LM4911LDX National Semiconductor, LM4911LDX Datasheet - Page 20

• Manufacturer Part Number: LM4911LDX
• Description: IC AMP AUDIO PWR .145W AB 10LLP
• Manufacturer: National Semiconductor
• Series: Boomer®r
• Type: Class ABr

Specifications of LM4911LDX

• Output Type: Headphones, 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 145mW x 2 @ 16 Ohm
• Voltage - Supply: 2 V ~ 5.5 V
• Features: Mute, Shutdown, Thermal Protection
• Mounting Type: Surface Mount
• Package / Case: 10-LLP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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As stated in the External Components section, R
junction with C
The high frequency pole is determined by the product of the
desired frequency pole, f
an A
which is much smaller than the LM4911 GBWP of 10MHz.
This figure displays that is a designer has a need to design
an amplifier with higher differential gain, the LM4911 can still
be used without running into bandwidth limitations.
Figure 4 shows an optional resistor connected between the
amplifier output that drives the headphone jack sleeve and
ground. This resistor provides a ground path that supressed
power supply hum. Thishum may occur in applications such
as notebook computers in a shutdown condition and con-
C
i
≥
V
= 1 and f
1 / (2
π
FIGURE 6. The PCDN042 provides additional ESD protection beyond the 2000V shown in the
i
* 20kΩ * 20Hz) = 0.397µF; use 0.39µF.
creates a
H
= 100kHz, the resulting GBWP = 100kHz
H
, and the differential gain, A
Absolute Maximum Ratings for the V
i
in con-
V
. With
20
nected to an external powered speaker. The resistor's 100Ω
value is a suggested starting point. Its final value must be de-
termined based on the tradeoff between the amount of noise
suppression that may be needed and minimizing the addi-
tional current drawn by the resistor (25mA for a 100Ω resistor
and a 5V supply).
ESD PROTECTION
As stated in the Absolute Maximum Ratings, the LM4911 has
a maximum ESD susceptibility rating of 2000V. For higher
ESD voltages, the addition of a PCDN042 dual transil (from
California Micro Devices), as shown in Figure 6, will provide
additional protection.
O
C output
200314b4