MAXSMBUS Datasheet, PDF (1/8 Pages) Maxim Integrated Products – 2-Wire Interface Board

19-1629; Rev 1; 2/00
2-Wire Interface Board
________________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.
MAXSMBus Interface Board
____________________________Component List
DESIGNATION QTY
DESCRIPTION
C1, C2, C3
C4–C7, C9
C8
D1
D2
D3
J1
J2
P1
3 0.1µF ceramic capacitors
5 3.3µF, 20V tantalum capacitors
1 2.2µF, 35V tantalum capacitor
1 1N4692 zener diode, 6.8V
1 1N4688 zener diode, 4.7V
1 1N4148 small-signal diode
1 DB25 right-angle plug
0 Not installed
1 2x10 right-angle male header
R1, R2, R3,
R8–R11
7 47kΩ ±5% resistors
R4–R7
4 4.7kΩ ±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
U7
NONE
1 MAX865EUA (8-pin µMAX)
1 MAX367CWN (18-pin SO)
1 PC board
____________________________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
_______________Ordering Information
PART
MAXSMBus
BOARD TYPE
Companion Board for SMBus EV Kits
___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.
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products 1
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.