US 2010/0148727 A1Published application

Single-Power-Transistor Battery-Charging Circuit Using Voltage-Boosted Clock

AssigneeHong Kong Applied Science and Technology Research Institute Company Limited

InventorsKwok Kuen Kwong, Yat To Wong, Ho Ming (Karen) Wan, Chik Wai Ng

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Abstract

A charge/discharge protection circuit protects a battery from inadvertent shorting on a charger node that can connect to a charger or to a power supply of a portable electronic device. A single n-channel power transistor has a gate that controls a channel between the battery and the charger node. The gate is connected to the charger node by a gate-coupling transistor to turn off the power transistor, providing battery isolation. The gate is driven by a voltage-boosted clock through a switch activated by an enable signal. The enable signal also activates a grounding transistor to ground a gate of the gate-coupling transistor. A comparator compares voltages of the charger and battery nodes, and the compare output is latched to generate the enable signal. An inverse enable signal activates a second switch that drives the voltage-boosted clock to the gate of the gate-coupling transistor to turn off the power transistor.

Claims20

Dependent claims

A battery protection circuit comprising:

a battery node for connecting to a terminal of a battery;
a charger node for connecting to a terminal of a charger that charges the battery;
a power transistor having a channel connected between the battery node and the charger node, and a gate that controls the channel, the gate connected to a first gate node;
a comparator having inputs connected to the battery node and to the charger node, for generating a compare output from a voltage difference between the battery node and the charger node;
a control circuit that receives the compare output from the comparator and generates a first enable signal and a second enable signal;
a voltage booster, receiving a clock, for generating a boosted clock, the boosted clock having a higher high voltage than a high voltage of the clock;
a first switch, receiving the boosted clock from the voltage booster, for applying the boosted clock to the first gate node in response to the first enable signal;
a gate-coupling transistor having a channel connected between the charger node and the first gate node, and a gate that controls the channel, the gate connected to a second gate node;
a second switch, receiving the boosted clock from the voltage booster, for applying the boosted clock to the second gate node in response to the second enable signal;
and
a grounding transistor that connects the second gate node to a ground when the second switch is not applying the boosted clock to the second gate node;
whereby the power transistor is biased by the gate-coupling transistor to shut off and isolate the battery node from the charger node when the second enable signal is activated and the first enable signal is de-activated.

9 more elements

A discharge protector comprising:

an external node;
a protected node;
an n-channel power transistor having a gate connected to a first gate node, a drain connected to the external node, and a source connected to the protected node;
a gate-coupling transistor having a gate connected to a second gate node, a drain connected to the external node, and a source connected to the first gate node;
a grounding transistor having a gate controlled at least in part by a first enable signal, a drain connected to the second gate node, and a source connected to a ground node;
a control circuit that generates the first enable signal and a second enable signal;
a voltage booster that receives a clock and generates a boosted clock, the boosted clock having a boosted voltage that is above a power-supply voltage;
a first switch that connects the boosted clock to the first gate node when the first enable signal is active, and isolates the first gate node from the boosted clock when the first enable signal is not active;
and
a second switch that connects the boosted clock to the second gate node when the second enable signal is active, and isolates the second gate node from the boosted clock when the second enable signal is not active.

7 more elements

An integrated pulse battery charger comprising:

a first terminal for connecting to a charger;
a second terminal for connecting to a battery;
power transistor means for conducting current between the first terminal and the second terminal in response to a first gate node;
compare means for comparing voltages of the first terminal and the second terminal to generate a compare output;
control circuit means, receiving the compare output, for generating a first enable signal and a second enable signal;
gate-coupling transistor means for conducting current between the first terminal and the first gate node in response to a second gate node;
grounding transistor means for conducting current between the second gate node and a ground node in response to a gate at least partially controlled by the first enable signal;
voltage boost means, receiving a clock, for generating a voltage-boosted clock having a high voltage in excess of a power-supply voltage;
first switch means for driving the voltage-boosted clock onto the first gate node in response to the first enable signal;
and
second switch means for driving the voltage-boosted clock onto the second gate node in response to the second enable signal,
whereby the battery is charged by the charger during high pulses of the voltage-boosted clock.

9 more elements

Dependencies are inferred from the claim text.