# US 11,114,881 B2 · Load switch circuit and method of controlling battery power using the same

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- Number: US 11,114,881 B2
- Document ID: US11114881B2
- Status: Granted
- Kind: B2
- Application number: 16/436,574
- Filed: 2019-06-10
- Published: 2020-03-26
- Granted: 2021-09-07
- Earliest claimed: 2018-09-21
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Tae-Jin Jeong; Hyun-Su Kim
- Web page: https://patentgrep.com/patent/US11114881B2

## CPC

- G05F 1/461: {using an operational amplifier as final control device}
- G01R 19/16519: {using FET's}
- H01M 10/425: {Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing (printed circuits H05K1/00)}
- H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00)
- H01M 10/48: Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569)
- H02J 7/663: {using battery or load disconnect circuits (H02J9/002 takes precedence)}
- H02J 7/933: {the cycle being controlled or terminated in response to electric parameters}
- H02J 7/96: in response to battery voltage
- H02M 3/07: using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps}
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- Y02E 60/10: Energy storage using batteries
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A load switch circuit includes a charging transistor, a current sensor, a voltage sensor, a selector, a current controller and a mode controller. The charging transistor is connected between a first switch node and a second switch node and controls a charging current in response to a charging control signal. The current sensor is connected to the first switch node and the second switch node and senses the charging current to generate a current sensing signal. The voltage sensor is connected to the first switch node and the second switch node and senses a source-drain voltage of the charging transistor to generate a voltage sensing signal. The selector selects the current sensing signal or the voltage sensing signal in response to a mode signal to generate a selection voltage signal. The current controller compares the selection voltage signal with a reference voltage to generate the charging control signal.

## Claims

### Claim 1

A load switch circuit comprising:
a charging transistor connected between a first switch node to which a battery voltage is applied and a second switch node to which a charging voltage is applied and configured to control a charging current in response to a charging control signal;
a current sensor connected to the first switch node and the second switch node and configured to sense the charging current to generate a current sensing signal;
a voltage sensor connected to the first switch node and the second switch node and configured to sense a source-drain voltage of the charging transistor to generate a voltage sensing signal;
a selector configured to select one of the current sensing signal and the voltage sensing signal in response to a mode signal to generate a selection voltage signal; and
a current controller configured to compare the selection voltage signal with a reference voltage to generate the charging control signal.

### Claim 2 (depends on 1)

The load switch circuit of claim 1, wherein the load switch circuit controls the charging current based on:
the voltage sensing signal in a voltage control mode when the charging current is lower than a limit current level, and
the current sensing signal in a current control mode when the charging current is higher than the limit current level.

### Claim 3 (depends on 1)

The load switch circuit of claim 1, wherein the current sensor includes a first variable resistor and adjust a resistance value of the first variable resistor based on a limit current setting value to adjust a limit current level of the charging current.

### Claim 4 (depends on 3)

The load switch circuit of claim 3, wherein the current sensor includes a second variable resistor and adjust a resistance value of the second variable resistor based on a voltage setting value to adjust a magnitude of the source-drain voltage of the charging transistor.

### Claim 5 (depends on 4)

The load switch circuit of claim 4, wherein the load switch circuit controls the limit current setting value and the voltage setting value such that the limit current level of the charging current is proportional to the magnitude of the source-drain voltage of the charging transistor.

### Claim 6 (depends on 1)

The load switch circuit of claim 1, wherein the current sensor includes:
an N-type metal oxide semiconductor (NMOS) transistor connected between the second switch node and a first node and configured to operate in response to the charging control signal;
a P-type metal oxide semiconductor (PMOS) transistor connected between the first node and a second node and configured to operate in response to an amplification signal;
a resistor connected between the second node and a ground voltage; and
a sense amplifier configured to amplify a difference between a sensing voltage at the first node and the battery voltage at the first switch node to generate the amplification signal.

### Claim 7 (depends on 6)

The load switch circuit of claim 6, wherein the resistor included in the current sensor is a variable resistor and the load switch circuit controls a resistance value of the variable resistor to adjust a magnitude of the charging current.

### Claim 8 (depends on 1)

The load switch circuit of claim 1, wherein the voltage sensor includes:
a first resistor connected between the second switch node and a first node;
a PMOS transistor connected between the first node and a second node and configured to operate in response to an amplification signal;
a second resistor connected between the second node and a ground voltage; and
a sense amplifier configured to amplify a difference between a sensing voltage at the first node and battery voltage at the first switch node to generate the amplification signal.

### Claim 9 (depends on 8)

The load switch circuit of claim 8, wherein the second resistor included in the voltage sensor is a variable resistor and the load switch circuit controls a resistance value of the variable resistor to adjust a magnitude of the source-drain voltage.

### Claim 10 (depends on 1)

The load switch circuit of claim 1, wherein the current controller includes:
an error amplifier configured to amplify a difference between the reference voltage and the selection voltage signal to generate an error amplification signal; and
a charge pump configured to sum the error amplification signal and the battery voltage to generate the charging control signal.

### Claim 11 (depends on 10)

The load switch circuit of claim 10, wherein the charge pump includes:
a first switch connected between an input node receiving the error amplification signal and a first node and configured to operate in response to a first signal;
a second switch connected between the first node and an output node outputting the charging control signal and configured to operate in response to a second signal corresponding to an inverted signal of the first signal;
a third switch connected between the input node and a second node and configured to operate in response to the second signal;
a fourth switch connected between the second node and the output node and configured to operate in response to the first signal;
a first capacitor connected between the first node and a third node;
a fifth switch connected between the third node and a ground voltage and configured to operate in response to the first signal;
a sixth switch connected between the third node and the battery voltage and configured to operate in response to the second signal;
a second capacitor connected between the first node and a fourth node;
a seventh switch connected between the fourth node and the ground voltage and configured to operate in response to the second signal; and
an eighth switch connected between the fourth node and the battery voltage and configured to operate in response to the first signal.

### Claim 12 (depends on 1)

The load switch circuit of claim 1, further comprising a mode controller configured to generate the mode signal indicating a voltage control mode or a current control mode based on the current sensing signal and the selection voltage signal.

### Claim 13 (depends on 12)

The load switch circuit of claim 12, wherein the mode controller transitions the mode signal from:
a first logic level to a second logic level at a time point when a voltage of the current sensing signal increases and exceeds the reference voltage, and
the second logic level to the first logic level at a time point when a voltage of an error amplification signal is equal to a power supply voltage, the error amplification signal being an amplified signal of a difference between the reference voltage and the selection voltage signal.

### Claim 14 (depends on 13)

The load switch circuit of claim 13, wherein the load switch circuit operates in:
a voltage control mode to control the charging current based on the voltage sensing signal when the mode signal has the first logic level, and
a current control mode to control the charging current based on the current sensing signal when the mode signal has the second logic level.

### Claim 15 (depends on 12)

The load switch circuit of claim 12, wherein mode controller includes:
a first selector configured to select and output one of the reference voltage and a lowered reference voltage lower than the reference voltage in response to a selection signal;
a second selector configured to select and output one of a power supply voltage and a lowered power supply voltage lower than the power supply voltage in response to a voltage mode setting signal;
a first comparator configured to compare an output of the first selector and the current sensing signal to generate a current mode setting signal;
a second comparator configured to compare an output of the second selector and an error amplification signal to generate the voltage mode setting signal;
a flip-flop configured to be reset in response to the voltage mode setting signal and configured to be set in response to the current mode setting signal to generate the mode signal; and
a logic gate configured to perform a logic operation on the current mode setting signal and the mode signal to generate the selection signal.

### Claim 16 (depends on 1)

The load switch circuit of claim 1, further comprising a diode including an anode electrode connected to the first switch node and a cathode electrode connected to the second switch node.

### Claim 17 (depends on 1)

The load switch circuit of claim 1, wherein the load switch circuit is directly connected to a battery that is mounted in a mobile device.

### Claim 18

A load switch circuit comprising:
a charging transistor connected between a first switch node to which a battery voltage is applied and a second switch node and configured to control a charging current in response to a charging control signal;
a discharging transistor connected between a third switch node to which a charging voltage is applied and the second switch node and configured to control a discharging current in response to a discharging control signal;
a first current sensor connected to the first switch node and the second switch node and configured to sense the charging current to generate a first current sensing signal;
a second current sensor connected to the third switch node and the second switch node and configured to sense the discharging current to generate a second current sensing signal;
a first voltage sensor connected to the first switch node and the second switch node and configured to sense a source-drain voltage of the charging transistor to generate a first voltage sensing signal;
a second voltage sensor connected to the third switch node and the second switch node and configured to sense a source-drain voltage of the discharging transistor to generate a second voltage sensing signal;
a first selector configured to select one of the first current sensing signal and the first voltage sensing signal in response to a first mode signal to generate a first selection voltage signal;
a second selector configured to select one of the second current sensing signal and the second voltage sensing signal in response to a second mode signal to generate a second selection voltage signal;
a first current controller configured to compare the first selection voltage signal with a first reference voltage to generate the charging control signal; and
a second current controller configured to compare the second selection voltage signal with a second reference voltage to generate the discharging control signal.

### Claim 19

A method of controlling battery power, comprising:
generating a first current sensing signal by sensing a charging current flowing through a charging transistor;
generating a first voltage sensing signal by sensing a source-drain voltage of the charging transistor;
generating a first selection voltage signal by selecting one of the first current sensing signal and the first voltage sensing signal in response to a first mode signal; and
controlling the charging current by comparing the first selection voltage signal with a first reference voltage.

### Claim 20 (depends on 19)

The method of claim 19, further comprising:
generating a second current sensing signal by sensing a discharging current flowing through a discharging transistor;
generating a second voltage sensing signal by sensing a source-drain voltage of the discharging transistor;
generating a second selection voltage signal by selecting one of the second current sensing signal and the second voltage sensing signal in response to a second mode signal; and
controlling the discharging current by comparing the second selection voltage signal with a second reference voltage.