Electrical Specifications - Tandy 1400LT Service Manual

4. Electrical Specifications
4-1 Absolute Maximum Rating
Item Symbol Minimum Maximum Unit Remarks
Supply voltage for logic circuit
Supply voltage for LCD driving
Supply voltage for EL back light
Supply frequency for EL back light
Input voltage
Storage temperature
Operating tempreature
VDD-VSS -0.3
+
6.0
V
VDD-VEE
0
+
30.0 V
VEL
1 -VEL2
+
150 ACVrms
f E L
+
800 Hz
V I N -0.3 vDD+o.3
V
Tstg -4 (-20) 140
(+60) "F
("C)
Topr 32
(0)
104
(+40)
"F
("C)
-
-
4-2 Electrical Characteristics
(VSS
=
OV)
Item Symbol Test condition Minmum Typical Maximum Unit
~ ~~
Supply voltage for logic circuit
Supply voltage for LCD driving
Supply voltage for EL back light
Supply frequency for EL back
light
H level
L level
Input voltage
Current Consumption
VDD-VSS
VDD-VEE
V E L 1 -VEL2
f E l
VIH
VIL
ISS
IEE
IEL
4.5
8.0
0.8VDD
vss
VDD-VSS
=5.OV-+I 10%
Ta=25"C
-
VDD-VSS
=
5.0V
VDD-VEE= 17.2V
-
Ta
=
20"
-
AClOOVrrns, 400Hz
~
f F R A H E
=
70Hz
5.0
100
400
-
5.6
7.9
31
5.5 V
28.0 V
-
ACVrms
-
Hz
VDD V
0.2VDD V
9.1 mA
12.2 mA
40 mA
*
VDD
>
Vss
>
VEE
4-3 Operating voltage for LCD driving (VDD-VEE)
The contrast of the liquid crystal display depends on viewing angle, ambient temperature, and operating voltage,
etc. Adjust the contrast by varying VEE as necessary.
The following values are recommended.
Ta= 32°F (0°C)
...............................................
18.3 Vtyp
4
=O"
Ta=77"F (25°C)
..............................................
17.2 Vtyp 8=0"
Ta= 104°F (40°C)
......................................................
16.2 Vtyp
A-3