LM391 datasheet(4/12 Pages) NSC

4 / 12 page

External Components (Figure 1)

Component

Typical Value

Comments

CIN

1 mF

Input coupling capacitor sets a low frequency pole with RIN

fL e

2qRINCIN

RIN

100k

Sets input impedance and DC bias to input

Rf2

100k

Feedback resistor for minimum offset voltage at the output this should be equal to RIN

Rf1

51k

Feedback resistor that works with Rf2 to set the voltage gain

AV e 1 a

Rf2

Rf1

10 mF

Feedback capacitor This reduces the gain to unity at DC for minimum offset voltage at the

output Also sets a low frequency pole with Rf1

fL e

2qRf1Cf

5 pF

Compensation capacitor Sets gain bandwidth product and a high frequency pole

GBW e

2q5000CC

fh e

GBW

Max fh for stable design

500 kHz

39k

AB bias resistor

10k

AB bias potentiometer Adjust to set bias current in the output stage

CAB

01 mF

Bypass capacitor for bias This improves high frequency distortion and transient response

5 pF

Ripple capacitor This improves negative supply rejection at midband and high frequencies

CR if used must equal CC

Reb

100X

Bleed resistor This removes stored charge in output transistors

27X

Output compensation resistor This resistor and CO compensate the output stage This value

will vary slightly for different output devices

01 mF

Output compensation capacitor This works with RO to form a zero that cancels fb of the

output power transistors

03X

Emitter degeneration resistor This resistor gives thermal stability to the output stage

quiescent current IRC PW5 type

RTH

39k

Shutdown resistor Sets the amount of current pulled out of pin 14 during shutdown

C2 C 2

1000 pF

Compensation capacitors for protection circuitry

10X

ll5 mH

Used to isolate capacitive loads usually 20 turns of wire wrapped around a 10X 2W resistor

LM391 Datasheet(PDF) 4 Page - National Semiconductor (TI)

LM391 Datasheet(HTML) 4 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12

Datasheet Download

Link URL