AS1976 datasheet(11/17 Pages) AMSCO

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AS1976/AS1977

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

The AS1976/AS1977 comparators are perfect for use with all 2-cell battery-powered applications. Figure 25 shows a

typical application for the AS1977.

Figure 25. AS1977 Typical Application Circuit

Internal Hysteresis

The comparators were designed with 3mV of internal hysteresis to neutralize the effects of parasitic feedback, i.e., to

prevent unwanted rapid changes between the two output states.

The internal hysteresis in the AS1976/AS1977 creates two trip points:

Rising Input Voltage (VTHR) – The comparator switches its output from low to high as VIN rises above this trip point.

Falling Input Voltage (VTHF) – The comparator switches its output from high to low as VIN falls below this trip point.

The area between the trip points is the hysteresis band (VHB) (see Figure 26). When the AS1976/AS1977 input volt-

ages are equivalent, the hysteresis effectively causes one input to move quickly past the other, thus taking the input

out of the region where oscillation occurs. In Figure 26 IN- has a fixed voltage applied and IN+ is varied.

Note:

If the inputs are reversed the output will be inverted.

Figure 26. Threshold Hysteresis Band

AS1977

RPULLUP

VIN

IN-

OUT

VCC

VEE

IN+

OUT

VTHR

VTHF

IN-

Thresholds

Hysteresis

Band

VHB

AS1976 датащи(PDF) 11 Page - ams AG