1. A system suitable to provide galvanic isolation between functional blocks, comprising: a signal source block to drive source signals through an LED optocoupler characterized by a forward voltage and a reverse breakdown voltage; an LED input emulator circuit with emulator anode and emulator cathode ports coupled to the signal source block, and an emulator output node, the LED input emulator circuit to emulate a forward voltage VF at the emulator output node, and a reverse bias voltage VR across the emulator anode and cathode ports; and an isolation circuit, including a galvanic isolation interface that is not based on optocoupling, coupled to the emulator anode port, through the emulator output node, and to the emulator cathode port, to receive the source signals through the LED input emulator circuit; the LED input emulator circuit including: VR reverse blocking circuitry coupled between the emulator anode port and both the emulator output node and the emulator cathode port, to emulate the reverse bias voltage VR, including MP 1 and MP 2 PMOS transistors drain-coupled to the emulator anode port, and gate-coupled to the emulator cathode port, with MP 1 source-coupled to the emulator output node; and MP 2 source-coupled to the emulator cathode port; and VF control circuitry coupled to the emulator output node, to control the forward voltage VF at the emulator output node, including a variable resistance circuit coupled between the emulator anode and cathode ports, to provide a variable resistance based on a VF control signal, and a current control circuit coupled to the emulator output node, to generate the VF control signal to control current through the variable resistance circuit based on a voltage at the emulator output node to maintain the voltage at the emulator output node at the forward voltage VF.