PCM1840: 3.3V is unintentionally input to the shutdown pin.

Ryu Yamashita

Part Number: PCM1840

Tool/software:

Hi team,

The shutdown pin is connected to the CPU.
Before the PCM1840 is turned on, the shutdown pin is subjected to a voltage of 3.3V for about 50ms by the CPU's specifications.
Is this problematic for the device?
I checked because the absolute maximum rating was IOVDD+0.3V.

Best Regards,
Ryu.

3 months ago

0 Daveon Douglas 3 months ago

TI__Mastermind 27280 points

Hi,

Yes, this can place device in an unstable state. Section 8.2.2 and 9 of the datasheet detail the power sequencing for SHDNz to ensure optimal performance.

0 Ryu Yamashita 3 months ago in reply to Daveon Douglas

Genius 3685 points

Hi Daveon,

I understand that the operation will be unstable.
Can components be broken by this operation?
If I follow the power sequence correctly afterwards, is there any problem with the operation?

Best Regards,
Ryu.

0 Daveon Douglas 3 months ago in reply to Ryu Yamashita

TI__Mastermind 27280 points

The IC will not break from this behavior.

However, SHDNz, IOVDD, and MD1 are intimately connected within the IC. If IOVDD is low and SHDNz has a toggle behavior, this can unintentionally enable analog blocks internally.

I suggest adding a 10k resistor to GND on MD1 to mitigate any overcurrent from IOVDD in this state.

0 Kengo.Y 3 months ago in reply to Daveon Douglas

Guru 11255 points

Hi Daveon,

Ryu has a holiday, so I'll contact you.
Thank you for answer.
If I have additional questions, I'll let you know.

0 Daveon Douglas 3 months ago in reply to Kengo.Y

TI__Mastermind 27280 points

Sure thing

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PCM1840: 3.3V is unintentionally input to the shutdown pin.