LM4892 NSC [National Semiconductor], LM4892 Datasheet - Page 5

• Manufacturer Part Number: LM4892
• Description: 1 Watt Audio Power Amplifier with Headphone Sense
• Manufacturer: NSC [National Semiconductor]

External Components Description
Typical Performance Characteristics
Components
4.
5.
6.
7.
8.
9.
at V
C
at V
R
R
C
C
R
OUT
PU
PD
S
B
S
DD
DD
= 2.6V, 8Ω R
= 5V, 8Ω 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
This output coupling capacitor blocks DC voltage while coupling the AC audio signal to the headphone
speaker. Combined with R
Refer to the section, Proper Selection of External Components for an explanation of how to determine the
value of C
This is the pull up resistor to activate headphone operation when a headphone plug is plugged into the
headphone jack.
This is the current limiting resistor for the headphone input pin.
This is the pull down resistor to de-activate headphone operation when no headphone is plugged into the
headphone jack.
THD+N vs Frequency
THD+N vs Frequency
OUT
L
L
, and PWR = 250mW
, and PWR = 100mW
.
L
, the headphone impedance, it creates a high pass filter at f
20012737
20012739
(Figure 1) (Continued)
Functional Description
5
at V
at V
DD
DD
= 3.3V, 8Ω R
= 2.6V, 4Ω R
THD+N vs Frequency
THD+N vs Frequency
L
L
, and PWR = 150mW
, and PWR = 100mW
B
.
c
= 1/(2πR
20012738
20012740
www.national.com
L
C
OUT
).