Datasheet

Drift +
ǒ
V
OUTMAX
* V
OUTMIN
V
OUT
Temp Range
Ǔ
10
6
(ppm)
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
C1
1 Fm
+V
SUPPLY
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
+V
SUPPLY
10kW
1kW
470W
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.
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.
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:
(1)
The REF50xx features a maximum drift coefficient of 8 ppm/°C for the standard-grade.
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