POR chip that works on 12v reset lines?

[cnt]

Hi All,

There seems to be thousands of open drain sot23 POR chips that hold the reset line low for 10's to 100's of ms on power up.  My problem is I'm working with a 12v system and they're all designed for 6v max.  Current consumption is not a problem and they only take microamps so I can divide VDD to get in range of their threshold voltage fine, but none of them spec a Vds max for their output FET. 

Does anyone know of a POR IC that has a open drain output with Vds max>12v?

[David Hess]

There are some:

https://www.analog.com/en/ltc2965

But the common solution is to add a common base transistor cascode to the output pin.  So the open collector output pulls the emitter/source to ground which pulls the collector/drain to ground but the transistor holds off the high voltage.

[SiliconWizard]

Well, yeah.

Many supervisor/reset ICs come in variants: different output polarity, OD or totem pole...

Just select one that has a totem pole output with inverted polarity, and drive a MOSFET with max VDS > 12V. Done.

The LTC2965 mentioned by David is interesting if PCB area is at a premium, but otherwise not sure it's worth it compared to the above solution. LTC2965 is not cheap.

[David Hess]

I only used the LTC2965 as an example.  I would do what I suggested and use the POR chip of my choice with a common emitter/source or common base/gate output transistor to provide a high voltage open collector/drain output.  With a MOSFET, only a single external part may be required.

[Yansi]

TL77xx (TL7702, TL7712,...) series chip.

More than cheap enough.

[cnt]

TL77xx is exactly what i was looking for!  Thanks.

Thanks to others too.  because I asked an overly specific question the other solutions didn't satisfy my constraints, but are much appreciated.

[temperance]

A common gate connected MOSFET circuit might work. But we don't know your requirements.

Gate: connect to POR VCC
Gate-source: high value resistor. (in order to not load the voltage divider powering the POR)
Drain: pull up to 12V, your level shifted copy