CN117477700A - Soft start circuit suitable for lithium battery charging circuit - Google Patents
Soft start circuit suitable for lithium battery charging circuit Download PDFInfo
- Publication number
- CN117477700A CN117477700A CN202311266711.9A CN202311266711A CN117477700A CN 117477700 A CN117477700 A CN 117477700A CN 202311266711 A CN202311266711 A CN 202311266711A CN 117477700 A CN117477700 A CN 117477700A
- Authority
- CN
- China
- Prior art keywords
- amplifier
- tube
- lithium battery
- switch tube
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000007600 charging Methods 0.000 title claims abstract description 62
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 30
- 239000003990 capacitor Substances 0.000 claims abstract description 13
- 238000010277 constant-current charging Methods 0.000 claims abstract description 6
- 230000003071 parasitic effect Effects 0.000 abstract description 6
- 230000006872 improvement Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/0071—Regulation of charging or discharging current or voltage with a programmable schedule
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00304—Overcurrent protection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Secondary Cells (AREA)
Abstract
The invention relates to an improvement of a lithium battery charging circuit, in particular to a soft start circuit suitable for the lithium battery charging circuit, which does not need to additionally arrange a buffer capacitor, reduces circuit cost by utilizing parasitic capacitance of a charging tube, and is suitable for switching two constant charging current modes of the lithium battery charging circuit; the constant-current charging circuit comprises an amplifier A, wherein the negative input end of the amplifier A is respectively connected with a constant-current charging current V through a switch 1 And trickle charge current V 2 The positive input end of the amplifier A is connected with the SD port through a diode D, and the amplifier A also comprises a switching tube M 1 And a switching tube M 2 The switch tube M 1 The grid electrode of the switch tube M is connected with the output end of the amplifier A 1 Is passed through the drain of resistor R L The positive electrode input end of the amplifier A is grounded and is also connected with a feedback resistor R 1 And a switch tube M 1 Is connected with the drain electrode of the switch tube M 2 Is a lithium battery charging tube, the switch tube M 2 The grid electrode of the switch tube M is connected with the output end of the amplifier A 1 Drain of (2)Output charging current I chrg 。
Description
Technical Field
The invention relates to improvement of a lithium battery charging circuit, in particular to a soft start circuit suitable for the lithium battery charging circuit.
Background
In recent years, with the rapid development of industries such as communications, computers, consumer electronics, etc., the demand for electronic products is increasing, and the development of industries related to integrated circuit chips is driven. In portable electronic products such as mobile phones, digital cameras, palm computers, etc., a charging circuit chip is required to manage the charging and discharging of the battery in order to improve the power efficiency and prolong the service life of the lithium battery. The lithium battery charging management chip has the characteristics of low cost, simple structure, high integration level, high precision, low power consumption and the like, and is widely used.
When the charging current of the lithium battery is above 500mA and the charging circuit provides larger load current, larger current peak overshoot is generated at the charging end, and the larger overshoot has the risk of damaging the charging circuit and the lithium battery. It is therefore necessary to provide a soft start circuit in the lithium battery charging circuit to suppress the surge current.
The prior art scheme is generally shown in FIG. 1, and includes an RC circuit formed by series connection of a resistor and a capacitor, and a current clamp circuit, when the current sets the voltage V 1 When the RC circuit is built, the input end of the operational amplifier is slowly raised. And the charging current is clamped through the current clamping operational amplifier, the voltage of the gate end of the charging tube is slowly increased until the output is stable, and the battery charging current is clamped. Due to the buffer function of the RC circuit, possible surge current is restrained, and stable operation of the circuit is ensured.
However, as can be seen from the above design, a larger buffer capacitor is required to be arranged to suppress the surge current, and a larger layout area consumed by the capacitor has a cost problem, and then the lithium battery charging circuit has two constant current modes of trickle charge and constant current fast charge, namely two V 1 Voltage V 1 Ringing is caused during jump, and current overshoot risks exist.
Disclosure of Invention
Aiming at the problems in the background art, the invention aims to provide a soft start circuit suitable for a lithium battery charging circuit, which does not need to additionally arrange a buffer capacitor, reduces the circuit cost by utilizing the parasitic capacitance of a charging tube, and is suitable for switching two constant charging current modes of the lithium battery charging circuit.
The technical aim of the invention is realized by the following technical scheme: a soft start circuit suitable for a lithium battery charging circuit comprises an amplifier A, wherein the negative input end of the amplifier A is respectively connected with constant current charging current V through a switch 1 And trickle charge current V 2 The positive input end of the amplifier A is connected with the SD port through a diode D, and the amplifier A also comprises a switching tube M 1 And a switching tube M 2 The switch tube M 1 The grid electrode of the switch tube M is connected with the output end of the amplifier A 1 Is passed through the drain of resistor R L The positive electrode input end of the amplifier A is grounded and is also connected with a feedback resistor R 1 And a switch tube M 1 Is connected with the drain electrode of the switch tube M 2 The lithium battery charging tube is characterized in that a grid electrode of the switching tube M2 is connected with an output end of the amplifier A, source electrodes of the switching tube M1 and the switching tube M2 are connected with a chip power supply, and a drain electrode of the switching tube M1 outputs charging current I chrg 。
Preferably, the switching tube M 2 Can be equivalently referred to as a capacitor C 1 。
In summary, the invention has the following advantages:
1. the current spike can be effectively prevented from being generated, and the surge current can be effectively restrained.
2. The method supports the switching of charging current and is used for a lithium battery charging circuit.
3. The integrated enabling control port can rapidly turn off the charging current.
4. Parasitic capacitance is adopted, so that the chip area is saved.
Drawings
FIG. 1 is a schematic diagram of a soft start circuit;
FIG. 2 is a schematic diagram of a soft start circuit suitable for use in a lithium battery charging circuit;
fig. 3 is a schematic diagram of an equivalent circuit of a soft start circuit suitable for a lithium battery charging circuit.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention relates to a soft start circuit suitable for a lithium battery charging circuit, which is characterized by comprising an amplifier A, wherein the negative input end of the amplifier A is respectively connected with constant current charging current V through a switch 1 And trickle charge current V 2 The positive input end of the amplifier A is connected with the SD port through a diode D, and the amplifier A also comprises a switching tube M 1 And a switching tube M 2 The switch tube M 1 The grid electrode of the switch tube M is connected with the output end of the amplifier A 1 Is passed through the drain of resistor R L The positive electrode input end of the amplifier A is grounded and is also connected with a feedback resistor R 1 And a switch tube M 1 Is connected with the drain electrode of the switch tube M 2 Is a lithium battery charging tube, the switch tube M 2 The grid electrode of the switch tube M1 and the source electrode of the switch tube M2 are connected with a chip power supply, and the drain electrode of the switch tube M1 outputs charging current Ichrg.
The switch tube M 2 Can be equivalently referred to as a capacitor C 1 。
The technical scheme of the invention is shown in the following figure 2, wherein V 1 And V 2 Voltage points are set for the constant current charging current and the trickle charging current respectively, and different charging currents can be set through voltage switching. The SD port is a turn-off signal, when the charging circuit needs to be turned off, the gate terminal voltage of the charging tube can be pulled up by giving a high level to the SD port, and the charging tube is turned off.
Wherein M is 2 The lithium battery charging tube has a large size and occupies the main area of a chip (the grid width of a common charging MOS is larger than 400 mu m, and the number of the charging MOS is larger than 200), so that parasitic capacitance of tens of pF exists. The invention adopts parasitic capacitance as buffer capacitance to realize soft start of circuit, which can be equivalent to the following figure 3. Wherein C is 1 For charging tube M 2 Is a capacitive equivalent of (a).
Circuit start-upV during movement 2 Build up due to equivalent capacitance C 1 The voltage at the gate end of the charging tube slowly drops, the charging current gradually increases and passes through the feedback resistor R 1 And feeding back the feedback current clamping operational amplifier. Due to the feedback resistance R 1 V is the presence of FB When the voltage is closer to the voltage of the input end, the lifting speed is slower, so that the voltage of the gate end of the charging tube is slower in falling speed, current overshoot can be effectively prevented, and surge current can be restrained. When V is FB And when the voltage rises to be equal to the voltage of the input end, ending the soft start over process and ending the current clamping process.
When the charging current is switched, the negative electrode input end of the operational amplifier is switched, and the voltage of the input end jumps. Because of the arrangement of the RC feedback loop, the voltage of the grid end of the charging tube can be changed slowly, and surge current formed by abrupt voltage change can be effectively prevented.
When the circuit needs to be closed for charging, the SD port is high-level, and the clamp operational amplifier is used for rapidly charging the capacitor without passing through a feedback loop, so that the circuit can respond to a turn-off signal relatively quickly.
The soft start circuit suitable for the lithium battery charging circuit is characterized in that a parasitic capacitor of a large output power tube is used as a buffer capacitor, an additional capacitor is not needed, the layout area is effectively reduced, and the cost is reduced. And the soft start circuit is modified according to the lithium battery charging control system, so that the method is suitable for current switching enabling control and other scenes in the charging circuit.
The technical scheme of the invention has the following main characteristics:
the method is characterized in that: no buffer capacitor is required to be additionally arranged;
and the second characteristic is that: the chip area is saved;
and the third characteristic is: the method is suitable for a lithium battery charging circuit control system;
and the characteristics are as follows: an integrated enable control function;
fifth characteristic is: effectively inhibit surge current and prevent current overshoot.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (2)
1. The soft start circuit suitable for the lithium battery charging circuit is characterized by comprising an amplifier A, wherein the negative electrode input end of the amplifier A is respectively connected with constant current charging current V through a switch 1 And trickle charge current V 2 The positive input end of the amplifier A is connected with the SD port through a diode D, and the amplifier A also comprises a switching tube M 1 And a switching tube M 2 The switch tube M 1 The grid electrode of the switch tube M is connected with the output end of the amplifier A 1 Is passed through the drain of resistor R L The positive electrode input end of the amplifier A is grounded and is also connected with a feedback resistor R 1 And a switch tube M 1 Is connected with the drain electrode of the switch tube M 2 Is a lithium battery charging tube, the switch tube M 2 The grid electrode of the switch tube M1 and the source electrode of the switch tube M2 are connected with a chip power supply, and the drain electrode of the switch tube M1 outputs charging current Ichrg.
2. A soft start circuit for a lithium battery charging circuit according to claim 1, wherein said switching tube M 2 Can be equivalently referred to as a capacitor C 1 。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311266711.9A CN117477700A (en) | 2023-09-28 | 2023-09-28 | Soft start circuit suitable for lithium battery charging circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311266711.9A CN117477700A (en) | 2023-09-28 | 2023-09-28 | Soft start circuit suitable for lithium battery charging circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117477700A true CN117477700A (en) | 2024-01-30 |
Family
ID=89635488
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311266711.9A Pending CN117477700A (en) | 2023-09-28 | 2023-09-28 | Soft start circuit suitable for lithium battery charging circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117477700A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118449252A (en) * | 2024-07-08 | 2024-08-06 | 深圳市明电环球科技有限公司 | Battery soft start BMS management system |
-
2023
- 2023-09-28 CN CN202311266711.9A patent/CN117477700A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118449252A (en) * | 2024-07-08 | 2024-08-06 | 深圳市明电环球科技有限公司 | Battery soft start BMS management system |
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