TEA2376BT / TEA2376DT: Are the AUX pins clamped to 12V?

[lauxt]

Hello,

For interleaved transition mode PFC controller family TEA2376xT, it is unclear how the series resistors and turns ratios of the PFC inductors should be scaled to meet the voltage requirements of the AUX1/AUX2 pins.

For TEA19162T, I believe there was no internal clamp on the AUX pin. For TEA2376xT, is there a 12V internal clamp? (It is not shown in the block diagram, but the value "Iclamp(Auxx)max" is given in the Characteristics table.) 

What does Iclamp(Aux)max mean? If there is an internal 12V zener clamp on each AUX pin, is there also a 1.2mA current limiter in series with each clamp? 

We are thinking that, for a normal 390V boost application (100-240V pinput voltage), turns ratio of 10:1 - 13:1 should be about right, and for 10:1, perhaps the series resistance can be increased slightly to 39 - 51K to limit the clamp current to < 0.9mA.

Can the wording of the datasheet be cleared up to make this more obvious? Is there an application note available?

Thank you,

Tim

[TomasVaverka]

Hello Tim,

The TEA2376 is a new product.

We are still working on making the support material (release target beginning of 2024).

There is a preliminary AN, but it is far from complete (and contains some incorrect information). If you create a standard support ticket (case), I can share it with you anyway along with some other draft documents that we provided to customers that started working with the IC during development.

I can also include the AUX1 and AUX2 protections document which is a Ringo info button explanation that provides info on how to scale the AUX pin signals with the series resistor value.

The AUX 12V Zener is for protection purpose, but not functional. The AUX pins sense the current. The current clamp is for protection of the circuit and not directly intended for functionality.

Thanks for your suggestion to improve the datasheet information on the AUX functionality.

BR, Tomas

[lauxt]

Hi Tomas,

Thanks for your reply. That sounds great. As far as this pin goes, after some more studying, seems like there might be some pull-down resistance internally on the pin. So, pin should not see the full aux winding voltage, but is rather a division of the external resistance and internal resistance. So, seems like higher turns ratio PFC inductor designs (e.g. 20:1) might use about 33K external, and lower turns ratio PFC inductor designs (e.g. 8:1), might use like 82K...just as an example. Anyway...we were just curious whether low turns ratio designs needed some sort of further external attenuation (divider or clamp) to keep the pin safe.

Thanks,

Tim

Thanks.