TPL7407L: TPL7407L without Power Supply

Norbert Nestler

Part Number: TPL7407L
Other Parts Discussed in Thread: ULN2003V12

I want to use a TPL7407L as a replacement for ULN2003. Unfortunatelly, the COM-Pin (Pin 9) is not connected in my circuit, as it was not necessary for ULN2003. The IC drives only LED's with a current of 2mA. I tried the TPL7407L in the circuit - and it works without a power supply on the COM-Pin. Do you think, using the TPL7407L without power supply can cause a problem (Pin open....)?

Thanks in advance,

best regards

Norbert

over 8 years ago

0 Clemens Ladisch over 8 years ago

Guru 316760 points

The datasheet says that COM must be have at least 8.5 V to get full output drive. Anyway, section 7.2 shows that the gate driver gets its power from COM.

I suspect that the circuit gets powered through the ESD protection diodes, which is something you should never do.

0 Michael J Schultis over 8 years ago in reply to Clemens Ladisch

TI__Mastermind 24975 points

Hello Norbert,

As Clemens mentioned, it would not be recommended to drive any peripherals without a power supply connected to the COM pin for this device.

If possible, I would recommend using the supply that you are using to drive your LEDs to power the COM pin.

You could also look into using the ULN2003V12 device for your application as it is similar to the TPL7407L in that it uses FETs instead of Darlington Pairs, but the outputs are only 18V tolerant. If 18V is enough, then that would be my recommendation.

Best,
Michael

0 Norbert Nestler over 8 years ago in reply to Michael J Schultis

Intellectual 340 points

Hello Michael,

thank you for your information. The ULN2003V12 solves my problem! Didn't know this device... As my LED's are powered with 5V, the 18V output range is sufficient.

Thanks for great support,

best regards

Norbert

0 Michael J Schultis over 8 years ago in reply to Norbert Nestler

TI__Mastermind 24975 points

Norbert,

Very happy to help!
Please feel free to let me know if you have any additional questions.

Best,
Michael

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TPL7407L: TPL7407L without Power Supply