TC7135
+5V
20 19 18 17 12
4 D1 D2 D3 D4 D5
INT OUT
0.33 µF
1 µF
5 AZ IN
6 BUFF
POL 23 4.7 kΩ
100 kΩ
200 kHz
22
100 kΩ
+
10
OUT
FIN
TC7135
CREF –
CREF+
7
8
+INPUT
1 µF
Analog
Input
–
1 µF9
–INPUT
3 ANALOG
COMMON
B8 16
B4
B2
B1
15
14
13
REF
V– IN
V+
12
11
V+
5V
MCP1525
100 kΩ
1 µF
bc
Blank MSD On Zero
6
2
1
D
C
7
B
A
7
7
7
7
X7
5 9 15
RBI
DM7447A
16 +5V
FIGURE 6-2:
4-1/2 Digit ADC With Multiplexed Common Anode Led Display.
R2
C
R1
FO
Gates are 74C04
1.
FO
=
------------------------1--------------------------
2C(0.41RP + 0.7R1)
,
RP
=
----R---1---R----2----
R1 + R2
a. If R1 = R2 = R1, F≅ 0.55/RC
b. If R2 >> R1, F ≅ 0.45/R1C
c. If R2 << R1, F ≅ 0.72/R1C
2. Examples:
a. F = 120 kHz, C = 420 pF
R1 = R2 ≈ 10.9 kΩ
b. F = 120 kHz, C = 420pF, R2 = 50 kΩ
R1 = 8.93 kΩ
c. F = 120 kHz, C = 220 pF, R2 = 5 kΩ
R1 = 27.3 kΩ
FIGURE 6-3:
RC Oscillator Circuit.
+5V
0.22 µF
16 kΩ
56 kΩ 1 kΩ
16 kΩ
2+ 8
LM311 7
3–
1
4
VOUT
30 kΩ
390 pF
R2
100 kΩ
+5V R4
2 kΩ
R2
100 kΩ
C1
0.1 µF
2+ 6
LM311
3–
4
1
C2
10 pF
7
VOUT
R3
50 kΩ
FIGURE 6-4:
Comparator Clock Circuits.
DS21460C-page 14
2004 Microchip Technology Inc.