VFC121 Datasheet, PDF (1/8 Pages) Burr-Brown (TI) – Precision Single Power Supply VOLTAGE-TO-FREQUENCY CONVERTER

®
VFC121
Precision Single Power Supply
VOLTAGE-TO-FREQUENCY CONVERTER
FEATURES
q SINGLE SUPPLY OPERATION:
+4.5V to +36V
q f = 1.5MHz max
O
q LOW NONLINEARITY: 0.03% max at
100kHz, 0.1% max at 1MHz
q HIGH INPUT IMPEDANCE
q VOLTAGE REFERENCE OUTPUT
q THERMOMETER OUTPUT: 1mV/°K
APPLICATIONS
q INTEGRATING A/D CONVERSION
q ANALOG SIGNAL TRANSMISSION
q PHASE-LOCKED LOOP VCO
q GALVANICALLY ISOLATED SYSTEMS
DESCRIPTION
The VFC121 is a monolithic voltage-to-frequency
converter consisting of an integrating amplifier, volt-
age reference, and one-shot charge pump circuitry.
High-frequency complementary NPN/PNP circuitry is
used to implement the charge-balance technique,
achieving speed and accuracy far superior to previous
single power supply VFCs.
The high-impedance input accepts signals from ground
potential to V_S – 2.5V. Power supplies from 4.5V to
36V may be used. A 2.6V reference voltage output
may be used to excite sensors or bias external cir-
cuitry. A thermometer output voltage proportional to
absolute temperature (°K) may be used as a tempera-
ture sensor or for temperature compensation of appli-
cations circuits.
Frequency output is an open-collector transistor. A
disable pin forces the output to the high impedance
state, allowing multiple VFCs to share a common
transmission path.
12
V_IN = 0 to +2V
11
R_BIAS = 8kΩ
(Optional)
R_IN = 8kΩ
R_TRIM
R_IN
C_INT = 2700pF
10
Integrator
+5V
+V_S
9
13
Comparator
V_REF
One
Shot
I_REF
V_REF
Ground
(Optional)
2
4
6
3
5
C_OS = 1200pF
2.6V
V_T
V_{PULL UP}
R_{PULL UP}
14
f_OUT =
0 to 100kHz
8
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© 1989 Burr-Brown Corporation
PDS-971A
Printed in U.S.A. March, 1992