CS4121
Speedometer/Odometer or Tachometer Application
R3
Speedo
Input
R2
C3
C
T
R4
1
2
3
4
5
6
CP+
CP+
SQ
OUT
FREQ
IN
CP-
16
F/V
OUT
15
V
REG
14
C4
+
R
T
Gnd
COS+
COS-
V
CC
CS4121
Gnd
Gnd
13
Gnd
12
SINE+
11
SINE-
10
BIAS
9
Battery
D1 R1
D2
C1
7
8
COSINE
Gnd
Air Core
Gauge
200W
SINE
Speedometer
Figure 6
R1 - 3.9, 500mW
R2 - 10k�½
R3 - 3k�½
R4 - 1k�½
R
T
- Trim Resistor +/- 20 PPM/¡C 243k�½
C1 - 0.1µF
C3 - 0.1µF
C4 - 0.47µF
C
T
- 0.0033µF, +/- 30 PPM/¡C
D1 - 1A, 600 PIV
D2 - 50V, 500mW Zener
Note 1: For 58% Speed Input T
MAX
² 5/f
MAX
where
T
MAX
= C
T
(R3+R4)
f
MAX
= maximum speed input frequency
R3
Speedo
Input
R2
C3
C
T
R4
1
2
3
4
5
6
CP+
CP+
SQ
OUT
FREQ
IN
CP-
16
F/V
OUT
15
V
REG
14
C4
+
R
T
Gnd
COS+
COS-
V
CC
CS4121
Gnd
Gnd
13
Gnd
12
SINE+
11
SINE-
10
BIAS
9
Battery
D1 R1
D2
C1
7
8
COSINE
Gnd
Air Core
Gauge
200W
SINE
Speedometer
C2
1
CS8441
Air Core
Stepper Motor
200W
Odometer
Figure 7
Note 1: The product of C
T
and R
T
have a direct effect on
gain and therefore directly affect temperature compensation
Note 2: C
T
Range; 20pF to .2µF
Note 3: R
T
Range; 100k�½ to 500k�½
Note 4: The IC must be protected from transients above 60V and
reverse battery conditions
Note 5: Additional filtering on FREQ
IN
lead may be required
7
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
