SNOSBI2B – JUNE 1999 – REVISED MARCH 2013
LM231A/LM231/LM331A/LM331 Precision Voltage-to-Frequency Converters
Check for Samples:
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FEATURES
Ensured Linearity 0.01% max
Improved Performance in Existing Voltage-to-
Frequency Conversion Applications
Split or Single Supply Operation
Operates on Single 5V Supply
Pulse Output Compatible with All Logic Forms
Excellent Temperature Stability: ±50 ppm/°C
max
Low Power Consumption: 15 mW Typical at 5V
Wide Dynamic Range, 100 dB min at 10 kHz
Full Scale Frequency
Wide Range of Full Scale Frequency: 1 Hz to
100 kHz
Low Cost
DESCRIPTION
The LM231/LM331 family of voltage-to-frequency
converters are ideally suited for use in simple low-
cost circuits for analog-to-digital conversion, precision
frequency-to-voltage
conversion,
long-term
integration,
linear
frequency
modulation
or
demodulation, and many other functions. The output
when used as a voltage-to-frequency converter is a
pulse train at a frequency precisely proportional to the
applied input voltage. Thus, it provides all the
inherent advantages of the voltage-to-frequency
conversion techniques, and is easy to apply in all
standard voltage-to-frequency converter applications.
Further, the LM231A/LM331A attain a new high level
of accuracy versus temperature which could only be
attained
with
expensive
voltage-to-frequency
modules. Additionally the LM231/331 are ideally
suited for use in digital systems at low power supply
voltages and can provide low-cost analog-to-digital
conversion in microprocessor-controlled systems.
And, the frequency from a battery powered voltage-
to-frequency converter can be easily channeled
through a simple photo isolator to provide isolation
against high common mode levels.
The LM231/LM331 utilize a new temperature-
compensated band-gap reference circuit, to provide
excellent accuracy over the full operating temperature
range, at power supplies as low as 4.0V. The
precision timer circuit has low bias currents without
degrading the quick response necessary for 100 kHz
voltage-to-frequency conversion. And the output are
capable of driving 3 TTL loads, or a high voltage
output up to 40V, yet is short-circuit-proof against
V
CC
.
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CONNECTION DIAGRAM
Figure 1. Plastic Dual-In-Line Package (PDIP)
See Package Number P (R-PDIP-T8)
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Copyright © 1999–2013, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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