single-shot command overrides the automatic conver-

sion. After the single shot is complete, the device

returns to automatic operation.

Simple SMBus Commands

There are two methods for communicating with the

MAX6654: through the normal user-interface panel or

through the SMBus commands available from pressing

the MAXSMBUS button. A display pops up that allows

the SMBus protocols, such as Read Byte and Write

Byte, to be executed. To stop normal user-interface

execution so that it does not override the manually set

values, turn off the update timer that slaves the pro-

gram to the conversion rate by unchecking the

Automatic Read checkbox.

The SMBus dialog boxes accept numeric data in bina-

ry, decimal, or hexadecimal. Hexadecimal numbers

should be prefixed by $ or 0x. Binary numbers must be

exactly eight digits. Note: In places where the slave

address asks for an 8-bit value, it must be the 7-bit

slave address of the MAX6654 as determined by ADD0

and ADD1 with the last bit always set to 1.

Data Logging

Check the Data Logging checkbox to activate data

logging. Data logging saves temperature and status

data to a text file that includes a time/date stamp next

to each data point. If Automatic Read is enabled, data

is sampled at 2Hz; however, the data is logged to the

file only if either the temperature or status change. This

slows the growth of the data-logging file. When

Automatic Read is disabled, the data is logged each

time the Read All button is clicked. To stop data log-

ging, uncheck the Data Logging checkbox.

Jumper and Switch Settings

Two jumpers set the MAX6654 slave address. The

JU1 corresponds to ADD0 and JU2 corresponds to

ADD1; see Table 1 for a complete list of addresses.

The MAX6654 must undergo a power-on reset for the

new address to become effective.

The +5V supply voltage for the MAX6654 comes from

the SMBus interface board. To evaluate the MAX6654

with a different voltage, cut the trace shorting the two

pins of JU4 and apply a voltage to the VCC pad. A

slide switch, SW1, is provided as a means to force a

power-on reset of the MAX6654. This switch disables

power to the device.

Evaluating PRC Mode

The MAX6654 includes a parasitic resistance cancella-

tion (PRC) mode. In PRC mode, the effect of series

resistance on the leads of the external diode is can-

celed. To test this feature, cut the trace shorting the two

pins of JU5 and solder a 100

Ω resistor at the R1 loca-

tion on the board. Then check the Parasitic Cancel

checkbox on the main display.

Using a Remote-Diode Sensor

The MAX6654 EV kit can be connected through a twist-

ed pair to a remote diode close to your system. Cut the

trace shorting the two pins of JU6 and solder the twist-

ed pair from your remote diode to the pads labeled

DXP and DXN.

MAX6654 Evaluation System

_______________________________________________________________________________________

3

SHUNT LOCATION

JU1 (ADD0)

JU2 (ADD1)

MAX6654

ADDRESS

2-3

2-3

0011 000

2-3

Open

0011 001

2-3

1-2

0011 010

Open

2-3

0101 001

Open

Open

0101 010

Open

1-2

0101 011

1-2

2-3

1001 100

1-2

Open

1001 101

1-2

1-2

1001 110

SHUNT

LOCATION

STBY PIN

FUNCTION

1-2

Connected to

VCC

In operate mode

Open

Connect an

external

signal to

STBY

2-3

Connected to

GND

In standby mode

Table 1. JU1 and JU2 Shunt Settings for

SMBus Address

Table 2. JU3 Shunt Settings for

STBY