CN213185879U - Charge pump circuit - Google Patents

Abstract

The utility model belongs to the technical field of lithium battery protection shield circuit design technique and specifically relates to a charge pump circuit, with the control circuit connection that charges, including singlechip, once overcharge protection circuit, secondary overcharge protection circuit, once overcharge protection circuit include resistance R19, MOS pipe Q2, electric capacity C11, diode Z1, power P +, diode Z1 negative pole, resistance R19 one end are connected respectively to MOS pipe Q2's source end; the grid end of the MOS tube Q2 is respectively connected with the anode of a diode Z1, the other end of a resistor R19 and one end of a capacitor C11, and the other end of the capacitor C11 is connected with the single chip microcomputer; the grid end of the MOS tube Q2 is connected with a secondary overcharge protection circuit. The utility model reduces MOS cost and improves the market competitiveness of products; the MOS heating value is smaller when the product is charged, the reliability is high, and the charging is safer; the circuit is simpler, the cost is lower, and the circuit layout space is larger.

Description

Charge pump circuit

Technical Field

The utility model belongs to the technical field of lithium battery protection shield circuit design technique and specifically relates to a charge pump circuit.

Background

The MOS tube has small loss and good switching characteristic, and is widely applied to circuits needing electronic switches, such as common application occasions as dust collectors, BMS protection boards, garden tools, switching power supplies, motor drives and the like. The traditional charging MOS is placed at the negative terminal, namely the MOS is placed at the C-or P-terminal; some are placed at the positive end of the charger, namely the MOS discharging C + or P + end; both of these drive modes have their own advantages and disadvantages; when the charging MOS is placed at the negative end, the MOS has the advantages that the N-channel MOS is used, and the driving voltage is more than 4.5V, so that the MOS can work normally, but the MOS has the disadvantages that a driving signal needs to be isolated from the ground used by the BMS system, otherwise, when the MOS is cut off, the high voltage of the BMS system can damage related elements or ICs of the protection board; when the charging MOS is placed at the positive terminal, there is an advantage in that the problem of ground isolation of the driving signal or other signals from the BMS system is solved, and there is a disadvantage in that the conventional method uses a P-channel MOS, which is turned on by pulling down the gate voltage of the MOS and then charges the battery pack, and the P-channel MOS has a disadvantage in that it is expensive and has a large internal resistance.

At present, in the existing circuit scheme of the lithium battery protection board, a charging MOS transistor with a positive terminal is generally adopted, a P-channel MOS is used, as shown in fig. 2, that is, M5 in the drawing, the conduction of the MOS is realized by controlling the gate of the MOS transistor Q2 through an I/O port CH _ EN of a single chip microcomputer, when the CH _ EN outputs a high level, the gate voltage of Q2 is completely conducted when being higher than 2V, so that the gate voltage of M5 is pulled low, and M5 is conducted; similarly, when CH _ EN outputs low, Q2 turns off, turning off M5. The conventional charge pump uses an IC to drive a MOS transistor, but the cost of using the IC is higher, which increases the cost of product investment and greatly reduces the competitiveness of the product. Therefore, the technical problem to be solved by the practitioners in the art is already becoming urgent.

Disclosure of Invention

The utility model discloses an one of the purpose lies in to prior art's defect and not enough, provides a security height, uses with low costs, goes a charge pump circuit of the N type MOS pipe that the control charges through singlechip IO mouth series capacitance.

The technical scheme of the utility model as follows:

a charge pump circuit is connected with a charge control circuit and comprises a single chip microcomputer, a primary overcharge protection circuit and a secondary overcharge protection circuit, wherein the primary overcharge protection circuit comprises a resistor R19, a MOS tube Q2, a capacitor C11 and a diode Z1, and a source electrode end of the MOS tube Q2 is respectively connected with a power supply P +, a cathode of the diode Z1 and one end of a resistor R19; the grid end of the MOS tube Q2 is respectively connected with the anode of a diode Z1, the other end of a resistor R19 and one end of a capacitor C11, and the other end of the capacitor C11 is connected with the single chip microcomputer; the grid end of the MOS tube Q2 is connected with a secondary overcharge protection circuit.

Preferably, the singlechip is an SC92F7423 singlechip, the CH _ EN end of the singlechip is connected with the other end of the capacitor C11, and the CH _ EN end of the singlechip has a PWM function.

Preferably, the MOS transistor Q2 is an N-channel MOS.

Preferably, the secondary overcharge protection circuit comprises a MOS transistor M4, a diode D1 is arranged between the MOS transistor M4 and the MOS transistor Q2, a cathode of the diode D1 is connected to a gate terminal of the MOS transistor Q2, and an anode of the diode D1 is connected to a source terminal of the MOS transistor M4.

Preferably, the resistance R19 is 1 Mega ohm.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model relates to a charge pump circuit goes the grid of the N type MOS pipe that control charges through the IO mouth series capacitance of singlechip, and what switch on of MOS pipe Q2 is by the CH _ EN end output PWM signal of singlechip, through quick charge and quick discharge to C11, makes MOS pipe Q2 switch on fast and end, accomplishes the charge pump function promptly. The N-channel MOS has lower internal resistance and lower price than the P-channel MOS, so that the MOS cost is reduced, and the market competitiveness of the product is improved; because the internal resistance of the N-channel MOS tube is low, compared with the temperature of the P-channel MOS tube during continuous current, the temperature of the N-channel MOS tube is lower, so that the MOS tube has smaller heat productivity during product charging, high reliability and safer charging; compared with a P-channel MOS control circuit, the positive-end charging MOS uses an N-channel MOS, so that the circuit is simpler, has lower cost and larger layout space.

Drawings

Fig. 1 is a block diagram of a circuit structure according to an embodiment of the present invention.

Fig. 2 is a circuit diagram of a related art control method.

Fig. 3 is a pin diagram of the single chip microcomputer according to the embodiment of the present invention.

Fig. 4 is a circuit diagram of an embodiment of the present invention.

Detailed Description

As shown in fig. 1, fig. 3, and fig. 4, a charge pump circuit in an embodiment of the present invention is connected to a charging control circuit 100, and includes a single chip 200, a primary overcharge protection circuit 101, and a secondary overcharge protection circuit 102, where the primary overcharge protection circuit 101 includes a resistor R19, a MOS transistor Q2, a capacitor C11, and a diode Z1, the resistance of the resistor R19 is 1 mega ohm, the MOS transistor Q2 is an N-channel MOS, and a source terminal of the MOS transistor Q2 is respectively connected to a power source P +, a cathode of the diode Z1, and one end of the resistor R19; the grid end of the MOS tube Q2 is respectively connected with the anode of a diode Z1, the other end of a resistor R19 and one end of a capacitor C11, and the other end of the capacitor C11 is connected with the single chip microcomputer; the gate terminal of the MOS transistor Q2 is connected to the secondary overcharge protection circuit 102, the secondary overcharge protection circuit 102 includes a MOS transistor M4, a resistor R20, a resistor R23, a resistor R3, a resistor R24, and a resistor R28, and the secondary overcharge protection circuit 102 is consistent with the existing secondary overcharge protection technical solution.

When the single-chip microcomputer 200 is used, the single-chip microcomputer 200 controls whether the charger charges the battery pack according to the voltage, the charging current and the temperature of each battery, when the voltage of each battery is normal, namely when no overcharge or disconnection occurs, the CH _ EN end of the single-chip microcomputer 200 outputs a PWM signal, the duty ratio is 98%, the MOS transistor Q2 is turned on, if one or more sections of batteries are overcharged, namely the voltage exceeds a protection point set by software, the single-chip microcomputer 200CH _ EN end outputs a low level, the MOS transistor Q2 is cut off, and similarly, when the charging overcurrent or the charging high temperature or the charging low temperature occurs, the single-chip microcomputer 200CH _ EN end also inputs a low level, and the MOS transistor Q2 is cut off; the secondary overcharge protection circuit 102 controls the MOS transistor M4 by the secondary overcharge protection IC and the charger together, and when the voltage of a certain battery or a plurality of batteries in the battery pack exceeds the voltage of the protection point of the IC, the secondary protection IC outputs a control signal to pull down the OV voltage to cut off the MOS transistor M4, so as to prevent the charger from continuing to charge the battery pack, thereby protecting the battery voltage from continuing to rise. The one-time overcharge protection circuit 101 is implemented by utilizing the PWM function of the I/O of the singlechip 200 and utilizing the capacitor C11 connected in series to charge and discharge.

In this embodiment, the single chip microcomputer 200 is an SC92F7423 single chip microcomputer, the end of the single chip microcomputer 200CH _ EN is connected to the other end of the capacitor C11, and the end of the single chip microcomputer 200CH _ EN has a PWM function.

In this embodiment, a diode D1 is disposed between the MOS transistor M4 and the MOS transistor Q2, the cathode of the diode D1 is connected to the gate terminal of the MOS transistor Q2, the anode of the diode D1 is connected to the source terminal of the MOS transistor M4, and the diode D1 plays a role of isolation, so as to prevent the voltage of the power supply P + from flowing backward to the CH + terminal, i.e., the charger terminal, and affecting the detection and the self-power consumption of the charger.

Specifically, the charge pump function is realized by utilizing the charge and discharge characteristics of the capacitor, namely the gate voltage of the MOS transistor Q2 is higher than the source voltage, the voltage difference is VDD, VDD is the supply voltage of the single chip microcomputer, VDD is 5V, and the voltage can completely turn on the MOS transistor Q2. The specific working process is as follows: when the PWM at the CH _ EN terminal of the single chip microcomputer 200 is at a high level, the capacitor C11 is rapidly charged by using the capacitance characteristic of the capacitor C11, so that the gate voltage of the MOS transistor Q2 is increased by about 5V at the moment of enabling, and VGS of the MOS transistor Q2 is approximately equal to 5V, that is, the source voltage is subtracted from the gate voltage of the MOS transistor Q2. The diode Z1 is added to clamp VGS voltage at 7.5V, so that VGS of the MOS transistor Q2 is protected within a normal working voltage range, and MOS transistor Q2 is prevented from being damaged. When the PWM at the CH _ EN end of the single chip microcomputer 200 is low, the capacitor C11 is used to discharge to the ground quickly, so that the electricity on the capacitor C11 is discharged completely, preparation is made for next PWM, the VGS voltage is about 0V, the diode Z1 is added to also discharge the charge on the gate of the MOS transistor Q2 quickly, so that the charge is pulled to P + quickly, and the MOS transistor Q2 is cut off, that is, the source voltage is subtracted from the gate voltage of the MOS transistor Q2; the PWM repeats this process to complete the charge pump function.

Through the technical scheme, the charge pump circuit controls the grid electrode of the charged N-type MOS tube through the series capacitor of the I/O port of the single chip microcomputer 200, the MOS tube Q2 is switched on by outputting a PWM signal from the CH _ EN end of the single chip microcomputer, and the MOS tube Q2 is switched on and off rapidly through rapid charging and rapid discharging of the C11, so that the function of the charge pump is completed. The N-channel MOS has lower internal resistance and lower price than the P-channel MOS, so that the MOS cost is reduced, and the market competitiveness of the product is improved; because the internal resistance of the N-channel MOS tube is low, compared with the temperature of the P-channel MOS tube during continuous current, the temperature of the N-channel MOS tube is lower, so that the MOS tube has smaller heat productivity during product charging, high reliability and safer charging; compared with a P-channel MOS control circuit, the positive-end charging MOS uses an N-channel MOS, so that the circuit is simpler, has lower cost and larger layout space.

When a charger is inserted, the singlechip 200 supplies 5V normally, the singlechip is initialized, is started for 1ms delay, then enters each functional module and starts 10ms delay, the singlechip 200 can judge whether a key is pressed or the charger is activated through an ADC (analog to digital converter) for detecting the voltage of the charger and the key, at the moment, the charger is activated, a charging mark is set, a discharging mark and a shutdown mark are cleared, whether the voltage of each battery core reaches an overcharge voltage or not and whether the temperature reaches a high temperature or a low temperature or not are detected, when the voltage and the temperature of each battery core do not reach the overcharge protection condition and do not reach the high temperature or the low temperature protection condition, the singlechip 200CH _ EN end outputs a PWM (pulse width modulation) function, the duty ratio is 98 percent, so that a charging MOS (metal oxide semiconductor) tube Q2 is opened, then whether the overcurrent protection occurs during charging or not, and when the overcurrent protection does, the duty cycle is 98%; when overcharge protection or overcurrent or high-temperature or low-temperature protection occurs, the end of the single chip microcomputer 200CH _ EN outputs low level, so that the charging MOS tube Q2 is cut off, and recharging is allowed until the recovery voltage and the recovery temperature are reached; in addition, overcurrent recovery can be realized only by plugging and unplugging the charger; in order to enable the low-power-consumption single chip microcomputer 200 to enter a power-off mode after overcharge protection or temperature protection for 1 minute or when a charger is unplugged, the power consumption of the whole single chip microcomputer is controlled within 5 uA.

What just go up be the preferred embodiment of the utility model discloses, not consequently the restriction the patent scope of the utility model, all utilize the equivalent structure or the equivalent flow transform that the content of the description and the attached drawing was done, or directly or indirectly use in other relevant technical field, all the same reason is included in the patent protection scope of the utility model.

Claims (5)

1. The utility model provides a charge pump circuit, is connected with charge control circuit, includes singlechip, once overcharge protection circuit, secondary overcharge protection circuit, its characterized in that: the primary overcharge protection circuit comprises a resistor R19, an MOS tube Q2, a capacitor C11 and a diode Z1, wherein a source end of the MOS tube Q2 is respectively connected with a power supply P +, a cathode of the diode Z1 and one end of a resistor R19; the grid end of the MOS tube Q2 is respectively connected with the anode of a diode Z1, the other end of a resistor R19 and one end of a capacitor C11, and the other end of the capacitor C11 is connected with the single chip microcomputer; the grid end of the MOS tube Q2 is connected with a secondary overcharge protection circuit.

2. A charge pump circuit as claimed in claim 1, wherein: the singlechip is an SC92F7423 singlechip, a CH _ EN pin of the singlechip is connected with the other end of the capacitor C11, and the CH _ EN end of the singlechip has a PWM function.

3. A charge pump circuit as claimed in claim 1, wherein: the MOS transistor Q2 is an N-channel MOS.

4. A charge pump circuit as claimed in claim 1, wherein: the secondary overcharge protection circuit comprises a MOS tube M4, a diode D1 is arranged between the MOS tube M4 and the MOS tube Q2, the cathode of the diode D1 is connected with the gate terminal of the MOS tube Q2, and the anode of the diode D1 is connected with the source terminal of the MOS tube M4.

5. A charge pump circuit as claimed in claim 1, wherein: the resistance value of the resistor R19 is 1 megaohm.

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