Here’s an interesting find on my CZ, one that I didn’t expect:
I noted on this forum before that I saw a respectable power drain when my CZ is off, I found it’s about 1-2%/day (I use Rockbox but noticed the same drain before with the Sandisk FW). After a recharge, I was noticing that drain when off for the most part was zero and couldn’t figure out why. I noticed I’d removed my microSD card to load some music on it and never reinserted it. I left the card out and after a week, my battery was still at 100%.
I plugged in the card into my CZ, recharged the battery and then turned it on once a day to monitor the battery charge state. Sure enough, the 1-2% drain showed up again, it only happens with the SD card in there. My wife has a CZ and I’m starting the test with hers today to see if it’s just mine or in the CZ design. For the record, my card is a Sandisk-branded 32GB card (class 4), and to the best of my knowledge it’s not a knock off, my player is the 8GB CZ running the lastest Rockbox FW (previously I had the latest Sandisk FW in it).
Anyone else noticed this? SD memory is flash and doesn’t need power in an off state. For some reason though the CZ hardware has a power drain when a micro SD card is inserted, the FW doesn’t make a difference. I thought that quite peculiar.
Interesting stuff, that. I saw mentioned here earlier that the player is never absolutely off–I wonder if having a card in the slot just causes a tiny bit more of the energy to drain.
Interesting stuff, that. I saw mentioned here earlier that the player is never absolutely off–I wonder if having a card in the slot just causes a tiny bit more of the energy to drain.
It’s more than a tiny amount. I don’t notice any drain after a week with no card, 7-10% after one week with the 32G card in. I figured NV memory would not be kept active, I see no reason for it as that’s it’s basic function, no power but memory retained. Apparently I’m wrong. I started a test with my wife’s CZ yesterday. Since it has the original Sandisk FW it’ll take longer to see the drain show up as a percentage as it doesn’t have the granularity of the Rockbox FW on my unit.
Also, no gizmo (that includes the CZ) can be fully off unless it has a true mechanical on/off switch. Those electronic switches like in the CZ require the guts to be active to some extent at all times so the switch can be sensed. That’s one gripe I have with a lot of electronics and I know why: either the designer wants fast start up (sometimes) or it’s cheaper (most likely). Items controlled by remote control could not be turned on/off with a pure mechanical switch for obvious reasons. Mechanical switches cost more than elecrtronic ones too. As an electronics engineer, namely designing power management ICs, I hate power usage when you’re not doing anything, aka ‘vampire power’ (the actual term used in the biz).
It’s more than a tiny amount. I don’t notice any drain after a week with no card, 7-10% after one week with the 32G card in. I figured NV memory would not be kept active, I see no reason for it as that’s it’s basic function, no power but memory retained.
As far as I know, all voltage regulators should be off when the device is powered down, so there shouldn’t be any way for a card to use power. I suspect this is just normal variation in how charged the battery appears.
Also, no gizmo (that includes the CZ) can be fully off unless it has a true mechanical on/off switch.
I’ve heard people say this before, but its absolutely nonsense. You can easily design devices with clip style buttons that require no power in the off state. You just have a circuit that powers up when a button press momentarily sends it a voltage.
Far from nonsense, the ULP circuit (clock) is actve; the Sansa is idle but not “off”.
The power swtch / button is the primary (hard wired) control input. Also, if the USB line goes active, the device will resume operation.
If the microSD card changes status while the device is in this “dormant” state, the device will begin with a refresh cycle upon power-up. This includes removal and reinsertion of the card while “off”.
It’s more than a tiny amount. I don’t notice any drain after a week with no card, 7-10% after one week with the 32G card in. I figured NV memory would not be kept active, I see no reason for it as that’s it’s basic function, no power but memory retained.
As far as I know, all voltage regulators should be off when the device is powered down, so there shouldn’t be any way for a card to use power. I suspect this is just normal variation in how charged the battery appears.
Also, no gizmo (that includes the CZ) can be fully off unless it has a true mechanical on/off switch.
I’ve heard people say this before, but its absolutely nonsense. You can easily design devices with clip style buttons that require no power in the off state. You just have a circuit that powers up when a button press momentarily sends it a voltage.
Sorry, but you’re wrong on some points. My CZ uses appreciable more power in off mode with the micro SD card in it than without. The amount is way outside of the “variation” in the battery indicator, way, way outside.
I also design ICs for pwr. management, there is ALWAYS some power in devices that don’t have true mechanical on/off switches. Show me a prodcut that has zero current draw that doesn’t have a true mechanical switch. I’ve never seen it. That’s why mobile power circuits are designed to stay at close to (but not quite) zero current, I know enough about the guts of many things like cell phones, TVs, and other products of the sort and they all have vampire current draw, all of them. It’s the nature of the beasts; without pulling the plug all electronic switches need some kind of keep-alive circuit, even if it’s nanoamps, since there’s no make/break ability in them if no power is used.
In any event, my CZ uses much more power with the SD card in place than not. I’m now experimenting with my wife’s unit to see if it does the same thing.
Sorry, but you’re wrong on some points. My CZ uses appreciable more power in off mode with the micro SD card in it than without. The amount is way outside of the “variation” in the battery indicator, way, way outside.
I guess you could try measuring the voltage on the SD pins and see if they’re powered up while the device is off. I doubt it though, there shouldn’t be any regulator on to provide that power.
I also design ICs for pwr. management, there is ALWAYS some power in devices that don’t have true mechanical on/off switches. Show me a prodcut that has zero current draw that doesn’t have a true mechanical switch.
Thats neither here nor there. Unless you physically put some millimeters of air in the ciruit, theres always some pico to nano amps of current just because FETs don’t really have infinite off resistance. Doesn’t mean its “on”, it just means theres some miniscule leakage.
That’s why mobile power circuits are designed to stay at close to (but not quite) zero current, I know enough about the guts of many things like cell phones, TVs, and other products of the sort and they all have vampire current draw, all of them.
Err, a TV can’t ever be off if it has a remote control since you have to keep the photodiode powered up. Likewise, most cell phones can’t actually be switched off since they perodically check in with the cellular network to see if they should reboot. If they didn’t, remotely powering a cell phone wouldn’t be possible.
So basically, what you’re saying is that devices that can’t actually be switched off will use power when they’re not switched off. Not exactly a brilliant observation, and certainly not evidence that you can’t build ICs that have negligible off current (say less then 1/10000 of the on current). You absolutely can. Just gate all the VRMs with a couple Megaohms off resistance and your off current can be made as small as you like.
Sometimes, I’ve noticed onboth my Fuze and Fuze+ that if, while the player is “off”, I remove the card, add music, and reinsert the card, when the device powers up, it recognizes that it needs to refresh the DB. I suspect that when the unit is “off”, it activates the SD controller chip every now and again to see if the card is present. Perhaps it stops when it detects the absence of the card, it stops, and if it detects the presence of a card AFTER , power-on, it refreshes.
If the MicroSD is monitering the presence/absence that might explain the the increased power usage.
Sometimes, I’ve noticed onboth my Fuze and Fuze+ that if, while the player is “off”, I remove the card, add music, and reinsert the card, when the device powers up, it recognizes that it needs to refresh the DB.
What happens is when you power up it checks to see if the FAT is modified since the last boot. If it is, you get a refresh. If not, you don’t. Theres no need to poll the SD card to do that though. It happens basically ‘for free’ when you mount the SD storage.
