System and method for startup bootstrap for internal regulators

A bootstrap regulator circuit comprising

• an op amp which generates a control signal during steady state operation,
• a regulator for providing an output signal and responsive to the control signal,
• a switch operatively connected to disconnect the control signal from the regulator during initialization,
• a bootstrap circuit connected substantially in parallel with the switch and the regulator, and which controls the operation of the switch such that, when the switch is opened, the bootstrap circuit substantially controls the output signal during initialization to prevent unregulated voltages from being applied to downstream devices and, when the switch is closed, the bootstrap circuit has substantially no effect on the output signal.

A method for preventing unregulated voltages from being applied to downstream devices during initialization of a circuit comprising the steps of

• providing a regulator which, during steady state operation, receives at one input an unregulated voltage and supplies at its output a regulated voltage to an output node,
• detecting an initialization event,
• preventing the unregulated voltage from being applied to the output node substantially when the initialization event begins by disabling the regulator,
• establishing a reference voltage which increases during the initialization event and reaches a steady state value by the end of the initialization event,
• enabling the regulator in response to the reference voltage reaching substantially steady state value.

A regulator circuit for use in solid state devices comprising

• A bootstrap regulator circuit comprising
• an op amp which generates a control signal during steady state operation,
• a regulator for providing an output signal to an output node and responsive to the control signal,
• a switch connected between the op amp and the regulator to disconnect the control signal from the regulator in response to a reset signal,
• a bootstrap circuit, responsive to a reference voltage, for generating a bias voltage which controls the output node from the time the reset signal is applied until the reference voltage reaches substantially steady state, the bootstrap circuit further causing the switch to reconnect the control signal to the regulator when the voltage reference reaches a substantially steady state value.