Integrated Circuit Voltage-to-Frequency Converter
Description
a
FEATURES Low Cost A–D Conversion Versatile Input Amplifier Positive or Negative Voltage Modes Negative Current Mode High Input Impedance, Low Drift Single Supply, 5 V to 36 V Linearity: ؎ 0.
05% FS Low Power: 1.
2 mA Quiescent Current Full-Scale Frequency up to 100 kHz 1.
00 V Reference Thermometer Output (1 mV/K) F-V Applications MIL-STD-883 Compliant Versions Available
Integrated Circuit Voltage-to-Frequency Converter AD537*
PIN CONFIGURATIONS D-14 Package H-10A Package
LOGIC GND 10
AD537
LOGIC GND SYNC IIN –VIN +VIN VTEMP VREF 1 2 3 4 5 6 7 VT VR PRECISION VOLTAGE REFERENCE CURRBUF TO-FREQ CONV DRIVER 14 13 12 11 10 9 8 OUTPUT +VS CAP CAP VOS VOS –VS
–VIN
1
9 OUTPUT
AD537
DRIVER 8 +VS CURRTO-FREQ CONV 7 CAP
+VIN 2
BUF 3 VTEMP 4 VREF
VT PRECISION VOLTAGE VR REFERENCE 6 5 CAP
–VS (CONNECTED TO CASE)
PRODUCT DESCRIPTION
The AD537 is a monolithic V-F converter consisting of an input amplifier, a precision oscillator system, an accurate internal reference generator and a high current output stage.
Only a single external RC network is required to set up any full-scale (F.
S.
) frequency up to 100 kHz and any F.
S.
input voltage up to ± 30 V.
Linearity error is as low as ± 0.
05% for 10 kHz F.
S.
, and operation is guaranteed over an 80 dB dynamic range.
The overall temperature coefficient (excluding the effects of external components) is typically ± 30 ppm/°C.
The AD537 operates from a single supply of 5 V to 36 V and consumes only 1.
2 mA quiescent current.
A temperature-proportional output, scaled to 1.
00 mV/K, enables the circuit to be used as a reliable temperature-tofrequency converter; in combination with the fixed reference output of 1.
00 V, offset scales such as 0°C or 0°F can be generated.
The low drift (1 µV/°C typ) input amplifier allows operation directly from small signals (e.
g.
, thermocouples or strain gages) while offering a high (250 MΩ) input resistance.
Unlike most V–F converters, the AD537 provides a square-wave output, and can drive up to 12 TTL...
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