AMC1200_15 Datasheet, PDF (18/31 Pages) Texas Instruments – AMC1200/B Fully-Differential Isolation Amplifier

AMC1200, AMC1200B
SBAS542D – APRIL 2011 – REVISED JULY 2015
www.ti.com
9 Power Supply Recommendations
In a typical frequency inverter application, the high-side power supply for the AMC1200 (VDD1) is derived from
the system supply, as shown in Figure 36. For lowest cost, a Zener diode can be used to limit the voltage to 5 V
± 10%. TI recommends using a 0.1-µF, low-ESR decoupling capacitor for filtering this power-supply. TI also
recommends using a 0.1-µF decoupling capacitor for filtering the power-supply on the VDD2 side. For best
performance, place these capacitors (C₁ and C₄) as close as possible to the VDD1 and VDD2 pins respectively.
If better filtering is required, an additional 1-µF to 10-µF capacitor can be used in parallel to C₁ and C₄.
Floating
Power Supply
HV+
20 V
to load
RSHUNT
Gate Driver
Z1
1N751A
R1
800 
5.1 V
C1
0.1F
Gate Driver
R2
12 
R3
12 
C3
330pF
AMC1200
VDD1
GND1
VDD2
GND2
C4
0.1F
VINP
VOUTP
VINN
VOUTN
3.3 V, or 5.0 V
ADS7263
HV-
Figure 36. Zener Diode Based High-Side Supply
For higher power efficiency and better performance, a buck converter can be used; an example of such an
approach is based on the LM5017. A reference design including performance test results and layout
documentation can be downloaded at PMP9480, Isolated Bias Supplies + Isolated Amplifier Combo for Line
Voltage or Current Measurement.
10 Layout
10.1 Layout Guidelines
A layout recommendation showing the critical placement of the decoupling capacitors that be placed as close as
possible to the AMC1200 while maintaining a differential routing of the input signals is shown in Figure 37.
To maintain the isolation barrier and the high CMTI of the device, the distance between the high-side ground
(GND1) and the low-side ground (GND2) should be kept at maximum; that is, the entire area underneath the
device should be kept free of any conducting materials.
18
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