Part Number: THS4131
Other Parts Discussed in Thread: ISO7710, TLV9301, TLV9302, TLV9031, TL331B, TLV1805, TLV7211
Hello team,
Customer will use THS4131 with dual supply and PD function.
Power-Down mode requires the negative voltage to control at /PD pin and are there any recommendation of level shifter at /PD pin ?
I would much appreciate your any advice.
Thank you and best regards,
Michiaki
All integrated level shifters require a common ground. An isolator like the ISO7710 would be overkill.
It is possible to construct a shifter with two discrete transistors (the input should be VCC, or be pulled to GND to pull PD to VCC−):
Morning Michiaki,
Well this was kind of a definitional mistake to require a level shift to a negative supply for the PD, in any case, assuming you would like to translate a typical logic level (say 0V to 3.3V here) into that PD requirement, one option might be to just use a low cost RRout op amp (TLV9302 here, only $0.17 in 1k) as a comparator. No feedback, just switch the input polarities and let the output go to the supply rails. Looks like this with a 1kHz input, The +/-15V swing would go to the THS4131 PD pin. The TINA reference design was using the dual TLV9302, but you would apply the single channel, TLV9301
I noticed the TLV9031 has a pretty high open loop output impedance, that will be divided against the internal 50kohm pullup in the THS4131 PD circuit.
Here I added that, and apparently that Zol is in the model as the low swing at the PD pin is -14.88 V not -15V. That would still shut off the FDA. And, they even show this comparator function in Fig. 8.1 in the datasheet.
