AM26C31: For PWM signals

Brian Wang0928

Part Number: AM26C31
Other Parts Discussed in Thread: AM26LV31, MC3487, AM26LS31, THVD1500, THVD2410

Tool/software:

Hello Team,

Customer is looking for a Single end to differential output transmitter for PWM signals on the long trace driver board of the MOTOR DRIVE for better noise immunity.

Original AM26C31 is being used, but since it has upper clamping diode on the input, it's not allowed in the functional safety requirements.

Here are more specific requirements of this transmitter:

Enable function

6CH PWM signals (Customer prefer multi-ch ic maybe 4ch, 6ch or 8ch)

SE input and Differential output

No upper ESD diode inside the device

Bias power =5Vcc

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 321960 points

The AM26LV31(E) needs a 3.3 V supply, but supports 5 V input signals.

0 Ethan Sempsrott over 1 year ago

TI__Mastermind 22462 points

Hi Brian,

Apologies for the delay. Your thread somehow slipped through, and I am now seeing it for the first time.

There are a couple devices that could work. I would recommend the MC3487 or AM26LS31. Both devices meet all of your requirements. We currently do not have differential drivers with more than 4 channels. Both devices have figures that show they do not have an ESD diode to VCC.

I would not recommend the AM26LV31 as operating at 5V VCC is outside the recommended operating conditions.

Best,

Ethan

0 Hung Shien Feng over 1 year ago in reply to Ethan Sempsrott

Prodigy 20 points

Hi Ethan,

This is Clark from Delta.

As Brian mentioned, the AM26C31 generates differential output, and these output signals are connected via long cables to the single-ended output IC (AM26C32IDR) on the driver board.

Are both devices you recommend suitable for applying 5Vcc and using a 3.3V PWM input?

Could you also recommend alternative ICs of the AM26C32IDR for MC3487 and AM26LS31?

Thank you!
Regards,

Clark

0 Clemens Ladisch over 1 year ago in reply to Hung Shien Feng

Guru 321960 points

All mentioned devices support 3.3 V input signals.

Where does the requirement for "no upper ESD diode" come from? When you have 3.3 V input signals with a 5 V supply, the diode does not matter.

0 Hung Shien Feng over 1 year ago in reply to Clemens Ladisch

Prodigy 20 points

It is a functional safety requirement for the Safe Torque Off (STO) feature. When there is no 5V supply and the 3.3V input signals continue to operate, it must be assured that Vcc is not charged. While this is not the only solution available, it is the current approach being implemented.

0 Clemens Ladisch over 1 year ago in reply to Hung Shien Feng

Guru 321960 points

All multichannel drivers are very old, and the MC3487/AM26LS31 are bipolar devices with a high power consumption. Consider using modern and more robust transceivers, e.g., 6× THVD1500, even if you do not need the receiver function. These 8-pin devices have many P2P replacements with improved ESD/transient voltage protection (e.g., THVD2410), if needed.

0 Ethan Sempsrott over 1 year ago in reply to Hung Shien Feng

TI__Mastermind 22462 points

MC3486 and AM26LS32A are the corresponding quad receivers.

I agree with Clemens points here. 3.3V inputs are supported. I would recommend the THVD1500. It is common to see designs that only use the receivers or drivers individually.

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AM26C31: For PWM signals