3-1/2 DIGIT A/D CONVERTERS
TC14433
TC14433A
(A) Crystal Oscillator Circuit
10
CLK1
L
C
(B) LC Oscillator Circuit
10
CLK1
C
1
18M
TC14433
11 CLK
0
11
C
f= 1
2
2/LC
TC14433
CLK 0
47k
C
2
10 pF < C
1
AND C
2
< 200 pF
FOR L = 5 mH AND C = 0.01
µF,
f
≅
32 kHz
Figure 9. Alternate Oscillator Circuits
Segment 3
— This segment of the conversion cycle is
the same as Segment 1.
Segment 4
— Segment 4 is an up-going ramp cycle with
the unknown input voltage (V
X
) 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
+5V
0.1
µF
1
3
2
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.
20K
–5V
+5V
0.1µF
300k
R
C
11 10 2 12 24
23
22
21
4
20
5
TC14433
6
13
3
1
7
8
9
14
15 19 18 17 16
0.1
0.1
µF
1
4
2
3
5
+5V
+5V
SEGMENT
RESISTORS
150
Ω
(7)
7
6
5
4
3
2
1
–5V
–5V
10
11
12
13
14
15
16
MINUS SIGN
200
Ω
PLUS SIGN
MPS-A12
110
Ω
COMMON
ANODE LED
DISPLAY
0.1
µF
MPS-A12
(4)
–5V
V
x
*
R
1
16
–5V
0.1
µF**
0.1
µF
–5V
9
10
11
12
13
4543B
14
15
8 6 7
1413
f g e d c b a
14013B
–5V
6
5
1
S
D Q
3
2
CRQ
4
8
9 D S Q 13
11 C Q 12
R
7 10
14
+5V
–5V
51k
+5V
50
µF
DS
4
*R
1
= 470k
Ω
FOR 2V RANGE
R
1
= 27k
Ω
FOR 200mV RANGE
**MYLAR CAPACITOR
DS
3
DS
2
DS
1
–5V
Figure 10. 3-1/2 Digit Voltmeter Common-Anode Displays, Flashing Overrange
3-132
TELCOM SEMICONDUCTOR, INC.
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
