DS1650 Datasheet, PDF (22/26 Pages) National Semiconductor (TI) – Quad Differential Line Receivers

RT1650
Battery Charge Complete Detection
The RT1650 supports battery charge complete
detection function. A programmable charge complete
current threshold and a programmable charge
complete delay time are provided. This function can be
used to send the Charge Status packet (0x05) to the
transmitter for indicating a full charged status 100%.
Note that this packet does not turn off the transmitter.
The charge complete current threshold is adjustable
from 0mA to 510mA and the default value is 50mA.
The charge complete time is also adjustable from 0
seconds to 3825 seconds and the default value is 180
seconds.
Charge Current
Charge Complete
Delay Time
Charge Complete
Current Threshold
time
Figure 14. Battery Charge Complete Detection
There are 3 operation modes when the charge
complete status is detected. The first mode is to send a
CS packet (0x05) to transmitter only. The CS packet
does not turn off the transmitter. In the second mode,
the RT1650 will send a CS packet (0x05) and an EPT
packet to transmitter. In the third mode, the RT1650 will
send a CS packet (0x05) and stop communication with
the transmitter.
Charge Complete
Detection
1
Send CS Packet
(0x05)
CS Mode
2
Send CS Packet
(0x05)
Send EPT Packet
(0x02)
3
Send CS Packet
(0x05)
Stop
Communication
Figure 15. Operation Modes of Charge Complete Detection
Receiver Coil and Resonant Capacitors
According to WPC specification, the dual resonant
circuit of the power receiver comprises the receiver coil
and capacitors C1 and C2. The receiver coil design is
related to system design. Coil shape, material,
C1=
1
L'_S  2 f_S ²
C2=
1
L_S


2
f_d
²
-
1
C1
inductance and shielding need to be considered.
Shielding provides protection from interference
between wireless power system and mobile electronic
device. The recommended coil self-inductance is
between 8H to 13H. The capacitance of the resonant
capacitors can be calculated by the following equations.
In these equations, fs is resonant frequency with typical
value 100kHz; and fd is another resonant frequency
with typical value 1000kHz. L’s is coil self-inductance
when placed on the interface surface of a transmitter;
and Ls is the self-inductance when placed away from
the transmitter.
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DS1650-00 July 2015