Low-Cost, Fail-Safe Temperature

In high-performance/high-reliability applications, multi-

ple temperature monitoring is important. The high-level

integration and low cost of the MAX6516 and MAX6518

facilitate the use of multiple temperature monitors to

increase system reliability. The application in Figure 3

uses two MAX6516s with different hot temperature

thresholds to ensure that fault conditions that can

overheat the monitored device cause no permanent

damage. The first temperature monitor activates the fan

when the die temperature exceeds +45°C. The second

MAX6516 triggers a system shutdown if the die

temperature reaches +75°C, preventing damage from

a wide variety of destructive fault conditions, including

latchups, short circuits, and cooling-system failures.

PC Board Testing

The MAX6516–MAX6519 temp sensor devices can be

tested after PC board assembly using OUT. Testing

can be used to verify proper assembly and functionality

of the temperature protection circuitry. Since OUT has

a weak drive capability, the voltage at OUT can be

forced to cause the digital outputs to change states,

thereby verifying that the internal comparators and out-

put circuitry function properly after assembly. Below is

a test procedure that can be used to test the

MAX6516–MAX6519:

• Power up the device, measure OUT, and observe the

state of the logic output.

Low-Cost, 2.7V to 5.5V, Analog Temperature

Sensor Switches in a SOT23

6

_______________________________________________________________________________________

MAX6516UKP075

HYST

GND

TOVER

TUNDER

MAX6516UKN005

HYST

GND

5V

OVERTEMP

UNDERTEMP

OUT OF RANGE

OUT

OUT

Figure 1. Temperature-Window Alarms Using the MAX6516

MAX6517UKP075

MAX6517UKN005

GND

TUNDER

5V

GND

HYST

HYST

OUT

TOVER

OUT

100k

Ω

OUT OF RANGE

Figure 2. Temperature Window Alarm Using the MAX6517

MAX6516UKP075

GND

5V

HYST

OUT

TOVER

SYSTEM

SHUTDOWN

MAX6516UKP045

GND

OUT

TOVER

FAN CONTROL

HYST

GND

μP

HEAT

HEAT

Figure 3. Low-Power, High-Reliability, Fail-Safe Temperature

Monitor