I have read the datasheets of the INA168 and the INA169 and can't see any difference, other than internal resistors value and quiscent current (25uA for INA168, 60uA for INA169). Those two were even made in pretty much the same period. Does anyone know if there is any differnce and maybe which one is better?
Or maybe I should go with something different for high-side current measurement on a 40V 5A Lab PSU, since there are things like LTC6101 or MAX4080 ?
The value of those input resistors is a factor in determining the gain. If you need high gain, choose the INA169. Lower gain, choose INA168.
From the INA169 datasheet:
The higher gain may allow you to use a lower RL, decreasing the output impedance of your sensing circuit.
As you noticed, the trade-off is higher quiescent current.
Aside from the 5:1 difference in load resistance for the same output voltage/input voltage, and Iq, the '169 is 10-15% more expensive (0.85 USD in 1K vs. 0.75 USD) and there seem to be fewer in stock. The temperature ranges are a bit different.
Because of the 1K vs. 5K resistors, the '169 will also draw more current as the load current increases from zero (where Iq is measured) (full scale with 100mV across the sense resistor is typically going to be Iq + 100uA for the '169 vs. Iq + 20uA for the '168).
The bandwidth difference is mostly due to load resistance.
I don't see a lot of reason to use the 169 unless you require the extended temperature range.
It might be a revision on the silicon, after signing contracts (hint: you can get them with automotive part number) you cannot abandon parts. So they just keep making them both.
There are subtle differences in the bandwidth and temperature ratings. Which might suggest an automotive client simply requested different specs.
You should definitely ask TI these kind of questions.
Does anyone know if there is any differnce and maybe which one is better?
The INA1x8 seems to have higher bandwidth. Which can be an advantage when used in an analog loop.
