tc9400 Microchip Technology Inc., tc9400 Datasheet - Page 17

• Manufacturer Part Number: tc9400
• Description: Voltage-to-frequency / Frequency-to-voltage Converters
• Manufacturer: Microchip Technology Inc.

7.0
In F/V mode, the TC9400 output voltage will occasion-
ally be at its maximum value when power is first
applied. This condition remains until the first pulse is
applied to F
applications, this is not a problem because proper
operation begins as soon as the frequency input is
applied.
FIGURE 7-1:
© 2007 Microchip Technology Inc.
F
IN
1 kΩ
F/V POWER-ON RESET
IN
. In most frequency measurement
1000 pF
Power-On Operation/Reset.
11
(a)
Threshold
Detector
TC9400
14
V
DD
100 kΩ
1 µF
V
DD
3
4
In some cases, however, the TC9400 output must be
zero at power-on without a frequency input. In such
cases, a capacitor connected from Pin 11 to V
usually be sufficient to pulse the TC9400 and provide a
Power-on Reset (see
predictable power-on operation is critical, a more
complicated circuit, such as
required.
CLRA
A
V
CC
16
TC9400/9401/9402
B
CD4538
5
V
SS
8
(b)
R
2
Figure 7-1
C
1
Q
Figure 7-1
6
F
(a) and (b)). Where
IN
DS21483D-page 17
(b), may be
To TC9400
DD
will