Battery charge/discharge protection circuit
View Patent ↗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.
1. A battery charge/discharge protection circuit configured to protect the battery from charge/discharge damage, the protection circuit comprising:
a first terminal configured to be connected to a negative electrode of a charger;
a second terminal configured to be connected to a negative electrode of a rechargeable battery, wherein a positive electrode of the charger is configured to be connected to a positive electrode of the rechargeable battery;
a charge over-current detection circuit including a plurality of transistors;
a discharge over-current detection circuit including a plurality of transistors;
a short circuit detection circuit including a plurality of transistors;
a p-channel metal-oxide-semiconductor field-effect (PMOS) transistor,
wherein a drain electrode of the PMOS transistor is connected to the first terminal, a gate electrode of the PMOS transistor is connected to the second terminal, and 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;
wherein when a voltage above an overvoltage threshold is output by the charger, the voltage of the source electrode of the PMOS transistor is maintained above a negative threshold voltage, such that the transistors of the charge over-current detection circuit, the discharge over-current detection circuit and the short circuit detection circuit do not receive the voltage above the overvoltage threshold output by the charger.
2. The protection circuit of claim 1 wherein the PMOS transistor is a depletion PMOS transistor, wherein the drain electrode of the depletion PMOS transistor is resistant to negative high voltage.
3. A battery system comprising:
a rechargeable battery; and
a charge/discharge protection circuit coupled to the rechargeable battery, comprising:
a first terminal configured to be connected to a negative electrode of a charger;
a second terminal configured to be connected to a negative electrode of the rechargeable battery, wherein a positive electrode of the charger is configured to be connected to a positive electrode of the rechargeable battery;
a charge over-current detection circuit including a plurality of transistors;
a discharge over-current detection circuit including a plurality of transistors;
a short circuit detection circuit including a plurality of transistors;
a p-channel metal-oxide-semiconductor field-effect (PMOS) transistor,
wherein a drain electrode of the PMOS transistor is connected to the first terminal, a gate electrode of the PMOS transistor is connected to the second terminal, and a source electrode of the PMOS transistor is connected to the discharge over-current detection circuit, the charge over-current detection circuit, and the short circuit detection circuit;
wherein when a voltage above an overvoltage threshold is output by the charger, the voltage of the source electrode PMOS transistor is maintained above a negative threshold voltage, such that the transistors of the charge over-current detection circuit, the discharge over-current detection circuit and the short circuit detection circuit do not receive the voltage above the overvoltage threshold output by the charger.
4. The battery system of claim 3 wherein the PMOS transistor is a depletion PMOS transistor, wherein the drain electrode of the depletion PMOS is resistant to negative high voltage.