9 Power Supply Recommendations

The AMC1202 does not require any specific power up sequencing. The high-side power-supply (VDD1) is

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

supply (VDD2) 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 (GND1) is derived from the end of the shunt resistor, which is connected

to the negative input (INN) of the device. For best DC accuracy, use a separate trace (as shown in Figure 9-1)

to make this connection instead of shorting GND1 to INN directly at the device input. If a four-terminal shunt

is used, the device inputs are connected to the inner leads and GND1 is connected to the outer lead on the

INN-side of the shunt.

R2 10

R1 10

C5

10 nF

VDD1

C2 1 µF

C1 100 nF

I

VDD2

C4 1 µF

C3 100 nF

to RC filter / ADC

to RC filter / ADC

VDD1

GND1

INP

INN

AMC1202

VDD2

OUTP

OUTN

GND2

INP

Figure 9-1. Decoupling of the AMC1202

Capacitors must provide adequate effective capacitance under the applicable DC bias conditions they

experience in the application. Multilayer ceramic capacitors (MLCCs) typically exhibit only a fraction of their

nominal capacitance under real-world conditions and this factor must be taken into consideration when selecting

these capacitors. This problem is especially acute in low-profile capacitors, in which the dielectric field strength is

higher than in taller components. Reputable capacitor manufacturers provide capacitance versus DC bias curves

that greatly simplify component selection.

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AMC1202

SBASAB8 – MAY 2021

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