AD537*

Low Cost AD 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

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 V/°C typ) input amplifier allows operation directly from small signals (e.g., thermocouples or strain gages) while offering a high (250M) input resistance. Unlike most VF converters, the AD537 provides a square-wave output, and can drive up to 12 TTL loads, LEDs, very long cables, etc.The excellent temperature characteristics and long-term stability of the AD537 are guaranteed by the primary bandgap reference generator and the low T.C. silicon chromium thin film resistors used throughout.

The device AD537 is available in either a 14-lead ceramic DIP or a 10-lead metal can; both are hermetically sealed packages.