INA1650 datasheet(21/41 Pages) TI1

21 / 41 page

VMID(OUT)

VMID(IN)

VCC

VEE

500

VMID(OUT)

VMID(IN)

VCC

VEE

500

VCC

ZD1

˜ S ˜

: ˜

3dB

250 k

100

Source Impedance Mismatch (O)

250 k

500 k

1 M

C006

INA1650-Q1, INA1651-Q1

www.ti.com

SBOS772B – AUGUST 2017 – REVISED APRIL 2019

Product Folder Links: INA1650-Q1 INA1651-Q1

Submit Documentation Feedback

Application Information (continued)

Figure 45. CMRR vs Source Impedance Mismatch for Different RCOM Values

RCOM does not need to be a high-precision resistor with a very tight tolerance. Low-cost 5% or 1% resistors can

be used with no degradation in overall performance. The addition of RCOM does not increase the noise of the

audio signal path.

In single-supply systems where AC coupling is used at the inputs of the INA165x-Q1, adding RCOM lengthens the

start-up time of the circuit. The input AC-coupling capacitors are charged to the midsupply voltage through the

RCOM resistor, which may take a substantial amount of time if RCOM has a large value (such as 1 MΩ). Do not

use RCOM in these systems if start-up time is a concern. In dual-supply systems with input AC-coupling

capacitors, the capacitor voltage does not need to be charged to a midsupply point, because the capacitor

voltage settles to ground by default. Therefore, RCOM does not increase start-up time in dual-supply systems.

8.1.3 Start-Up Time in Single-Supply Applications

The internal supply divider of the INA165x-Q1 is constructed using two 500-kΩ resistors connected in series

between the VCC and VEE pins. These resistors are matched on-chip to provide a reference voltage that is

exactly one half of the power supply voltage. Noise from the power supplies and thermal noise from the resistors

degrades the overall audio performance of the INA165x-Q1 if allowed to enter the signal path. Therefore, TI

recommends a filter capacitor (CF) is connected to the VMID(IN) pin, as shown in Figure 46 The CF capacitor

forms a low-pass filter with the internal 500-kΩ resistors. Noise above the corner frequency of this filter is passed

to ground and is removed from the audio signal path. The corner frequency of the filter is shown in Equation 3:

(3)

Figure 46. Connect a Capacitor (CF) to the VMID(IN)

Pin to Reduce Noise from the Voltage Divider

Figure 47. A Zener Diode (ZD1) Connected to the

Positive Supply Can Decrease Start-Up Time

INA1650 Datasheet(PDF) 21 Page - Texas Instruments

INA1650 Datasheet(HTML) 21 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Datasheet Download

Link URL