CN111313366B - Undervoltage self-turn-off output stage circuit - Google Patents
Undervoltage self-turn-off output stage circuit Download PDFInfo
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- CN111313366B CN111313366B CN202010247010.0A CN202010247010A CN111313366B CN 111313366 B CN111313366 B CN 111313366B CN 202010247010 A CN202010247010 A CN 202010247010A CN 111313366 B CN111313366 B CN 111313366B
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- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/24—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to undervoltage or no-voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
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Abstract
The invention discloses an undervoltage self-turn-off OUTPUT stage circuit, which adopts an OUTPUT stage circuit consisting of a transistor QN1 and a transistor QN2 to be connected with a self-turn-off OUTPUT stage driving circuit, the input end of the self-turn-off OUTPUT stage driving circuit is connected with the OUTPUT end of an undervoltage locking judgment circuit and the OUTPUT end of a control circuit, the OUTPUT of the self-turn-off OUTPUT stage driving circuit is connected with the OUTPUT stage circuit, when the voltage of a Vcc power supply drops to be lower than the undervoltage locking threshold voltage, a current leakage path is provided for an OUTPUT OUTPUT node by utilizing the conduction of a transistor QP1, the base potential of the transistor QN1 is raised at the same time, the conduction of the transistor QN1 increases the current leakage path of the OUTPUT OUTPUT node, the OUTPUT potential can be quickly pulled down, and the reliability of a switching power supply system is improved.
Description
Technical Field
The invention belongs to the technical field of circuit design of switching power supply controller chips, and particularly relates to an undervoltage self-turn-off output stage circuit.
Background
With the high-speed integrated development of electronic system design, power management chips have been widely used in the fields of communication, electronic computers, consumer electronics, and the like, and the performance requirements thereof are higher and higher. In order to ensure that the circuit can enter a normal working state and work stably after being started and to ensure that the fluctuation of the power supply voltage can not damage the whole circuit and a system when the circuit works, an under-voltage locking method is generally adopted to ensure that the circuit stops working when the power supply voltage is lower than an under-voltage locking turn-off threshold voltage, the circuit continues working when the power supply voltage is higher than the under-voltage locking turn-on threshold voltage, and a certain hysteresis quantity exists between the turn-on threshold voltage and the turn-off threshold voltage to prevent the system from being unstable due to the jitter of the power supply voltage in the recovery process. The most critical of them are: when the power supply voltage drops to the undervoltage locking turn-off threshold voltage, the power switch tube can be turned off rapidly. If the power supply voltage drops to the undervoltage locking turn-off threshold voltage, the control circuit cannot rapidly turn off the power switch tube, and the output pulse width is not modulated and is normally high in the undervoltage power-down process, as shown in fig. 3, so that the power of the rear-stage power switch tube is easily over-high and burnt.
Disclosure of Invention
The invention aims to provide an undervoltage self-turn-off output stage circuit to overcome the defects of the prior art, and the undervoltage self-turn-off output stage circuit can avoid the long-time conduction of a power switch tube in a switch power supply system when undervoltage power fails.
In order to achieve the purpose, the invention adopts the following technical scheme:
an under-voltage self-turn-off OUTPUT stage circuit comprises an OUTPUT stage circuit and a self-turn-off OUTPUT stage driving circuit, wherein the input end of the self-turn-off OUTPUT stage driving circuit is connected with the OUTPUT end of an under-voltage locking judgment circuit and the OUTPUT end of a control circuit, the OUTPUT stage circuit comprises a transistor QN1 and a transistor QN2, the base electrode of the transistor QN1 is connected with the primary OUTPUT end of the self-turn-off OUTPUT stage driving circuit, the base electrode of the transistor QN2 is connected with the secondary OUTPUT end of the self-turn-off OUTPUT stage driving circuit, the emitter electrode of the transistor QN1 is grounded, the collector electrode of the transistor QN2 is connected with a power supply Vcc, and the emitter electrode of the transistor QN2, the collector electrode of the transistor QN1 and the tertiary OUTPUT end of the self-turn-off OUTPUT stage driving circuit are connected with an OUTPUT node OUTPUT.
Further, the self-turn-off output stage driving circuit includes a transistor QN3, a transistor QN4, a transistor QN5, a transistor QN6, a transistor QP1, a resistor R1, a resistor R2, a resistor R3, and a resistor R4;
the base electrode of the transistor QN5 is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the output end of the undervoltage locking judgment circuit; the collector of the transistor QN5 is connected with the base of the transistor QN6 and one end of the resistor R2; the collector of the transistor QN6 is connected with the base of the transistor QP1 and one end of the mirror current source I2;
the base of the transistor QN3 is connected with the output end of the PWM control circuit, the collector of the transistor QN3 is connected with one end of a mirror current source I1 and the base of the transistor QN4, and the emitter of the transistor QN3 is connected with the collector of the transistor QP1, the base of the transistor QN1 and one end of a resistor R4; the emitter of the transistor QN4 is connected with one end of the resistor R3 and the base of the transistor QN 2;
the emitter of the transistor QN5, the emitter of the transistor QN6, the emitter of the transistor QN1 and the other end of the resistor R4 are all grounded;
the collector of the transistor QN4, the collector of the transistor QN2, the other end of the mirror current source I2 and the other end of the mirror current source I1 are connected with a power supply Vcc;
the other end of the resistor R2, the other end of the resistor R3, the emitter of the transistor QN2, the emitter of the transistor QP1, and the collector of the transistor QN1 are all connected to the OUTPUT node OUTPUT.
Further, the transistor QP1 is a PNP transistor.
Further, the transistor QN1 is an NPN transistor.
Further, the transistor QN2 is an NPN transistor.
Further, the transistor QN3 is an NPN transistor.
Further, the transistor QN4 is an NPN transistor.
Further, the transistor QN5 is an NPN transistor.
Further, the transistor QN6 is an NPN transistor.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention relates to an undervoltage self-turn-off OUTPUT stage circuit, which adopts an OUTPUT stage circuit composed of a transistor QN1 and a transistor QN2 to be connected with a self-turn-off OUTPUT stage driving circuit, the input end of the self-turn-off OUTPUT stage driving circuit is connected with the OUTPUT end of an undervoltage locking judgment circuit and the OUTPUT end of a control circuit, the OUTPUT of the self-turn-off OUTPUT stage driving circuit is connected with the OUTPUT stage circuit, when Vcc power voltage drops below undervoltage locking threshold voltage, the conduction of the self-turn-off OUTPUT stage driving circuit is utilized to provide a current leakage path for an OUTPUT OUTPUT node, simultaneously, the base potential of a transistor QN1 is raised, the conduction of a transistor QN1 enlarges the current leakage path of the OUTPUT OUTPUT node, the OUTPUT potential can be quickly pulled down, thereby improving the reliability of a switching power supply system, a current leakage path independent of other signals is directly formed for the OUTPUT node OUTPUT of the switching power supply control circuit, the rear-stage power switch tube is quickly turned off, and the reliability of the switching power supply system is improved.
Further, when the Vcc power voltage drops below the under-voltage locking threshold voltage, the OUTPUT control signal rgo of the preceding under-voltage locking circuit changes to low level, the transistor QN5 is turned off, the transistor QN6 and the transistor QP1 are turned on, the transistor QP1 provides a current leakage path for the OUTPUT node of OUTPUT, the base potential of the transistor QN1 is raised, the transistor QN1 is turned on, the current leakage path of the OUTPUT node of OUTPUT is increased, the OUTPUT potential can be pulled down rapidly, and therefore the reliability of the switching power supply system is improved.
Drawings
Fig. 1 is a schematic diagram of the circuit connection of the undervoltage self-turn-off output stage according to the embodiment of the present invention.
Fig. 2 is a specific circuit diagram of the undervoltage self-turn-off output stage circuit according to the embodiment of the present invention.
Fig. 3 is a graph of output pulse width during undervoltage power-down.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
as shown in fig. 1, the undervoltage self-turn-off OUTPUT stage circuit of the present invention includes an OUTPUT stage circuit and a self-turn-off OUTPUT stage driving circuit, wherein an input terminal of the self-turn-off OUTPUT stage driving circuit is connected to an OUTPUT terminal of the undervoltage locking judgment circuit and an OUTPUT terminal of the control circuit, the OUTPUT stage circuit includes a transistor QN1 and a transistor QN2, a base of the transistor QN1 is connected to a primary OUTPUT terminal of the self-turn-off OUTPUT stage driving circuit, a base of the transistor QN2 is connected to a secondary OUTPUT terminal of the self-turn-off OUTPUT stage driving circuit, an emitter of the transistor QN1 is grounded, a collector of the transistor QN2 is connected to a power Vcc, and an emitter of the transistor QN2, a collector of the transistor QN1 and a tertiary OUTPUT terminal of the self-turn-off OUTPUT stage driving circuit are connected to an OUTPUT node OUTPUT.
As shown in fig. 2, the self-turn-off output stage driving circuit includes a transistor QN3, a transistor QN4, a transistor QN5, a transistor QN6, a transistor QP1, a resistor R1, a resistor R2, a resistor R3, and a resistor R4;
the base electrode of the transistor QN5 is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the output end of the undervoltage locking judgment circuit; the collector of the transistor QN5 is connected with the base of the transistor QN6 and one end of the resistor R2; the collector of the transistor QN6 is connected with the base of the transistor QP1 and one end of the mirror current source I2;
the base of the transistor QN3 is connected with the output end of the PWM control circuit, the collector of the transistor QN3 is connected with one end of a mirror current source I1 and the base of the transistor QN4, and the emitter of the transistor QN3 is connected with the collector of the transistor QP1, the base of the transistor QN1 and one end of a resistor R4; the emitter of the transistor QN4 is connected with one end of the resistor R3 and the base of the transistor QN 2;
the emitter of the transistor QN5, the emitter of the transistor QN6, the emitter of the transistor QN1 and the other end of the resistor R4 are all grounded;
the collector of the transistor QN4, the collector of the transistor QN2, the other end of the mirror current source I2 and the other end of the mirror current source I1 are connected with a power supply Vcc;
the other end of the resistor R2, the other end of the resistor R3, the emitter of the transistor QN2, the emitter of the transistor QP1 and the collector of the transistor QN1 are all connected with an OUTPUT node OUTPUT;
the transistors QN1, QN2, QN3, QN4, QN5 and QN6 are NPN transistors; the transistor QP1 is a PNP transistor.
As shown in fig. 2, one end of the resistor R1 of the undervoltage self-turn-off OUTPUT stage circuit is connected to the OUTPUT end of the undervoltage locking determination circuit, the base of the transistor QN3 of the undervoltage self-turn-off OUTPUT stage circuit is connected to the OUTPUT end of the PWM control circuit, when the Vcc power voltage drops below the undervoltage locking threshold voltage, the OUTPUT control signal rgo of the undervoltage locking determination circuit opens the leakage path of the undervoltage self-turn-off OUTPUT stage circuit to ground, and positively feeds back the base potential of the transistor QP1, so that the transistor QN1 is also turned on, a larger current leakage path is formed, and the potential of the OUTPUT node OUTPUT is pulled down rapidly.
When the circuit works normally, the output control signal rgo of the front-stage undervoltage locking judgment circuit is in a high level, the transistor QN5 is turned on, the transistor QN6 and the transistor QP1 are both turned off, and the current leakage channel is closed; when the voltage of a Vcc power supply is reduced to be lower than an under-voltage locking threshold voltage, the OUTPUT control signal rgo of the front-stage under-voltage locking judging circuit is changed into a low level, the transistor QN5 is cut off, the transistor QN6 and the transistor QP1 are conducted, the conduction of the transistor QP1 provides a current leakage path for an OUTPUT node, the base potential of the transistor QN1 is raised, the conduction of the transistor QN1 further increases the current leakage path of the OUTPUT node, the OUTPUT potential can be quickly pulled down, and therefore the reliability of the switching power supply system is improved.
The undervoltage self-turn-off OUTPUT stage circuit provided by the application can provide a rapid current leakage channel for the OUTPUT node OUTPUT no matter how other control signals change, and can rapidly pull down the voltage of the OUTPUT OUTPUT node to turn off a rear-stage power switch tube and improve the reliability of a switching power supply system no matter how a 'preceding-stage PWM control signal' is '0' or '1' as long as the power supply voltage VCC drops below an undervoltage locking threshold voltage.
By adopting the invention, the output stage undervoltage self-turn-off protection function of the PWM controller circuit is designed, and tests prove that under the condition that the grid capacitance of a rear-stage MOSFET power tube is about 3nF, when the power supply voltage Vcc is reduced to be lower than the undervoltage locking turn-off threshold voltage, no matter how the signals such as voltage reference and the like are changed, the output control signal rgo of the circuit can be pulled down to be lower than 100mV within 2 mu s. The verification result shows that the back-stage power switch tube can be quickly and reliably turned off when the undervoltage power fails. The circuit of the invention has simple design and easy realization of the process, and can be widely applied to the design of chips of switching power supply controllers.
Claims (8)
1. An undervoltage self-turn-off OUTPUT stage circuit is characterized by comprising an OUTPUT stage circuit and a self-turn-off OUTPUT stage driving circuit, wherein the input end of the self-turn-off OUTPUT stage driving circuit is connected with the OUTPUT end of an undervoltage locking judgment circuit and the OUTPUT end of a control circuit, the OUTPUT stage circuit comprises a transistor QN1 and a transistor QN2, the base electrode of the transistor QN1 is connected with the primary OUTPUT end of the self-turn-off OUTPUT stage driving circuit, the base electrode of the transistor QN2 is connected with the secondary OUTPUT end of the self-turn-off OUTPUT stage driving circuit, the emitter electrode of the transistor QN1 is grounded, the collector electrode of the transistor QN2 is connected with a power supply Vcc, and the emitter electrode of the transistor QN2, the collector electrode of the transistor QN1 and the tertiary OUTPUT end of the self-turn-off OUTPUT stage driving circuit are connected with an OUTPUT node OUTPUT; the self-turn-off output stage driving circuit comprises a transistor QN3, a transistor QN4, a transistor QN5, a transistor QN6, a transistor QP1, a resistor R1, a resistor R2, a resistor R3 and a resistor R4;
the base electrode of the transistor QN5 is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the output end of the undervoltage locking judgment circuit; the collector of the transistor QN5 is connected with the base of the transistor QN6 and one end of the resistor R2; the collector of the transistor QN6 is connected with the base of the transistor QP1 and one end of the mirror current source I2;
the base of the transistor QN3 is connected with the output end of the PWM control circuit, the collector of the transistor QN3 is connected with one end of a mirror current source I1 and the base of the transistor QN4, and the emitter of the transistor QN3 is connected with the collector of the transistor QP1, the base of the transistor QN1 and one end of a resistor R4; the emitter of the transistor QN4 is connected with one end of the resistor R3 and the base of the transistor QN 2;
the emitter of the transistor QN5, the emitter of the transistor QN6, the emitter of the transistor QN1 and the other end of the resistor R4 are all grounded;
the collector of the transistor QN4, the collector of the transistor QN2, the other end of the mirror current source I2 and the other end of the mirror current source I1 are connected with a power supply Vcc;
the other end of the resistor R2, the other end of the resistor R3, the emitter of the transistor QN2, the emitter of the transistor QP1, and the collector of the transistor QN1 are all connected to the OUTPUT node OUTPUT.
2. The undervoltage self-turn-off output stage circuit as claimed in claim 1, wherein the transistor QP1 is a PNP transistor.
3. The undervoltage self-turn-off output stage circuit according to claim 1, wherein the transistor QN1 is an NPN transistor.
4. The undervoltage self-turn-off output stage circuit according to claim 1, wherein the transistor QN2 is an NPN transistor.
5. The undervoltage self-turn-off output stage circuit according to claim 1, wherein the transistor QN3 is an NPN transistor.
6. The undervoltage self-turn-off output stage circuit according to claim 1, wherein the transistor QN4 is an NPN transistor.
7. The undervoltage self-turn-off output stage circuit according to claim 1, wherein the transistor QN5 is an NPN transistor.
8. The undervoltage self-turn-off output stage circuit according to claim 1, wherein the transistor QN6 is an NPN transistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010247010.0A CN111313366B (en) | 2020-03-31 | 2020-03-31 | Undervoltage self-turn-off output stage circuit |
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| CN202010247010.0A CN111313366B (en) | 2020-03-31 | 2020-03-31 | Undervoltage self-turn-off output stage circuit |
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| CN111313366A CN111313366A (en) | 2020-06-19 |
| CN111313366B true CN111313366B (en) | 2021-12-14 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104037748A (en) * | 2014-06-18 | 2014-09-10 | 电子科技大学 | Anti-latch-up trigger circuit for ESD (Electronic Static Discharge) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN2810022Y (en) * | 2005-04-11 | 2006-08-23 | Bcd半导体制造有限公司 | Under-voltage locking circuit for PWM controller |
| JP2006311419A (en) * | 2005-05-02 | 2006-11-09 | Nec Electronics Corp | Signal output circuit |
| KR101974024B1 (en) * | 2012-11-26 | 2019-05-02 | 온세미컨덕터코리아 주식회사 | Undervoltage lockout circuit, switch control circuit and power supply device comprising the undervoltage lockout circuit |
| JP6419597B2 (en) * | 2015-02-16 | 2018-11-07 | ルネサスエレクトロニクス株式会社 | Motor driving method, motor driving device and hard disk device |
| US10225005B1 (en) * | 2018-03-09 | 2019-03-05 | Elbex Video Ltd. | Communication infrastructure devices and support tools for intelligent residences or businesses and communicating method with and operating intelligent electrical devices |
| CN110208673B (en) * | 2019-06-12 | 2021-04-23 | 电子科技大学 | A power tube gate-source voltage under-voltage detection circuit suitable for DC-DC converters |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104037748A (en) * | 2014-06-18 | 2014-09-10 | 电子科技大学 | Anti-latch-up trigger circuit for ESD (Electronic Static Discharge) |
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