data is logged each time Read All is selected from the

Options menu bar. To stop data logging, uncheck the

Data Logging checkbox.

Temperature

The MAX6639 monitors its own die temperature and the

junction temperature of one external diode-connected

transistor, or the junction temperature of two external

diode-connected transistors. The temperature mea-

surements are capable of either 8-bit or 11-bit (extend-

ed) resolution; 8-bit resolution results in a temperature

resolution of 1°C/LSB. Extended resolution results in a

temperature resolution of 0.125°C/LSB and is enabled

by checking the Enable Extended Resolution (0x05)

checkbox (Figure 1).

Read the temperatures by pressing the Read buttons

within the Temperature tab sheet (Figure 1). The tem-

perature is shown to the right of the buttons.

External Diodes

The MAX6639AEE remote temperature sensor is opti-

mized for use with a diode-connected transistor whose

ideality factor is equal to 1.008. Transistors with different

ideality factors produce different remote temperature

readings. Some typical discrete transistors may produce

readings that vary approximately 3°C from the correct

value. Refer to Application Note 1057:

Compensating for

Ideality Factor and Series Resistance Differences Between

Thermal Sense Diodes for additional information.

ALERT, THERM, and OT

Temperature Limits

The MAX6639 has

ALERT, THERM, and overtempera-

ture (

OT) limit registers. Temperatures exceeding the

ALERT limit register generate an alert interrupt.

Exceeding the

THERM or OT limits sets the THERM or

overtemperature bit in the status register and asserts

the

THERM or OT output pin.

Read a limit by pressing the Read button (Figure 1). The

value (in Celsius) is shown to the right of the button.

Change a limit by entering the value (in Celsius) into the

appropriate edit field and pressing the Write button.

MAX6639 Evaluation Kit

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5

Figure 2. MAX6639 EV Kit Software Main Window (Global Configuration Tab)