9 Power Supply Recommendations

The AMC3302-Q1 is powered from the low-side power supply (VDD) with a nominal value of 3.3 V or 5 V. TI

recommends a low-ESR decoupling capacitor of 1 nF (C8 in Figure 9-1) placed as close as possible to the VDD

pin, followed by a 1-µF capacitor (C9) to filter this power-supply path.

The low-side of the DC/DC converter is decoupled with a low-ESR 100-nF capacitor (C4) positioned close to

the device between the DCDC_IN and DCDC_GND pins. Use a 1-µF capacitor (C2) to decouple the high-side

in addition to a low-ESR, 1-nF capacitor (C3) placed as close as possible to the device and connected to the

DCDC_OUT and DCDC_HGND pins.

For the high-side LDO, use low-ESR capacitors of 1-nF (C6), placed as close as possible to the AMC3302-Q1,

followed by a 100-nF decoupling capacitor (C5).

The ground reference for the high-side (HGND) is derived from the terminal 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 HGND to INN directly at the device input. The high-side DC/DC ground terminal

(DCDC_HGND) is shorted to HGND directly at the device pins.

As shown in Figure 9-1, TI recommends placing ferrite beads in the INP, INN, and HGND signal lines for best

EMI performance. For more information on reducing radiated emissions and guidelines for component selection,

see the Best Practices to Attenuate AMC3301 Family Radiated Emissions EMI application note available for

download at www.ti.com

C2 1 µF

C6 1 nF

C5 100 nF

C3 1 nF

C1 100 nF

R2 10

R4 10

C10 10 nF

DCDC_OUT

DCDC_HGND

HLDO_IN

HLDO_OUT

HGND

INP

INN

NC

AMC3302-Q1

C9

1 µF

C8

1 nF

C4

100 nF

R1

47 k

DCDC_IN

LDO_OUT

VDD

OUTP

OUTN

GND

DIAG

DCDC_GND

3.3 V / 5 V supply

to uC (optional)

I

to RC filter / ADC

to RC filter / ADC

FB1

FB2

FB3

Figure 9-1. Decoupling the AMC3302-Q1

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

experience in the application. Multilayer ceramic capacitors (MLCC) 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.

Table 9-1 lists components suitable for use with the AMC3302-Q1. This list is not exhaustive. Other components

may exist that are equally suitable (or better), however these listed components have been validated during the

development of the AMC3302-Q1.

AMC3302-Q1

SBASA84A – FEBRUARY 2021 – REVISED JULY 2021

www.ti.com

26

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