What microcontroller is used in car keys? Why is the power consumption so low?

大牛哥

What microcontroller is used in car keys? Why is the power consumption so low? [Copy link]

 

The car key has been used for 8 or 9 years and seems to still work. I was very curious and measured it. Why is the standby power consumption so low? How can the MCU sleep current be so low? Is it because the MCU is not used? Or does it turn on the power only when the switch is pressed?

sint27

A car key is so expensive, it's not too much to use a good MCU

大牛哥

sint27 posted on 2020-10-21 15:48 A car key is so expensive, it’s not too much to use a good MCU

The key point is that I have never seen an MCU with such low power consumption for sale. The lowest is around 1uA. Have you ever seen an MCU with around 10nA?

chunyang

Some have MCU, some don't, just a rolling code encoding and transmission circuit. There are many common MCU manufacturers for remote controls with MCU, including major international mainstream MCU manufacturers, such as TI, NXP, MicroChip, etc. The models are all dedicated, integrating MCU, encoding and wireless transmission together. Because the chip is dedicated and has a single function, the power consumption control can be highly optimized.

sint27

Da Niu Ge published on 2020-10-21 16:05 The key is that I have never seen an MCU with such low power consumption for sale. The lowest is about 1uA. Have you ever seen an MCU with about 10nA?

As far as I know, TI has such low power consumption, nA is not a problem

qwqwqw2088

This shows that low-power products from 7 or 8 years ago are still OK

Which car key?

The current of TI wireless MCU CC2650F128RGZ in sleep mode is 1 A.

w494143467

Is it possible to not sleep, just turn off the power, and then power on and send commands after pressing? I always thought that some key remote controls work in this way, but I'm just guessing. You can take it apart and look at the chip inside (if the silk screen is still there).

freebsder

Take one apart when it's scrapped.

szcqcc

w494143467 posted on 2020-10-21 20:40 Is it possible not to sleep, but to directly cut off the power, and then power on and send commands after pressing. I have always thought that some key remote controls work in this way, but I am just guessing...

I thought so at first, but the button time was very short, and it took 1 second to send the code.

szcqcc

sint27 posted on 2020-10-21 17:10 As far as I know, TI has such low power consumption, nA is not a problem

I'll check it out too. There's a project that I can use for 10 or 8 years. That would be great.

szcqcc

chunyang posted on 2020-10-21 16:14 Some have MCU, some don't, just a rolling code encoding and transmitting circuit. There are many common MCU manufacturers for remote controls with MCU, including major international MCU manufacturers...

The moderator is indeed the moderator, well-informed

szcqcc

qwqwqw2088 Published on 2020-10-21 20:32 Explain which car key of 7 or 8 years of low power consumption products is still good. Now I know that TI wireless MCU CC2650F128RGZ is in sleep mode, power...

Ford, all brands are similar, I see people around me say they haven't changed the battery for several years

大牛哥

sint27 posted on 2020-10-21 17:10 As far as I know, TI has such low power consumption, nA is not a problem

Does anyone have any specific model recommendations? I'm thinking of making a product that's similar to a car key, with wireless code transmission and a longer standby time, but I looked around on ti but couldn't find one that's exactly like a car key.

qwqwqw2088

Brother Daniu published on 2020-10-22 10:37 Do you have any specific model recommendations? I am planning to make a product similar to a car key, with wireless code transmission and a longer standby time, but I have searched around on ti but couldn't find one...

TI has a Passive Entry Passive Start (PEPS) solution

CC_wei

Recently, the company is preparing to develop products with ultra-long standby time, and has also encountered a problem that the industry cannot overcome.

wsmysyn

w494143467 posted on 2020-10-21 20:40 Is it possible not to sleep, but to directly cut off the power, and then power on and send commands after pressing. I have always thought that some key remote controls work in this way, but I am just guessing...

It seems that there is a fully shut down mode. In the low power mode of the image and speech recognition chip we make, all power except the always on module is indeed turned off in the chip. Only some external wake-up interrupts and some necessary small modules are kept working in the always on mode, which can reach dozens of uA.

w494143467

szcqcc posted on 2020-10-21 21:27 I thought so at first, but the button time was very short, and it took 1 second to send the code

Is there a capacitor or program that is a switch that opens when pressed, and then waits for a while for it to close, similar to self-locking, but can be controlled by itself?

w494143467

wsmysyn posted on 2020-10-22 11:23 It seems that there is a full shutdown. The chip we make, the image and speech recognition chip, in the low power mode, it does turn off the modules except the always on module...

There should be many ways to achieve low power consumption, and different methods should be selected according to different scenarios. However, this requires in-depth research. As an outsider, I can only watch the show.

大牛哥

wsmysyn posted on 2020-10-22 11:23 It seems that there is a full shutdown. The chip we make, the image and speech recognition chip, in the low power mode, it does turn off the modules except the always on module...

Haha, a few uA is not considered low power consumption. What confuses me is that the MOS off-state current is not at the nA level either.

大牛哥

w494143467 Published on 2020-10-22 12:40 Is there a capacitor or program that is a switch that opens when pressed, and then waits for a while for it to close, similar to self-locking, but can be controlled by itself...

Well, even MOS electronic switches will leak electricity, and it is still a bit difficult to make external switches. Maybe it is this mechanism, but chip manufacturers should have the conditions to do better. I have seen that TI does have nA-level MCUs, but I haven't found one that can send codes yet.