Rainbow-electronics MAX6677 Bedienungsanleitung PDF herunterladen (Seite 5)

MAX6676/MAX6677

Low-Voltage, 1.8kHz PWM Output Temperature

Sensors

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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

. As shown in Figure 4, connect a pullup resistor

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

ISO

MAX6676AUT3

Figure 3. Galvanic Isolation Using an Optocoupler

DOUT

MAX6676

5.1kΩ

Figure 4. Low-Voltage Logic

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Rainbow-electronics MAX6677 Bedienungsanleitung Seite 5