LM48580TL/NOPB National Semiconductor, LM48580TL/NOPB Datasheet - Page 9

• Manufacturer Part Number: LM48580TL/NOPB
• Description: IC AMP AUDIO SPEAKER DVR 12USMD
• Manufacturer: National Semiconductor
• Series: Boomer®, PowerWise®r
• Type: Class Hr

Specifications of LM48580TL/NOPB

• Output Type: 1-Channel (Mono)
• Voltage - Supply: 2.5 V ~ 5.5 V
• Features: Differential Inputs, Shutdown, Thermal Protection
• Mounting Type: Surface Mount
• Package / Case: 12-MicroSMD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Max Output Power X Channels @ Load: -

SHUTDOWN FUNCTION
The LM48580 features a low current shutdown mode. Set
SD = GND to disable the amplifier and boost converter and
reduce supply current to 0.01µA.
PROPER SELECTION OF EXTERNAL COMPONENTS
Boost Converter Capacitor Selection
The LM48580 boost converter requires three external capac-
itors for proper operation: a 1μF supply bypass capacitor, and
1μF + 100pF output reservoir capacitors. Place the supply
bypass capacitor as close to V
voir capacitors as close to VBST and VAMP as possible. Low
ESR surface-mount multi-layer ceramic capacitors with X7R
or X5R temperature characteristics are recommended. Select
output capacitors with voltage rating of 25V or higher. Tanta-
lum, OS-CON and aluminum electrolytic capacitors are not
recommended. See Table 4 for suggested capacitor manu-
facturers.
BOOST CONVERTER OUTPUT CAPACITOR SELECTION
Inductor Selection
The LM48580 boost converter is designed for use with a
4.7μH inductor. Table 3 lists various inductors and their man-
ufacturers. Choose an inductor with a saturation current rating
greater than the maximum operating peak current of the
LM48580 (> 1A). This ensures that the inductor does not sat-
urate, preventing excess efficiency loss, over heating and
possible damage to the inductor. Additionally, choose an in-
ductor with the lowest possible DCR (series resistance) to
further minimize efficiency losses.
MANUFACTURER
Taiyo Yuden
Coilcraft
TABLE 3. Recommended Inductors
BRL3225T4R7M
LP3015
PART#
DD
as possible. Place the reser-
INDUCTANCE/
FIGURE 5. Single-Ended Configuration
4.7µH/1.1A
4.7µH/1.1A
ISAT
9
SINGLE-ENDED INPUT CONFIGURATION
The LM48580 is compatible with single-ended sources. When
configured for single-ended inputs, input capacitors must be
used to block and DC component at the input of the device.
Figure 5 shows the typical single-ended applications circuit.
Diode Selection
Use a Schottkey diode as shown in Figure 1. A 20V diode
such as the NSR0520V2T1G from On Semiconductor is rec-
ommended. The NSR0520V2T1G is designed to handle a
maximum average current of 500mA.
PCB LAYOUT GUIDELINES
Minimize trace impedance of the power, ground and all output
traces for optimum performance. Voltage loss due to trace
resistance between the LM48580 and the load results in de-
creased output power and efficiency. Trace resistance be-
tween the power supply and ground has the same effect as a
poorly regulated supply, increased ripple and reduced peak
output power. Use wide traces for power supply inputs and
amplifier outputs to minimize losses due to trace resistance,
as well as route heat away from the device. Proper grounding
improves audio performance, minimizes crosstalk between
channels and prevents switching noise from interfering with
the audio signal. Use of power and ground planes is recom-
mended.
Place all digital components and route digital signal traces as
far as possible from analog components and traces. Do not
run digital and analog traces in parallel on the same PCB lay-
er. If digital and analog signal lines must cross either over or
under each other, ensure that they cross in a perpendicular
fashion.
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