8.3 Best Design Practices

Do not leave the inputs of the AMC1301 unconnected (floating) when the device is powered up. If the device

inputs are left floating, the input bias current can possibly drive the inputs to a positive value that exceeds the

operating common-mode input voltage, thus causing the device to output the fail-safe voltage as described in the

Analog Output section.

Connect the high-side ground (GND1) to INN, either by a hard short or through a resistive path. A DC current

path between INN and GND1 is required to define the input common-mode voltage. Take care not to exceed

the input common-mode range as specified in the Recommended Operating Conditions table. For best accuracy,

route the ground connection as a separate trace that connects directly to the shunt resistor rather than shorting

GND1 to INN directly at the input to the device. See the Layout section for more details.

8.4 Power Supply Recommendations

The AMC1301 does not require any specific power-up sequencing. The high-side power supply (AVDD) is

decoupled with a low-ESR, 100-nF capacitor (C1) parallel to a low-ESR, 1-µF capacitor (C2). The low-side

power supply (DVDD) is equally decoupled with a low-ESR, 100-nF capacitor (C3) parallel to a low-ESR, 1-µF

capacitor (C4). Place all four capacitors (C1, C2, C3, and C4) as close to the device as possible.

The ground reference for the high-side (AGND) is derived from the end of the shunt resistor that is connected

to the negative input (INN) of the device. For best DC accuracy, use a separate trace to make this connection

instead of shorting AGND to INN directly at the device input. If a four-terminal shunt is used, the device inputs

are connected to the inner leads and AGND is connected to the outer lead on the INN side of the shunt. Figure

8-5 shows a decoupling diagram of the AMC1301.

R2 10

R1 10

C5 10 nF

VDD1

I

VDD2

INP

C2 1 µF

C1 100 nF

C4 1 µF

C3 100 nF

C6 1 nF

C7 1 nF

to RC filter / ADC

to RC filter / ADC

VDD1

GND1

INP

INN

AMC1301

VDD2

OUTP

OUTN

GND2

Figure 8-5. Decoupling of the AMC1301

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AMC1301

SBAS667G – APRIL 2016 – REVISED APRIL 2023

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