CN111355370A

CN111355370A - Medium-power low-cost charge pump charging method

Info

Publication number: CN111355370A
Application number: CN202010397158.2A
Authority: CN
Inventors: 卞坚坚
Original assignee: Southchip Semiconductor Technology Shanghai Co Ltd
Current assignee: Shanghai Southchip Semiconductor Technology Co Ltd
Priority date: 2019-12-16
Filing date: 2020-05-12
Publication date: 2020-06-30
Anticipated expiration: 2040-05-12
Also published as: CN111355370B; CN111049371A

Abstract

The invention discloses a charge pump charging method with medium power and low cost, which realizes high-voltage direct charging with low power of about 20-30 watts by utilizing a high-voltage direct charging chip with a similar charge pump structure with SC8551 or lower cost to match with a charging head which is commonly used in the market at present and has a very low cost within a 200mV first-gear voltage regulation range. U1 is SC8551 or Shanghai south China core with series charge pump high voltage direct charging chip, can detect USB interface voltage in real time, namely VAC, when the voltage of VAC is higher than the voltage of required work, through the conducting state of OVP _ GATE signal control Q1, clamp VBUS in required voltage range. The Q1 is an NMOS tube, is matched with the U1 to be used as overvoltage protection of the USB interface, and is controlled by the U1, so that the low-cost isolation of 200mV change of each level of the USB input voltage is realized. The invention can well balance the cost and the charging efficiency and has great advantages in the range of about 20-30 watts, thereby having high practical value and popularization value.

Description

Medium-power low-cost charge pump charging method

Technical Field

The invention relates to the technical field of mobile phone charge pump charging circuits, in particular to a charge pump charging method with medium power and low cost.

Background

At present, a charge pump structure high-voltage direct charging chip in a mobile phone must be matched with a charging head for accurately regulating voltage and current, such as voltage regulation stepping of a first gear from 20mv to 50mv and current regulation stepping of a first gear from 50mA to 200mA, so that the voltage and current parameters of the charging head are configured by the mobile phone according to a communication protocol customized by PPS, SCP or some mobile phone manufacturers. The charging head is controlled by the mobile phone by using an interface chip with higher cost, and the system control scheme is very complicated.

The high-voltage direct charging scheme with lower power of about 20-30 watts can be realized by matching with a charging head which is commonly used in the market at present and has a very low cost within a 200mV first-gear voltage regulating range based on a special arrangement and a corresponding system design of a SC8551 or similar charge pump architecture high-voltage direct charging chip.

SC8551 is the most recently introduced charge pump fast-fill IC for the mobile phone fast-fill market. As a domestic first high-voltage charge pump quick-charging IC, the SC8551 also creates a dual-mode charging function of high-voltage quick-charging and low-voltage direct-charging. SC8551 is packaged with 56pin CSP, chip size 3.32mm by 3.35 mm. In the charging process, the SC8551 serves as a slave charging IC in the master-slave charging architecture, and starts to work after the mobile phone enters a fast charging stage.

Disclosure of Invention

The invention aims to provide a charge pump charging method with medium power and low cost, and mainly solves the problems that an interface chip of a charge pump of a mobile phone is high in cost and a charging system control scheme is complicated.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a medium-power low-cost charge pump charging method comprises the following steps:

(S1) configuring and enabling operating parameters of the charge pump;

(S2) sending a command to control the output voltage of the charging head of each stage of 200mV through the USB interface, so that the output current of the charge pump approaches the set value; at this time, Q1 is always in a full conducting state;

(S3) gradually increasing the voltage of the USB interface until Q1 enters a clamping state, stopping adjusting the USB voltage, and charging the battery until Q1 is completely conducted when the charge pump reaches the set output current;

(S4) sending a command to the charging head again through the USB, raising the voltage of the USB interface by 200mV, and the Q1 entering the clamp mode again, continuing to charge the battery until the Q1 is fully turned on again;

(S5) repeating the process of the step (S4) until the battery reaches the set voltage;

(S6) reducing the voltage of the USB interface by 200mV through the USB interface, and if the output current of the charge pump is suddenly reduced, the battery voltage is also suddenly reduced, and the charging state is maintained until the battery voltage rises to the set value again;

(S7) the USB interface voltage is decreased by 200mV again, and the step (S6) is repeated until the charging current of the charge pump decreases to the set value, the charge pump stops working, and the main charger completes the subsequent charging process alone.

Further, in the step (S3), the specific process that Q1 is fully turned on is: as the charging process proceeds, the battery voltage rises, the voltage of VBUS rises, and the voltage difference between the USB interface and VBUS gradually decreases until Q1 is fully turned on.

Further, in step (S4), the control method for the Q1 to enter the clamp mode again is: when the Q1 of the step (S3) is completely turned on, the voltage of the USB interface is the same as the VBUS voltage, a command is sent to the charging head through the USB, the voltage of the USB interface is immediately raised by 200mV, and the Q1 enters the clamp mode again.

Further, in step (S4), the control method for the Q1 to enter the clamp mode again is: when the Q1 of the step (S3) is completely turned on, the voltage of the USB interface is the same as the VBUS voltage, and after waiting for a while, the charging current decreases by a certain value, and then the voltage of the USB interface is increased, and the Q1 enters the clamp mode again.

Compared with the prior art, the invention has the following beneficial effects:

the invention uses SC8551 or similar charge pump high-voltage direct charging chip to charge system of mobile phone battery, and detects voltage VAC of USB interface in real time, and uses the cooperation of NMOS tube Q1 and charge pump high-voltage direct charging chip to realize the isolation of low-cost USB input voltage 200mV change per gear, and make NMOS tube Q1 work in a clamping state in a certain range for a long time, thereby realizing stable charging current, and through corresponding chip internal design and system design, NMOS tube Q1 is protected correspondingly, and there is no possibility of overheating and burning. Not only is low cost achieved but also the system control scheme is simplified.

Drawings

FIG. 1 is a block diagram of a low cost charge pump charging circuit according to the present invention.

Fig. 2 is a flow chart of the charging method of the present invention.

Detailed Description

The present invention will be further described with reference to the following description and examples, which include but are not limited to the following examples.

Examples

As shown in fig. 1 and 2, the charging circuit block diagram of the charge pump charging method with medium power and low cost disclosed in the present invention utilizes the SC8551 charge pump structure high voltage direct charging chip to cooperate with the charging head commonly used in the market at present and with a very low cost within a 200mV first-gear voltage regulation range, so as to realize low power high voltage direct charging with about 20 w-30 w. U1 is SC8551 or Shanghai nan core with the high-pressure chip that directly fills of series charge pump, can detect USB interface voltage in real time, namely VAC, when the voltage of VAC is higher than the voltage of required work, through the conducting state of OVP _ GATE signal control Q1, clamp VBUS in required voltage range, realize the isolation of low-cost USB input voltage every grade 200mV change.

The specific charging method is as follows:

configuring and enabling working parameters of the charge pump, and sending a command to control the output voltage of the charging head of each gear of 200mV through a USB interface so as to enable the output current of the charge pump to be close to a set value; at this time Q1 is always in a fully on state.

Gradually increasing the voltage of the USB interface, namely VAC, until Q1 enters a clamping state, stopping adjusting the USB voltage, enabling the charge pump to reach the set output current to charge the battery, increasing the voltage of Vbus along with the increase of the voltage of the battery, and gradually reducing the voltage difference between VAC and VBUS until Q1 is completely conducted until Q1 is completely conducted.

At this time, there are two control manners that can be adopted, one is to send a command to the charging head through the USB again, the voltage of the USB interface, that is, VAC, is raised by 200mV, Q1 enters the clamping mode again, VBUS continuously rises at the same time as the voltage of the battery rises, and the voltage difference between VAC and VBUS is gradually reduced until the N-MOS is completely conducted again.

The other is that when Q1 is fully on, the VAC and VBUS voltages are the same, and instead of immediately raising the VAC voltage by 200mV, the charging current is lowered slightly, for example by 300mA, and the VAC voltage is raised. The charging current returns to the set value again and Q1 enters the clamped state again, but the voltage difference between VAC and VBUS is less than 200mV, so that the heat generation of the NMOS transistor Q1 can be reduced.

The above process is repeated until the battery reaches the set voltage. Then, the VAC voltage is reduced by 200mV through the USB interface, and at this time, the output current of the charge pump is reduced by one step, and the battery voltage is also reduced by one step. This state of charge is maintained until the battery voltage rises again to the set value, and the VAC voltage of the USB interface is lowered again by 200 mV. And repeating the steps until the charging current of the charge pump is reduced to a set value, stopping the charge pump, and completing the subsequent charging process by the main charger independently.

In the whole process, the charge pump can continuously detect VAC, VBUS, input and output current, heat dissipation and other various information, and can detect Q1 and the temperature of the charge pump through the thermistor, and the charge pump can stop working when any index in any situation exceeds the design range.

Through the design, the high-voltage direct charging scheme with lower power of about 20-30 watts is realized by matching the high-voltage direct charging chip of the charge pump structure in the mobile phone with the charging head which is commonly used in the market at present and has a very low cost within a 200mV one-gear voltage regulation range. The invention can well balance the cost and the charging efficiency and has great advantages in the range of about 20-30 watts, so the invention has high practical value and popularization value.

The above-mentioned embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or changes made within the spirit and scope of the main design of the present invention, which still solve the technical problems consistent with the present invention, should be included in the scope of the present invention.

Claims

1. A medium-power low-cost charge pump charging method is characterized by comprising the following steps:

(S1) configuring and enabling operating parameters of the charge pump;

(S2) sending a command to control the output voltage of each charging head of 200mV via the USB interface, so that the output current of the charge pump approaches the set value; at this time, Q1 is always in a full conducting state;

(S7) the USB interface voltage is lowered by 200mV again, and the process is repeated (S6) until the charging current of the charge pump is lowered to the set value, the charge pump stops working, and the main charger completes the subsequent charging process alone.

2. The medium-power low-cost charge pump charging method of claim 1, wherein in the step (S3), the Q1 is fully turned on by: as the charging process proceeds, the battery voltage rises, the voltage of VBUS rises, and the voltage difference between the USB interface and VBUS gradually decreases until Q1 is fully turned on.

3. The medium power low cost charge pump charging method of claim 2, wherein in step (S4), the Q1 is controlled to enter the clamp mode again by: when the Q1 of the step (S3) is completely turned on, the voltage of the USB interface is the same as the VBUS voltage, a command is sent to the charging head through the USB, the voltage of the USB interface is immediately raised by 200mV, and the Q1 enters the clamp mode again.

4. The method of claim 2, wherein in step (S4), the Q1 is controlled to enter the clamp mode again by: when the Q1 of the step (S3) is completely turned on, the voltage of the USB interface is the same as the VBUS voltage, and after waiting for a while, the charging current decreases by a certain value, and then the voltage of the USB interface is increased, and the Q1 enters the clamp mode again.