AMC1200-Q1_16 Datasheet, PDF (17/30 Pages) Texas Instruments – Fully-Differential Isolation Amplifier

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AMC1200-Q1
SBAS585A – SEPTEMBER 2012 – REVISED JANUARY 2016
8.2.1.3 Application Curves
In traction inverter applications, the power switches must be protected in case of an overcurrent condition. To
allow fast powering off of the system, a low delay caused by the isolation amplifier is required. Figure 33 shows
the typical full-scale step response of the AMC1200-Q1.
The high linearity of the AMC1200-Q1, as shown in Figure 34, allows design of traction inverters with low torque
ripple.
500 mV/div
200 mV/div
500 mV/div
Time (2 ms/div)
Figure 33. Step Response of the AMC1200-Q1
0.1
VDD2 = 3 V
0.08
VDD2 = 5 V
0.06
0.04
0.02
0
−0.02
−0.04
−0.06
−0.08
−0.1
−250 −200 −150 −100 −50 0 50 100 150 200 250
Input Voltage (mV)
Figure 34. Typical Nonlinearity of the AMC1200-Q1
8.2.2 Isolated Voltage Measurement
The AMC1200-Q1 can also be used for isolated voltage measurement applications, as shown in a simplified way
in Figure 35. In such applications, usually a resistor divider (as conceptually indicated by R₁ and R₂) is used to
scale the voltage amplitude. Choose the value of R₂ to match the maximum voltage to be measured to the
differential input voltage range V_IN of the device. R₂ and the input resistance R_IN of the AMC1200-Q1 also create
a resistance divider that results in additional gain error. With the assumption that R₁ and R_IN have a considerably
higher value than R₂, the resulting total gain error can be estimated using Equation 1:
G_ERRTOT
=
G_ERR
+
R₂
R_IN
where
• G_ERR = the gain error of the AMC1200-Q1
(1)
L1
R₁
R₂
R_IN
L2
Figure 35. Voltage Measurement Application
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