AMC1200STDUBRQ1 Datasheet, PDF (13/23 Pages) Texas Instruments – Fully Differential Isolation Amplifier

AMC1200-Q1
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APPLICATION INFORMATION
SBAS585 – SEPTEMBER 2012
MOTOR CONTROL
A typical operation of the AMC1200-Q1 in a motor-control application is shown in Figure 32. Measurement of the
motor phase current is done through the shunt resistor, R_SHUNT (in this case, a two-terminal shunt). For better
performance, the differential signal is filtered using RC filters (components R₂, R₃, and C₂). Optionally, C₃ and C₄
can be used to reduce charge dumping from the inputs. In this case, care should be taken when choosing the
quality of these capacitors; mismatch in values of these capacitors leads to a common-mode error at the input of
the modulator.
Floating
HV+ ^{Power Supply}
Isolation
Barrier
To Load
R_SHUNT
Gated
Drive
Circuit
Power
Supply
Gated
Drive
Circuit
R₁
D₁
R₂
5.1V 12W
R₃
12W
AMC1200-Q1
C₂₍₁₎
330pF
C₃
10pF
(optional)
C₄
10pF
(optional)
C₁₍₁₎
0.1mF
VDD1
VINP
VDD2
VOUTP
VINN VOUTN
GND1 GND2
C₅₍₁₎
0.1mF
TMC320
C/F28xxx
ADC
HV-
(1) Place these capacitors as close as possible to the AMC1200-Q1.
Figure 32. Typical Application Diagram for the AMC1200-Q1
The high-side power supply for the AMC1200-Q1 (VDD1) is derived from the power supply of the upper gate
driver. For lowest cost, a Zener diode can be used to limit the voltage to 5 V ±10%. A decoupling capacitor of 0.1
µF is recommended for filtering this power-supply path. This capacitor (C₁ in Figure 32) should be placed as
close as possible to the VDD1 pin for best performance. If better filtering is required, an additional 1-µF to 10-µF
capacitor can be used. The floating ground reference (GND1) is derived from the end of the shunt resistor that is
connected to the negative input of the AMC1200-Q1 (VINN). If a four-terminal shunt is used, the inputs of
AMC1200-Q1 are connected to the inner leads, whereas GND1 is connected to one of the outer leads of the
shunt.
The high transient immunity of the AMC1200-Q1 ensures reliable and accurate operation even in high-noise
environments such as the power stages of the motor drives.
The differential output of the AMC1200-Q1 can either directly drive an analog-to-digital converter (ADC) input or
can be further filtered before being processed by the ADC.
As shown in Figure 33, it is recommended to place the bypass and filter capacitors as close as possible to the
AMC1200-Q1 to ensure best performance.
Copyright © 2012, Texas Instruments Incorporated
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