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 (250MΩ) input resistance. Unlike most
V–F 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 is available in either a 14-lead ceramic DIP or a 10-lead
metal can; both are hermetically sealed packages.

The AD537 is available in three performance/temperature
grades; the J and K grades are specified for operation over the
0°C to +70°C range while the AD537S is specified for operation
over the extended temperature range, –55°C to +125°C.