CD4093B: pin 4 peak current and peak power consumption

Johnny Guo

Part Number: CD4093B

Hi, Team,

I have one question about CD4093B from customer.

Customer found that in their design for CD4093B, pin 4 will be damaged and short to pin 7. And they found that the pulse current through pin 4 will be 36.8mA peak, time is 20ns, and the peak V*I is 449mW.

How do you think about the risk for pin 4 with below pulse current and power consumption?

In datasheet, what does the 100mW mean in below picture?

Is it static power consumption? Or peak power? Do you have peak power or current data?

Thanks.

Johnny

over 6 years ago

0 Emrys Maier over 6 years ago

TI__Guru* 96591 points

Hi Johnny,
The device h as an absolute maximum current rating of 10mA. This is nearly 4 times the maximum rating, and almost definitely would cause severe damage to the device. The maximum current rating cannot be exceeded.

0 Johnny Guo over 6 years ago in reply to Emrys Maier

TI__Expert 4910 points

Emrys,

Thanks for your reply.
I have another question. What is the current limitation on pin 14? Customer's test result is that the pulse current into pin 14 is 77mA peak, time is 30ns.
Will this pulse current affect CD4093B?

Thanks.
Johnny

0 Emrys Maier over 6 years ago in reply to Johnny Guo

TI__Guru* 96591 points

Hi Johnny,
There is no listed limit for the supply or ground pins on this device, however that current must be going somewhere. What are the conditions of this test?

0 Johnny Guo over 6 years ago in reply to Emrys Maier

TI__Expert 4910 points

Emrys,

Customer just tested the current flowing into pin 14, below is the test waveform. Could you review it and tell me whether it is a normal result?

Thanks.

Johnny

0 Emrys Maier over 6 years ago in reply to Johnny Guo

TI__Guru* 96591 points

I still need to know the condition of the test.

0 Johnny Guo over 6 years ago in reply to Emrys Maier

TI__Expert 4910 points

Emrys,

The test is in device normal working condition. Pin10 and pin11 will output PWM, when PWM is in rising edge, we can see a pulse current into pin14. The maximum pulse current into pin14 is 77mA/34ns.

Thanks.
Johnny

0 Emrys Maier over 6 years ago in reply to Johnny Guo

TI__Guru* 96591 points

I would recommend looking at the edge rates on the inputs - it's likely that there is a slow edge that is causing excessive current.

It's not uncommon for slow inputs to cause excessive current like this. Since the device doesn't list a maximum supply current or a minimum edge rate, the current should not be a problem - except that it uses up a lot of power.

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CD4093B: pin 4 peak current and peak power consumption