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dc1969aabfb
DEMO MANUAL
DC1969A-A/DC1969A-B
DEMO BOARD PROCEDURE
Refer to Figure 7 for the proper measurement equipment
setup and jumper settings and follow the procedure be‑
low. Please test DC1968A first, by itself.
NOTE: When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. Measure the input or output voltage
ripple by touching the probe tip directly across the V
CC
or V
IN
and GND terminals. See Figure 8 for proper scope
probe technique.
1. Set PS1 = 36V, observe V
CC
(VM1) and I
HVIN
AM1. The
DC1968A can be powered by 5V on the V
CC
pin or up
to 38V on the HVIN pins. The HVIN pins are connected
to an LT3480 buck regulator that makes 5V at the V
CC
pins. Standby power in the DC1968A basic transmitter
varies between 0.5W and 0.6W, for a V
CC
current at 5V
of 100mA ~ 130mA. If the DC1968A is powered via the
HVIN pins then this current is scaled by the ratio 5V/
[V
HVIN
× 0.92], where 0.92 is efficiency of the regula‑
tor. So the standby HVIN current is approximately 5.5/
[V
HVIN
× (100mA ~ 130mA)].
2. Remove PS1, VM1 and AM1. Attach PS2 and AM2.
3. Set PS2 to 5V, and observe AM2. The transmitter is
being powered directly with no intervening buck regula‑
tor, so the standby current should be between 100mA
~ 130mA.
4. Connect a bipolar
1
supply (PS3) to the DC1967A demo
board BAT pin. Set the supply to 3.7V and turn on.
Observe AM3.
5. Place the DC1967A board atop the DC1968A board, by
aligning:
DC1967A Mounting Hole DC1968A Mounting Hole
MH1 => MH1
MH2 => MH2
MH3 => MH3
MH4 => MH4
This should result in the transmit antenna being directly
above the receive antenna, with the centers aligned.
Observe AM2 and AM3. All the charge LEDs on the
DC1967A should now be lit. AM2 should have increased
from 100mA ~ 130mA to about 600mA. AM3 should
be reading 380mA ~ 400mA of charge current into the
battery emulator.
Figure 6 shows the approximate full power (400mA of
charge current into 4.15V ≈ 1.7W) and half power contours.
The DC1969A kit demonstrates operation of a double tuned
magnetically coupled resonant power transfer circuit.
DC1968A – Basic Transmitter
The DC1968A Basic Transmitter is used to transmit wire‑
less power and is used in conjunction with the DC1967A
wireless power receiver board featuring the LTC4120.
The DC1968A is configured as a current fed astable multi‑
vibrator, with oscillation frequency set by a resonant tank.
1
A bipolar supply can both sink and source current to maintain the correct
output voltage. A unipolar supply can be converted into a suitable bipolar
supply by putting a 3.6Ω, 10W, resistor across the output.
THEORY OF OPERATION
The DC1968A basic transmitter is set to 130kHz operation
and the DC1967A LTC4120 demonstration board resonant
frequency is 127kHz with DHC enabled and 140kHz with
DHC disabled. For the DC1968A basic transmitter the
resonant components are the 2X 0.15µF PPE film capaci‑
tors (Cx1 and Cx2) and the 5.0µH (Lx) transmit coil. This
gives a resonant frequency of 129.95kHz. The tolerance
on the transmit coil and resonant capacitors is ±2%, or
2.6kHz. Inductors L1 and L2 are used to make the resonant
structure current fed.
