3-1/2 DIGIT A/D CONVERTERS
TC14433
TC14433A
(B) LC Oscillator Circuit
(A) Crystal Oscillator Circuit
10
10
CLK
1
CLK
1
C
L
18M
47k
C
TC14433
CLK
1
TC14433
11
11
CLK
0
0
1
͌
f =
2/LC
C
C
2
2
10 pF < C AND C < 200 pF
FOR L = 5 mH AND C = 0.01 µF, f 32 kHz
1
2
Figure 9. Alternate Oscillator Circuits
Segment 3 — This segment of the conversion cycle is
the same as Segment 1.
period with the reference voltage as the input to the integra-
tor. Segment 5 of the conversion cycle has a time equal to
the number of counts stored in the offset storage latches
during Segment 2. As a result, the system zeros automati-
cally.
Segment 6 — This is an extension of Segment 5. The
time period for this portion is 4000 clock periods. The results
of the A/D conversion cycle are determined in this portion of
the conversion cycle.
Segment4—Segment4isanup-goingrampcyclewith
the unknown input voltage (VX) as the input to the integrator.
Figure 8 shows the equivalent configuration of the analog
section of the TC14433. The actual configuration of the
analog section is dependent upon the polarity of the input
voltage during the previous conversion cycle.
Segment 5 — This segment is a down-going ramp
TC04
20K
1
+5V
2
3
0.1 µF
–5V
+5V
0.1
+5V
+5V
16
300k
R
µF
0.1
0.1 µF
C
SEGMENT
RESISTORS
150Ω (7)
11 10
2
12 24
23
1
4
2
3
5
V
x
3
1
9
7
6
5
4
3
2
1
10
11
12
13
14
15
16
22
21
20
10
11
12
13
14
15
*
R
1
4
5
6
TC14433
4543B
13
–5V
0.1 µF**
0.1 µF
1413
8
6 7
7
8
9
14
–5V
–5V
–5V
MINUS SIGN
15 19 18 17 16
f g e d c b a
200Ω
PLUS SIGN
–5V
MPS-A12
6
–5V
110Ω
COMMON
ANODE LED
DISPLAY
5
3
1
2
S
51k
Q
Q
D
C
R
+5V
4
8
14013B
S
R
9
11
13
12
Q
Q
D
C
50 µF
0.1 µF
MPS-A12
(4)
7 10
14
+5V
–5V
–5V
DS
4
DS
3
*R = 470kΩ FOR 2V RANGE
1
DS
1
2
R
= 27kΩ FOR 200mV RANGE
1
DS
**MYLAR CAPACITOR
Figure 10. 3-1/2 Digit Voltmeter Common-Anode Displays, Flashing Overrange
3-132
TELCOM SEMICONDUCTOR, INC.
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
