JPH11220871A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an output voltage to be outputted by resetting a latch circuit during a specific period when the output voltage of a power supply circuit for control circuit reaches the starting voltage of a start/stop control circuit and hence preventing the latch circuit from malfunctioning when a DC input voltage rapidly changes. SOLUTION: A reset from a reset circuit 9 is outputted immediately before reaching the operation start voltage of a start/stop control circuit 4. The latching of a latch circuit 8 is canceled by the reset, thus resulting in an initial state. More specifically, when a DC input voltage Vin momentarily stops and a DC output voltage Vcc, to the start/stop control circuit 4-drops and reaches an operation stop voltage and then the start/stop control circuit 4 stops the operation of a conversion control circuit 2, a reset for canceling latching is inputted from the reset circuit 9 to the latch circuit 8 immediately before the Dc output voltage Vcc reaches an operation start voltage, thus resulting in an initial state. As a result, the DC input voltage Vin is thrown again, thus enabling an output voltage to be outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a power supply device.

[0002]

2. Description of the Related Art In a conventional power supply device, the continuation of operation of a protection circuit is released by reducing the output voltage of a power supply circuit for a control circuit to a voltage lower than an operation stop voltage due to a decrease in DC input voltage. The cancellation has been performed. In the case of a power control IC manufactured by Hitachi as an example, the operation stop voltage is 9.5 V, but the release voltage of the latch circuit is 6.5 V. (HA16107FP / P ・ HA16107
8FP / P 600kHz PWM Swicting Regurator / Controller RE
(See V.0 90.6)

[0003]

However, when the latch circuit is released because the output voltage of the power supply circuit for the control circuit drops below the operation stop voltage, the continuation of the operation of the above-mentioned protection circuit is released. When the output voltage of the power supply circuit for the control circuit drops when the output voltage suddenly changes, for example, when the output voltage of the control circuit drops and then rises again, the protection circuit malfunctions in an unstable voltage range where the protection circuit operation cannot operate stably. The output voltage is not output while the conversion operation is stopped because it cannot be canceled. In an extreme case, the input of the DC input voltage is cut off during the period when the output voltage of the power supply circuit for the control circuit falls completely. If not, there is a problem that cannot be restarted.

An object of the present invention is to provide a power supply device that prevents output voltage from being output when the DC input voltage changes suddenly.

[0005]

A power supply unit according to the present invention comprises a DC / DC converter circuit for converting a DC input voltage to a predetermined output voltage, a conversion control circuit for controlling a conversion operation, and a control for the conversion control circuit. A start / stop control circuit that detects the output voltage of the circuit power supply circuit and controls the start of operation of the conversion control circuit and the stop of operation of the conversion control circuit based on the detected value; an overvoltage protection circuit and an overcurrent protection circuit of the power supply; In a power supply device comprising an overheat protection circuit, the protection circuit stops a conversion control circuit at the time of operation thereof, stops a conversion operation of a DC / DC converter circuit, and comprises a latch circuit which continues the operation of the protection circuit. A reset circuit resets the latch circuit during a predetermined period in which the output voltage of the circuit power supply circuit reaches the start voltage of the start / stop control circuit.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a power supply device, which is DC / D
C converter circuit 1, conversion control circuit 2, power supply circuit for control circuit 3, start / stop control circuit 4, overvoltage protection circuit 5, overcurrent protection circuit 6, overheat protection circuit 7, and latch circuit for continuing the above-mentioned protection circuit operation 8, a reset circuit 9 for releasing the latch circuit 8, a starting resistor 10 and a starting capacitor 11 of a power supply device. The DC / DC converter circuit 1 converts a DC input voltage (Vin) and outputs a DC output voltage (V
out). The conversion operation is controlled by the conversion control circuit 2, and if the DC / DC converter circuit 1 is a forward circuit system, the pulse width is varied so that the DC output voltage (Vout) is controlled to output a stable voltage. . The control circuit power supply circuit 3 converts the DC input voltage (Vin) and supplies a voltage necessary for control. In FIG. 1, the conversion control circuit 2, the start / stop control circuit 4, the latch circuit 8 for continuing the protection circuit operation, and It is supplied to a reset circuit 9 for releasing the latch circuit 8. The start / stop control circuit 4 is connected to a start resistor 10 and a start capacitor 11 to obtain a voltage required at the time of starting the power supply device.
Receive more power supply. The start / stop control circuit 4 starts and stops the operation of the conversion control circuit 2 by detecting two voltages, an operation start voltage (Vhigt) and an operation stop voltage (Vlow). When one of the overvoltage protection circuit 5, the overcurrent protection circuit 6, and the overheat protection circuit 7 operates, the operation of the conversion control circuit 2 is stopped. The latch circuit 8 maintains the stop control of the start / stop control circuit 4 so that the operation of the protection circuit is continued when any one of the overvoltage protection circuit 5, the overcurrent protection circuit 6, and the overheat protection circuit 7 operates. Things. The reset circuit 9 releases the latch circuit 8 before the operation start voltage (Vhigt) of the start / stop control circuit 4 and after the operation stop voltage (Vlow).

FIG. 2 is a main time chart at the time of application of a DC input voltage and at the time of an instantaneous stop. Hereinafter, the detailed operation of FIG. 1 will be described with reference to FIG. When the DC input voltage (Vin) shown in FIG. 2A is applied, charge of the start capacitor 11 is started through the start resistor 10 and the DC output (Vcc) which is the input voltage of the start / stop control circuit 4 is input. ) Rises as shown in FIG. The start / stop control circuit 4 operates at an operation start voltage (Vhig
(t0), the operation of the conversion control circuit 2 is started at the time (t0), so that the DC control is performed as shown in FIG.
The DC / DC output (Vout), which is the output voltage of the / DC converter circuit 1, is 0V. If the reset output of the reset circuit 9 is represented by a true value of “H”, it is output at the timing shown in FIG. 2C and is output immediately before reaching the operation start voltage (Vhigt) (t0).
As a result, the latch circuit 8 is temporarily reset by releasing the latch and enters an initial state. In the period from (t0) to (t1) in FIG. 2, DC which is the output voltage of the DC / DC converter circuit 1 is used.
2 shows a stable operation period from the start of the / DC output (Vout), and the output voltage of the control circuit power supply circuit 3 during the stable operation period maintains Vop in FIG. When the DC input voltage (Vin) in FIG. 2 (a) stops instantaneously, the DC output (Vcc) in FIG. 2 (b) starts dropping and reaches (Vlow) ((t2) in FIG. 2 (b)). The stop control circuit 4 stops the operation of the conversion control circuit 2. At this time, if the DC output (Vcc) does not decrease to (V1) in the conventional circuit if the protection circuit malfunctions or the latch circuit 8 malfunctions ((t3) in FIG. 2B), the latch circuit 8 latches. Cannot be released and the output voltage is not output when the DC input voltage (Vin) is turned on again. However, in the present invention, the DC output (Vcc) reaches the operation start voltage (Vhigt)
(t4) Immediately before, the reset circuit 9 performs reset output and the latch circuit 8 is reset by releasing the latch again, so that the reset circuit 9 is in the initial state and prevents the output voltage from being output when the DC input voltage (Vin) is turned on again. Can be.

Although the above embodiment has been described with reference to the DC input voltage as the input of the power supply, any AC input may be used as long as it has a circuit for converting AC to DC. It is clear. DC /
Although the forward circuit method has been described as an example of the DC converter circuit, the same applies to this case.

[0009]

As described above, according to the present invention, when the output voltage of the control circuit power supply circuit drops when the input voltage suddenly changes, for example, instantaneously decreases or stops instantaneously, the protection circuit operates stably when the output voltage rises again. The protection circuit malfunctions in the indeterminate voltage region where operation cannot be performed. The latch circuit cannot be released and the output voltage is not output while the conversion operation is stopped. In extreme cases, the control circuit power supply circuit is completely used. There is an effect that it is possible to prevent restart without shutting off the input of the input voltage during a period in which the output voltage of the device decreases.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a main time chart of the present invention.

[Explanation of symbols]

 1 DC / DC converter circuit 2 Conversion control circuit 3 Power circuit for control circuit 4 Start / stop control circuit 5 ... overvoltage protection circuit 6 ... overcurrent protection circuit 7 ... overheat protection circuit 8 ... latch circuit 9 ... reset circuit 10 ... .Startup resistor 11 ..... Startup capacitor

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Minoru Kani 1st Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Prefecture Inside Hitachi Asahi Electronics Co., Ltd. Inside Asahi Electronics (72) Inventor Yukio Aoyama 1st Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Prefecture Inside Hitachi Asahi Electronics Co., Ltd. (72) Inventor Eisuke Yamato 1 Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Prefecture Inside Hitachi Asahi Electronics Co., Ltd.

Claims (1)

[Claims] A DC / DC converter circuit for converting a DC input voltage to a predetermined output voltage; a conversion control circuit for controlling a conversion operation; and an output voltage of a power supply circuit for a control circuit for the conversion control circuit. A start / stop control circuit that controls the start of operation of the conversion control circuit and the stop of operation of the conversion control circuit based on the detected value; an overvoltage protection circuit, an overcurrent protection circuit, and an overheat protection circuit of the power supply device; In a power supply device comprising a latch circuit which stops a conversion control circuit during operation, stops a conversion operation of a DC / DC converter circuit, and continues the operation of the protection circuit, the output voltage of the power supply circuit for the control circuit starts and stops. A reset circuit for resetting the latch circuit during a predetermined period when the activation voltage of the control circuit is reached, to prevent malfunction of the latch circuit when the DC input voltage is momentarily stopped Switching control in accordance with and.