagram
BIAS
SHDN
V DD
AGND
DN (SDA)
UP (SCL)
SHDN (SUS)
POL
REF
FB
BATT
POK
( ) ARE FOR MAX1621 ONLY.
DOUT
LX
DHI
DLO
PGND
LCDON
DIGITAL
INTERFACE
BANDGAP
REFERENCE
5-BIT
DAC
1.0V
1.5V
ON-TIME
CONTROL
MAX1620
MAX1621