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Frequency to Voltage Converters
Using the 9000 Series of Frequency Converters
Output/Input Considerations
Without external circuitry these modules accept input sig-
nals down to
+2 volts peak; sine, triangular or square wave;
DTL and TTL Input signals differing from these character-
istics may require external pulse shaping and / or level con-
version.
In most applications, the factory-trimmed full scale output is
adequate, and the FULL-SCALE ADJUST Pin should be
shorted to the OUTPUT Pin.
If desired, full-scale output can be adjusted to exactly 10,000
with an optional 100 gain ohm trim potentiometer connected
between the OUTPUT and FULL-SCALE ADJUST pins.
If a large modification in scale factor is required, an external
resistor can be added between the SUMMING POINT Pin
and the OUTPUT Pin. This method will provide full scale
output for bandwidths as large as 150 kHz (9110), 11 kHz
(9010) or 1.1 kHz (9200) and as low as 1 kHz (9110), 100
Hz (9010) or 10 Hz (9200) with only a very slight effect
upon output accuracy. The resistor value is given by:
R =
∝
∝ = 3.3 Χ 109 (9110)
Full -scale frequency (Hz)
∝ = .95 Χ 109 (9010)
∝ = 0.095 Χ 109 (9200)
When using this scale factor modification, a potentiometer
can be connected in series with the external resistor, if fine-
tuning of full scale frequency is desired.
These modules will not operate if the FULL SCALE AD-
JUST Pin is left open, unless a feedback path is provided via
an external resistor connected between the OUTPUT Pin
and either the FULL SCALE ADJUST Pin or the SUM-
MING POINT Pin.
Output offset is guaranteed to be less than
± 5 mV without
external compensation when the input frequency is zero.
For extreme precision, a trim potentiometer can be used to
adjust the output to zero.
General Application Notes
These Frequency to Voltage Converters are simple to under-
stand and easy to use. They are the most precise frequency
to voltage converters available, and the following provisions
will ensure optimum performance.
As is good practice with all precise electronic conversion in-
struments, it is recommended that supply bypass capacitors
be added in close proximity to the module. Tantalum ca-
pacitors, 15
f / 35 V, from both the + 15 V and 15V pins
to analog ground serve the purpose and are especially advis-
able if the power supplies are some distance away and /or
multiple connectors are used.
Low TC (100 ppm), 10 to 20 turn trim 100 ohm (9110) or
200 ohm (9010 & 9200) potentiometers are recommended
for the gain adjustment potentiometer. A large TC potenti-
ometer will degrade the overall effective TC.
In systems or environments where power supplies may drift
significantly with time and temperature variations, it might
be well to zener regulate the voltages applied to each end of
the E∝ trim potentiometer. This will attenuate the effect of
supply drift on output voltage offset.
Useful Configurations
For Use with HNIL Input
(High Noise Immunity Logic)
1.2 K
± 10%
A
B
C
D
E
F
G
H
J
A
B
C
D
E
F
G
H
J
200 ohms
10 K
± 5%
For use with Signals < 2V
Peak
(In this configuration, pick-off
level is 0 Volts and hysteresis is
40 m V)
A
B
C
D
E
F
G
H
J
10 K
1
M
0.1
F
Capacitive Coupling for
AC Signals With DC offset
+ 100 V dc plus AC signal
Capacitive Coupling and Protection
Network for large DC Levels
A
B
C
D
E
F
G
H
J
1 K
1
M
0.1
F