AMC1203 Datasheet, PDF (17/23 Pages) Texas Instruments – 1-Bit, 10MHz, 2nd-Order, Isolated Delta-Sigma Modulator

AMC1203
www.ti.com
SBAS427 – FEBRUARY 2008
APPLICATION INFORMATION
A typical operation of the AMC1203 in a motor-control
application is shown in Figure 30. Measurement of
the motor phase current is done via the shunt resistor
(R_SHUNT; in this case, a 2-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 will lead to a
common-mode error at the input of the modulator.
The high-side power supply for the AMC1203 (V_DD1)
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 5V ±10%. A decoupling capacitor
of 0.1µF is recommended for filtering this
power-supply path. This capacitor (C₁ in Figure 30)
should be placed as close as possible to the V_DD1 pin
for best performance. If better filtering is required, an
additional 1µF to 10µF 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 of the AMC1203 (V_IN–). If a 4-terminal
shunt is used, the inputs of the AMC1203 are
connected to the inner leads, while GND1 is
connected to one of the outer leads of the shunt.
Both digital outputs, MCLK and MDAT, can be
directly connected to a digital filter (that is, the
AMC1210); see Figure 23.
HV+
Floating
Power Supply
Isolation
Barrier
To Load
R_SHUNT
Gated
Drive
Circuit
Power
Supply
R₁
D₁
R₂
5.1V 12W
R₃
12W
C₂
330pF
C₃
10pF
(optional)
C₄
10pF
(optional)
AMC1203
C₁₍₁₎
0.1mF
V_DD1
V_IN+
V_DD2
MDAT
V_IN-
MCLK
GND1 GND2
Gated
Drive
Circuit
NOTE: (1) Place C₁ close to AMC1203.
HV-
Figure 30. Typical Application Diagram
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): AMC1203
Submit Documentation Feedback
17