LM4865M National Semiconductor, LM4865M Datasheet - Page 11

• Manufacturer Part Number: LM4865M
• Description: IC, AUDIO PWR AMP, CLASS AB 750mW, SOIC8
• Manufacturer: National Semiconductor

Specifications of LM4865M

• Audio Control Type: Volume
• Output Power: 1W
• Control / Process Application: GSM Phones And Accessories, DECT, Office Phones, Hand Held Radio
• Supply Voltage Range: 2.7V To 5.5V
• No. Of Channels: 1
• Thd + N: 0.6% @ 8ohm, VDD=5V
• Load Impedance: 8ohm
• Operating Temperature Range: -40°C To +85°C
• Amplifier Case Style: MSOP
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Information
an external 1kΩ - 5kΩ resistor can be placed in parallel with
the internal 20kΩ resistor. The tradeoff for using this resistor
is increased quiescent current.
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figure 4 through Figure 6 show the recommended two-layer
PC board layout that is optimized for the SO-8 packaged
LM4865 and associated external components. Figure 7
through Figure 11 show the recommended four-layer PC
board layout for the micro SMD packaged LM4865. A
four-layer board is recommended when using the micro
SMD packaged LM4865: the two inner layers, one con-
nected to the GND pin, the other to the V
heatsinking. Both layouts are designed for use with an ex-
ternal 5V supply, 8Ω speakers, and 32Ω headphones. The
schematic for both recommended PC board layouts is Figure
1.
Both circuit boards are easy to use. Apply a 5V supply
voltage and ground to the board’s V
respectively. Connect a speaker with an 8Ω minimum imped-
ance between the board’s -OUT and +OUT pads. For head-
phone use, the layout has provisions for a headphone jack,
J1. When a jack is connected as shown, inserting a head-
phone plug automatically switches off the external speaker.
FIGURE 4. Recommended SO PC board layout:
component side silkscreen
DD
(Continued)
and GND pads,
DD
pin, provide
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11
FIGURE 5. Recommended SO PC board layout:
FIGURE 6. Recommended SO PC board layout:
component side layout
bottom side layout
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