Shanghai Sim-bcd Semiconductor Manufacturing Co., Ltd.

Zutao Liu

Shaohua Peng

A voltage reference circuit includes a first enhancement-mode PMOS transistor, a first enhancement mode NMOS transistor, and a first depletion-mode PMOS transistor coupled in series between a voltage supply and a ground. A second depletion-mode PMOS transistor is coupled to the first enhancement PMOS transistor to form a feedback circuit. A first resistive device is coupled between the voltage supply and the second depletion-mode PMOS transistor, and a second resistive device is coupled between the second depletion-mode PMOS transistor and the ground. A bias circuit is coupled to a gate of the first enhancement-mode NMOS transistor. The first enhancement-mode PMOS transistor and the first depletion-mode PMOS transistor are configured to operate in saturation region. A first reference voltage across the first resistor and a second reference voltage across the second resistor are configured to be independent of the magnitude of the voltage supply and have low temperature drift.

Low temperature drift voltage reference circuit

The present invention relates to a battery charge/discharge protection circuit that protects an associated battery from charge/discharge damage. The charge/discharge protection circuit includes a first terminal, a second terminal, a charge over-current detection circuit, a discharge over-current detection circuit, a short circuit detection circuit, and a PMOS transistor. A drain electrode and a gate electrode of the PMOS transistor are connected to the first terminal and the second terminal respectively. A source electrode of the PMOS transistor is connected to the charge over-current detection circuit, the discharge over-current detection circuit and the short circuit detection circuit, such that when a voltage above an overvoltage threshold is supported by the charger, the voltage of the source electrode of the PMOS transistor is maintained above a negative threshold voltage and the elements in these circuits do not receive such a voltage output by the charger.

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Shanghai, China

Zutao Liu