8.2 Typical Application

Isolated amplifiers are widely used for shunt-based current measurements in high-voltage applications that must

be isolated from a low-voltage domain. Typical applications are phase current measurements in traction

inverters, or DC current measurements at the output of a power factor correction (PFC) stage or DC/DC

converter in an on-board charger (OBC). The AMC3301-Q1 integrates an isolated power supply for the high-

voltage side and therefore is particularly easy to use in applications that do not have a high-side supply readily

available or where a high-side supply is referenced to a different ground potential than the signal to be

measured.

Figure 8-1 shows a simplified schematic using the AMC3301-Q1 to measure the output current of a PFC stage

of an OBC. At this location in the system, there is no supply readily available for powering the high-side of the

isolated amplifier. The integrated isolated power supply solves this problem and, together with its bipolar input

voltage range, makes the AMC3301-Q1 ideally suited for bidirectional current sensing. In this example, the AC

line-voltage is sensed by the AMC3330-Q1 on the grid-side where there is also no suitable supply available for

powering the high-side of the isolated amplifier. The integrated power supply, high input impedance, and bipolar

input voltage range of the AMC3330-Q1 makes the device ideally suited for AC voltage sensing applications.

to MCU

Analog

Filter

to MCU

Analog

Filter

N

L1

L2

L3

PFC

To Battery Management System

DC-Link

+

DC/DC

±

N

N

N

1 µF

100 nF

1 nF

1 nF

100 nF

10 Ÿ

10 Ÿ

8.2 nF

DCDC_OUT

DCDC_HGND

HLDO_IN

HLDO_OUT

HGND

INP

INN

NC

AMC3330-Q1

1 µF

1 nF

100 nF

47 NŸ

DCDC_IN

LDO_OUT

VDD

OUTP

OUTN

GND

DIAG

DCDC_GND

3.3 V / 5 V supply

to uC (optional)

GND

1 µF

100 nF

1 nF

1 nF

100 nF

10 Ÿ

10 Ÿ

8.2 nF

DCDC_OUT

DCDC_HGND

HLDO_IN

HLDO_OUT

HGND

INP

INN

NC

AMC3301-Q1

1 µF

1 nF

100 nF

47 NŸ

DCDC_IN

LDO_OUT

VDD

OUTP

OUTN

GND

DIAG

DCDC_GND

3.3 V / 5 V supply

to uC (optional)

GND

1 µF

100 nF

1 nF

1 nF

100 nF

10 Ÿ

10 Ÿ

8.2 nF

DCDC_OUT

DCDC_HGND

HLDO_IN

HLDO_OUT

HGND

INP

INN

NC

AMC3330-Q1

1 µF

1 nF

100 nF

47 NŸ

DCDC_IN

LDO_OUT

VDD

OUTP

OUTN

GND

DIAG

DCDC_GND

3.3 V / 5 V supply

to uC (optional)

GND

N

to MCU

Analog

Filter

Figure 8-1. The AMC3301-Q1 in in an OBC Application

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AMC3301-Q1

SBASA73 – JULY 2020

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