# US 9,882,484 B2 · Switching power supply device having pulse-by-pulse type overcurrent protection function

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- Number: US 9,882,484 B2
- Document ID: US9882484B2
- Status: Granted
- Kind: B2
- Application number: 15/381,353
- Filed: 2016-12-16
- Published: 2017-06-29
- Granted: 2018-01-30
- Earliest claimed: 2015-12-25
- Assignees: Rohm Co., Ltd.
- Applicants: Rohm Co., Ltd.
- Inventors: Yosuke Fukumoto
- Web page: https://patentgrep.com/patent/US9882484B2

## CPC

- H02M 3/158: including plural semiconductor devices as final control devices for a single load
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 1/32: Means for protecting converters other than automatic disconnection
- H03K 17/08: Modifications for protecting switching circuit against overcurrent or overvoltage
- H02M 1/0003: {Details of control, feedback or regulation circuits}
- H02M 1/0009: {Devices or circuits for detecting current in a converter}
- 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)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A switching power supply device includes: a switching output circuit configured to generate an output voltage from an input voltage; an oscillation circuit configured to generate a clock signal; a control circuit configured to control driving of the switching output circuit in synchronization with the clock signal; a pulse-by-pulse type overcurrent protection circuit configured to detect an overcurrent flowing through the switching output circuit to generate an overcurrent protection signal for forcibly stopping a switching operation of the switching output circuit; and a pulse skip circuit configured to perform a pulse skip operation of the clock signal in response to the overcurrent protection signal.

## Claims

### Claim 1

A switching power supply device, comprising:
a switching output circuit configured to generate an output voltage from an input voltage;
an oscillation circuit configured to generate a clock signal;
a control circuit configured to control driving of the switching output circuit in synchronization with the clock signal;
a pulse-by-pulse type overcurrent protection circuit configured to detect an overcurrent flowing through the switching output circuit to generate an overcurrent protection signal for forcibly stopping a switching operation of the switching output circuit; and
a pulse skip circuit configured to perform a pulse skip operation of the clock signal in response to the overcurrent protection signal, the pulse skip circuit including:
a timer part configured to start a counting operation in response to the overcurrent protection signal to generate a mask period expiration signal;
an RS flipflop configured to generate a mask signal set to a first logic level in response to the overcurrent protection signal and reset to a second logic level in response to the mask period expiration signal; and
a logic gate configured to block the clock signal over a mask period during which the mask signal is set to the first logic level,
wherein the timer part is configured to extend the mask period as the output voltage is lowered.

### Claim 2 (depends on 1)

The device of claim 1, wherein the timer part comprises:
a current source configured to generate a charge current;
a capacitor charged by the charge current;
a charge/discharge switch configured to conduct and block current between both ends of the capacitor in response to the mask signal;
a voltage source configured to generate a threshold voltage; and
a comparator configured to compare a charge voltage of the capacitor with the threshold voltage to generate an expiration timing signal.

### Claim 3 (depends on 2)

The device of claim 2, wherein the current source is configured to decrease the charge current as the output voltage is lowered.

### Claim 4 (depends on 2)

The device of claim 2, wherein the voltage source is configured to increase the threshold voltage as the output voltage is lowered.

### Claim 5 (depends on 1)

An electronic device comprising the switching power supply device of claim 1.