VFC100_00 Datasheet, PDF (1/16 Pages) Texas Instruments – Synchronized VOLTAGE-TO-FREQUENCY CONVERTER

®
VFC100
FPO
SBVS018
Synchronized
VOLTAGE-TO-FREQUENCY CONVERTER
FEATURES
q FULL-SCALE FREQUENCY SET BY
SYSTEM CLOCK; NO CRITICAL
EXTERNAL COMPONENTS REQUIRED
q PRECISION 10V FULL-SCALE INPUT,
0.5% max GAIN ERROR
q ACCURATE 5V REFERENCE VOLTAGE
q EXCELLENT LINEARITY:
0.02% max at 100kHz FS
0.1% max at 1MHz FS
q VERY LOW GAIN DRIFT: 50ppm/°C
APPLICATIONS
q A/D CONVERSION
q PROCESS CONTROL
q DATA ACQUISITION
q VOLTAGE ISOLATION
DESCRIPTION
The VFC100 voltage-to-frequency converter is an
important advance in VFCs. The well-proven charge
balance technique is used; however, the critical reset
integration period is derived from an external clock
frequency. The external clock accurately sets an out-
put full-scale frequency, eliminating error and drift
from the external timing components required for
other VFCs. A precision input resistor is provided
which accurately sets a 10V full-scale input voltage.
In many applications the required accuracy can be
achieved without external adjustment.
The open collector active-low output provides fast fall
time on the important leading edge of output pulses,
and interfaces easily with TTL and CMOS circuitry.
An output one-shot circuit is particularly useful to
provide optimum output pulse widths for optical cou-
plers and transformers to achieve voltage isolation. An
accurate 5V reference is also provided which is useful
for applications such as offsetting for bipolar input
voltages, exciting bridges and sensors, and autocali-
bration schemes.
V_IN
Non-Inverting
Input
C _INT
5
– Comparator
V_OUT
Input
4
14
Clock
Input
10
7
R_IN
Integrator
Amplifier
6 20kΩ
SW₁
Comparator
Clocked
Logic
+V_CC
1
Output
One-Shot
11
f_OUT
12 _Digital
Common
1mA
–V_CC
13
Analog
Common
15
+ Comparator
Input
5V
Reference
16
V_REF
9
C_OS
8
–V_CC
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© 1984 Burr-Brown Corporation
PDS-547H
Printed in U.S.A. June, 1995