A High-Voltage Pre-Regulator Circuit for Wide-Input LDO

Aiming at the application environment of LDO chip in automotive electronic system, a high voltage pre-regulator circuit is proposed, which converts the input high voltage into stable low power supply voltage to power the low voltage module inside the LDO chip. The circuit can be started normally after the bias current is established, and can quickly respond to transient changes in the external input of the automotive electronic system and perform negative feedback adjustment to obtain a stable pre-regulation voltage. The simulation results show that the input voltage range of the circuit can reach 40V high voltage, only 0.5mV changes in the change of input voltage 3~40V. The maximum load is 2.8mA. The loop is stable with a phase margin of 50°, and there is only a small overshoot and fast stability when the input voltage occurs a transient jump of about 30V.