REF5050AQDRQ1 Datasheet, PDF (10/21 Pages) Texas Instruments – LOW-NOISE, VERY LOW DRIFT, PRECISION VOLTAGE REFERENCE

REF5020-Q1, REF5025-Q1, REF5030-Q1
REF5040-Q1, REF5045-Q1, REF5050-Q1
SBOS456G – SEPTEMBER 2008 – REVISED OCTOBER 2013
www.ti.com
USING THE TRIM/NR PIN
The REF50xx provides a very accurate voltage output. However, V_OUT can be adjusted to reduce noise and shift
the output voltage from the nominal value by configuring the trim and noise reduction pin (TRIM/NR, pin 5). The
TRIM/NR pin provides a ±15-mV adjustment of the device bandgap, which produces a ±15-mV change on the
V_OUT pin. Figure 27 shows a typical circuit using the TRIM/NR pin to adjust V_OUT. When using this technique, the
temperature coefficients of the resistors can degrade the temperature drift at the output.
+V_SUPPLY
REF50xx
DNC
DNC
V_IN
TEMP
NC
V_OUT
GND TRIM/NR
470W
10kW
1kW
Figure 27. V_OUT Adjustment Using TRIM/NR Pin
The REF50xx allows access to the bandgap through the TRIM/NR pin. Placing a capacitor from the TRIM/NR pin
to GND (as Figure 28 illustrates) in combination with the internal 1-kΩ resistor creates a low-pass filter that
lowers the overall noise measured on the V_OUT pin. A capacitance of 1 μF is suggested for a low-pass filter with
a corner frequency of 14.5 Hz. Higher capacitance results in a lower cutoff frequency.
+V_SUPPLY
REF50xx
DNC DNC
V_IN
TEMP
NC
V_OUT
GND TRIM/NR
C1
1mF
Figure 28. Noise Reduction Using TRIM/NR Pin
TEMPERATURE DRIFT
The REF50xx is designed for minimal drift error, which is defined as the change in output voltage over
temperature. The drift is calculated using the box method, as described by the following equation:
ǒ Ǔ Drift +
V_OUTMAX * V_OUTMIN
V_OUT Temp Range
10⁶(ppm)
(1)
The REF50xx features a maximum drift coefficient of 8 ppm/°C for the standard-grade.
10
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