Datasheet

R
2
12W
R
3
12W
R
SHUNT
AMC1200
AMC1200B
Gated
Drive
Circuit
To Load
Floating
Power Supply
HV+
Isolation
Barrier
C
2
(1)
330pF
C
3
10pF
(optional)
VDD1
VINP
VINN
GND1
VDD2
VOUTP
VOUTN
GND2
C
4
10pF
(optional)
C
1
(1)
0.1 Fm
D
1
5.1V
R
1
Gated
Drive
Circuit
Power
Supply
HV-
C
5
(1)
0.1 Fm
ADC
TMC320
C/F28xxx
AMC1200
AMC1200B
SBAS542C –APRIL 2011–REVISED SEPTEMBER 2013 www.ti.com
APPLICATION INFORMATION
MOTOR CONTROL
A typical operation of the AMC1200 and AMC1200B 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 R
2
, R
3
, and C
2
).
Optionally, C
3
and C
4
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.
(1) Place these capacitors as close as possible to the AMC device.
Figure 32. Typical Application Diagram
The high-side power supply (VDD1) for the AMC1200 and AMC1200B are 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 (C
1
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, which is connected to the negative input (VINN) of the AMC device. If a four-terminal shunt is used, the
inputs of AMC device are connected to the inner leads, while GND1 is connected to one of the outer leads of the
shunt.
The high transient immunity of the AMC1200 and AMC1200B 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 and AMC1200B 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
AMC device to ensure best performance.
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