9.2.2 Typical Application Circuits

9.2.2.1 Precision Voltage Divider Connection

Precision data converters typically require voltage reference which is less than or equal to 5V. REF80 requires a

precision resistor divider followed by low noise buffer to generate reference voltage for data converters as shown

in Figure 9-3.

The selection of resistor depends on the current capability (< 1mA is preferred) and noise requirement. Minimum

value of resistors are decided by the output current as per Equation 4.

R1 + R2≥ 7.6kΩ

(4)

Maximum value of the resistors are decided by the noise consideration. Thermal noise of the resistors (parallel

equivalent) is added as per Equation 5

VREFNoise =  R2R1 + R2×REF_ZNoise2+ R1 R2Thermal Noise2

(5)

Where

• VREFNoise = Reference noise requirement in desired frequency band

• REF_ZNoise = REF80 noise in desired frequency band

• R1||R2Thermal noise = Thermal noise of parallel equivalent of R1 and R2 resistor

R1 and R2 must be precision foil resistors with matched temperature drift for best performance.

VREF

7.6V OUTPUT

OP-STBL

VDD

T-SET

REF_Z

REF_GND

HEATP

HEATM

+24 V

10 V

3.3V

Stable Temp Indicator

REF80

1µF

1µF

Figure 9-3. Precision Resistor Divider Connection

9.2.2.2 Calibration Signal

Ultra low long term stability and temperature drift makes REF80 an excellent choice for metrology grade

calibration signal generation.

REF80

SNAS856A – SEPTEMBER 2024 – REVISED MARCH 2025

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