I am attempting to get a TAS5715EVM up and running to do an evaluation of this amplifier, but the behavior I'm seeing doesn't make a lot of sense, and the documentation is not entirely clear on a number of issues. I am attempting to run the amplifier in stereo BTL mode with analog input (via ADC). For simplicity, I'm trying to run it without any DRC, EQ, 3D, etc. In general I'm very frustrated and disappointed by the overall lack of quality of the documentation and the tool. I keep thinking I must be missing something or doing something wrong, but I'm very methodical and most people tell me I'm pretty smart. I hope I'm just missing something obvious. I am making sure to select the TAS5715 from the Devices menu in the GDE before I attempt to change any settings or connect to the EVM.
Jumpers don't match documentation: In the EVM User Manual SLOU304, page 12, section 4.2 Switches, it says "JP1 on the daughter card is for PBTL select", but there is no JP1 on the daughter card (either on the physical one I received in the package of on the schematics on pages 15-16. There is a JP1 on the MC57xxPSIA, but this does not control PBTL, it is connected to PSCK1 on DIR9001 and according to the note in the schematic on page 18 it controls SCKO = 512/256 Fs. There is no mention of this function/option in the text of the EVM User Manual.
MUTE button on MC57xxPSIA seems to have no effect.
Volume control behaves unpredictably, whether it is set before connecting to the EVM or while connected. Volume of the 2 channels doesn't match, typically one channel is horribly clipping and the other is silent or in a reasonable range. Master mute check box seems to have little to no effect for most volume settings. Some volume settings seem to make MUTE work for one channel (i.e. AB BTL), but not the other (i.e. CD BTL), but go even one step up *or* down from that volume setting, and MUTE no longer works and the volume change (if any) is completely uncorrelated to the direction of the volume setting change.
TAS57XX GUI "I2C Memory Tool" shows bits set after connect/reset that don't match spec sheet, some reserved bits set when I read registers listed in the spec sheet.
TAS57XX GUI Tool doesn't say what I2C registers/bits correspond to many settings. For example, there are many options available in the Properties window when nothing is selected, but no clear indication what I2C registers/bits are effected by these options. There are also several options here which have no clear explanation inthe spec sheet or user manual, such as the "NoDRC" option for DRCBand, and the "ternary" modulation type.
TAS57XX GUI Tool has a menu option for "I2C Logging", which would be very useful if it was what it's name implied, but enabling it doesn't seem to have any effect other than adding a check mark next to it in the menu, and I can't find anything in the on-line (built in Windows help from the program's Help menu) documentation for this feature. It isn't even mentioned. Indeed, much of the online help documentation for the software tool doesn't make sense. It talks about things like drawing signal flows and stuff as if it were a generic DAP/DSP designer for loading into a highly programmable DSP/DAP, not controlling the parameters of a fixed data flow device like the TAX5715.
The DAP functionality is not documented very well. In the spec sheet SLOS645, page 24 in "PWM Section", last sentence "For detailed description of using audio processing features like DRC, EQ, 3D, and bass boost, see the User's Guide and TAS570X GDE software development tool documentation". Isn't the software for this device actually TAS57xx GDE? Does one supersede the other? TAS570X GDE Software is provided in the forum post "TAS570X GDE software???" by Ravi Singh in this link:
7608.TAS570X_v2.0.1_Build_14.zip
I downloaded it and checked it out and it is different software than the TAS57X GUI Setup (Rev. A) linked from the TAS5715EVM page. Also, the TAS5715 doesn't have 3D, does it?
Is there some documentation I'm overlooking? There's no clear explanation of the "pre-scale" and "post-scale" values, or of how to select an appropriate volume setting to provide a particular output level/power for a given input signal
In spec sheet SLOS645, page 32, under "Headphone Support in the TAS5715", it refers to "lineout mode", but I can't find any other reference to "lineout" in the specification documents. Is that a copy and paste error of a feature from a different part?
No clear explanation of the difference, advantages, disadvantages, restrictions, etc. between "BD" and "AD" modulation, other than that for AD outputs are 180 degrees out of phase, and that this is the default. Also in the EVM User Manual SLOU304, page 11, the instructions say to "Select the Input MUX from the GDE", but there is no apparent input MUX. The modulation parameter does seem to be in the properties dialog box when nothing is selected, though.
Finally, a few nitpicky things about the documentation:
Spec sheet SLOS645 - AUGUST 2012
Page 1 in the "Benefits" bullet points, the last one "- Thgermal Dissipation..." Really? You don't run a spell check on documentation before releasing it?
Page 30, under "I2C SERIAL CONTROL INTERFACE" in the first paragraph, first sentence: "...single- and multiple-yte write and read..." "b" missing from "byte"
Page 32, under "Headphone Support in the TAS5715" last sentence of the first paragraph: "...and quite turn on and off." I assume this is supposed to be "quiet", nto "quite".
Page 33, under "Digital THD Manager", first sentence "...to achieve digitally the {specified ?} THD..." Why the braces and question mark? The purpose and function is also not clear. Why would you ever want to clip prematurely?
Page 39, under "26-Bit 3.23 Number Format", there is Table 2 "9.17 Format" significant text and figures and this entire section are dedicated to the "3.23" number format, but only Table 2 and one note in Table 3 on page 50 refer to the "9.17" format (for the Output pre-scale register contents). 9.17 seems like an afterthought.
Page 45, has sections for "Restrictions in Using 432-kHz Output Switching" and "I2C Commands to enable 423-kHz Switching" but this feature is not mentioned anywhere else in any documentation for TAS5715. Is this truly a feature? What is it used for, why would one want to use it, what are the effects of using it?
