AMIS492X0GEVB Datasheet AMIS492X0GEVB | P1-P3

April, 2013 − Rev. 3

1 Publication Order Number:

EVBUM2180/D

AMIS-49200EVB

AMIS-492x0 Fieldbus MAU

Evaluation Board User's

Manual

Introduction

ON Semiconductor offers the AMIS-492x0 Fieldbus

Media Access Unit (MAU) as part of an overall industrial

network communication solution. Please refer to the

AMIS-492x0 data sheet for more information on this

integrated circuit. The scope of this user’s manual focuses

on a reference design and board that ON Semiconductor also

offers its customers, and which satisfies the Foundation

Fieldbus H1 or Profibus PA physical layer network

requirement.

This user’s manual helps the user design in the

AMIS-492x0 MAU, by referring to a usable board design

known to pass the Foundation Fieldbus Physical Layer

Conformance (Specification FF830, Rev 1.5).

The reference design discussed in this document also

includes additional flexible sub-circuits not discussed in the

AMIS-492x0 data sheet, that help the user optimally fit the

AMIS-492x0 to their application.

Fieldbus Node Description

Figure 1 shows a typical, complete node using the

AMIS-492x0.

Process

Sensor

Microprocessor,

I/O (A/D)

RAM ROM

Fieldbus or

Profibus Link

Controller

Reference Design in Figure 12 of Data Sheet

RXA

RXS

TXE

TXS

Fieldbus

Segment

Connection

Figure 1. Complete Fieldbus Device using AMIS-492x0

Discrete

Components

AMIS−492x0

Fieldbus MAU

PFAIL2

PFAIL1

SHUNT

A link controller is placed between a typical

microprocessor and the AMIS-492x0 MAU to provide

Manchester encoding and decoding of the data to be

transmitted or received, respectively. It may be possible to

program a high-end microprocessor to handle the

Manchester style data stream, but the effort to do so is likely

cost prohibitive.

One example of a suitable link controller is the

UFC100-F1 by Softing/Aniotek, Inc.

(http://www.softing.com/home/en/industrial-automation/p

roducts/foundation-fieldbus/device-integration/universal-f

ield-controller.php?navanchor=3010446)

AMIS-492x0 Fieldbus MAU Reference Design

ON Semiconductor has developed a reference design for

commercial use in a Foundation Fieldbus H1 or Profibus PA

application.

Figure 12 in the AMIS-492x0 data sheet shows an

example of external circuitry required to connect the

AMIS-492x0 to an IEC 61158-2 conformant network. That

schematic is of a circuit that passed the Foundation Fieldbus

Physical Layer Conformance test as specified in Foundation

Fieldbus Specification FF830, Rev 1.5.

There are many alternative designs and it is beyond the

scope of this document to identify all possible

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EVAL BOARD USER’S MANUAL

AMIS−49200EVB

http://onsemi.com

configurations. We strongly encourage customers to use the

ON Semiconductor reference design to provide the most

effective application support.

Whether or not the ON Semiconductor reference design

is used, we recommend that the customer perform their own

physical layer board test to ensure conformance. In addition,

board layout can alter the behavior of all circuit

implementations, even designs that follow the

recommended implementation. Fieldbus Foundation

(www.fieldbus.org

) provides the required test specifications

to their membership only. ON Semiconductor cannot

provide these specifications to customers.

Although the ON Semiconductor reference design in the

AMIS-492x0 data sheet passed physical layer conformance

as is, often this design can be slightly modified given unique

application-related traits. Figure 12 in the AMIS-492x0 data

sheet shows a general schematic independent of board

layout. Figure 2 shows the AMIS-492x0 reference design

that includes extra components to accommodate such

application flexibility. This schematic together with PCB

build files and a bill of material (BOM) constitute the

AMIS-492x0 reference design package which can be found

at the link listed in this document’s reference section. The

design in Figure 2 also passes the Foundation Fieldbus test

(FF830, Rev. 1.5).

Figure 2. AMIS-492x0 Reference Design Schematic

Please note the following:

• A bridge rectifier was added to interface with the

medium. This allows proper, correct operation

regardless of polarity hook-up.

• Test points are included to provide convenient access to

the circuit for development purposes.

• Certain sub-circuits (e.g. voltage dividers) have been

added to adjust analog (shunt regulator) supply voltage,

digital (series regulator) supply voltage, and loop current

settings (loop current regulator). Figure 2 shows these

components as “TBD” to be adjusted by the customer as

needed to modify the design to their application

requirements. The “TBD” resistors not installed by

default on the reference board are listed in Table 1.

AMIS−49200EVB

http://onsemi.com

Table 1. Components That May Be Modified on the

Reference Board

Resistor Used to Adjust

R12 Shunt regulator voltage

R13 Shunt regulator voltage

R8 Series regulator voltage

R23 Series regulator voltage

R22 Loop current

Shunt Regulator

See Section 4.2.1 and Figure 4 in the AMIS-492x0 data

sheet.

As assembled the shunt regulator output will be 5.02 V at

Pin 8 (SHUNT). This voltage is set by connecting Pin 7

(SHSET) to Pin 6 (SHSETin) via R11 (zero W). This

connection connects the internal voltage divider to the shunt

regulator amplifier non-inverting input.

To set the shunt regulator output to another voltage,

remove R11 and install R12 and R13. The shunt regulator

voltage can be set in the range of 4.75 V to 6.2 V. The formula

for this is:

SHUNT

+ V

ref

1 )

where V

ref

+ 1.18 V

(eq. 1)

Series Regulator

See Section 4.2.2 and Figure 5 in the AMIS-492x0 data

sheet.

As assembled the series regulator output will be 3.04 V at

Pin 16 (VO). This voltage is set by connecting Pin 13

(SRSET) to Pin 12 (SRSETin) via R7 (zero W). This

connection connects the internal voltage divider to the shunt

regulator amplifier non-inverting input. Also Pin 14

(SRAO) is connected to Pin 15 (SRTR) via R10 (zero W).

This connects the output of the series regulator amplifier to

the pass transistor.

To set the series regulator output to another voltage,

remove R7 and install R8 and R23. The series regulator

voltage can be set in the range of 2.85V to 3.5V. The formula

for this is:

+ V

ref

1 )

where V

ref

+ 1.18 V

(eq. 2)

The board as shipped will be configured to have the series

regulator operating and set to 3 V using the internal voltage

divider. In this configuration R24, R10 and R7 are all

installed with 0 ohm resistors. R9, R8 and R23 are not

populated.

To disable the series regulator (e.g. to consume as little

power as possible), remove R24, R10 and R7. Install 0 Ohm

jumpers in R9 and R23, and leave R8 empty.

R9 shorts out the pass transistor so that it cannot turn on.

R23 grounds the non-inverting input to the regulator

amplifier and forces the output to saturate so that it cannot

oscillate. Removing R10 relieves the regulator amplifier

output of any possible load. Removing R7 isolates the

internal divider. Removing R24 disconnects the series

regulator output from the external (digital) rail.

Loop Current Regulator

The value of the loop current is set by the parallel

combination of R21 and R22. As shipped, R22 is not

installed and R21 = 49.9 kW. This sets the loop current to

10 mA. Decreasing the value of the parallel combination of

R21 and R22 increases the loop current. The formula to

calculate the value of the loop current is in Equation 3.

Customer Board Tips and Suggestions for Production

The customer might find the following suggestions

helpful in planning for production and/or development:

• Use full embedded power and ground planes in a

four-layer PCB configuration to reduce the likelihood

of noise. The AMIS-492x0 reference board is a

two-layer board to ease evaluation and development.

• To accommodate board space constraints, you might want

to use surface-mount components. The AMIS-492x0

reference board uses a few thru-hole components.

• Pin 36 (TXE) and Pin 37 (TXS) are CMOS digital

inputs and cannot float. If the board is not connected to

a link controller or other circuitry at JP1, TXS

(FB_TXS on JP1) must be pulled to VDD, and TXE

(FB_TXE on JP1) must be pulled to ground.

AMIS-492x0 Evaluation Kit (AMIS-49200EVB)

ON Semiconductor provides an evaluation kit that

showcases the AMIS-492x0 Fieldbus MAU on-board for

real-time demonstration and evaluation. The

AMIS-49200EVB kit includes:

• Reference board following the schematic in Figure 2,

including the AMIS-49200 device.

• Connector to aid evaluation of MAU and link controller

interface.

Please contact your local ON Semiconductor sales

representative for AMIS-49200EVB price and availability.

loop

drv

* V

mid

21ø22

@(R

21ø22

)

@ R

mid

21ø22

(eq. 3)

where: V

drv

= 2.5 V, V

mid

= 2.0 V, R

= R

= 249 kW, R

= 10 W, R

⎪⎪

≤ 49.9 kW

P1-P3 P4-P4

AMIS492X0GEVB

Mfr. #:

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