3-3/4 A/D CONVERTER WITH
FREQUENCY COUNTER
AND LOGIC PROBE
TC820
ELECTRICAL CHARACTERISTICS
(Cont.)
Symbol
Parameter
Buzzer Frequency
Counter Timebase Period
Low Battery Flag Voltage
Input Low Voltage
Input High Voltage
Output Low Voltage,
UR, OR Outputs
Output High Voltage,
UR, OR Outputs
Control Pin
Pull-Down Current
Test Conditions
f
OSC
= 40kHz
f
OSC
= 40kHz
V
DD
to V
SS
Min
—
—
6.7
—
V
DD
– 1.5
—
V
DD
– 1.5
—
Typ
5
1
7
—
—
—
—
5
Max
—
—
7.3
DGND + 1.5
—
DGND + 0.4
—
—
Units
kHz
Second
V
V
V
V
V
µA
V
IL
V
IH
V
OL
V
OL
I
L
= 50µA
I
L
= 50µA
V
IN
= V
DD
PIN DESCRIPTION
Pin No.
(40-Pin
Package)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
—
16
17
Pin No.
(44-Pin Flat
Package)
40
41
42
43
44
1
2
3
4
5
6
7
8
9
10
11
12
13
Symbol
L-E4
AGD4
BC4P3
HFE3
AGD3
BC3P2
OFE2
AGD2
BC2P1
PKFE1
AGD1
BC1BT
BP3
BP2
BP1
V
DISP
DGND
ANNUNC
Description
LCD segment driver for L ("logic LOW"), polarity, and "e" segment of most
significant digit (MSD).
LCD segment drive for "a," "g," and "d" segments of MSD.
LCD segment drive for "b" and "c" segments of MSD and decimal point 3.
LCD segment drive for H ("logic HIGH"), and "f" and "e" segments of third LSD.
LCD segment drive for "a," "g," and "d" segments of third LSD.
LCD segment drive for "b" and "c" segments of third LSD and decimal point 2.
LCD segment drive for "overrange," and "f" and "e" segments of second LSD.
LCD segment drive for "a," "g," and "d" segments of second LSD.
LCD segment drive for "b " and "c" segments of second LSD and decimal point 1.
LCD segment drive for "hold peak reading," and "f" and "e" segments of LSD.
LCD segment drive for "a," "g," and "d" segments of LSD.
LCD segment drive for "b" and "c" segments of LSD and "low battery."
LCD backplane #3.
LCD backplane #2.
LCD backplane #1.
Sets peak LCD drive signal: V
PEAK
= (V
DD
) –V
DISP
. V
DISP
may also be used to
compensate for temperature variation of LCD crystal threshold voltage.
Internal logic digital ground, the logic "0" level. Nominally 4.7V below V
DD
.
Square-wave output at the backplane frequency, synchronized to BP1. ANNUNC
can be used to control display annunciators. Connecting an LCD segment to
ANNUNC turns it on; connecting it to its backplane turns it off.
Logic mode control input. When connected to V
DD
, the converter is in logic mode.
The LCD displays "OL" and the decimal point inputs control the HIGH and LOW
annunciators. When the "low" annunciator is on, the buzzer will also be on. When
unconnected or connected to DGND, the TC820 is in the voltage/frequency
measurement mode. This pin has a 5µA internal pull-down to DGND.
Dual-purpose input. In range mode, when connected to V
DD
, the integration time
will be 200 counts instead of 2000 counts and the LCD will display the analog input
divided by 10. (See text for limitation with TC820.) In frequency mode, this pin is the
frequency input. A digital signal applied to this pin will be measured with a 1-second
time base. There is an internal 5µA pull-down to DGND.
18
14
LOGIC
19
15
RANGE/
FREQ
3-152
TELCOM SEMICONDUCTOR, INC.
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
