lm48311tlx National Semiconductor Corporation, lm48311tlx Datasheet - Page 11

• Manufacturer Part Number: lm48311tlx
• Description: Ultra-low Emi, Filterless, 2.6w, Mono, Class D Audio Power Amplifier With E2s
• Manufacturer: National Semiconductor Corporation

Where R
additional external resistor.
SINGLE-ENDED AUDIO AMPLIFIER CONFIGURATION
The LM48311 is compatible with single-ended sources. When
configured for single-ended inputs, input capacitors must be
PCB LAYOUT GUIDELINES
As output power increases, interconnect resistance (PCB
traces and wires) between the amplifier, load and power sup-
ply create a voltage drop. The voltage loss due to the traces
between the LM48311 and the load results in lower output
power and decreased efficiency. Higher trace resistance be-
tween the supply and the LM48311 has the same effect as a
poorly regulated supply, increasing ripple on the supply line,
and reducing peak output power. The effects of residual trace
resistance increases as output current increases due to high-
er output power, decreased load impedance or both. To main-
tain the highest output voltage swing and corresponding peak
output power, the PCB traces that connect the output pins to
the load and the supply pins to the power supply should be
as wide as possible to minimize trace resistance.
The use of power and ground planes will give the best THD
+N performance. In addition to reducing trace resistance, the
BUILD OF MATERIALS
LM48311TL
Designator
F
FIGURE 4. Reduced Gain Configuration
C3, C4
is 40kΩ, R
JU1
C1
C2
A
V
= 2 x [R
IN
is 20kΩ, and R
F
/ (R
Quantity
INEXT
1
1
2
1
1
INEXT
+ R
IN
10µF ±10% 16V Tantalum Capacitor (B Case) AVX TPSB106K016R0800
1µF ±10% 16V X5R Ceramic Capacitor (603) Panasonic ECJ-1VB1C105K
1µF ±10% 16V X7R Ceramic Capacitor (1206) Panasonic ECJ-3YB1C105K
3-Pin Header
LM48311TL (9-Bump microSMD)
LM48311TL Demoboard Bill of Materials
is the value of the
)]
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used to block and DC component at the input of the device.
Figure 5 shows the typical single-ended applications circuit.
use of power planes creates parasitic capacitors that help to
filter the power supply line.
The inductive nature of the transducer load can also result in
overshoot on one of both edges, clamped by the parasitic
diodes to GND and V
point, this is an aggressive waveform that can radiate or
conduct to other components in the system and cause inter-
ference. In is essential to keep the power and output traces
short and well shielded if possible. Use of ground planes
beads and micros-strip layout techniques are all useful in pre-
venting unwanted interference.
wires or traces acting as antennas become more efficient with
length. Ferrite chip inductors places close to the LM48311
outputs may be needed to reduce EMI radiation.
FIGURE 5. Single-Ended Input Configuration
Description
DD
in each case. From an EMI stand-
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