LM4865MX National Semiconductor, LM4865MX Datasheet - Page 11

• Manufacturer Part Number: LM4865MX
• Manufacturer: National Semiconductor

Specifications of LM4865MX

• Operational Class: Class-AB
• Audio Amplifier Output Configuration: 1-Channel Mono
• Output Power (typ): 1x1@8Ohm/0.11x1@8OhmW
• Audio Amplifier Function: Headphone/Speaker
• Total Harmonic Distortion: 0.6@8Ohm@300mW%
• Single Supply Voltage (typ): 3/5V
• Dual Supply Voltage (typ): Not RequiredV
• Power Supply Requirement: Single
• Rail/rail I/o Type: No
• Power Supply Rejection Ratio: 50dB
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• Lead Free Status / Rohs Status: Not 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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