LM48512

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SNAS497A – OCTOBER 2010 – REVISED APRIL 2012

BOOST INPUT CAPACITOR SELECTION

An input capacitor is required to serve as an energy reservoir for the current which must flow into the coil each

time the switch turns ON. The input capacitor will also help keep the noise low from the power supply. This

capacitor must have extremely low ESR, so ceramic capacitors are recommended. A nominal value of 10

μF is

recommended for this application.

MAXIMUM CURRENT

The boost converter of the LM48512 has two maximum current limits to prevent damage to the device and also

battery shutdown when the current gets too high. First is the control of the start-up current, where the boost

internally limited to 2.25A.

AUTOMATIC GAIN CONTROL AND AUTOMATIC LEVEL CONTROL

The LM48512 features either Automatic Gain Control (AGC) or Automatic Level Control (ALC) by configuring the

Table 2. Automatic Gain/Level Control Table

Operation

Disable AGC and ALC

Resistor

AGC

GND

ALC

Automatic Gain Control Operation

The AGC circuitry is designed to limit the output swing to the load for speaker protection and to prolong battery

to ground, refer to Table 3.

Table 3. AGC Table

20.0

3.7

24.8

3.6

27.5

3.55

30.3

3.5

36.3

3.4

42.8

3.3

49.7

3.2

57.1

3.1

64.9

3.0

73.2

2.9

82.0

2.8

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