LM4954TLBD National Semiconductor, LM4954TLBD Datasheet - Page 14

• Manufacturer Part Number: LM4954TLBD
• Description: BOARD EVALUATION LM4954TL
• Manufacturer: National Semiconductor
• Series: Boomer®r

Specifications of LM4954TLBD

• Amplifier Type: Class AB
• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 3W x 1 @ 8 Ohm
• Voltage - Supply: 2.7 V ~ 9 V
• Operating Temperature: -40°C ~ 85°C
• Board Type: Fully Populated
• Utilized Ic / Part: LM4954
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

www.national.com
Application Information
PCB LAYOUT GUIDELINES
This section provides practical guidelines for mixed signal
PCB layout that involves various digital/analog power and
ground traces. Designers should note that these are only
"rule-of-thumb" recommendations and the actual results will
depend heavily on the final layout.
GENERAL MIXED SIGNAL LAYOUT
RECOMMENDATIONS
Power and Ground Circuits
For a two layer mixed signal design, it is important to isolate
the digital power and ground trace paths from the analog
power and ground trace paths. Star trace routing techniques
(bringing individual traces back to a central point rather than
daisy chaining traces together in a serial manner) can have
a major impact on low level signal performance. Star trace
routing refers to using individual traces to feed power and
ground to each circuit or even device. This technique re-
quires a greater amount of design time but will not increase
the final price of the board. The only extra parts required may
be some jumpers.
Designator
J
1
, J
R
C
C
C
R
C
J
3
2
F
F
S
B
i
i
, J
4
TABLE 1. Mono LM4954 Reference Design Boards Bill of Materials
0.39µF
Value
2.2µF
2.2µF
20kΩ
20kΩ
(Continued)
Tolerance
10%
10%
10%
1%
1%
Ceramic 1206 Capacitor, 10%
16V Tantalum 1210 Capacitor
16V Tantalum 1210 Capacitor
0.100” 1x2 header, vertical
0.100” 1x3 header, vertical
1/10W, 1% 0805 Resistor
1/10W, 1% 0805 Resistor
14
Part Description
Single-Point Power / Ground Connections
The analog power traces should be connected to the digital
traces through a single point (link). A "Pi-filter" can be helpful
in minimizing high frequency noise coupling between the
analog and digital sections. It is further recommended to put
digital and analog power traces over the corresponding digi-
tal and analog ground traces to minimize noise coupling.
Placement of Digital and Analog Components
All digital components and high-speed digital signals traces
should be located as far away as possible from analog
components and circuit traces.
Avoiding Typical Design / Layout Problems
Avoid ground loops or running digital and analog traces
parallel to each other (side-by-side) on the same PCB layer.
When traces must cross over each other do it at 90 degrees.
Running digital and analog traces at 90 degrees to each
other from the top to the bottom side as much as possible will
minimize capacitive noise coupling and cross talk.
mount
mount
Shutdown control
Input, Output,
Part not used
Comment
Vdd/GND