Patent ID: 7868604

Claim:
A voltage regulator comprising: an operational amplifier including a first input coupled to a voltage terminal, including a second terminal, and including an output node that provides an enable pump oscillator signal for enabling or disabling an oscillator in a charge pump; a capacitor divider circuit coupled to the first input; a resistor divider circuit coupled to the capacitor divider by a first metal oxide semiconductor (MOS) transistor and comprising 3 terminals, including a first terminal coupled to a high voltage node, a second terminal, and a third terminal connected to the first MOS transistor and characterized by a divided resistance, wherein the voltage regulator is configured such that, when the first MOS transistor is in an off condition, a divided capacitance node of the capacitor divider is isolated from the resistor divider; a second MOS transistor attached to the second terminal of the resistor divider circuit, wherein the first MOS transistor and the second MOS transistor have separate timing control signals; circuitry connected to the second terminal of the operational amplifier, the circuitry including a third MOS transistor that is diode-connected, a fixed resistor, and an adjustable resistor having a first terminal in series with the fixed resistor and a second terminal connected to the third MOS transistor at a node coupled to the second terminal of the operational amplifier, wherein the circuitry is configured: to set a reference voltage on the second terminal of the operational amplifier via sized resistance formed of the fixed resistor and the adjustable resistor into the third NMOS transistor to provide a zero temperature coefficient voltage on the second terminal of the operational amplifier; and wherein resistance of the fixed resistor and the adjustable resistor may be adjusted to provide zero temperature coefficient reference and/or output adjustment; and a reference circuit coupled to the second terminal of the operational amplifier; wherein the enable pump oscillator signal is provided in response to a voltage on the divided capacitance node and the reference voltage; and wherein, in conjunction with the divided capacitance node being isolated from the resistor divider, the enable pump oscillator signal is provided as a timing control signal that enables or disables the oscillator without disturbance associated with operation of the resistor divider.