LM48560

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SNAS513F – AUGUST 2011 – REVISED NOVEMBER 2015

8.3.6 Release Time

Release time (tRL) is the time it takes for the gain to return from 6 dB to its normal level once the audio signal

returns below the ALC threshold. A fast release time allows the ALC to react quickly to transients, preserving the

original dynamics of the audio source. However, similar to a fast attack time, a fast release time contributes to

volume pumping. A slow release time reduces the effect of volume pumping. The release time is set by a

combination of the value of CSET and release time coefficient as given by Equation 2:

tRL = 20 MΩCSET / αRL (s)

(2)

where

αRL is the release time coefficient (Table 2) set by bits B6:B5 in the No Clip Control Register. The release

time coefficient allows the user to set a nominal release time. The internal 20 M

Ω is subject to temperature

change, and it has tolerance between -11% to +20%.

Table 2. Release Time Coefficient

B6

B5

αRL

0

0

4

0

1

5.3

1

0

9.5

1

1

11.8

8.3.7 Boost Converter

The LM48560 device features an integrated boost converter with a dynamic output control. The device monitors

the output signal of the amplifier, and adjusts the output voltage of the boost converter to maintain sufficient

headroom while improving efficiency.

8.3.8 Gain Setting

The LM48560 device features four internally configured gain settings 0 db, 6 dB, and 30 dB. The device gain is

selected through a single pin (GAIN). The gain settings are shown in Table 3.

Table 3. Gain Setting

GAIN SETTING

GAIN SETTING

GAIN

IN1

IN2

0

0 dB

24 dB

1

6 dB

30 dB

8.3.9 Shutdown Function

The LM48560 device features a low current shutdown mode. Set SD = GND to disable the amplifier and boost

converter and reduce supply current to 0.01 µA.

8.4 Device Functional Modes

8.4.1 Software or Hardware Mode

Device operation in hardware or software mode is determined by the state of the SW/HW pin. Connect SW/HW

to ground for hardware mode, and connect to VDD for software mode.

SW/HW

SDA/SEL

SCL/GAIN

MODE

0

IN1, Av = 0

0

(Boost Disabled)

1

IN1, Av = 6

0

0

IN2, Av = 24

1

(Boost Enabled)

1

IN2, Av = 30

1

SDA

SCL

I2C Mode

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