VMID(OUT)

VMID(IN)

VCC

VEE

500

k

500

k

REF A

REF B

Copyright © 2016, Texas Instruments Incorporated

50

55

60

65

70

75

80

85

90

95

10

100

1k

10k

Frequency (Hz)

F

F / 1 M

F

F / 1 M

C007

21

INA1650, INA1651

www.ti.com

SBOS818A – DECEMBER 2016 – REVISED SEPTEMBER 2018

Product Folder Links: INA1650 INA1651

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Copyright © 2016–2018, Texas Instruments Incorporated

Application Information (continued)

Although the input resistors of the INA165x are matched typically within 0.01%, large capacitors are usually

mismatched. The mismatch in the values of the AC-coupling capacitors causes the corner frequencies at the two

signal inputs (IN+ and IN–) to be different, which can degrade CMRR at low frequency. For this reason, TI

recommends placing the high-pass corner frequency well below the audio bandwidth and to use a resistor in

section for more information on placing a resistor in series with the COM pin. Figure 48 shows the effect of a 5%

at 100 Hz: 1-µF AC-coupling capacitors with a 5% mismatch degrade the CMRR to 75 dB, while 10-µF

Figure 48. CMRR Degradation Due to a 5% Mismatch in AC-Coupling Capacitors

8.1.5 Supply Divider Capacitive Loading

Figure 49), must be used if capacitive loads larger than 150 pF are connected to the VMID(OUT) pin. Figure 49

shows the recommended configuration of an isolation resistor in series with the capacitive load. The REF pins of

the INA1650 must connect directly to the VMID(OUT) pin before the isolation resistor. Any resistance placed

between the VMID(OUT) pin and the reference pins degrades the CMRR of the device. Figure 50 shows the

recommended value for the isolation resistor for increasing capacitive loads.

Figure 49. Place an Isolation Resistor Between the VMID(OUT) Pin and Large Capacitive Loads