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Transmitter
F
D
EATURE
ESCRIPTION
Foreign Object Detection
The PAC5220WP implements the WPC's Foreign Object Detection (FOD) according to the low-power
specification, version 1.1.
The PAC5220WP has four levels of foreign object detection using temperature, current, voltage and
communication disruptions to determine if a foreign object is on or near the charge pad. If a foreign object
is detected, then the EVK's red LED will be illuminated. The device then waits for the receiver to be
removed from the charge pad, and then will delay for 30 seconds before resetting the state machine. At
that time, the state machine will return to the selection phase.
Power Limited Operation
The PAC5220WP EVK implements the WPC low-power transmitter specification. This specifies operation
for up to 5W receivers.
If a power supply is used that cannot deliver enough power for the receiver, then the PAC5220WP will
deliver as much power as it can, without affecting operation of the device and EVK.
When the PAC5220WP detects this condition (not enough supply power), the system will stay in this
power limiting mode and the LED is illuminated orange for the duration of the time that the receiver is
2
charging.
When the input voltage sensed is less than 4.6V, the system is put into this mode.
When the receiver is removed and re-placed on the charge pad, the WPC state machine starts over and
this condition is cleared and the EVK will attempt to deliver full power.
Thermal Protection
The PAC5220WP EVK periodically checks the temperature of the coil using an NTC thermistor.
If this temperature is ever greater than 45C, then the power transfer is stopped, the green and red LEDs
will be turned on. Operation will resume and the LED will be turned off when both the coil temperature
has fallen below 40C and 5 minutes has elapsed.
Over-Current Protection
The PAC5220WP EVK contains over-current protection for this application. This scenario is abnormal,
and implies a hardware failure.
If the coil current is ever more than 10A, then power transfer is stopped, and the red LED is illuminated
and the system is latched off until the EVK is reset.
2
This is the default behavior and can be changed via configuration.
© 2014 Copyright, Active-Semi International, Inc.
No portion of this document may be reproduced or reused in any form without Active-Semi's prior written consent
PAC5220WP A11 WPC
Power Application Controller
- 18
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Rev 1.7 May, 2014
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