CS289
Circuit Description
Charge Pump
Function Generator/Sine and Cosine Amplifiers
The input frequency is buffered through a transistor, then
applied to the charge pump for frequency-to-voltage con-
version (Figure 1). The charge pump output voltage, EÆ,
will range from 2.1V with no input (Æ= 0¡) to 7.1V at
Æ
=
270¡. The charge that appears on C
T
is reflected to C
OUT
through a Norton amplifier. The frequency applied at
S
Q
IN charges and discharges C
T
through R
1
and R
2
. C
OUT
reflects the charge as a voltage across resistor R
T
.
The output waveforms of the sine and cosine amplifiers
are derived by On-Chip Amplifier/Comparator circuitry.
The various trip points for the circuit (i.e. 90¡, 180¡, 270¡)
are determined by an internal resistor divider connected
to the voltage regulator. The voltage EÆ is compared to
the divider network by the function generator circuitry.
Use of an external zener reference at V
Z
allows both sine
and cosine amplifiers to swing positive and negative with
respect to this reference. The output magnitudes and
directions have the relationship as shown in Typical
Characteristics diagrams.
Note: Pin connections referenced are for the 14L DIP.
Function Generator Output (Æ): V
CC
=13.1V, T
A
=25¡C
Æ=ArcTan
V
sine
(Measured angle after calibration at 180¡C)
V
cos
1kW
For
Æ
A
=45¡, 90¡, 135¡, 180¡, 225¡, 270¡, (Desired angle)
(Æ
A
-Æ
M
)²4.0¡
Temperature Sensitivity: V
CC
=13.1V
ÆÆ
MT
=Æ
M
(T=25¡C) -ÆM (-20¡C²T²+85¡C)
(ÆÆ
MT
)²3.5¡C, -20¡C²T²+85¡C
Voltage Sensitivity: T
A
=25¡C
ÆÆ
MV
=Æ
M
(V
CC
=13.1V) -Æ
M
(11.3V²V
CC
²15V)
(ÆÆ
MV
)²2¡, 11.3V²V
CC
²15V
V
Z
100W
B+
V
SINE
V
BIAS
Gnd
V
COS
V
REG
V
CC
15
B+
18V
R2
2kW
TACH INPUT
2kW
E
Q
S
Q
OUT
F-V
OUT
C
OUT
1mF
±10%
S
Q
IN
CS289
R
T
180kW
*
C
P
Ð
80mH
225
R1
SINE
80mH
225
1kW
C
T
0.01mF
ZENER
5.4V
* ADJUST FOR TRIMMING
Figure 1. Functional Diagram of CS289 Circuit.
4
C
P
+
Gnd
NC
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
