• VOUT|t=n = output voltage at time = n hr

8.3.6 Output Adjustment Using the TRIM/NR Pin

The REF50xxI, REF50xxAI 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 8-5 shows a typical circuit that allows

an output adjustment of ±15 mV.

GND TRIM/NR

TEMP

VOUT

VIN

NC

DNC

DNC

REF50XX

1M

R1 = 10k

R2 = 2k

VSUPPLY

Figure 8-5. VOUT Adjustment Using the TRIM/NR Pin

The REF50xx allows access to the band-gap through the TRIM/NR pin. Placing a capacitor from the TRIM/NR

pin to GND (Figure 8-4) in combination with the internal R3 and R4 resistors creates a low-pass filter. A

capacitance of 1μF creates a low-pass filter with the corner frequency from 10Hz to 20Hz. 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.

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REF5010, REF5020, REF5025, REF5030, REF5040, REF5045, REF5050

SBOS410L – JUNE 2007 – REVISED OCTOBER 2024

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