TAS5822MDCPR datasheet(29/90 Pages) TI

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inductors to be used because the current is divided between the two inductors. The process is called Post-Filter

PBTL. On the input side of the TAS5822M device, the input signal to the PBTL amplifier is left frame of I2S or

TDM data.

7.4.3 Minimize EMI with Spread Spectrum

This device supports spread spectrum with triangle mode, Spread spectrum is used to minimize the EMI noise.

User need configure register SS_CTRL0 (0x6B) to Enable triangle mode and enable spread spectrum, and

select spread spectrum frequency and range with SS_CTRL1 (0x6C). For 384kHz FSW which configured by

DEVICE_CTRL1 (0x02), the spread spectrum frequency and range are described in Table 3.

Table 7-5. Spread Spectrum Setting

SS_TRI_CTR

L[3:0]

Triangle Freq

24k

48k

Spread

Spectrum

Range

10%

20%

25%

10%

20%

25%

User Application example-Central Switching Frequency is 384kHz, Triangle Frequency is 24kHz:

w 58 6b 03 //Enable Spread Spectrum

w 58 6c 03 //SS_TRI_CTRL[3:0]0011, Triangle Frequency = 24kHz, Spread Spectrum Range should be 25%

(336kHz~432kHz)

7.4.4 Minimize EMI with channel to channel phase shift

This device support channel to channel 180 degree PWM phase shift to minimize the EMI. Bit 0 of Register 0x53

can be used to disable or enable the phase shift.

7.4.5 Minimize EMI with Multi-Devices PWM Phase Synchronization

This device support up to 4 phases selection for the multi devices application system. For example, when a

system integrated 4 TAS5822M devices, user can select phase 0/1/2/3 for each device by register

PHASE_CTRL (0x6A), which means there is a 45 degree phase shift between each device to minimize the EMI.

Recommend to do the Phase Synchronization with I2S clock during the Startup Phase.

1. Halt I2S clock.

2. Halt I2S clock.

3. Configure each device phase selection and enable the phase synchronization. For example: Register 0x6A =

0x03 for device 0; Register 0x6A = 0x07 for device 1; Register 0x6A = 0x0B for device 2; Register 0x6A =

0x0F for device 3. There should be a 45 degree PWM phase shift between each device to minimize the EMI.

4. Configure each device into Hi-Z mode.

5. Provide I2S to each device. Phase synchronization for all 4 devices will be automatically done by internal

sequence.

6. Initialize the DSP code. (This step can be skipped if only need to do the PWM Phase Synchronization).

7. Device to Device PWM phase shift should be fixed with 45 degree.

7.4.6 Thermal Foldback

The Thermal Foldback (TFB) or Over temperature foldback, is designed to protect TAS5822M from excessive

die temperature increases, in case the device operates beyond the recommended temperature/power limit, or

with a weaker thermal system design than recommended. It allows the TAS5822M to play as loud as possible

without triggering unexpected thermal shutdown. When the die temperature triggers the over-temperature

warning (OTW) level (135C typ), an internal AGL (Automatic Gain Limiter) will reduce the digital gain

automatically. Once the die temperature drops below the OTW, the device’s digital gain gradually returns to the

former setting. Both the attenuation gain and adjustable rate are programmable. The TFB gain regulation speed

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TAS5822M

SLASEV8 – DECEMBER 2020

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