___MAXSMBus Functionality Check

Follow these steps to verify that the MAXSMBus inter-

face board is functioning properly. All necessary soft-

ware is supplied on a disk with the companion EV kit.

Instructions for operating the software are included in

the EV kit manual.

1) Connect a +9VDC supply (+7V minimum, +30V

maximum) to the MAXSMBus interface board at the

terminals labeled POS9 and GND in the lower left

corner of the board.

2) Use a digital voltmeter to verify that the oval pad

labeled POS5 is +5V (+4.75V minimum, +5.25V

maximum). Also verify that the pads labeled

SBDAT1, SBCLK1, SBSUS1, ALERT1, and ALERT2

are above +4V.

3) If these DC voltages are correct, MAXSMBus pass-

es the functionality test.

_______________Detailed Description

The MAXSMBus interface board provides all of the

interface signals necessary to interface an IBM PC-

compatible computer with an SMBus-compliant device.

A DB25 right-angle plug connects to the computer

(Table 1). The companion board plugs into a 20-pin

dual-row right-angle header at the edge of the board

(Table 2). Alternatively, connection can be made by

soldering wires to the oval pads as appropriate. This

allows the companion board to be placed in an environ-

mental chamber for evaluation over temperature.

Refer to the documentation of the companion Maxim EV

kit for quick start and operating instructions.

________________General Description

MAXSMBus is an interface between an IBM-compatible

PC and System Management Bus (SMBus™)-

compatible serial-interface devices such as tempera-

ture monitors, voltage regulators, or A/D converters

(ADCs). The MAXSMBus interface board is connected

between the PC parallel port and the device under test,

converting parallel data into 2-wire, open-drain serial

data. The board is provided for use with selected

Maxim products and is not intended to replace com-

mercially available SMBus hardware. MAXSMBus is

shipped with a companion EV kit board, including all

relevant software.

Note that the MAXSMBus board, combined with a PC,

is intended only for the functional evaluation of Maxim

SMBus-interfaced devices. The PC functions as the

only bus master, and does not yield to any other SMBus

master. The SMBus emulation system is not designed

to meet all of the SMBus specifications.

____________________________Features

o SMBus-Compatible 2-Wire Interface

o SMBus Suspend Output

o Two SMBus Alert Inputs

o Overvoltage Fault Protection

o PC Parallel Port Interface

2-Wire Interface Board

________________________________________________________________ Maxim Integrated Products

1

19-1629; Rev 1; 2/00

QTY

DESCRIPTION

C1, C2, C3

3

0.1µF ceramic capacitors

C4–C7, C9

5

3.3µF, 20V tantalum capacitors

D1

1

1N4692 zener diode, 6.8V

D2

1

1N4688 zener diode, 4.7V

D3

1

1N4148 small-signal diode

J1

1

DB25 right-angle plug

DESIGNATION

_______________Ordering Information

PART

MAXSMBus

BOARD TYPE

Companion Board for SMBus EV Kits

MAXSMBus Interface Board

____________________________Component List

J2

0

Not installed

P1

1

2x10 right-angle male header

R1, R2, R3,

R8–R11

7

47k

Ω ±5% resistors

R4–R7

4

4.7k

Ω ±5% resistors

U1

1

74HCT05 hex open-collector inverter

U2

1

74HCT04 hex inverter

U3

1

74HCT08 quad AND gate

U4

1

74HCT74 dual D flip-flop

U5

1

+5V, 100mA regulator

LM78L05ACM

U6

1

MAX865EUA (8-pin µMAX)

U7

1

MAX367CWN (18-pin SO)

NONE

1

PC board

SMBus is a trademark of Intel Corp.

C8

1

2.2µF, 35V tantalum capacitor

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.