TC14433/A
FIGURE 4-2:
3-1/2 DIGIT LED VOLTMETER WITH LOW COMPONENT COUNT USING
COMMON CATHODE DISPLAYS
470k 0.1µF 0.1µF
+5V
MCP1525
V
IN
V
OUT
V
SS
1µF
V
X
Input
20k
R
1
R
1
/C C
1
C0
1
C0
2
V
X
CLK1
V
AG
CLK0
DU
OR
Q
0
EOE
Q
1
TC14433
Q
2
V
REF
V
SS
V
DD
V
EE
DS
4
DS
3
DS
2
DS
1
300k
+5V
A B1 a
B
b
C I4511B c
d
D
e
LT
f
LE
V
SS
V
DD
g
Resitor Network
or Individual
Resistor*
R
R
DP
Alternate Overrange Circuit
with Separated LED
OR
1/6 75492
OR
1/7 1413
R
R
+5V
RM
V
EE*
*
(Minus)
+5V
Minus
Control
75492
OR
1413*
Digit Drivers
Common
Cathode
Led Display
Note 1:
For V
REF
= 2000V; V: 1.999V full scale.
2:
For V
REF
= 200mV; V: 199.9mV full scale (change 470k to R = 27k and decimal point position.
3:
Peak digit current for an eight displayed is 7 times the segment current:
*To increase segment current capability, add two 75491 ICs between 14511B and resistor network.
The use of the 1413 as digit driver increases digit current capability over the 75492.
**V can range between -2.8V and -11V.
FIGURE 4-3:
ALTERNATE OSCILLATOR CIRCUITS
(A) Crystal Oscillator Circuit
(B) LC Oscillator Circuit
10
CLK
1
10
C
11
C
f=
1
2
π
2/LC
CLK
1
C
1
18M
11
TC14433
CLK
0
L
TC14433
CLK
0
C
2
47k
10pF < C
1
and C
2
< 200pF
For L = 5mH and C = 0.01µF, f
≅
32kHz
2002 Microchip Technology Inc.
DS21394B-page 11
©
MICROCHIP [ MICROCHIP TECHNOLOGY ]
