TC9400CPD TELCOM SEMICONDUCTOR, TC9400CPD Datasheet - Page 12

• Manufacturer Part Number: TC9400CPD
• Description: IC, F/V-V/F CONVERTER, 9400, DIP14
• Manufacturer: TELCOM SEMICONDUCTOR

Specifications of TC9400CPD

• Frequency: 100kHz
• Linearity %: 0.05%
• Supply Voltage Range: ± 4V To ± 7.5V
• Digital Ic Case Style: DIP
• No. Of Pins: 14
• Operating Temperature Max: 70°C
• Operating Temperature Min: 0°C
• Package /: RoHS Compliant
• Full Scale Range: 10Hz To 100kHz
• Rohs Compliant: Yes
• Bandwidth: 100kHz
• Base Number: 9400

TC9400/9401/9402
6.0
When used as an F/V converter, the TC9400 generates
an output voltage linearly proportional to the input
frequency waveform.
Each zero crossing at the threshold detector's input
causes a precise amount of charge (q = C
to be dispensed into the Op Amp's summing junction.
This charge, in turn, flows through the feedback resis-
tor, generating voltage pulses at the output of the Op
Amp. A capacitor (C
pulses into a DC voltage, which is linearly proportional
to the input frequency.
7.0
7.1
The output voltage is related to the input frequency
(F
EQUATION 7-1:
The response time to a change in F
C
proportional to C
FIGURE 7-1:
DS21483B-page 12
INT
IN
Frequency
) by the transfer equation:
). The amount of ripple on V
Input
+5V
FREQUENCY-TO-VOLTAGE
(F/V) CIRCUIT DESCRIPTION
F/V CONVERTER DESIGN
INFORMATION
Input/Output Relationships
0V
V
OUT
INT
= [V
33k
and the input frequency.
INT
REF
FREQUENCY INPUT LEVEL SHIFTER
0.01µF
) across R
(a) ±5V Supply
C
REF
IN914
R
INT
INT
IN
] F
OUT
is equal to (R
1.0M
averages these
IN
11
REF
is inversely
GND
DET
TC9400
6
∞ V
+5V
V
-5V
REF
DD
V
14
INT
4
SS
)
Frequency
C
to 100µF are perfectly acceptable for low frequencies.
When the TC9400 is used in the Single Supply mode,
V
and Pin 2.
7.2
The input frequency is applied to the Threshold Detec-
tor input (Pin 11). As discussed in the V/F circuit section
of this data sheet, the threshold of Pin 11 is approxi-
mately (V
range extends from V
old. If the voltage on Pin 11 goes more than 2.5 volts
below the threshold, the V/F mode start-up comparator
will turn on and corrupt the output voltage. The Thresh-
old Detector input has about 200mV of hysteresis.
In ±5V applications, the input voltage levels for the
TC9400 are ±400mV, minimum. If the frequency
source being measured is unipolar, such as TTL or
CMOS operating from a +5V source, then an AC cou-
pled level shifter should be used. One such circuit is
shown in Figure 7-1(a).
The level shifter circuit in Figure 7-1(b) can be used in
single supply F/V applications. The resistor divider
ensures that the input threshold will track the supply
voltages. The diode clamp prevents the input from
going far enough in the negative direction to turn on the
start-up comparator. The diode's forward voltage
decreases by 2.1mV/°C, so for high ambient tempera-
ture operation, two diodes in series are recommended;
also, see Figure 7-2.
Input
REF
INT
+5V
0V
can be increased to lower the ripple. Values of 1µF
is defined as the voltage difference between Pin 7
Input Voltage Levels
DD
33k
+ V
SS
0.01µF
)/2 ±400mV. Pin 11's input voltage
DD
©
to about 2.5V below the thresh-
0.1µF
IN914
2002 Microchip Technology Inc.
(b) Single Supply
10k
10k
1.0M
11
DET
TC9400
+8V to +5V
V
DD
V
14
4
SS