Chapter 1 Hardware Structure
V M A X
V L C D
(= V L C D
´
1 .5 )
( H T 4 9 R U 8 0 /H T 4 9 C U 8 0 o n ly )
L C D
P o w e r S u p p ly
V M A X
V L C D
( H T 4 9 R U 8 0 /H T 4 9 C U 8 0 o n ly )
L C D
P o w e r S u p p ly
V
A
C 1
C h a rg e
P u m p
(= V L C D )
V
B
C 2
V 1
0 .1
m
F
(= V L C D )
V
A
C 1
C h a rg e
P u m p
C 2
V 1
0 .1
m
F
0 .1
m
F
(= V L C D
´ 0
.5 )
V
C
V 2
0 .1
m
F
(= V L C D
´ 0
.5 )
V
B
0 .1
m
F
V 2
0 .1
m
F
C
ty p e 1 /3 B ia s
E x c e p t H T 4 9 C 3 0 L , H T 4 9 C 5 0 L , H T 4 9 C 7 0 L
C ty p e 1 /2 B ia s
E x c e p t H T 4 9 C 3 0 L , H T 4 9 C 5 0 L , H T 4 9 C 7 0 L
V L C D
0 .1
m
F
(= V 2
´
2 )
V
A
(= V 2 )
V
B
C h a r
P u m
V o lta
D o u b
g e
p
g e
le r
C 1
C 2
V 1
0 .1
m
F
V 2
L C D
P o w e r S u p p ly
( n o r m a lly c o n n e c te d to V D D )
0 .1
m
F
C
ty p e 1 /2 B ia s
H T 4 9 C 3 0 L , H T 4 9 C 5 0 L , H T 4 9 C 7 0 L o n ly
C Type Bias Voltage Levels
Note
1. The R type and 1/3 bias configuration options are not available for the HT49C30L, HT49C50L
and HT49C70L devices.
2. The VMAX pin only exists on the HT49RU80/HT49CU80 devices.
VMAX Pin Connection
-
HT49RU80/HT49CU80 only
On the HT49RU80/HT49CU80 devices there is an additional VMAX pin which must be connected
in a certain way depending upon the voltage that is applied to the VLCD pin. The following table
should be consulted to ensure the correct connection of this pin.
Biasing Type
1/3 Bias
C Type
1/2 Bias
Otherwise
VDD>VLCD
R Type
1/2 or 1/3 Bias
Otherwise
Connect VMAX to VLCD
Connect VMAX to VLCD
Connect VMAX to VDD
VLCD Voltage
VDD>VLCD´1.5
Otherwise
VDD>VLCD
VMAX Pin Connection
Connect VMAX to VDD
Connect VMAX to V1
Connect VMAX to VDD
57
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