TS4975 datasheet(30/36 Pages) STMICROELECTRONICS

Part #	TS4975

Description	Stereo Headphone Drive Amplifier with Digital Volume Control via I2C Bus

PDF	36 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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30 / 36 page

Application Information

TS4975

30/36

4.7

Notes on PSRR measurement

What is PSRR?

The PSRR is the Power Supply Rejection Ratio. The PSRR of a device is the ratio between a

power supply disturbance and the result on the output. In other words, the PSRR is the ability of

a device to minimize the impact of power supply disturbance to the output.

How we measure the PSRR?

The PSRR was measured according to the schematic shown in

Figure 62.

Figure 62. PSRR measurement schematic

Principles of operation

●

The DC voltage supply (VCC) is fixed

●

The AC sinusoidal ripple voltage (Vripple) is fixed

●

No bypasss capacitor Cs is used

The PSRR value for each frequency is calculated as:

RMS is a rms selective measurement.

PSRR

20Log

RMS

Out put

()

RMS

ri pple

()

--------------------------------- dB

()

TS4975 Datasheet(PDF) 30 Page - STMicroelectronics