DA7212 datasheet(39/136 Pages) RENESAS

39 / 136 page

Ultra-Low Power Stereo Codec

DA7212 Revision 3.6

Nov 1, 2024

CFR011-120-00

Page 39

13.12 Output Mixer

For playback, the output mixer amplifier is enabled using MIXOUT_L_AMP_EN and MIXOUT_R_AMP_EN. The

audio signal can be mixed from all sources and can be output simultaneously to both headphones and speakers.

The mixing takes place only after asserting the control MIXOUT_L_MIX_EN and MIXOUT_R_MIX_EN.

The output mixer is configured using register MIXOUT_L_SELECT and MIXOUT_R_SELECT. This output-mixer

control is independent of the input path, so recording of one audio signal while listening to another signal such as

FM Radio or an MP3 file is possible. The playback sound can be mixed with background signals or with inverted

background microphone signals (side tone) to enable a basic headphone environmental noise reduction, or to

compensate for unwanted damping of environmental sound while listening with sealed headphones. Playback

signals coming from the AUX or microphone input channels can be individually inverted before being mixed out

to the left and right channel (see MIXOUT_L_SELECT and MIXOUT_R_SELECT registers).

A stereo to mono conversion can be implemented by using either the input or the output mixer. This allows direct

feeding of high power speaker amplifiers and other mono devices with the complete audio content.

13.13 Headphone Amplifier

The headphone Class G amplifiers offer 'true ground' technology, which allows cost and space optimisation by

removing the need for bulky headphone-coupling capacitors. This also enhances the bass performance, which is

typically reduced by conventional AC-co

upling. In comparison to alternative approaches like ‘phantom ground’,

‘true ground’ technology generates real ground-centred output signals, which provide common GND as required

for Mini-USB connectors and CEA 936 A-compliant interfaces. An embedded offset compensation circuit

suppresses click and pop noise during start-up and dynamic supply voltage adjustments.

Integrated short circuit protection enables a ‘resistors free’ connection to a standard audio jack, to achieve a

maximum output power of up to 67 mW per channel (referenced to VDD_A). Headphone load impedance is

typically 16

Ω, but the paths can also be used as volume controlled lineout signals for external speaker amplifiers

and audio devices. The headphone Class G amplifiers are supplied from the positive VDD_A rail via a capacitive

charge pump that generates the negative rail required for "True ground" mode. For improved power efficiency,

the headphone headphone supply voltage levels are dynamically adjusted between ± VDD_A and ± VDD_A/2 to

match the levels of the left and right headphone signals.

The headphone amplifiers are enabled with controls HP_L_AMP_EN and HP_R_AMP_EN. For optimum pop

and click performance when switching the amplifier On and Off, the headphone amplifier provides a High

impedance mode that can be enabled via HP_L_AMP_OE / HP_R_AMP_OE.

Balance is controlled by programming the left and right gains separately. The gain of each headphone channel

can be programmed independently in steps of 1.0 dB from +6 dB down to

–57 dB using controls

HP_L_AMP_GAIN / HP_R_AMP_GAIN.

Settings such as mute, gain changes at signal zero cross (for smooth volume changes), and the ramping of gain

changes are controlled using the dedicated HP_L_CTRL and HP_R_CTRL registers. If the ramping is enabled

using the control bits HP_L_AMP_RAMP_EN and HP_R_AMP_RAMP_EN, the rate of the ramping is controlled

using GAIN_RAMP_RATE.

For smooth volume changes, the gain update can be synchronised to audio signal zero-crossings using

HP_L_AMP_ZC_EN and HP_R_AMP_ZC_EN. If no zero crossing is detected within approximately 85 ms, the

gain change is applied unconditionally. The left and right channels are synchronised independently.

DA7212 Datasheet(PDF) 39 Page - Renesas Technology Corp

DA7212 Datasheet(HTML) 39 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL