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  Microchip Technology Semiconductor Electronic Components Datasheet  

AY0438 Datasheet

32-Segment CMOS LCD Driver

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AY0438 pdf
AY0438
32-Segment CMOS LCD Driver
FEATURES
• Drives up to 32 LCD segments of arbitrary config-
uration
• CMOS process for: wide supply voltage range,
low- power operation, high-noise immunity, wide
temperature range
• CMOS and TTL-compatible inputs
• Electrostatic discharge protection on all pins
• Cascadable
• On-chip oscillator
• Requires only three control lines
APPLICATIONS
• Industrial displays
• Consumer product displays
• Telecom product displays
• Automotive dashboard displays
DESCRIPTION
The AY0438 is a CMOS integrated device that drives a
liquid crystal display, usually under microprocessor
control. The part acts as a smart peripheral that drives
up to 32 LCD segments. It needs only three control
lines due to its serial input construction. It latches the
data to be displayed and relieves the microprocessor
from the task of generating the required waveforms.
The AY0438 can drive any standard or custom parallel
drive LCD display, whether it be field effect or dynamic
scattering; 7-, 9-, 14- or 16-segment characters; deci-
mals; leading + or -; or special symbols. Several
AY0438 devices can be cascaded. The AC frequency
of the LCD waveforms can either be supplied by the
user or generated by attaching a capacitor to the LCD
input, which controls the frequency of an internal oscil-
lator.
The AY0438 is available in 40-lead dual in-line plastic
and 44-lead PLCC packages. Unpackaged dice are
also available.
PIN CONFIGURATION
40-Lead Dual In-line
VDD
LOAD
SEG 32
SEG 31
SEG 30
SEG 29
SEG 28
SEG 27
SEG 26
SEG 25
SEG 24
SEG 23
SEG 22
SEG 21
SEG 20
SEG 19
SEG 18
SEG 17
SEG 16
SEG 15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
CLOCK
SEG 1
SEG 2
SEG 3
VSS
DATA OUT
DATA IN
SEG 4
SEG 5
LCDΦ
BP
SEG 6
SEG 7
SEG 8
SEG 9
SEG 10
SEG 11
SEG 12
SEG 13
SEG 14
44 PLCC
SEG 29
SEG 28
SEG 27
SEG 26
SEG 25
SEG 24
SEG 23
SEG 22
SEG 21
SEG 20
SEG 19
7 39
8 38
9 37
10 36
11 35
12
13
AY0438
34
33
14 32
15 31
16 30
17 29
NC
DATA OUT
DATA IN
SEG 4
SEG 5
LCDΦ
BP
SEG 6
SEG 7
SEG 8
NC
© 1995 Microchip Technology Inc.
DS70010I-page 1


  Microchip Technology Semiconductor Electronic Components Datasheet  

AY0438 Datasheet

32-Segment CMOS LCD Driver

No Preview Available !

AY0438 pdf
AY0438
FIGURE 1: PIN DESCRIPTIONS
Pin # (PDIP Only)
1
2
3-29, 32, 33, 37-39
30
31
34
35
36
40
Name
VDD
Load
Seg 1-32
BP
LCDΦ
Data In
Data Out
VSS
Clock
Direction
-
Input
Output
Output
Input
Input
Output
Ground
Input
Description
Supply voltage
Latch data from registers
Direct drive outputs
Backplane drive output
Backplane drive input
Data input to shift register
Data output from shift register
Ground
System clock input
FIGURE 2: BLOCK DIAGRAM
Data in
Clock
32-bit Static Shift Register
Load
32 Latches
Data out
FIGURE 3: BACKPLANE AND SEGMENT
OUTPUT
SEG On
32 Segment Drivers
LCDΦ
LCD AC
Generator
32 Outputs
Backplane
output
Backplane
SEG Off
FIGURE 4: TIMING DIAGRAM
CLOCK
Data in
Data out
Load
START
1
SEG 32
1/f
31
SEG 2
32
SEG 1
tDS tDH
tPD
tPW
1.0 OPERATION:
1.1 Data In and Clock
The shift register shifts and outputs on the falling edge
of the clock. Every clock falling edge does a logical left
shift. As an example, if 32 clock pulses are supplied as
in Figure 4, then the data input at the first clock will out-
put at SEG 32, and the last data input (# 32) will output
at SEG 1 when a LOAD signal is enabled (Figure 2). It
is recommended that a complete 32 bit transfer be
done every time the outputs are updated. A logic 1 at
the Data In causes the corresponding segment to be
DS70010I-page 2
enabled or visible, i.e. the output at Segment Output is
180° out-of-phase with the Backplane output
(Figure 3).
1.2 Load
A logic 1 at the Load input (Figure 2) causes the paral-
lel load of the data in the shift register into the latches
that control the segment drivers. If the Load signal is
tied high, then the latches become transparent and the
segment drivers are always connected to the shift reg-
isters.
© 1995 Microchip Technology Inc.


Part Number AY0438
Description 32-Segment CMOS LCD Driver
Maker Microchip Technology
Total Page 11 Pages
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