PDF《TC7718FTG》

4 IINF VINF VSS VDD33 VDD33/2 IIN VIN HYS VSS VDD33 COMP_EN_IN VSS VDD33 COMP_OUT1 COMP_OUT2 VSS VDD33 7. Equivalent circuit for input/output pins and power supply pins Table

2 Equivalent circuit for power supply pins Pin name Equivalent circuit IIN IINF VIN VINF HYS COMP_EN_IN COMP_OUT1 COMP_OUT2 TC7718FTG 2018-04-24

5 QDET_CNT Bridge_CNT PWM_IN3 PWM_IN2 PWM_IN1 PWM_IN0 LS2_IN LS1_IN VSS VDD33 VSS VCC LDRV3 HDRV3 LS1_OUT LS2_OUT VSS VCC HDRV2 LDRV2 LDRV1 HDRV1 VSS PVDD VDD33 VCC Pin name Equivalent circuit Qdet_CNT Bridge_CNT PWM_IN3 PWM_IN2 PWM_IN1 PWM_IN0 LS2_IN LS1_IN LDRV3 HDRV3 LS1_OUT LS2_OUT HDRV2 LDRV2 LDRV1 HDRV1 VDD33 (Note) Equivalent circuit may be simplified to illustrate circuits. Qdet_CNT TC7718FTG 2018-04-24

6 8. Function and operation description 8.1 General outline of wireless power system Qi compliant wireless power system consists of the first side (Tx) which transmits power and the second side (Rx) which receives power. Power is transmitted by adjoining coils included in Tx and Rx and by sharing and combining flux. Rx controls the power by monitoring receiving power and sending feedback signal to Tx. Tx controls the power by controlling transmitting power with feedback signal which is received from Rx. Configuration example of wireless power system is shown in Figure

3 Communication signal from Rx to Tx is transmitted (modulated) by ASK modulation. The communication rate and its packet in this communication are defined by Qi compliant. Communication rate is

2 kbps. Packets are ID, identification signal, error information, receive power, and stop signal. TX stops its operation in normal mode. It is powered on intermittently and confirms the existence of Rx on the Tx pad. When Tx recognizes Rx and succeeds the identification, transmit operation starts. Tx continues transmit operation until Tx cannot recognize the existence of Rx or receives transmit stop signal from Rx. Qi Medium power v1.2 system adjusts the parameter to transmit the electrical power by interactive communication. And the electrical power of 15W (max) can be transmitted. The communication from TX to RX is performed by FSK modulation method. As for details of Qi system, please refer to the HP of WPC. Tx coil Tx pad Rx coil DC input DC output Communication Adjoin Rx pad Power Figure

3 General outline of wireless power system TC7718FTG 2018-04-24

7 8.2 Pre driver The TC7718FTG controls the external FET that drives the coil of transmission side by the signal from MCU (PWM_IN [0:3], Bridge_CNT, and Qdet_CNT) as shown in below truth table. The signal of Bridge_CNT switches Half and Full. The signal of Qdet_CNT configures the Break mode in measuring Q value of the transmission coil. When improper configuration, which causes shorting the external FET, is inputted to PWM_IN [0:3], penetration protection function operates to fix the corresponded pin in the HDRV [1:3] at high level. To control the Phase shift, four or more independent output pins of PWM signal are required for MCU. [X]: Don'

t care Both drivers of HDRV and LDRV are operated by VCC and VSS. 8.2.1 Configuration Figure

4 Equivalent circuit of pre driver TC7718FTG 2018-04-24

8 R HDRV3 LDRV3 HDRV2 LDRV2 HDRV1 LDRV1 R HDRV3 LDRV3 HDRV2 LDRV2 HDRV1 LDRV1 R HDRV3 LDRV3 HDRV2 LDRV2 HDRV1 LDRV1 PWM PWM Low High PWM PWM High High High High PWM PWM PWM PWM Low High Low Low Figure

5 Driver control TC7718FTG 2018-04-24

9 BGR LDO 3.3V LPF HDRV[1:3] LDRV[1:3] PVDD VCC VDD33 Level Shifter Driver Logic 8.3 LDO The TC7718FTG has LDO (VDD33) for the power supply to the internal logic block and the external MCU block. 8.3.1 VDD33 VDD33 is 3.3V-voltage source for the internal logic block and the external MCU block. (Note) Connect the capacitor of 1μF (COUT) between VDD33 and GND. Figure