TC7135 View Datasheet(PDF) - TelCom Semiconductor Inc => Microchip
Part Name
Description
Manufacturer
TC7135 Datasheet PDF : 13 Pages
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4-1/2 DIGIT
ANALOG-TO-DIGITAL CONVERTER
1
V+
REF
IN
TC7135
ANALOG
COMMON
V+
TC05
2.5VREF
IREF
V–
V+
V+
6.8 kΩ
REF
IN
TC7135
TC04
20
k Ω 1.25V REF
ANALOG
COMMON
ANALOG
GROUND
Figure 5. Using an External Reference Voltage
TC7135
Digital Section Functional Description
2 The major digital subsystems within the TC7135 are
illustrated in Figure 6, with timing relationships shown in
Figure 7. The multiplexed BCD output data can be displayed
on an LCD with the TC7211A.
The digital section is best described through a discus-
sion of the control signals and data outputs.
3 RUN/HOLD Input
When left open, the RUN/HOLD (R/H) input (pin 25)
assumes a logic "1" level. With R/H = 1, the TC7135
performs conversions continuously, with a new measure-
ment cycle beginning every 40,002 clock pulses.
When R/H changes to logic "0," the measurement cycle
in progress will be completed, and data held and displayed,
as long as the logic "0" condition exists.
4 A positive pulse (>300nsec) at R/H initiates a new
measurement cycle. The measurement cycle in progress
when R/H initially assumed logic "0" must be completed
before the positive pulse can be recognized as a single
conversion run command.
The new measurement cycle begins with a 10,001-
count auto-zero phase. At the end of this phase, the busy
signal goes high.
5
POLARITY D5
MSB
FROM
ANALOG
SECTION
POLARITY
FF
ZERO
CROSS
DETECT
LATCH
D4
DIGIT
D3
D2
D1
DRIVE
SIGNAL
MULTIPLEXER
LSB
DATA
OUTPUT
13 B1
14 B2
15 B4
16 B8
LATCH
LATCH
LATCH
LATCH
COUNTERS
CONTROL LOGIC
24
22
25
27
28
26
DIGITAL CLOCK
GND
IN
RUN/
HOLD
OVER–
RANGE
UNDER–
RANGE
STROBE
Figure 6. Digital Section Functional Diagram
TELCOM SEMICONDUCTOR, INC.
21
BUSY
6
7
8
3-119
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