14

Figure 18. Typical application circuit with the HCPL-0872.

ACPL-7970

3-WIRE

SERIAL

INTERFACE

INPUT

CURRENT

GND1

ISOLATED

5 V

0.1

µF

MCLK

MDAT

GND2

NON-

ISOLATED

5 V

1

µF

HCPL-0872

MCLK1

MDAT1

GND

SCLK

SDAT

CS

ISOLATION

BARRIER

GND1

GND2

1

µF

0.1

µF

Digital Interface IC

The HCPL-0872 Digital Interface IC (SO-16 package) is a

digital filter that converts the single-bit data stream from

the modulator into 15-bit output words and provides a

microcontroller. Instead of a digital filter implemented in

software, the HCPL-0872 can be used together with the

ACPL-7970 to form an isolated programmable two-chip

A/D converter.

Available in an SO-16 surface-mount package, the Digital

Interface IC has features include five different conversion

modes (combinations of speed and resolution), three

differentpre-triggermodes(allowsconversiontime<1

ms),

offset calibration, fast over-range (over-current, or short

circuits) detection, and adjustable threshold detection.

Figure 19. Typical application circuit for motor phase current sensing.

Programmable features are configured via the Serial Con-

figuration port. A second multiplexed input is available to

allow measurements with a second isolated modulator

without additional hardware. Refer to the HCPL-0872 data

sheet for details.

Notes:

SPI and QSPI are trademarks of Motorola Corp.

Microwire is a trademark of National Semiconductor Inc.

Application Information

Digital Current Sensing Circuit

Figure 19 shows a typical application circuit for motor

control phase current sensing. By choosing the appro-

priate shunt resistance, a wide range of current can be

monitored, from less than 1 A to more than 100 A.

ACPL-7970

FLOATING

POSITIVE SUPPLY

GND1

MCLK

MDAT

GND2

NON-

ISOLATED

5 V/3.3 V

ISOLATION

BARRIER

GATE

DRIVE

CIRCUIT

HV+

HV–

C1b

0.1

µF

D1

5.1 V

C2

10 nF

MOTOR

R2a

22

Ω

R1

R2b

22

Ω

+

–

GND2

C1a

1

µF

C3b

1

µF

C3a

0.1

µF