The TWL6041 is an audio codec with a high level of integration providing analog audio
codec functions for portable applications, as shown in . The device contains multiple audio analog inputs and outputs, as
well as microphone biases and accessory detection. The device is connected to the
OMAP 4 host processor through a proprietary PDM
interface for audio data communication enabling partitioning with optimized power consumption and
performance. Multichannel audio data is multiplexed to a single wire for downlink (PDML) and uplink
The OMAP4 device provides the TWL6041 device with five PDM audio-input channels
(DL0–DL4). Channels DL0–DL3 are connected to four parallel DAC channels multiplexed to stereo
headphone (HSL, HSR), stereo speaker (HFL, HFR), and earpiece (EAR) or stereo line outputs (AUXL,
The stereo headphone path has a low-power (LP) mode operating from a 32-kHz sleep clock
to enable more than 100 hours of MP3 playback time. Very-high dynamic range of 104 dBA is achieved
when using the system clock input and DAC path high-performance (HP) mode. Class-AB headphone
drivers provide a 1-Vrms output and are ground centered for capless connection to a headphone, thus
enabling system size and cost reduction. The earpiece driver is a differential class-AB driver with
2-Vrms capability to a typical 32-Ω load or 1.4-Vrms to a typical 16-Ω load.
Stereo speaker path has filterless class-D outputs with 1.5-W capability per channel.
Additionally, the 4-Ω load is supported. For output-power maximization, supply connection to an
external boost is supported. Speaker drivers also support hearing aid coil loads.
For vibrator and haptic feedback support, the TWL6041 device has two PWM channels with
independent input signals from DL4 or I2C. Vibra drivers are
differential H-bridge outputs, enabling fast acceleration and deceleration of vibra motor. An
external driver for a hearing aid coil or a piezo speaker requiring high voltage can be connected
to line outputs.
The TWL6041 supports three differential microphone inputs (MMIC, HMIC, and SMIC) and a
stereo line-input (AFML, AFMR) multiplexed to two parallel ADCs. The PDM output from the ADCs is
transmitted to the OMAP4 processor through UL0 and UL1. AFML, AFMR inputs can also be looped to
analog outputs (LB0, LB1).
Two LDOs provide a voltage of 2.1 V to bias analog microphones (MBIAS and HBIAS). The
maximum output current is 2 mA for each analog bias, allowing up to two microphones on one bias.
Two LDOs provide a voltage of 1.8 V to 1.85 V to bias digital microphones (DBIAS1 and DBIAS2). One
bias generator can bias several digital microphones at the same time, with a total maximum output
current of 10 mA.
The TWL6041 device has an integrated negative charge pump and two LDOs (HS LDO and LS
LDO) for high PSRR. The only external supply needed is 2.1 V, which is available from the 2.1-V
DC-DC of TWL6030/6032 power-management IC (PMIC) in the OMAP4 system. By powering audio from
low-noise 2.1-V DC-DC of low power consumption, high dynamic range and high output swing at the
headset output are achieved. All other supply inputs can be directly connected to battery or system
Two integrated PLLs enable operation from a 12-, 19.2-, 26-, and 38.4-MHz system clock
(MCLK) or, in LP playback mode, from a 32-kHz sleep clock (CLK32K). The frequency plan is based on
a 48-kS/s audio data rate for all channels, and the host processor uses sample-rate converters to
interface with different sample rates (for example, 44.1 kHz). In the specific case of low-power
audio playback, the TWL6041 supports the 44.1-kS/s and 48-kS/s rates. Transitions between sample
rates or input clocks are seamless.
Accessory plug and unplug detections are supported (PLUGDET). Some headsets have a
manual switch for submitting send/end signal to the terminal through the microphone input pin. This
feature is supported by a periodic accessory button press detection to minimize current consumption
in sleep mode. Detection cycle properties can be programmed according to system
The TWL6041BSRS, when connected to OMAP4 and OMAP5 platform, includes SRS Audio
Effects, SRS pre-processing solutions and SRS TruMedia as standard feature for
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