CD40106B: Quiescent current of the decvice.

Chris van Niekerk

Part Number: CD40106B
Other Parts Discussed in Thread: TLV7034

Tool/software:

Hi.

I have a very low power design where I used this part. It pulses two LED's 30ms apart for 20ms each every 6seconds as illustrated.

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The circuit is power from 4xAAA Duracell Optimum batteries. The white LED's are driven through a 1kOhm limiting resistor each with a N-Ch MOSFET each to not load the CD40106.

The average current using the CD40106 is 190uA. Replacing the CD40106 with a HEF40106 from NXP, the average current drops to 70uA.

I have tested several circuits with each manufacturers' part and there is very little variation.

This 120uA variation results in a 2year reduction in battery life.

Per your datasheet, the quiescent current is a max of 2uA at 0-10V at 25degC.

Attached is a picture of the chips used.

Is there an explanation for the large variation?

Your assistance will be appreciated as we have a few hundred of the units in stock and customers return them due to the short battery life.

Best regards

Chris

2 months ago

0 Clemens Ladisch 2 months ago

Guru 261430 points

Please show the schematic.

0 Chris van Niekerk 2 months ago in reply to Clemens Ladisch

Prodigy 130 points

Hi Clemens

R1 and R6 are 1kOhm now, not 47Ohm.

A correction. The batteries are AA, not AAA as stated in the case.

P23064_SCH.PDF

Thanks and regards

Chris

0 Clemens Ladisch 2 months ago in reply to Chris van Niekerk

Guru 261430 points

These are shoot-through currents; they happen when the input voltage is not near the rails. See [FAQ] How does a slow or floating input affect a CMOS device? Below are typical values for the HEF40106B:

The CD40106B datasheet is based on the original one from RCA and does not specify this; the only information about this is implied by figure 18:

Apparently, the input transistors of HEF4000 devices have a higher gate-to-source threshold voltage than those of CD4000 devices. For this particular application, thew HEF device would be more appropriate.

But all these devices are optimized for digital signals; neither Nexperia nor TI make any guarantees about this particular analog characteristic. If you care about power consumption, use low-power comparators like the TLV7034.

0 Chris van Niekerk 2 months ago in reply to Clemens Ladisch

Prodigy 130 points

Thank you Clemens

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CD40106B: Quiescent current of the decvice.