LM339 Просмотр технического описания (PDF) - Unspecified

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LM339

36V Low Power Dual/Quad Differential Comparators

Unspecified 

LM393/LM339

36V Low Power Dual/Quad Differential Comparators

6

Input Voltage

4

2

0

VDD=5V

-2

Output Voltage

Time (100μs/div)

Figure 1. Comparator Response to Input Voltage

The electrostatic discharge (ESD) protection input structure of two back-to-back diodes and 1kΩ series resistors are

used to limit the differential input voltage applied to the precision input of the comparator by clamping input voltages

that exceed supply voltages, as shown in Figure 2. Large differential voltages exceeding the supply voltage should be

avoided to prevent damage to the input stage.

1KΩ

+In

1KΩ

Core

-In

Chip

Figure 2. Equivalent Input Structure

External Hysteresis

Greater flexibility in selecting hysteresis is achieved by using external resistors. Hysteresis reduces output chattering

when one input is slowly moving past the other. It also helps in systems where it is best not to cycle between high and

low states too frequently (e.g., air conditioner thermostatic control). Output chatter also increases the dynamic supply

current.

Non-Inverting Comparator with Hysteresis

A non-inverting comparator with hysteresis requires a two-resistor network, as shown in Figure 3 and a voltage

reference (Vr) at the inverting input.

Figure 3. Non-Inverting Configuration with Hysteresis

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Rev. B.2

6

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