Figure 11 Resonance signal
The circuit for free resonance Q measurement is as shown in the following figure, which samples the
signal on resonance capacitors.
Figure 12 Free resonance Q measurement circuit
4.8 Coil selection
The Qi specification defines the MP-A9 as the more-than-one coil topology with one coil energized at a
time to realize the free position charging.
The coil selection topology connects only one coil to the full-bridge inverter at a time. The coil is equipped
with the dual N-MOSFETs, Q9, Q12, or Q16, controlled by the WCT1011A/WCT1013A controller
through the control interface based on the low power bipolar transistors.
4.9 Analog sensing
Some ports of the ADC A-channel of WCT1011A/WCT1013A are used for sensing analog signals, such
as temperature, full-bridge input current, input voltage, and rail voltage.
TP23
DNP
C407
330pF
C406
330pF
D53
BAT54SW
1
2
3
R371
221K
R372
221K
V3.3A_Q
COILS 5
Q_RESONANCE_VOLT
3
V3.3A_Q
R531
100
R532
100
-
+
U28C
LMV824-N-Q1
10
9
8
C271
27PF
WCT1011A/WCT1013A Automotive MP-A9 Wireless Charging Application User’s Guide, Rev. 0, 10/2017
14
NXP Semiconductors
