WO2019165596A1

WO2019165596A1 - Farad capacitor charging circuit and electronic device

Info

Publication number: WO2019165596A1
Application number: PCT/CN2018/077540
Authority: WO
Inventors: 张耿旭; 李文祥
Original assignee: 深圳辰锐软件开发有限公司
Priority date: 2018-02-28
Filing date: 2018-02-28
Publication date: 2019-09-06
Also published as: CN108496291A; CN108496291B

Abstract

A Farad capacitor charging circuit and an electronic device. The Farad capacitor charging circuit comprises a direct-current/direct-current controller (10), a sampling unit (20), a discharging unit (40) and a comparison unit (30). An output pin of the direct-current/direct-current controller (10) is connected to one end of a Farad capacitor (C), and an output regulation pin (SS) thereof is grounded by means of a starting capacitor (Css); the sampling unit (20) is connected in series between the other end of the Farad capacitor (C) and the ground; the discharging unit (40) is connected in parallel to the starting capacitor (Css); and the comparison unit (30) is used for detecting a voltage component of the sampling unit (20), and comparing the voltage component to a preset voltage, such that the discharging unit (40) is controlled, according to a comparison result, to discharge so as to regulate the magnitude of the current of the charging signal. An output current of a charging controller is regulated by means of a structurally simple and low-cost detection, comparison and discharging feedback link. Moreover, a limit value of the output current can be set by regulating a resistance value of the sampling unit (20) or regulating a reference voltage of the comparison unit (30).

Description

Farah capacitor charging circuit and electronic equipment

Technical field

The invention belongs to the technical field of electronic circuits, and in particular relates to a Fara capacitor current limiting charging circuit and an electronic device.

Background technique

In electronic circuit application design, the Farad capacitor can be applied to power-off data protection, as an application scenario such as backup power supply and power supply battery. As in MDVR (Mobile Digital Video In Recorders, Car DVRs, the power can be supplied by the pull-up capacitor after power-off, allowing MDVR to complete data storage and other operations. In order to increase the life of the farad capacitor, the charging current of the farad capacitor is generally limited.

At present, the conventional technical solution uses a constant current chip to perform constant current charging on the farad capacitor, but it has the following disadvantages: the larger the charging current, the higher the specification of the constant current chip and the peripheral device required, and the higher the cost.

technical problem

The conventional farad capacitor charging circuit has a complicated circuit structure, and the high specification of the required device leads to a high cost.

Technical solution

A farad capacitor charging circuit comprising:

a DC/DC controller having an input pin, an output regulation pin, and an output pin, the output pin being coupled to one end of a farad capacitor, the DC/DC controller being coupled to a power signal at an input pin After performing a DC conversion, a charging signal is outputted to the output pin to charge the farad capacitor, and the output adjusting pin is grounded through a starting capacitor;

a sampling unit connected in series between the other end of the farad capacitor and the ground;

a discharge unit in parallel with the startup capacitor; and

Connecting to the comparison unit between the sampling unit and the discharge unit;

The comparison unit is configured to detect a voltage component of the sampling unit, compare the voltage component with a preset voltage, and control a discharge of the discharge unit by a comparison result to adjust a current magnitude of the charging signal.

In one embodiment, the comparing unit is specifically configured to compare the voltage component and compare the predetermined voltage to obtain the comparison result.

In one embodiment, the sampling unit is a circuit composed of at least one of a resistor, a capacitor, and an inductor.

In one embodiment, the discharge unit includes a switch tube, and a control end of the switch tube is connected to the comparison unit, and a high potential end and a low potential end of the switch tube respectively are opposite to the start capacitor Parallel connection.

In one embodiment, the switching transistor is a triode, a field effect transistor or an IGBT.

In one embodiment, the discharge unit further includes a discharge resistor in series with the switch tube.

In one embodiment, the discharge unit further includes a signal source, a first voltage dividing bias resistor, and a second voltage dividing bias resistor, wherein the first voltage dividing bias resistor is connected to the signal source at one end. The other end is grounded through the second voltage dividing bias resistor, and the second voltage dividing bias resistor is connected in parallel with the starting capacitor.

In one embodiment, the comparison unit includes an operational amplifier and a comparator, a non-inverting input terminal of the operational amplifier is coupled to the common terminal of the farad capacitor and the sampling unit, and the inverting of the operational amplifier The input terminal is connected to the other end of the sampling unit, the input end of the operational amplifier is connected to the non-inverting input end of the comparator, and the inverting input end of the comparator is connected as a reference voltage of the preset voltage. The output of the comparator is connected to the discharge unit.

In one of the embodiments, the output adjustment pin is a slow start pin.

In addition, an electronic device including a farad capacitor and the above-described farad capacitor charging circuit is also provided.

Beneficial effect

The above-mentioned farad capacitor charging circuit and the electronic device adjust the output current of the charging controller through a simple, low-cost detection, comparison and discharge feedback link, wherein the output current is adjusted by adjusting the power voltage of the starting capacitor; The current limit value of the current can be set by adjusting the resistance of the sampling unit or adjusting the reference voltage of the comparison unit to set the current limit value of the output current; and the charging controller can also select the device with low cost and low specification, and the adjustment of other circuits Basically does not affect the circuit cost.

DRAWINGS

FIG. 1 is a schematic circuit diagram showing an example of a farad capacitor charging circuit according to a preferred embodiment of the present invention.

Embodiments of the invention

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to FIG. 1, a preferred embodiment of a preferred embodiment of a present invention relates to a DC/DC controller (DC-DC chip) 10, a sampling unit 20, a comparison unit 30, and a discharge unit 40.

The DC/DC controller 10 has an input pin Vin, an output adjustment pin SS and an output pin Vout, the output pin Vout is connected to one end of the farad capacitor C, and the DC/DC controller 10 is connected to the input pin Vin. After the power signal is DC-converted, the charging signal is output to the output pin Vout to charge the farad capacitor C, and the output adjusting pin SS is grounded through a starting capacitor Css; the sampling unit 20 is connected in series between the other end of the farad capacitor C and the ground; The unit 40 is connected in parallel with the starting capacitor Css; the comparing unit 30 is connected between the sampling unit 20 and the discharging unit 40, and the comparing unit 30 is for detecting the voltage component of the sampling unit 20, and comparing the voltage component with the preset voltage, by comparison As a result, the discharge cells 40 are controlled to discharge to adjust the magnitude of the current Is of the charging signal, that is, whether or not to control the discharge of the discharge cells 40 according to the comparison result.

In this embodiment, the output adjustment pin SS is a slow start pin; in other embodiments, according to different specifications or pin definitions of the DC-DC chip, the output adjustment pin SS may be an output current Is Adjustment pin, output voltage adjustment pin, dimming pin, etc.

The sampling unit 20 is a circuit composed of at least one of a resistor, a capacitor, and an inductor. In this embodiment, the sampling unit 20 is a sampling resistor Rs; in other embodiments, the sampling unit 20 may also be a sampling resistor Rs series-parallel capacitor and/or inductor.

In one embodiment, the comparing unit 30 is specifically configured to compare the voltage component and compare it with the preset voltage to obtain a comparison result. Specifically, the comparison unit 30 includes an operational amplifier U1 and a comparator U2. The non-inverting input terminal of the operational amplifier U1 is connected to the common terminal of the pull-up capacitor C and the sampling unit 20. The inverting input terminal of the operational amplifier U1 is connected to the sampling unit 20. At the other end, the input terminal of the operational amplifier U1 is connected to the non-inverting input terminal of the comparator U2, the inverting input terminal of the comparator U2 is connected to the reference voltage Vref as a preset voltage, and the output terminal of the comparator U2 is connected to the discharge unit 40. In the present embodiment, the operational amplifier U1 and the comparator U2 are described by taking an integrated circuit as an example. It will be appreciated that the amplifier may be implemented with an integrated amplifier, discrete components, or other circuitry capable of amplifying the signal; comparator U2 may be implemented with an integrated comparator U2, an amplifying circuit, or other circuitry capable of thresholding.

In one embodiment, the discharge unit 40 includes a switching transistor Q1. The control terminal of the switching transistor Q1 is connected to the comparison unit 30. The high potential terminal and the low potential terminal of the switching transistor Q1 are respectively connected in parallel with the two ends of the starting capacitor Css. The switching transistor Q1 is a triode, a field effect transistor (FET) tube or an IGBT (Insulated Gate Bipolar Transistor). When the power voltage of the starting capacitor Css is too large, it can be connected in parallel with the starting capacitor Css by the conduction switch Q1 to consume the power of the starting capacitor Css to reduce the power voltage, thereby reducing the output pin of the DC/DC controller 10. The current Is of the charging signal of Vout.

Further, in order to consume the speed of the power of the starting capacitor Css, that is, to provide the speed of the current Is that lowers the charging signal, the discharge unit 40 further includes a discharging resistor Rd which is connected in series with the switching transistor Q1. In this way, the discharge resistor Rd and the switching transistor Q1 consume the amount of the starting capacitor Css together, preventing the discharge from being too fast and improving the circuit stability. It can be understood that the discharge resistor Rd can be a single resistor or a series/parallel implementation of multiple resistors.

Further, the discharge unit 40 further includes a signal source V1, a first voltage dividing bias resistor Rb1 and a second voltage dividing bias resistor Rb2, wherein the first voltage dividing bias resistor Rb1 is connected to the signal source V1 at one end and the other end is passed. The second voltage dividing bias resistor Rb2 is grounded, and the second voltage dividing bias resistor Rb2 is connected in parallel with the starting capacitor Css. The signal source V1, the first voltage dividing bias resistor Rb1 and the second voltage dividing bias resistor Rb2 constitute a charging circuit of the starting capacitor Css. When the power voltage of the starting capacitor Css is too low, the switching transistor Q1 is turned off to stop the starting capacitor Css. Discharge, and the charging circuit charges the starting capacitor Css. In this way, the current Is of the charging signal can be flexibly adjusted. Signal source V1 can be a voltage source or a current Is source. The signal source V1, the first voltage dividing bias resistor Rb1 and the second voltage dividing bias resistor Rb2 are optional devices, and can be judged according to the actually selected controller.

Specifically, the sampling unit 20 takes a sampling resistor Rs as an example. When the Faraday capacitor C is charged, the charging current Is flows through the farad capacitor C and the sampling resistor Rs, and the amplifier U1 amplifies the voltage on the sampling resistor Rs. When the charging current Is is too large, When the voltage of the sampling resistor Rs is too large, so that the output voltage of the amplifier U1 exceeds the comparator U2 to compare the threshold value - the reference voltage Vref, the comparator U2 outputs a high level, the switching transistor Q1 is turned on, discharges the starting capacitor Css, and the charging voltage Css of the capacitor Css is activated. When the voltage is lowered, the voltage of the charging signal Vout is lowered, and the charging current Is is lowered, so that the current Is is maintained at a predetermined value when the farad capacitor C is charged. The charge limiting current Is = Vref / (Rs * A), where A is the amplifier magnification. As such, in some embodiments, the current limit value of the output current can be output by limiting the resistance of the sampling unit 20, the reference voltage Vref of the comparator U2, and the multiple A of the operational amplifier U1.

It can be understood that the level signal output by the comparator U2 is the above comparison result. In the embodiment, the high level is the active level, and the switch tube Q1 is a device that is turned on at a high level; in other embodiments, According to different needs, the low level can be set to the active level. Thus, the output terminal of the amplifier U1 can be connected to the inverting input terminal of the comparator U2, the reference voltage Vref is connected to the positive phase input terminal of the comparator U2, and the switching transistor Q1 can be low. A device that is level-on.

In addition, an electronic device including a farad capacitor C and the above-described farad capacitor C charging circuit is also provided. The electronic device can be an MDVR or the like.

The above-mentioned farad capacitor charging circuit and the electronic device adjust the output current of the charging controller through a simple, low-cost detection, comparison and discharge feedback link, wherein the output current is adjusted by adjusting the power voltage of the starting capacitor; The current limit value of the current can be set by adjusting the resistance of the sampling unit or adjusting the reference voltage of the comparison unit, and the charge controller can also select the device with low cost and low specification, and the adjustment of other circuits. Basically does not affect the circuit cost.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A farad capacitor charging circuit, comprising:

a DC/DC controller having an input pin, an output regulation pin, and an output pin, the output pin being coupled to one end of a farad capacitor, the DC/DC controller being coupled to a power signal at an input pin After performing a DC conversion, a charging signal is outputted to the output pin to charge the farad capacitor, and the output adjusting pin is grounded through a starting capacitor;

a sampling unit connected in series between the other end of the farad capacitor and the ground;

a discharge unit in parallel with the startup capacitor; and

Connecting to the comparison unit between the sampling unit and the discharge unit;

The comparison unit is configured to detect a voltage component of the sampling unit, compare the voltage component with a preset voltage, and control a discharge of the discharge unit by a comparison result to adjust a current magnitude of the charging signal.
The pull-up capacitor charging circuit of claim 1 , wherein the comparing unit is configured to: after the voltage component is amplified, compare the predetermined voltage to obtain the comparison result.
The pull-capacitor charging circuit according to claim 1, wherein the sampling unit is a circuit composed of at least one of a resistor, a capacitor, and an inductor.
The method according to claim 1, wherein the discharge unit comprises a switch tube, and a control end of the switch tube is connected to the comparison unit, and the high potential end and the low potential of the switch tube The terminals are respectively connected in parallel with both ends of the starting capacitor.
The farad capacitor charging circuit according to claim 4, wherein the switching transistor is a triode, a field effect transistor or an IGBT.
A Faraday capacitor charging circuit according to claim 4, wherein said discharge cell further comprises a discharge resistor, said discharge resistor being in series with said switching transistor.
The pull-up capacitor charging circuit according to claim 4, 5 or 6, wherein the discharge unit further comprises a signal source, a first voltage dividing bias resistor and a second voltage dividing bias resistor, wherein The first voltage dividing bias resistor is connected to the signal source at one end, the other end is grounded through the second voltage dividing bias resistor, and the second voltage dividing bias resistor is connected in parallel with the starting capacitor.
The farad capacitor charging circuit according to any one of claims 1 to 6, wherein the comparison unit comprises an operational amplifier and a comparator, and a non-inverting input terminal of the operational amplifier is connected to the farad capacitor and the a common terminal of the sampling unit, an inverting input terminal of the operational amplifier is connected to the other end of the sampling unit, an input end of the operational amplifier is connected to a positive phase input terminal of the comparator, and an inverting phase of the comparator The input terminal is a reference voltage of the preset voltage, and an output terminal of the comparator is connected to the discharge unit.
The farad capacitor charging circuit according to any one of claims 1 to 6, wherein the output adjustment pin is a slow start pin.
An electronic device comprising a farad capacitor, characterized by further comprising the farad capacitor charging circuit of any one of claims 1 to 9.