Electrical Characteristics V

The following specifications apply for V

Ω Load unless otherwise specified. Limits apply for T

25˚C. (Continued)

Symbol

Parameter

Conditions

LM4891

Units

(Limits)

Typical

Limit

(Note 6)

(Note 7)

P

0

Output Power ( 8

Ω )

Output Power ( 4

Ω )

THD = 1% (max);f=1kHz THD =

1% (max);f=1kHz

0.25

0.28

W

W

THD+N

Total Harmonic Distortion+Noise

P

0.08

%

PSRR

Power Supply Rejection Ratio

V

44 (f =

217Hz)

44 (f = 1kHz)

dB

Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.

Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which

guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit

is given, however, the typical value is a good indication of device performance.

curves for additional information.

Note 4: Human body model, 100 pF discharged through a 1.5 k

Ω resistor.

Note 5: Machine Model, 220 pF–240 pF discharged through all pins.

Note 6: Typicals are measured at 25˚C and represent the parametric norm.

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 9: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

Note 10: ROUT is measured from each of the output pins to ground. This value represents the parallel combination of the 10k ohm output resistors and the two 20k

ohm resistors.

no damage will occur, although operational life will be reduced. Operation above 6.5V with no current limit will result in permanent damage.

Note 12: All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. All bumps must be connected to achieve

specified thermal resistance.

Equation 1 shown in the Application section. It may also be obtained from the power dissipation graphs.

of gain increase. A system gain of 10 represents a gain increase of 14dB. PSRR will be reduced by 14dB and applies to all operating voltages.

External Components Description

(Figure 1)

Components

Functional Description

1.

R

i

Inverting input resistance which sets the closed-loop gain in conjunction with R

high pass filter with C

π R

2.

C

i

Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a

highpass filter with R

π R

for an explanation of how to determine the value of C

3.

R

f

Feedback resistance which sets the closed-loop gain in conjunction with R

4.

C

S

Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing

section for information concerning proper placement and selection of the supply bypass capacitor.

5.

C

B

Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External

Components, for information concerning proper placement and selection of C

www.national.com

4