Finding the psrr of an amplifier

[Alex_77]

Hello,

I've bought a SAP15 based amplifier. Module Amplificateur - Module amplificateur stéréo SAP15 2x100W ClassAB

But to design the power supply I want to know the PSRR of this amplifier.

The LM4702 PSRR is 110dB typ (95dB min). I don't find any PSRR value for the SAP15 transistors.

Sorry for my poor english

Alexandre, from France

[ostripper]

The input stage/VAS, (an IC in your case) determines the PSRR. The output devices are enclosed within the global feedback loop , which makes them a part of the IC's circuit.

OS

[Alex_77]

So the PSRR of this amp is 95/110dB ?

[peranders]

It's rather high at least.

[Alex_77]

According to the datasheet :
Vcc PSRR @ 20Hz = -120dB
Vcc PSRR @ 20KHz = -75dB

Vee PSRR @ 20Hz = -120dB
Vee PSRR @ 20KHz = -65dB

[forr]

For estimation of amps circuits PSRR, I built regulated power supplies with an AC input which can modulate the DC output voltage. I set this one for a 1 V sine signal, short the amp input and measure the residual AC voltage of the amp output at various frequencies.

[Alex_77]

Now, how to find the ripple on the out of the amp with 1v ripple on the PSU ?

VCC = 30v

[ostripper]

Run the IC with capacitance multipliers , that -75db @ 20k figure might improve to -90 + db.

OS