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DEMO MANUAL
DC1969A-A/DC1969A-B
THEORY OF OPERATION
17mm
Full Power
±1mm
½ Power
±1mm
½ Power
Envelope
18mm
13mm
15mm
2mm
3mm
4mm
5mm
6mm
7mm
8mm
9mm
Full Power
Envelope
DC1967A-B with
25mm Receive
Antenna
DC1969A F06
Transmit Antenna
1mm Minimum Clearance
Figure 6. Power Transfer vs Axial Distance and Misalignment
and receive coils. The LTC4120 wireless power receiver
IC increases power transfer when power transfer is insuf‑
ficient. This is accomplished by switching capacitors into
the resonant circuit using the DHC pin. This gives a much
wider operating transmit distance, see Figure 5.
distance of 8mm, to the battery. There is negligible transmit
frequency ripple on V
IN
, and the voltage is well above the
14V DHC voltage. This indicates that the input rectifiers are
operating in peak detect mode, and that DHC is inactive.
35mm Ferrite Disk
The DC1969A‑A/DC1969A‑B kit includes a 35mm ferrite
disk. The purpose of this disk is to increase the power
received by the DC1967A‑A/DC1967A‑B receiver board.
The 25mm ferrite disk that is shipped and attached to the
DC1967A‑A/DC1967A‑B board is attached with double‑
sided tape, and is likely to break if removed. Laying the
35mm ferrite on top of the shipped 25mm ferrite disc will
increase received power approximately 30%. Removing
the 25mm ferrite disk and attaching the 35mm disk will
increase received power approximately 20%. In both
cases the minimum clearance distance will increase to
approximately 3mm. Since the 25mm ferrite disk shipped
on the DC1967A‑A/DC1967A‑B board is likely to break,
exchanging disks can only be done once.
Figure 5. DC1967A Receiver
2µs/DIV
V
IN
TO GND
5V/DIV
DC1969A F05
I
BAT
V
BAT
= 3.7V
100mA/DIV
The blue trace is the charge current into the battery, and
the red trace is the voltage at V
IN
on the receiver board.
V
IN
is about 25V, while the LTC4120 delivers 1.5W at a
