ACPL-785J datasheet(2/20 Pages) AVAGO

2 / 20 page

Figure 1. Current sensing circuit.

Description

The ACPL-785J isolation amplifier is designed for current

sensing in electronic motor drives. In a typical implemen-

tation, motor currents flow through an external resistor

and the resulting analog voltage drop is sensed by the

ACPL-785J. A larger analog output voltage is created

on the other side of the ACPL-785J’s optical isolation

barrier. The output voltage is proportional to the motor

current and can be connected directly to a single-supply

A/D converter. A digital over-range output (FAULT) and

an analog rectified output (ABSVAL) are also provided.

The wire OR-able over-range output (FAULT) is useful

for quick detection of short circuit conditions on any

of the motor phases. The wire-OR-able rectified output

(ABSVAL), simplifies measure-ment of motor load since

it performs polyphase rectification. Since the common-

mode voltage swings several hundred volts in tens of

nanoseconds in modern electronic motor drives, the

ACPL-785J was designed to ignore very high common-

mode transient slew rates (10 kV/

µs).

Symbol

Description

FAULT

Short circuit fault output. FAULT changes from a

high to low output voltage within 6 µs after

IN exceeds the FAULT Detection Threshold. FAULT

is an open drain output which allows outputs from

all the ACPL-785Js in a circuit to be connected

together (“wired-OR”) forming a single fault signal

for interfacing directly to the micro-controller.

ABSVAL Absolute value of V

OUT output. ABSVAL is 0 V

when V

IN=0 and increases toward VREF as VIN

approaches +256 mV or -256 mV. ABSVAL is

“wired-OR” able and is used for detecting

overloads.

OUT

Voltage output. Swings from 0 to V

REF.

The nominal gain is V

REF /504 mV.

REF

Reference voltage input (4.0 V to V

DD2). This

voltage establishes the full scale output ranges

and gains of V

OUT and ABSVAL.

DD2

Supply voltage input (4.5 V to 5.5 V).

GND

Ground input.

Symbol

Description

IN+

Positive input voltage (±200 mV recommended).

IN-

Negative input voltage (normally connected to

GND

1).

Internal Bias Node. Connections to or between C

and C

L other than the required 0.1 µF capacitor

shown, are not recommended.

DD1

Supply voltage input (4.5 V to 5.5 V).

LED+

LED anode. This pin must be left unconnected for

guaranteed data sheet performance. (For optical

coupling testing only.)

DD1

Supply voltage input (4.5 V to 5.5 V).

GND

Ground input.

GND

Ground input.

DD2

Supply voltage input (4.5 V to 5.5 V).

Pin Descriptions

GND2

VDD2

FAULT

ABSVAL

VOUT

VREF

VDD2

GND2

VIN+

VIN-

VDD1

VLED+

VDD1

GND1

RSHUNT

0.02

Ω

ISOLATED +5 V

4.7 k

Ω

.01

µF

0.1

µF

0.1

µF

ISOLATION BOUNDARY

INPUT

CURRENT

+5 V

A/D

VREF

GND

µC

TO OTHER

PHASE

OUTPUTS

0.1

µF

ACPL-785J

ACPL-785J Folha de dados(PDF) 2 Page - AVAGO TECHNOLOGIES LIMITED

ACPL-785J Folha de dados(HTML) 2 Page - AVAGO TECHNOLOGIES LIMITED

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Folha de dados Download

Ligação URL