Patent ID: 8723492

Claim:
A controlled headroom low dropout regulator (CHLDO) comprising: a low dropout regulator (LDO) having an input terminal and an output terminal, wherein an output voltage (V_OUT_P) of the CHLDO is provided on the output terminal of the LDO; a capacitor (C 1 ) coupled to the input terminal of the LDO; a voltage source that adds an incremental voltage (V_DIFF) to the output voltage of the CHLDO, thereby providing a reference voltage (V_REF); a comparator having a first input terminal coupled to receive the reference voltage and a second input terminal coupled to receive an input voltage (V_IN_P) from the input terminal of the LDO, wherein the comparator exhibits a hysteresis voltage V_H; a current input terminal I_POS that receives an input current; a switch coupled between the current input terminal and the input terminal of the LDO, the switch having a control terminal coupled to an output terminal of the comparator, wherein the switch is turned on when the input voltage of the LDO is less than the reference voltage by more than the hysteresis voltage, and wherein the switch is turned off when the input voltage of the LDO is greater than the reference voltage.