Self-adaptive protection circuit and method for double-voltage startup of wireless charging system
View Patent ↗A self-adaptive protection circuit and method for double-voltage startup of a wireless charging system are provided. The method controls a double-voltage logic control module of a double-voltage starting circuit to send a signal for exiting a double-voltage mode by detecting an input voltage of a receiving terminal of the wireless charging system. By the input voltage of the receiving terminal of the wireless charging system, the double-voltage logic control module of the double-voltage starting circuit is controlled to send the signal for exiting the double-voltage mode, thus protecting the receiving terminal of the wireless charging system from the over-high input voltage in the double-voltage mode.
1 . A self-adaptive protection method for switching on or off a double-voltage mode of a wireless charging system through a self-adaptive protective circuit, wherein:
the self-adaptive protection circuit comprises a first clamping circuit 1 , a second clamping circuit 2 , a third clamping circuit 3 , a first resistor R 1 , a second resistor R 2 , a third resistor R 3 , a first switching transistor NM 1 , a second switching transistor NM 2 , a Schmitt trigger and a NOT gate;
an input voltage vrect of a receiving terminal of the wireless charging system is connected to a GND VSS through the first clamping circuit 1 , the second clamping circuit 2 , the third clamping circuit 3 , R 1 , and R 2 in sequence;
a drain of NM 2 is connected to the first clamping circuit 1 and the second clamping circuit 2 ;
a source of NM 2 and a gate of NM 1 are connected to R 1 and R 2 ;
a source of NM 1 is connected to the GND VSS, a drain of NM 1 is connected to a first end of R 3 and an input end of the Schmitt trigger;
a second end of R 3 is connected to the Schmitt trigger and a power end of the NOT gate;
an output end of the Schmitt trigger is connected to a double-voltage logic control module through the NOT gate; and
a gate of NM 2 is connected to the double-voltage logic control module and the NOT gate,
the method comprising:
inputting an input voltage vrect to the self-adaptive protection circuit the first clamping circuit 1 , whereby:
generating a switching control voltage vgate NM 1 , R 1 , R 2 , wherein vgate=(vrect−vc 1 −vc 2 −vc 3 )×R 2 /(R 1 +R 2 ), vc 1 , vc 2 , vc 3 being clamping voltages of the first clamping circuit 1 , the second clamping circuit 2 , and the third clamping circuit 3 , respectively;
generating a low-voltage power supply V 0 as a power supply to the Schmitt trigger and the NOT gate and pulling up a voltage at the drain of NM 1 through the resistor R 3 to set a reference voltage at the input end of the Schmitt trigger;
when the input voltage vrect increases until NM 1 is switched on at the switching control voltage vgate, pulling down the refence voltage at the input end of the Schmitt trigger, and generating an output signal vrect_start_ov above a preset threshold level through the Schmitt trigger and the NOT gate as an input into the double-voltage logic control module to cause the double-voltage logic control module to exit the double-voltage mode;
when the output signal vrect_start_ov is generated, the switching control voltage vgate=vrect−vc 1 , and when vrect−vc 1 >V 0 −Vth 2 , Vth 2 being a threshold voltage of the switching transistor NM 2 , and the switching control voltage vgate is clamped to V 0 −Vth 2 ; and
when the input voltage vrect decreases, the switching control voltage vgate decreases until the switching transistor NM 1 is switched off, pulling up the reference voltage at the input end to the Schmitt trigger to V 0 by means of the resistor R 3 , and reducing the output signal vrect_start_ov to below the preset threshold level, thus causing the double-voltage logic control module to enter the double-voltage mode.
2 . A receiving terminal of a wireless charging system, comprising a double-voltage starting circuit and a self-adaptive protection circuit, wherein:
the self-adaptive protection circuit comprises a first clamping circuit 1 , a second clamping circuit 2 , a third clamping circuit 3 , a first resistor R 1 , a second resistor R 2 , a third resistor R 3 , a first switching transistor NM 1 , a second switching transistor NM 2 , a Schmitt trigger and a NOT gate;
an input voltage vrect of a receiving terminal of the wireless charging system is connected to a GND VSS through the first clamping circuit 1 , the second clamping circuit 2 , the third clamping circuit 3 , R 1 , and R 2 in sequence;
a drain of NM 2 is connected to the first clamping circuit 1 and the second clamping circuit 2 ;
a source of NM 2 and a gate of NM 1 are connected to R 1 and R 2 ;
a source of NM 1 is connected to the GND VSS, a drain of NM 1 is connected to a first end of R 3 and an input end of the Schmitt trigger;
a second end of R 3 is connected to the Schmitt trigger and a power end of the NOT gate;
an output end of the Schmitt trigger is connected to a double-voltage logic control module through the NOT gate; and
a gate of NM 2 is connected to the double-voltage logic control module and the NOT gate.
3 . A wireless charging system, comprising a transmitting terminal and the receiving terminal according to claim 2 .