You need an op-amp that can handle the high-side common mode voltage from the sense resistor. Linear Tech (now part of Analog Devices), TI and others make devices with this ‘over the top’ capability.

Here’s an ADI appnote with a catalog of current sense techniques: https://www.analog.com/en/app-notes/an-105fa.html

Regardless, always check the common-mode input range of any op-amp you use. As it so happens, the LTC6100/LTC6101 can have inputs far above its own Vcc supply making it suitable for what you’re doing here.

You need an op-amp that can handle the high-side common mode voltage from the sense resistor. Linear Tech (now part of Analog Devices), TI and others make devices with this ‘over the top’ capability.

Here’s an ADI appnote with a catalog of current sense techniques: https://www.analog.com/en/app-notes/an-105fa.html

Regardless, always check the common-mode input range of any op-amp you use. As it so happens, the LTC6100/LTC6101 can have inputs far above its own Vcc supply making it suitable for what you’re doing here.

If your goal is merely to limit the current, this can be done much more simply with just two transistors. Fancier ones can do fold-back, offering even better protection. Some ideas here: https://www.electronics-notes.com/articles/analogue_circuits/power-supply-electronics/current-limiter-circuit.php

You need an op-amp that can handle the high-side common mode voltage from the sense resistor. Linear Tech (now part of Analog Devices), TI and others make devices with this ‘over the top’ capability.

More here: https://www.analog.com/en/app-notes/an-105fa.html

You need an op-amp that can handle the high-side common mode voltage from the sense resistor. Linear Tech (now part of Analog Devices), TI and others make devices with this ‘over the top’ capability.

Here’s an ADI appnote with a catalog of current sense techniques: https://www.analog.com/en/app-notes/an-105fa.html

Regardless, always check the common-mode input range of any op-amp you use. As it so happens, the LTC6100/LTC6101 can have inputs far above its own Vcc supply making it suitable for what you’re doing here.