TAS2505: Question for Power Saving Mode

Hi, Sakai-san,

Please take a look at my responses below and let me know if you have additional questions or comments.

For questions 1)

• Is Standby Mode more suitable for starting up as soon as possible?
  • This is correct. The standby mode requires less time to respond to the audio input.
• In that case, SLAU472 2.8.1.2.1 states that SPK VDD and 1.8V voltages (AVDD and DVDD) should be left on to power down the other blocks. Could you please tell me how to power down other blocks (whether it is a register control somewhere or should I disconnect the power supply of IO VDD)?
  • The other blocks refer to the Class-D driver (page 1 / register 45) and DAC block (page 0 / register 63). In standby mode, all power supplies are enabled, so IOVDD must not be disconnected.
• Also, the datasheet says "device responds very quickly to playback requests", but could you please tell me how long it will take to get up?
  • Since the DAC block and the Class-D driver are the only blocks that need to be enabled to exit from standby mode, the device will take just 8 BCLK pulses to be initialized.

For questions 2)

• Is it possible to stop this by register control?
  • The customer may try using an auto-mute control if no valid data is input (page 0 / register 64). This will mute the DAC block. In case the Class-D driver switching activity is causing this noise, the customer may try muting the Class-D driver by page 1 / register 46 or powering down the Class-D driver with page 1 / register 45.

Best regards,
Luis Fernando Rodríguez S.

Hi, Sakai-san,

These posts refer to the standby mode. In summary, the standby mode refers to disable all the internal blocks to save the most part of power consumption. As mentioned in the two posts, there are many options that can be disabled to enable the standby mode: DAC block, Class-D driver, PLL (in case it is used to generate the sampling frequency), master reference, etc.

The difference with the shutdown mode is that the shutdown mode needs to disable the internal LDO and some external supplies to save more power.

Best regards,
Luis Fernando Rodríguez S.

Hi, Sakai-san,

Sorry for the confusion, let me clarify the correct way to enable the standby mode.

In order to enter in this mode, all the power supplies must remain enabled and stable, including the internal LDO (in case it is being used).

The blocks that must be disabled are listed below:

- DAC Channels (page 0 / register 63 / bit D7).
- Master reference (page 1 / register 1 / bit D4).
- Headphone output and analog inputs (page 1 / register 9 / bits D5, D1, D0).
- Speaker Class-D driver (page 1 / register 45 / bit D1).

This configuration will allow to place the device in a low power consumption.

Best regards,
Luis Fernando Rodríguez S.