Linear Technology LTC4120EUD, Demo Manual

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dc1969aabfb
DEMO MANUAL
DC1969A-A/DC1969A-B
GND VIN
Figure 8. Measuring Input or Output Ripple
THEORY OF OPERATION
Figure 9. LTC4120 (DC1968A and DC1967A-B) Radiated Emissions
FREQUENCY (MHz)
GTEM CELL MEASUREMENT
CORRECTED PER IEC 61000-4-20 TO 10m
DETECTOR = PEAK HOLD
RBW = 120kHz
VBW = 300kHz
SWEEP TIME = 680ms
# OF POINTS = 501
# OF SWEEPS ≥ 10
10
dBµV/m
30
60
DC1969A F09
20
0
40
50
10
–10
–20
100 1,000
CISPR 11 CLASS A LIMIT
CISPR 11 CLASS B LIMIT
1968A ONLY
1968A AND 1967A-B
1968A AND 1967A-B
AND BATT
Radiated Emissions
Radiated emissions information was gathered using a
gigahertz transverse electromagnetic (GTEM) cell. The
GTEM cell dimensions were 0.2m × 0.2m × 0.15m. The
data was normalized to a 10m semi‑anechoic chamber
(SAC) per IEC61000‑4‑20 using peak hold detection.
The limits shown on the graph are for CISPR 11 class A
(yellow) and class B (red). The CISPR 11 limits are ap‑
plicable to industrial commercial and medical equipment.
The emissions detection method was peak hold of the
square root of the sum of the emissions from each face,
X, Y, Z, squared. As the emissions are always at least 6dB
from the regulatory limits, the use of quasi‑peak detec‑
tion was not necessary. Data was gathered on a single
representative system.
The blue line shape is data gathered from a DC1968A basic
transmitter operating alone and powered at V
CC
= 5V from
a bench supply. The yellow line shape is data gathered
from a DC1968A basic transmitter powered at V
CC
= 5V
from a bench supply, and energizing a DC1967A LTC4120
wireless power receive board with no battery. And the
green line shape is data gathered from a DC1968A basic
transmitter powered at V
CC
= 5V from a bench supply, and
energizing a DC1967A LTC4120 wireless power receive
board charging a Li‑Ion battery at 400mA.
The LTC4120 wireless power system is intended to be a
part of a complete end product. Only the complete end
product needs to be FCC certified. The data presented here
on the wireless power system is for end product design
purposes only, not to obtain FCC certification.