Resistors on the digital in/output of a PGA2310 chip, why? - Page 1
Forum section: electronics / beginners

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 23, 2024, 07:30:11 pm
content: Hello again EEVblog people.I am fooling around with a little pre-amplifier design in EasyEDA, and I have hit a split in the design road regarding the PGA2310 chip.The chip itself have some options for chip-select, mute, Zero-crossing enable/disable and serial data output. The problem is that I have seen "conflicting implementation designs" when googling the chip.Some just connect the input pins directly to 5v and digital ground when operating the chip. Some have all signal pins connected to 5V through 10K resistors, which I have a hard time understanding why?I would thing if you wanted to hold the line "clean" you would drain all the line through 10K to ground?The datasheet doesn't mention anything about this. What is the proper way to do implement this chip?Also, there needs to be a single point link between the "AGND" audio ground and "DGND" digital ground, which if I understand, would benefit greatly from a ferrite bead "link", but witch one?I plan on using a cheap Arduino NANO clone as the controller, which I believe will be running at 20Mhz, if that matters regarding the noise I would try to impede?Is there a good choice for those on Mouser? I can't seem to find any.And lastly, is it an absolute must to have the link between AGND and DGND as close as possible to the chip, or can it be done elsewhere on the board?I do have a unity-gain buffer before the chip's audio inputs, so all sources should have enough power to drive it.If anyone have some knowledge to share, It will be greatly appreciated.Cheers from Denmark.

author: ledtester
author_rank: Super Contributor
timestamp: August 23, 2024, 07:52:39 pm
content: The resistors in R1 are being used as "pull-up resistors" to give digital signal lines a default logic high value when there is no overriding signal present.For example, the 10K resistor attached to the /MUTE line makes the /MUTE input line HIGH unless Q1 is turned on.Another example - the ZSEN is pulled high by one of the resistors in R1. This allows you to use the circuit without attaching anything to the JP6 header.Digital inputs should never "float" - they should always have a well-defined logic value and pull-up/pull-down resistors are one way to ensure that.For more info see, e.g.:https://www.electrical4u.com/pull-up-resistor/

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 23, 2024, 07:57:35 pm
content: Quote from: ledtester on August 23, 2024, 07:52:39 pmYes, but why not pulling them to ground? Is it just to keep the line high enough for the chip not to misunderstand something as being low when it isn't, or is it to make it easier for the logic to drive?If the Arduino is set to a low state, will it actually pull it's pin "low" or will it just float with no output?

author: ledtester
author_rank: Super Contributor
timestamp: August 23, 2024, 08:01:12 pm
content: You probably could pull some of them to ground.But look at /CS - if you pulled that to ground it would always select the chip. Or if /MUTE was pulled to ground it would mute the PGA by default.If you only want to use a single resistor network, pulling the lines high is the better option.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 23, 2024, 08:07:32 pm
content: Quote from: ledtester on August 23, 2024, 08:01:12 pmI guess it makes sense since the chip seems to have a threshold for when it actually sees something as a "high state".Could the chip be in a constant selected mode without problems? I only plan on using one chip.I guess the serial output needs to be connected to ground through a resistor?

author: ledtester
author_rank: Super Contributor
timestamp: August 23, 2024, 08:13:23 pm
content: Pull-ups/pull-down resistors are only needed if there is a chance that a digital input will not be presented with a well-defined logic voltage.If the /CS line of the PGA is more-or-less permanently connected to an Arduino digital output, you won't need the pull-up.You don't want a pull-up or -down on the serial output pin.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 23, 2024, 08:35:34 pm
content: Quote from: ledtester on August 23, 2024, 08:13:23 pmWell in that case I would prefer to just connect Zero-crossing and Mute to 5V.Quote from: ledtester on August 23, 2024, 08:13:23 pmI guess I can connect it directly to DGND in my case then?Quote from: ledtester on August 23, 2024, 08:13:23 pmGot it. floating it is then.Do you have any tips on the ferrite bead link between the AGND and DGND?Thank you for your time so far. It's nice to get these things confirmed.

author: ledtester
author_rank: Super Contributor
timestamp: August 23, 2024, 09:10:46 pm
content: QuoteYou should familiarize yourself with the SPI protocol. This stackexchange question addresses permanently grounding /CS:https://electronics.stackexchange.com/questions/443839/spi-with-chip-select-to-ground

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 23, 2024, 09:41:24 pm
content: Quote from: ledtester on August 23, 2024, 09:10:46 pmI have seen more than one solution that seemingly don't use anything other than the Serial date and Clock.I have uploaded a product that seems to get away with it?

author: ledtester
author_rank: Super Contributor
timestamp: August 23, 2024, 09:51:36 pm
content: Why do you want to cut so many corners? Get the circuit working first and then you can optimize it.Since you're designing a PCB the smart thing to do would be to add a footprints for a pull-down and pull-up resistor. Then you would have the flexibility to add a pull-up, ground the line or leave it alone.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 23, 2024, 10:04:40 pm
content: Quote from: ledtester on August 23, 2024, 09:51:36 pmThat's the thing. There isn't much room for what I have in mind, nor pins to go around from the Arduino.

author: ArdWar
author_rank: Frequent Contributor
timestamp: August 24, 2024, 03:34:44 am
content: If your SPI is only point-to-point you can get away with permanently pulling down the slave's nCS, and if you reallyreallyshort on space/pin there are even devices that support half duplex SPI.If your SPI is bussed then nCS control for each slave is a must. You can use decoder or shift register if pin count is a concern (irony aside).

author: ledtester
author_rank: Super Contributor
timestamp: August 24, 2024, 04:12:29 am
content: Quote from: ArdWar on August 24, 2024, 03:34:44 amYou really have to read the datasheet for the device.For instance, for the MAX7219 it explicitly says:Datasheet:https://www.analog.com/media/en/technical-documentation/data-sheets/MAX7219-MAX7221.pdfThis is because you can daisy-chain multiple 7219's like one long shift register so the CS line tells all chips when to lock in their data.The datasheet for the PGA2310:https://www.ti.com/lit/ds/symlink/pga2310.pdfdoesn't explicitly say that CS has to go HIGH but it does show it going HIGH after the 16th bit on page 9.Moreover, in Figure 12 on page 11 it shows how to daisy-chain multiple PGA2310's so -- like with the MAX7219 -- it stands to reason that CS needs to go HIGH in order for each chip to know when the controller has stopped sending data.

author: ArdWar
author_rank: Frequent Contributor
timestamp: August 24, 2024, 04:49:44 am
content: Okay my bad. It's one of those "technically up to standard but not in the usual expected way" devices.They really need to rename or append nCS into DL (for data latch) or something when it does more than just select (i.e. gating in) the data lines.

author: dietert1
author_rank: Super Contributor
timestamp: August 24, 2024, 09:22:12 am
content: Grounding the nCS input of a SPI device means it can't tell one bus transaction from the other. Once it got out of sync for whatever reason there won't be any recovery except power down and even that might not work well. Bad idea.Regards, Dieter

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 24, 2024, 10:14:55 am
content: Quote from: dietert1 on August 24, 2024, 09:22:12 amThat sound like it could result in some rather unpleasant sudden sound level changes in an noisy environments/ badly designed beginner circuits.In my case it would properly be best to utilize the CS so I can avoid being blasted by sudden +30db attenuation.Man, I fear the programming part of this project.I am still thinking about that bridge between AGND and DGND. Values and location.

author: dietert1
author_rank: Super Contributor
timestamp: August 24, 2024, 02:28:10 pm
content: The PGA2310 and PGA2311 are good and well known parts with code examples on the web, e.g.https://forum.arduino.cc/t/any-pga2310-volume-control-examples/22479/25.I remember fitting one into a vintage KMT N300 power amplifier. Those PA amplifiers had separate level controls for both channels. But for use with a TV set i wanted level and left/right balance instead and i wanted remote control. So the old pots were replaced by incremental encoders and a PGA2310 with MCU board. The firmware needs to save and restore the previous levels after power on.Regards, Dieter

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 24, 2024, 03:34:21 pm
content: Quote from: dietert1 on August 24, 2024, 02:28:10 pmOne thing is for sure, when the time comes for the coding, there will be pain between the eyes.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 25, 2024, 02:34:20 pm
content: Does anyone have some suggestion to a good choice for the ferrite bead bridge between AGND and DGND? Would it hurt if it was not located near the chip?

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 28, 2024, 09:48:06 pm
content: Anyone who can give me some tips regarding the ferrite bead bridge between AGND DGND?

author: dietert1
author_rank: Super Contributor
timestamp: August 28, 2024, 10:54:33 pm
content: Don't remember using a bead there, but you could design a SMD 0805 pattern to be fitted- as a solder bridge or- as a bead (like 22 uH or so)When using it for audio, there won't be much traffic on the digital side and close by buffer caps may be more important for low Gnd noise.Regards, Dieter

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 29, 2024, 07:40:29 am
content: Quote from: dietert1 on August 28, 2024, 10:54:33 pmI am avoiding SMD designs for now. I have seen the ferrite bead mentioned and used on some designs before.But perhaps it really is only needed in a fancy big audio/video receiver, or for professional equipment that could end up in all kinds of noisy environments?Regarding the noise and traffic on the digital side; The Arduino controlling the pga2310, will also be driving a display and 2 rotary encoders over I2C, as well as IR input and relays over dedicated pins.

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 29, 2024, 01:03:11 pm
content: Quote from: Dan R. Hansen on August 23, 2024, 07:57:35 pmit's easier to control perturbation with 5v level than gnd. in english, some 1V interference spike is coming from another device, if your line is staying to gnd with pull-down resistor, then on the line the result is 1V, triggering a logic 1, if your line is staying to 5 V with pull up, the result is 4V or 6V, so the line stays on logic 1,where it was before the spike. usually this technique helps with interference control, the discussion is longer but i tried to put it simple

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 29, 2024, 02:23:52 pm
content: Quote from: perieanuo on August 29, 2024, 01:03:11 pmI see.I think I read the chip rejects anything under 3 volt and won't read it as a "logic 1"?

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 30, 2024, 12:34:32 pm
content: Quote from: Dan R. Hansen on August 29, 2024, 02:23:52 pmSee Electrical Characteristics in the datasheet, Digital characteristic, and VIH(min 2V) and VIL(max 0.8V).VIH– voltage, input high – means that anything above 2V is considered high/logic 1.VIL– voltage, input low – means anything under 0.8V is considered low/logic 0.The range between those has no defined logic state, and should be crossed "quickly" by incoming signals.VOH– voltage, output high, min VD+- 1V at 200µA – means the digital outputs from PGA2310 will be within a volt or so of the positive digital supply when high/logic 1, if you draw at most 0.2mA from such pins.VOL– voltage, output low, max 0.4V at -3.2mA – means the digital outputs will be pulled to 0.4V or lower closer to ground, sinking up to 3.2mA of current, when low/logic 0.You'll find these specs in datasheets for all digital logic, including microcontrollers, although they usually depend on the supply voltage (in a nonlinear manner).

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 30, 2024, 02:06:48 pm
content: Quote from: Nominal Animal on August 30, 2024, 12:34:32 pmAs a newbie, I must admit a motorized potentiometer seems temptingly easy at times.

author: dietert1
author_rank: Super Contributor
timestamp: August 30, 2024, 02:22:18 pm
content: Whatever you pay for the potentiometer, it can't compete with the parameters of the PGA solution. A mechanical potentiometer may be good enough but we should not confuse things.Regards, Dieter

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 30, 2024, 02:30:34 pm
content: Quote from: dietert1 on August 30, 2024, 02:22:18 pmI am fully aware of that, and I am just saying a motorized pot is easy in many way, including programming. I know, since I have made more than once of these.I even strapped a little 5V servo to a potentiometer and controlled to position for volume. But that is the extend of my programming abilities. And that code for servo and IR were borrowed from around the internet.Have you seen one of these babies in the uploaded picture?

author: dietert1
author_rank: Super Contributor
timestamp: August 30, 2024, 03:26:57 pm
content: Looks good, yet still has the mechanical moving contact that we can nowadays avoid by switching inside a semiconductor.About 10 years ago i reported in one of those audio forums about my good experience with replacing output relays in active speakers by mosfet switches and everybody was like "Nobody does that, we have always been using relays." It takes a lot of time for people to understand the difference and some won't ever get it.Regards, Dieter

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 30, 2024, 04:14:04 pm
content: I'm only a hobbyist myself! Being able to read the datasheets has beenextremelyuseful for me, so I warmly recommend all electronics hobbyists to learn that._ _ _ _ _What kind of supply voltages do you have available? The PGA2310 needs basically three different supplies plus ground: +4.5V to +5.5V for the digital stuff, +4.5V to +15.5V positive analog rail, and a -4.5V to -15.5V negative analog rail. Even if you use +5V for both digital and positive analog rail, you still need a -5V negative analog rail.I suspect that you'll need a bit more complex solution to get all three, either from AC/DC converters from mains, or perhaps by using switchmode DC-DC converter(s) followed by some heavy filtering followed by linear regulator followed by filtering, for all three rails separately. This is more complicated, but much more effective than just a ferrite between shared analog and digital supply.There is at leastone thread at e2e.ti.comabout an user having a "noisy pga2310" discussing issues you might want to avoid. Clean analog supplies are crucial, but using aPGA2311instead is also suggested; Mouser has these in stock in various footprints, and JLCPCB has in stock in SOIC16 for assembly.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: August 30, 2024, 05:15:52 pm
content: Quote from: Nominal AnimalI am aware of these things. in my case it's going to be +/- 12v and 5v for logic. I am going for very simple 7812, 7912 and 7805.Quote from: Nominal AnimalSince I am still able to get relatively inexpensive toroidal transformers, it seems to still be cheater to go full "Old School" linear, and much easier for me to achieve good results.Dealing with the heat from the liner converters voltage drop, multiple relays, Arduino, etc, while not using a giant footprint for cooling could end up being a challenge, unless I use some active cooling.But if you know of some plans for a circuit that is cheap and effective at filtering the output of various switch-mode power supplies, please refer me to them. I would be delighted by such.Quote from: Nominal AnimalI fear the PGA2311 will not be able to achieve sufficiently wide peak to peak swing on its output, plus the low voltage becomes a problem when there are DRV134 op-amps in the mix. Which there are.I want to keep the amount of voltage supplies to a minimum, and that seems to limit my choice to voltages above what the PGA2311 is happy with.

author: quadtech
author_rank: Regular Contributor
timestamp: September 01, 2024, 09:05:18 am
content: I found this page to be quite useful for a volume control I needed -http://audio.gotroot.ca/minivol/

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 01, 2024, 09:43:43 am
content: Quote from: Dan R. Hansen on August 30, 2024, 05:15:52 pmSounds good to me. Forgive me for asking, I just wanted to check since it wasn't mentioned before.Quote from: Dan R. Hansen on August 30, 2024, 05:15:52 pmMost definitely, yes.Quote from: Dan R. Hansen on August 30, 2024, 05:15:52 pmNot a tested one yet, no, but the basic idea is very simple: a capacitive multiplier and/or a Pi low-pass filter between the switch mode supply and each linear regulator.TI Webenchis a very useful free online tool for various switchmode supply circuits, and KiCad can easily simulate various passive low-pass filter configurations, to find out how much noise is filtered out.Most of my projects are USB-powered; I prefer not to touch anything over 20V. I like to use microcontrollers with native USB to interface to Linux/Android-based appliances like switches, routers, TV boxes, even oscilloscopes –– now considering getting a Rigol DHO804, although it would consume my small electronics budget for months. My very first microcontroller project over a decade ago was an arcade controller on a birch glulam board, using Teensy 2.0++ to implement a keyboard, with selectable keys. I used it to play Flash-based online puzzle platform games, so needed a few different keyboard "layouts". No drivers needed on any OS, since its AT90USB1286 has a native full-speed USB 2.0 interface. Later on, Teensy LC (now discontinued too) made that very, very easy.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 03, 2024, 07:25:07 am
content: Quote from: quadtech on September 01, 2024, 09:05:18 amIt is indeed useful.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 03, 2024, 07:35:43 am
content: Quote from: Nominal Animal on September 01, 2024, 09:43:43 amSounds like a more advanced project. Adding impedance to the power supply seems like something the manuals of the OP-amps are warning against due to potential oscillation problems?Also, the reason "in my eyes to go for a switch-mode power supply, would be to avoid the negatives of a linear one. Mainly the the heat/waste, the need for big heatsinks, size, transformers etc.I don't see any reason to go with a switch-mode power supply, only to have to filter it heavily and then hook it up to a linear regulator. It just sounds like you get the worst of both worlds? A more complicated transformer.

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 03, 2024, 11:20:32 am
content: Quote from: Dan R. Hansen on September 03, 2024, 07:35:43 amIt's only between the switchmode supply and the regulator, to reduce the voltage ripple. There will be a few volts of headroom above the regulated voltage, so it won't actually increase the supply impedance because of the linear regulator following the filter. And, as usual, you'll have some bulk capacitance after the linear regulator too, reducing the effective output impedance.Quote from: Dan R. Hansen on September 03, 2024, 07:35:43 amSwitch-mode supplies are efficient, from something like 85% to 97% depending on the implementation.The linear regulator drops only a couple of volts, say 2.5V, but they have very good supply ripple rejection ratio (PSRR).If the load draws say two amps, the regulator only wastes five watts of power into heat.With a transformer, you need a higher nominal voltage to ensure the voltage is sufficiently high even at full load, so the linear regulator tends to waste more power into heat (possibly excepting the maximum load, where the transformer voltage is lowest, and the difference between transformer voltage and output voltage the smallest).At half the load, the regulator wastes two and a half watts, but the transformer one much more, because the lower load on the transformer causes its voltage to be higher, too.As I said, I'm only a hobbyist myself, but in proper designs, the switchmode supply is considered a "preregulator". You can even tie its voltage to a couple of volts above the output voltage from an adjustable regulator, and have the same efficiency/heat generation in the linear regulator over the entire output voltage range. For me, as I hate to work with mains voltages (~240 Vrms AC 50Hz here), I can use a typical laptop charger for about 20V DC, and work from that. TI Webench shows several DC-DC designs one could start from, adding a suitable feedback adjustment and the linear regulator stage. A TPS563300-based design from 17V-23V input to 7.5V output only needs a 10µH inductor, input and output and boot capacitors, and the feedback voltage divider, and will still be over 96% efficient over 200mA to 2A load range. Or, I can use aMean Well RPS-30-7.5AC/DC module, for a low-leakage class II supply; it has 80mV peak-to-peak ripple, so adding some bulk capacitance and a linear regulator to 5V should suppress the noise to microvolt range, peak-to-peak. 50µV peak-to-peak ripple at 5V corresponds to about 100 dB noise floor.If you have suitable transformers, and can get rid of the extra heat, it should be a better/easier/more robust solution – if you are willing to work with mains AC. I do like the idea of using a grounded AC plug, and linear regulators with their tab GND, so you can use a large heatsink at ground potential for cooling. Here, we don't have polarized plugs (so no live/neutral; both are effectively "live"), and I've heard lots of tales of live and neutral being wired incorrectly, soIpersonally would not want to try to make one myself; but if somebody else, more experienced, built one for me I'd sure use it.

author: selcuk
author_rank: Frequent Contributor
timestamp: September 03, 2024, 12:05:14 pm
content: You can omit the ferrite bead and connect AGND to DGND with a solid copper. The noise is coupled through a common impedance. So decreasing the impedance decreases the noise. And there is a risk of routing signals over split planes. Be careful about that when you route signals over different planes since you are planning to separate AGND and DGND planes according to the datasheet of PGA2310.Check "16.2 Guideline # 1: Never Route Signals Over Split Reference Planes":https://link.springer.com/chapter/10.1007/978-3-031-14186-7_16https://link.springer.com/chapter/10.1007/978-3-031-14186-7_14

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 03, 2024, 12:54:35 pm
content: Excellent link, selcuk; thanks! It seems a very good summary/guide especially for hobbyists like myself using EasyEDA or KiCad. (I don't presume to say on behalf of Dan R. Hansen.)I wanted to add that four-layer designs are quite cheap at JLCPCB (directly manufacturable from EasyEDA; similarly at others like PCBWay et cetera), and makes better EMC designs easier. I've done some hobbyist-level 2-layer boards (applying datasheets for digital microcontroller stuff, basically), and realized I have shied away from 4-layer boards for no good reason myself. (I still find BGA scary, mostly the soldering part.) In many cases at JLCPCB, the difference between five two-layer and five four-layer boards of the same size is just a couple of USD; typically it is just a few dollars, less than the shipping cost. Even if you intend to solder all components yourself, it can make sense to use a four-layer board just for EMC reasons.In EasyEDA, it is just as easy to do four-layer boards as it is to do two-layer ones. Just learn to use the Copper Area tool –– not that much to learn, just how to draw more complex polygons, adding and removing points (double-clicking), and how the settings like clearance and islands work ––, and the Tools > Layer Manager to control layer drawing order, colors, and transparency. On some tricky parts, like crystal oscillators that work better without a ground plane below, it can be useful to use multiple Copper Area polygons to achieve a continuous area with "holes", so learning how to do those can be useful.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 03, 2024, 07:35:06 pm
content: Quote from: selcuk on September 03, 2024, 12:05:14 pmI will attach a picture of something arranges quickly for demonstration purpose, within what little room I plan to give the circuit and PCB.In this case, would it be better to just have one big ground plane shared? Did Texas Instruments suggest the ferrite bead bridge because it works well in noise digital environments?The two 100ohm resistors seen in the picture are for giving the OP-amp a chance to survive a short on it's output. Although 100ohms might not be enough.

author: selcuk
author_rank: Frequent Contributor
timestamp: September 03, 2024, 09:13:01 pm
content: You may want to use a ferrite for special cases where you have a particular noise frequency and known source and load impedances. Then you can calculate the required ferrite impedance with the given data and have a resistive load (ferrite) for that particular noise frequency in order to convert noise energy into heat. But it can alter other circuit parameters so you want to use it if you have to. It acts as a common impedance on the signal return plane !In "Figure 15. Typical PCB Layout Floor Plan" in the datasheet, TI recommended to use separate planes and a single ground connection between AGND and DGND. And there is no signal going over to the other plane. I believe this is a very important detail on that figure. So using single ground plane on your design may be a better idea since you route the digital and analog signals all over the board.Additionally, if you are going to use a 4-layer board, you may use digital signals on top layer, DGND on inner top layer, AGND on inner bottom layer and analog signals on bottom layer. You can connect inner planes with multiple vias on one point under the chip. That should be equivalent of Figure 15, although I've never used this layer configuration myself.

author: dietert1
author_rank: Super Contributor
timestamp: September 04, 2024, 05:42:40 am
content: If you put analog and digital Gnd planes on top of each other, that's a capacitor, so about the opposite of a ferrite bead. To be honest, any relevant discussion requires making several alternative designs plus a test setup that can determine their differences.On the last design the MCU and rotary encoders are missing. Or read an existing potentiometer with the MCU's ADC and use that to drive the digital potentiometers.Regards, Dieter

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 04, 2024, 06:15:40 am
content: Quote from: selcuk on September 03, 2024, 09:13:01 pmIn my case, the header pins are actually sticking out from the bottom, which is why the power goes on the top layer, sort of.The same layout can actually be done on a two layer board, but then it will be impossible to join the grounds on the board itself. And it would clearly be much easier to make traces, if the output didn't have to terminate at two sets of output.I will work on the ground plane layout.

author: ArdWar
author_rank: Frequent Contributor
timestamp: September 04, 2024, 06:24:51 am
content: With this particular IC pin configuration it is indeed awkward trying to group inputs and outputs together.Your project got me interested in this part, partly because I rarely seen it in the wild. Now after I see the unit cost I understand why, wow.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 04, 2024, 06:38:33 am
content: Quote from: dietert1 on September 04, 2024, 05:42:40 amI think this would be a better option for my layout. It's two ground planes (analog and digital), meeting and a single 2.54mm point, as seen in the picture attached.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 04, 2024, 06:52:09 am
content: Quote from: ArdWar on September 04, 2024, 06:24:51 amThese chips use to be much cheaper 15 years ago. The PGA2310 is much more expensive than the PGA2311 and I would gladly have gone with that one, had it not been for the limited voltage of +/-5v, which seems to be limiting the max output to a little under 7.5v peak to peak output?That in itself is fine normally, but I plan to also have DRV134 outputs in the mix, and I don't think they like the low +/- 5v supply.Alternatively I could make a dedicated power stage for a PGA2311, regulating a +/-15v power down to +/- 5v, but then I will run out of space on the footprint plus it will add some cost and complexity. With that in mind, the PGA2310 seems like a better option for me.What is also a funny way to justify the cost of a PGA2310, is to simply compare it with the price of a motorized ALPS potentiometer. Chances are that the Alps motorized pot is significantly more expensive, it still requires some for of logic process, so you still have to get the same parts for that.And the PGA2310 performs much better than a motor pot. IF I can mangage to make it properly.

author: ArdWar
author_rank: Frequent Contributor
timestamp: September 04, 2024, 08:52:48 am
content: Quote from: Dan R. Hansen on September 04, 2024, 06:52:09 amIt's so expensive that two (in series to get comparable dynamic range) dual log digipot and a dual opamp still ends up much cheaper. Granted few are designed with audio in mind (noise, THD etc).

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 04, 2024, 09:02:11 am
content: Quote from: ArdWar on September 04, 2024, 08:52:48 amAnd the performance would be the same, or better? What about the footprint?

author: MarkS
author_rank: Unknown
timestamp: September 06, 2024, 09:44:27 am
content: In regards to the split ground, watch this. It's worth the time.https://youtu.be/vALt6Sd9vlY

author: ledtester
author_rank: Super Contributor
timestamp: September 06, 2024, 09:53:23 am
content: Quote from: MarkS on September 06, 2024, 09:44:27 ambtw - you can safely remove the si=... part of the url -- it is simply a tracking identifier.

author: wraper
author_rank: Unknown
timestamp: September 06, 2024, 10:13:47 am
content: IMHO pull-up resistors for otherwise unused CMOS IC inputs (that cannot become an output) come mostly from incompetence and because whoever designed it had seen it done somewhere else. It was needed for TTL (not really for LS TTL) but for CMOS it's just a waste of parts. On other hand it's not that rare to see CMOS inputs just left floating without external or internal pull-up. It was OK for TTL but not for CMOS.

author: MarkS
author_rank: Unknown
timestamp: September 06, 2024, 02:30:12 pm
content: Quote from: ledtester on September 06, 2024, 09:53:23 amTrue, but I posted it at 4:30 AM and just copied and pasted.

author: Dan R. Hansen
author_rank: Regular Contributor
timestamp: September 07, 2024, 09:23:14 am
content: Quote from: MarkS on September 06, 2024, 09:44:27 amIt seemed like it had a lot of interesting information, if the guy is right.From what I understand, in my specific case, I would actually want split ground plains because of the low frequencies that occur in audio.But I am still in doubt as to what way is the best to bridge the ground plain together?