LM49352_14 Datasheet, PDF (44/104 Pages) Texas Instruments – Mono Class D Audio Codec Subsystem with Ground Referenced Headphone Amplifiers Earpiece Driver, and Audio DSP

LM49352
SNAS467D – MARCH 2009 – REVISED JUNE 2010
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Table 23. MONO_LEVEL (0x19h)
Bits
Field
Description
5:0
MONO_LEVEL This programs the MONO input level. All gain changes are performed at zero crossings.
MONO_LEVEL
Level
MONO_LEVEL
Level
000000
–46.5dB
100000
1.5dB
000001
–45dB
100001
3dB
000010
–43.5dB
100010
4.5dB
000011
–42dB
100011
6dB
000100
–40.5dB
100100
7.5dB
000101
–39dB
100101
9dB
000110
–37.5dB
100110
10.5dB
000111
–36dB
100111
12dB
001000
–34.5dB
101000
13.5dB
001001
–33dB
101001
15dB
001010
–31.5dB
101010
16.5dB
001011
–30dB
101011
18dB
001100
–28.5dB
001101
–27dB
001110
–25.5dB
001111
–24dB
010000
–22.5dB
010001
–21dB
010010
–19.5dB
010011
–18dB
010100
–16.5dB
010101
–15dB
010110
–13.5dB
010111
–12dB
011000
–10.5dB
011000
–9dB
011001
–7.5dB
011010
–6dB
011100
–4.5dB
011101
–3dB
011110
–1.5dB
011111
0dB
6
SE/DIFF
If set, the MONO– input is ignored. In single-ended mode, the MONO- input pin should be left floating.
7
AUXL_MONO
If set, AUXL is routed to the MONO Input Amplifier.
Headphone Detection Circuit
The LM49352 features a headphone detection circuit (HDC) that automatically enables the headphone amplifier
whenever the insertion of a headphone plug is detected and disables the headphone amplifier during the removal
of a headphone plug. The HDC optimizes power management by automatically disabling any output amplifier
that is not in use. The HDC eliminates the necessity of polling the I²C bus for status changes. However, since the
HDC requires the use of the GPIO pin, the PORT2_SDO functionality sensing is required.
The HDC requires a headphone jack with a normally closed mechanical switch and a pullup resistor, R_PU, tied
between the mechanical switch and I/O_V_DD (Refer to Figure 59). Choosing a R_PU value of at least 500kΩ
ensures minimal current draw through the pullup resistor. When the headphone amplifier is disabled, an internal
50kΩ pulldown, R_PD, is connected to each headphone amplifier output. Without the presence of a headphone
plug, the headphone jack’s mechanical switch is closed thereby connecting the right headphone amplifier output
44
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