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AS1923

Datasheet - Application In form atio n

Negative Voltage Monitoring Beyond -5V

The AS1923 is available with options to monitor -5V supplies using internally trimmed thresholds. In cases where monitored supplies are more

negative than -5V, an external low-impedance resistor-divider network can be used as shown in Figure 14.

The current through the external resistor-divider should be greater than the input current for the -5V monitor options. For an input monitor current

error of <1%, the resistor-divider current should be

Figure 14. Negative Voltage Monitoring Beyond -5V

Where:

≤ 2.49kΩ

Ω.

Ω

Power-Supply Bypassing and Grounding

The AS1923 is powered from the IN2 supply input. All monitor inputs are immune to fast supply transients.

If higher immunity is required in noisy systems, connect 0.1µF bypass capacitors from the IN2 input to ground (see Figure 15). Additional capac-

itance can be added to IN1, IN3, and IN4 to improve noise immunity at these inputs.

Figure 15. IN2 Additional Noise Immunity

–

+

+

–

1.23V

-5V

(EQ 3)

1,23V

----------------1

–

⎝⎠

⎛⎞

×

=

2,49k

Ω

11,1V

–

4,63V

–

-------------------1

–

⎝⎠

⎛⎞

×

=

5

IN2

2

GND

3.0 to

3.3V

0.1µF

AS1923