Low-Voltage, 1.8kHz PWM Output Temperature

Sensors

6

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Galvanic Isolation

Use an optocoupler to isolate the MAX6676/MAX6677

whenever a high common-mode voltage is present.

Choose an optocoupler with equal turn-on and turn-off

times. Unequal turn-on/turn-off times produce an error

in the temperature reading (Figure 3).

Thermal Considerations

Self-heating may cause the temperature measurement

accuracy of the MAX6676/MAX6677 to degrade in

some applications. The quiescent dissipation and the

power dissipated by the digital output may cause

errors in obtaining the accurate temperature measure-

ment. The temperature errors depend on the thermal

conductivity of the package (SOT23, +140°C/W), the

mounting technique, and the airflow. Static dissipation

is typically 4.0µW operating at 5V with no load. For

example, an out load of 3mA creates a maximum error

of less than 0.1°C.

Multiple Logic Voltages

Use the MAX6676 open-drain output to drive devices

operating at supply voltages other than the MAX6676’s

from the other supply voltage to the MAX6676 output.

Limit the resistor’s current to less than 1mA, thus main-

taining an output low logic level of less than 200mV.

Chip Information

TRANSISTOR COUNT: 2096

PROCESS: BiCMOS

3.3V

DOUT

MAX6676AUT3

Figure 3. Galvanic Isolation Using an Optocoupler

DOUT

MAX6676

5.1k

Ω

Figure 4. Low-Voltage Logic