LM48580
SNAS491A –FEBRUARY 2010–REVISED MAY 2013
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GAIN SETTING
The LM48580 features three internally configured gain settings 18, 24, and 30dB. The device gain is selected
through a single pin (GAIN). The gain settings are shown in Table 1.
Table 1. Gain Setting
Gain
FLOAT
GND
Gain Setting
18dB
24dB
VDD
30dB
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.
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 18 shows the typical
single-ended applications circuit.
LM48580
SINGLE-ENDED
IN-
INPUT
IN+
Figure 18. Single-Ended Configuration
PROPER SELECTION OF EXTERNAL COMPONENTS
Boost Converter Capacitor Selection
The LM48580 boost converter requires three external capacitors for proper operation: a 1μF supply bypass
capacitor, and 1μF + 100pF output reservoir capacitors. Place the supply bypass capacitor as close to VDD as
possible. Place the reservoir 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. Tantalum, OS-CON and aluminum electrolytic capacitors are not
recommended. See Demoboard Bill of Materials for suggested capacitor manufacturers.
BOOST CONVERTER OUTPUT CAPACITOR SELECTION
Inductor Selection
The LM48580 boost converter is designed for use with a 4.7μH inductor. Table 2 lists various inductors and their
manufacturers. 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 saturate, preventing excess efficiency
loss, over heating and possible damage to the inductor. Additionally, choose an inductor with the lowest possible
DCR (series resistance) to further minimize efficiency losses.
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