lm4990mm National Semiconductor Corporation, lm4990mm Datasheet - Page 6

• Manufacturer Part Number: lm4990mm
• Description: 2 Watt Audio Power Amplifier With Selectable Shutdown Logic Level
• Manufacturer: National Semiconductor Corporation

www.national.com
Electrical Characteristics V
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
25˚C. (Continued)
Note 13: The Exposed-DAP of the LDA10B package should be electrically connected to GND or an electrically isolated copper area. the LM4990LD demo board
has the Exposed-DAP connected to GND with a PCB area of 86.7mils x 585mils (2.02mm x 14.86mm) on the copper top layer and 550mils x 710mils (13.97mm
x 18.03mm) on the copper bottom layer.
Note 14: The thermal performance of the LLP and exposed-DAP TSSOP packages when used with the exposed-DAP connected to a thermal plane is sufficient for
driving 4Ω loads. The MSOP and ITL packages do not have the thermal performance necessary for driving 4Ω loads with a 5V supply and is not recommended for
this application.
Note 15: 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.
External Components Description
Typical Performance Characteristics
LD and MH Specific Characteristics
Components
See ( Figure 1 )
1.
2.
3.
4.
5.
C
C
R
R
C
S
B
i
i
f
V
DD
THD+N+N vs Frequency
Inverting input resistance which sets the closed-loop gain in conjunction with R
high pass filter with C
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
highpass filter with R
for an explanation of how to determine the value of C
Feedback resistance which sets the closed-loop gain in conjunction with R
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.
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
= 5V, R
L
= 4Ω, and P
i
i
at f
O
at f
= 1W
c
C
= 1/(2π R
DD
= 1/(2π R
20051030
= 2.6V
i
i
C
C
i
i
). Refer to the section, Proper Selection of External Components,
).
Functional Description
(Notes 1, 2)
6
i
.
V
DD
THD+N+N vs Output Power
= 5V, R
L
i
= 4Ω, and f = 1 kHz
.
B
f
. This resistor also forms a
.
A
20051031
=