Avago ACPL-C79B, ACPL-C79A, ACPL-C790 User Manual

ACPL-C79B, ACPL-C79A & ACPL-C790

Isolation Ampli er Evaluation Board User Manual

User Guide

Quick-Start Guide

Once visual inspection is done to ensure that the Evaluation Board is received in good condition, the Evaluation Board
can be powered up in just 3 simple steps according to Figure 1 as shown:

1. Select either one of the provided sensing resistors (10mΩ or 15mΩ), or user’s own sensing resistor and mount it
(through soldering) on pads provided for R1 on the Evaluation Board;

2. Connect the necessary power supplies and current source as shown:

a. Connect 1st isolated 5V DC supply (DC Supply 1) to connector CON1 as shown;

b. Connect a 3.3V DC supply (DC Supply 2, can be non-isolated) to connector CON2 as shown;

c. Connect, through soldering, the required input current source (for sensing) cables as shown;

3. Supply the input current (subject to a maximum signal level of 250mVpp, or ±125mVdc across resistor R1) through
the cables (as shown in 2c) and monitor the output through an oscilloscope.

2c

Current Source Cables
for sensing

2a

+5V

Gnd1

DC Supply 1

1

1

2b

+3.3V

DC Supply 2

Gnd2

Output to
Oscilloscope
for monitoring
/or MCU for
Readings

3

Figure 1. Default Test Setup of Evaluation Board

Schematics

Schematics of the Evaluation Board are as shown in Figure 2.

+V dd2

GND1

GND1

ACPL-C79X

1

C5

100nF

2

3

U1

VDD1

VDD2

Vin+

Vout+

Vin-

Vout-

Gnd14Gnd2

CON 1

Vdd1

Rsense+

Rsense-

CON 1X3

1

2

3

GND1

9V Batt+

Batt-/Gnd1

R1

GND1

GND1

C1

100nF

TP4

TP5

LM78L05ACM

8

236

GND1

U2

R2

10R, 1%

R3

10R, 1%

1

C2

7

100nF

GND1

C3

22nF

Figure 2. Schematics of ACPL-C79X Evaluation Board

J1

8

7

6

5

TP1

GND2

GND2

C6

100nF

GND2

J3

+V dd3

J2

R4
1K, 1%

R5

1K, 1%

GND2 GND2 GND2

GND2GND2

C13

10uF

-V dd3

Vref

J4

+V dd3

GND2

+V dd2

1
2
3
4
5
6

6PIN HEADER

CON 2

U3

L78L33ACD13T R

8

C7

100nF

GND2

GND2

TP2

10K, 1%

R6

10K, 1%

R8

TP3

C15

C9

68pF

NM

Vref

2

3

C14 NM

C10 68pF

R7

2

3

R9
10K, 1%

6

7

10K, 1%

7

+-U4

4

1

C8

100nF

GND2

0.1uF
C11

6

OPA2 37UA

C12

0.1uF

-V dd3

Board Description

The ACPL-C79X evaluation boards (shown in Figure 3),
can accommodate either a ACPL-C79B(0.5% tolerance),
ACPL-C79A(1% tolerance), or ACPL-C790(3% tolerance)
device on U1, to demonstrate the high linearity and low­o set capability of Avago’s Isolation Ampli er over a wide
range of input current conditions. It allows a designer to
easily test the performance of the high-precision isola­tion ampli er in an actual application under real-life op­erating conditions. Many of the circuit recommendations
discussed in Application Note 1078 are implemented on
the board. Operation requires merely the addition of a
5V Supply and a low-resistance shunt resistor on the in­put side of the isolation ampli er. The board has holes for
mounting a through-hole shunt, and pads for mounting
a surface-mount shunt. The board may also be used for
general voltage isolation without any shunt resistor.

As can be seen on the board, the isolation circuitry is easily
contained within a small area while maintaining adequate
spacing for good voltage isolation and easy assembly. The
overall size of the evaluation board has been enlarged to
allow mounting of feet for stand-alone use (using the 4
drilled holes at the corners of the board).

Using the Board

The evaluation board is easily prepared for use. Only mi­nor preparations (just by soldering of shunt resistor, wires
for power / sense current path and output signal) are re­quired. The evaluation board is having a default setup 1 as
shown in the tables when shipped to customer. Customer
is free to choose any one of the 6 setup con gurations as
shown in the tables by setting J1, J2, J3 and J4 as shown.

2

Figure 3. Top View of ACPL-C79X Evaluation Board