REF54 datasheet(22/44 Pages) TI2

22 / 44 page

Flicker Noise (ppmp-p)

100

0.04 0.08 0.12 0.16

0.2

0.24 0.28 0.32

0.4

Figure 7-8. 0.1Hz to 10Hz Voltage Noise

(CNR = 100μF)

Flicker Noise (ppmp-p)

100

0.1

0.2

0.3

0.4

0.5

0.6

Figure 7-9. 0.1Hz to 10Hz Voltage Noise

(CNR = 10μF)

7.3.2 Broadband Noise

Broadband noise or white noise is flat over the whole spectrum which is restricted by the bandwidth of internal

bandgap reference. The broadband noise is measured by high-pass filtering the output of the REF54 and

measuring the result on a precision spectrum analyzer as shown in Figure 7-10. The DC component of the

REF54 is removed by using a high-pass filter and then amplified. Two stages of small gain has been used to

maximize the noise bandwidth analysis.

REF54

GND

VREF

VIN

CIN

VREF

CNR

Spectrum

Analyzer

Post Amplifier

G = 11

High-pass Filter

G = 11

Figure 7-10. Broadband Noise Test Setup

Figure 7-11 shows the typical white noise floor for REF54. Designer can use NR pin to restrict the noise

bandwidth to achieve required resolution for the signal chain. Connecting 1μF at NR pin creates a typical low

pass filter of 12Hz for the band gap noise which reduces the white noise floor of REF54. Capacitor > 1μF

eliminates all the noise in > 10Hz band.

Figure 7-11. Noise Performance 10Hz to 100kHz

(CNR = Open)

Frequency

1x101

1x102

1x103

1x104

1x105

100

CNR = open

CNR = 10 F

CNR = 1 F

Figure 7-12. Noise Performance 10Hz to 100kHz

(COUT) = 10μF

REF54

SNVSCN7D – NOVEMBER 2023 – REVISED JUNE 2026

www.ti.com

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