Battery charger

[0014] Most of the known battery chargers need to manually or use other devices to adjust the battery polarity to complete the normal charging function when the battery is reversed. Some chargers have the function of recharging the battery, but they are all built with discrete components. , occupying a large PCB board area, and accurate detection voltage will further increase the circuit cost. In view of this, the present invention proposes a battery charger that can automatically identify the polarity of the battery and can charge the battery in reverse connection.

[0015] As shown in Fig. 2A, this figure is a simple schematic diagram of a preferred embodiment of the present invention. In this example, a MOS field effect transistor is used as a controlled source, wherein the first field effect transistor (110) is a P channel MOS transistor, which has a source (113), a drain (117) and a gate (115), wherein The source (113) is connected to the power supply, the drain (117) is connected to the node X, and the gate (115) is connected to the first output of the controller (300); the second field effect transistor (120) is an N-channel MOS transistor, which has Source (123), drain (127) and gate (125), wherein the source (123) is grounded, and the drain (127) is coupled to the drain (117) of the first field effect transistor (110) at node X , the gate (125) is connected to the second output of the controller (300); the third field effect transistor (130) is a P channel MOS transistor, which has a source (133), a drain (137) and a gate (135 ), wherein the source (133) is connected to the power supply, the drain (137) is connected to the node Y, and the gate (135) is connected to the third output of the controller (300); the fourth field effect transistor (140) is an N-channel MOS transistor , which has a source (143), a drain (147) and a gate (145), wherein the source (143) is grounded, and the drain (147) is coupled to the drain (137) of the third field effect transistor at node Y , the gate (145) is connected to the fourth output of the controller (300). In a preferred embodiment of the present invention, the state/polarity identification unit (200) will automatically identify the charger's no-load, short circuit, overcurrent, battery positive connection and battery reverse connection conditions and detect battery voltage status, and generate corresponding status signals to the control The input of the device (300). The charger is connected to the battery and the battery is not saturated: when the battery terminal connected to node X is the positive pole of the battery and the battery terminal connected to node Y is the negative pole of the battery, the first field effect transistor (110) and the fourth field effect transistor (140) are turned on , the second field effect transistor (120) and the third field effect transistor (130) are turned off, at this time the battery charging circuit is: power supply VDD---first field effect transistor (110)---battery positive pole---battery Negative pole---the fourth field effect transistor (140)---ground; The field effect transistor (130) is turned on, and the first field effect transistor (110) and the fourth field effect transistor (140) are turned off. At this time, the battery charging circuit is: power supply VDD --- the third field effect transistor (130) -- -battery positive pole---battery negative pole---second field effect transistor (120)---ground. When the charger is connected to the battery and the battery is saturated: the controller (300) controls the switching action of the four MOS transistors to cut off the battery charging circuit to prevent the battery from being overcharged. In addition, the jumper (Metal Option) in the IC layout can be used to adjust the size of the MOS transistor to obtain the required charging current value.

[0016] As shown in FIG. 2B , this figure is a simple schematic diagram of another preferred embodiment of the present invention. Compared with Figure 2A, this preferred embodiment uses bipolar transistors instead of MOS field effect transistors, that is, both controlled source 1 and controlled source 3 use PNP transistors, and controlled source 2 and controlled source 4 both use NPN transistors , the same circuit function can be accomplished through different process options.

[0017]As shown in FIG. 2C , this figure is a simple schematic diagram of another preferred embodiment of the present invention. Compared with Fig. 2A, this preferred embodiment also uses MOS field effect transistors as controlled sources, that is, both controlled source 1 and controlled source 3 use P-channel MOS transistors, and controlled source 2 and controlled source 4 both use P-channel MOS transistors. N-channel MOS transistors are used, only the gate of the first field effect transistor is coupled to the gate of the second field effect transistor and connected to the node Y through the connection R, and the gate of the third field effect transistor is coupled to the gate of the fourth field effect transistor And connected to the node X through the connection Q, a fifth field effect transistor (150) is added, which is a P channel MOS transistor with a source (153), a drain (155) and a gate (157), Wherein the source (153) is connected to the power supply, and the drain (157) is coupled to the source (113) of the first field effect transistor and the source (133) of the third field effect transistor. From a functional point of view, the fifth field effect transistor, the connection Q and the connection R belong to the state/polarity recognition unit and the controller category, and this embodiment realizes automatic adjustment charging through simple circuit connections such as the connection Q and the connection R The purpose of the loop simplifies the circuit structure.

[0018] The above are only preferred embodiments of the present invention, and other control switching devices and combinations can also be selected as the charging drive unit in the present invention, which will not be listed here.

[0019] As before, the battery charger that can automatically identify the battery polarity of the present invention has the advantages of:

[0020] 1. It can automatically identify the polarity of the battery and realize the function of recharging the battery in reverse connection;

[0021] 2. The circuit is integrated into the chip, which greatly reduces the number of components and PCB board area, and saves the cost of the circuit.

[0022] In summary, the preferred embodiments of the present invention are as described above, but they are not intended to limit the scope of the present invention. The protection scope of the present invention should be based on the claims. The present invention can be made by those of ordinary skill in the art. Modifications and modifications, but still belong to the creative spirit of the present invention and the scope defined by the appended claims.