Low voltage detect and/or regulation circuit
OwnerT. V. Chanakya Rao, Badrinarayanan Kothandaramaninventors
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Abstract
A low voltage detect and supply circuit (200) can include a detect circuit (202), a bias circuit (204) and a power supply transistor structure (P1). In operation, when a device power supply (Vext) remains above a predetermined limit, a detect circuit (202) can provide low impedance, thus maintaining transistor structure P1 in a high impedance state. When a device power supply (Vext) falls below a predetermined limit, a detect circuit can provide a high impedance. Embodiments of the circuit (200) do not include a differential voltage type comparator, and can be biased to draw relatively small amounts of current.
Claims20
A low voltage detect and supply circuit, comprising:
- at least one power supply transistor having a source connected to a power supply node, a gate coupled to a control node, and a drain coupled to a regulated supply node;
- a detect circuit having a controllable impedance path coupled between the power supply node and the control node that provides an impedance that varies according to a potential between the power supply node and the control node;
- and
- a bias circuit coupled between the control node a reference supply node that enables a bias current for the detect circuit.
A circuit, comprising:
- a low voltage detect circuit comprising
- a first controllable impedance path coupled between a power supply node and a regulated voltage node that provides an impedance according to the potential at a control node, and
- a threshold current path coupled between the power supply node and the control node that provides an impedance that switches from a low impedance to a high impedance when the potential between the power supply node and the control node falls below a predetermined potential;
- and
- a memory cell array coupled to the regulated voltage node.
A method of regulating an internal power supply node, comprising the steps of:
- enabling a shorting current path between a power supply node and a regulated power supply node when a power supply voltage at the power supply node falls below a predetermined low voltage threshold;
- and
- disabling the shorting current path between the power supply node and the regulated power supply node when the power supply voltage rises above the predetermined low voltage threshold;
- wherein
- the low voltage threshold is established by a threshold voltage of a p-channel transistor and a bias voltage.
Dependencies are inferred from the claim text.