GENERAL DESCRIPTION
The ADR1000 is a 6.62 V, output highly stable, oven-controlled,
buried Zener reference component built on an Analog Devices, Inc.,
proprietary bipolar process and is a pin-compatible replacement for
the LTZ1000. Included on the chip is a buried Zener reference,
a heater resistor for temperature stabilization, and a temperature
sensing transistor. External circuitry is used to set the operating currents
and the temperature of the reference, allowing the maximum
flexibility to achieve maximum long-term stability and minimum noise.
The ADR1000 application circuit can achieve a temperature coefficient
of <0.2 ppm/°C and a long-term drift of 0.5 ppm per year
(typical) after the first 3000 hours when properly implemented with
the recommended external circuitry shown in Figure 9 and with the
recommended layout.
The low long-term drift of the ADR1000 is well suited for any application
that must maintain accuracy over long calibration intervals
or product lifetime. The low thermal drift ensures the output is
constant with temperature variation because the on‑chip heater of
the ADR1000 maintains a constant temperature higher than the
expected ambient range.
The ADR1000 is specified for operation over the extended industrial
temperature range of −40°C to +125°C. To obtain the optimal
thermal drift performance, the temperature set point of the heater
needs to be 10°C higher than the maximum ambient temperature to
provide optimum stability of the buried Zener reference.
The ADR1000 comes packaged in an industry-standard, 8-pin
TO-99 metal can package that is hermetically sealed to resist the
effects of humidity.

FEATURES
► High long-term stability
► 0.5 ppm/year long-term drift, typical (after first 3000 hours)
► Low Zener reference noise: 0.14 ppm p-p (0.9 μV p-p)
► Low temperature coefficient: <0.2 ppm/°C
► On-chip heater and temperature sensor
► Specified for −40°C to +125°C operation
► Pin‐compatible upgrade to LTZ1000

APPLICATIONS
► High accuracy instrumentation
► Multimeters
► Weigh scales
► Electric balance
► Automatic test equipment
► Metrology equipment
► Standard cells
► Calibrators