AMC1301-Q1 Datasheet, PDF (20/34 Pages) Texas Instruments – Precision, 250-mV Input, Delay, Reinforced Isolated Amplifier

AMC1301-Q1
SBAS792A – APRIL 2017 – REVISED APRIL 2017
Typical Applications (continued)
9.2.1.1 Design Requirements
Table 1 lists the parameters for the typical application in Figure 49.
Table 1. Design Requirements
PARAMETER
High-side supply voltage
Low-side supply voltage
Voltage drop across the shunt for a linear response
VALUE
3.3 V or 5 V
3.3 V or 5 V
± 250 mV (maximum)
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9.2.1.2 Detailed Design Procedure
The high-side power supply (VDD1) for the AMC1301-Q1 device is derived from the power supply of the upper
gate driver. Further details are provided in the Power Supply Recommendations section.
The floating ground reference (GND1) is derived from one of the ends of the shunt resistor that is connected to
the negative input of the AMC1301-Q1 device (VINN). If a four-pin shunt is used, the inputs of the AMC1301-Q1
device are connected to the inner leads and GND1 is connected to one of the outer shunt leads.
Use Ohm's Law to calculate the voltage drop across the shunt resistor (V_SHUNT) for the desired measured
current: V_SHUNT = I × R_SHUNT.
Consider the following two restrictions to choose the proper value of the shunt resistor R_SHUNT:
• The voltage drop caused by the nominal current range must not exceed the recommended differential input
voltage range: V_SHUNT ≤ ± 250 mV
• The voltage drop caused by the maximum allowed overcurrent must not exceed the input voltage that causes
a clipping output: V_SHUNT ≤ V_Clipping
For best performance, use an RC filter (components R₂, R₃, and C₃ in Figure 49) to minimize the noise of the
differential output signal. Tailor the bandwidth of this RC filter to the bandwidth requirement of the system. TI
recommends an NP0-type capacitor to be used for C₃.
For more information on the general procedure to design the filtering and driving stages of SAR ADCs, consult
the TI Precision Designs 18-Bit, 1MSPS Data Acquisition Block (DAQ) Optimized for Lowest Distortion and Noise
(SLAU515) and 18-Bit Data Acquisition Block (DAQ) Optimized for Lowest Power (SLAU513), available for
download at www.ti.com.
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