LM2877P datasheet(7/8 Pages) NSC

7 / 8 page

Typical Applications (Continued)

Window Comparator Driving High Low Lamps

TLH7933 – 8

Truth Table

VIN

High

Low

Off

Va to

Off

Application Hints

The LM2877 is an improved LM377 in typical audio applica-

tions In the LM2877 the internal voltage regulator for the

input stage is generated from the voltage on pin 1 Normally

the input common-mode range is within g07V of this pin 1

voltage Nevertheless the common-mode range can be in-

creased by externally forcing the voltage on pin 1 One way

to do this is to short pin 1 to the positive supply pin 11

The only special care required with the LM2877 is to limit

the maximum input differential voltage to g7V If this differ-

ential voltage is exceeded the input characteristics may

change

Figure 1 shows a power op amp application with AV e 1

The 100k and 10k resistors set a noise gain of 10 and are

dictated by amplifier stability The 10k resistor is boot-

strapped by the feedback so the input resistance is domi-

nated by the 1 MX resistor

TLH7933 – 9

FIGURE 1

LM2877P Datenblatt(PDF) 7 Page - National Semiconductor (TI)