The REF50xx provides a very accurate, factory-trimmed voltage output. However, VOUT can be adjusted using the trim and noise reduction pin (TRIM/NR, pin 5). Figure 9-3 shows a typical circuit that allows an output adjustment of ±15 mV.
The REF50xx allows access to the band-gap through the TRIM/NR pin. Placing a capacitor from the TRIM/NR pin to GND (Figure 9-2) in combination with the internal R3 and R4 resistors creates a low-pass filter. A capacitance of 1 μF creates a low-pass filter with the corner frequency from 10 Hz to 20 Hz. Such a filter decreases the overall noise measured on the VOUT pin by half. Higher capacitance results in a lower filter cutoff frequency, further reducing output noise. Using this capacitor increases start-up time.