Slew rate of LM2832

Takahiro Nishizawa

Genius 5575 points

Other Parts Discussed in Thread: LM2832

We have a question about LM2832.

Is there limit on input slew rate in EN pin?

If this IC has limit, please tell us the range of slew rate.

Best regards,

Takahiro Nishizawa

over 5 years ago

0 JohnTucker over 5 years ago

TI__Guru**** 191445 points

Nishizawa-san,

EN is a logic input. You should be able to drive it with any typical logic drive slew rate.

0 Takahiro Nishizawa over 5 years ago in reply to JohnTucker

Genius 5575 points

Thank you for your answer!

We have new questions.

Does EN pin have hysteresis?
Will not it happen that the IC repeats on / off when EN pin is started very slowly?

Best regards,

Takahiro Nishizawa

0 JohnTucker over 5 years ago in reply to Takahiro Nishizawa

TI__Guru**** 191445 points

Nishizawa-san,

The datasheet is unclear about the actual circuit details. The Electrical Characteristics Table suggests that this is a digital input, but from experience, it may be that it is actually an analog input with or without hysteresis (ask me how I know...). I will need to check it in an actual circuit. I have ordered an EVM and will get back to you next week.

0 JohnTucker over 5 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Nishizawa-san,

I was able to secure an EVM to test. It is as I suspected. The datasheet specifies the EN start threshold as 1.8 V minimum and the EN shutdown threshold as 0.4 V maximum. This is similar to how logic threshold for TTL logic are specified. In actual measurement, the EN start threshold is about 1.18 V with about 50 mV of hysteresis, so teh EN shutdown threshold is about 1.13 V. In between those voltages, the circuit may start and stop randomly. I would ensure that my rise time for EN is much less than 1 msec and that the on and off values are within the range as specified in the datasheet.

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Slew rate of LM2832