TPA3255: How to configure the input of OSC_M and OSC_P of TPA3255 in slave mode

Yunjing Wang1

Part Number: TPA3255

Dear team,

I need to use a low frequency of PWM frequency like 50kHz to my TPA3255, so I need to configure TPA3255 as slave mode, then use an external clock source connect to OSC_M and OSC_P.

Q1: Can you tell me how to configure external clock source that connect to OSC_M and OSC_P ?

Q2: Can I use a 50kHz external square connect to OSC_M and OSC_P?

Q3: What's the requirement of the external clock that connect to OSC_N and OSC_P?

Thank you!

Best regards

over 6 years ago

0 Xiaolin Qin over 6 years ago

TI__Expert 6295 points

Hello Yunjun,

this device Freq range is 430KHZ-625KHZ. 50KHZ may out of spec OSC range.

OSC is asked 6xFsw. 50KHZ could be out of spec. see datasheet page7

regards

Linda

0 Yunjing Wang1 over 6 years ago in reply to Xiaolin Qin

TI__Expert 4660 points

Got it. Thank you Linda!

0 Yining Liu over 6 years ago in reply to Xiaolin Qin

TI__Prodigy 50 points

hello Linda,

I have some questions about this answer:

I did not find any specifications and explaniations about this device frequency range of 430kHz~625kHz, why should the frequency be in this range and is it determined by the internal structure?

What will happen if my input osc frequency is higher than 6x625kHz?

Thank you and best regards

0 Luis Fernandes de Pina over 6 years ago in reply to Yining Liu

TI__Genius 15390 points

Hello Yining,

In our datasheet in section 7.5 the oscillator frequency we put is F_PWM x 6, If you take the OSC frequency and divide by 6 you get the PWM frequency range. We cannot guarantee proper device operation if you exceed the spec we put in the datasheet.

Best Regards,

Luis

0 Yining Liu over 6 years ago in reply to Luis Fernandes de Pina

TI__Prodigy 50 points

Hello Luis,

Thank you! I get it now. But the 7.5 section on datasheet only shows the fosc in master mode, when I need to use the slave mode and be able to set the external frequency by myself, what is the available frequency range?

Best regards

0 Luis Fernandes de Pina over 6 years ago in reply to Yining Liu

TI__Genius 15390 points

So the minimum spec for F_PWM we would recommend is 430k even in slave mode, but if you go lower the device could still operate but it will impact your THD performance.

Best Regards,

Luis

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TPA3255: How to configure the input of OSC_M and OSC_P of TPA3255 in slave mode