I bought one of this modules (link), with the SYN470 chip on it.

In the datasheet it's mentioned that in continuous mode with 433 MHz the current consumption is 3.9 mA which is a lot in my case.

But there's a polled operation mode which uses way less current and it also have a WAKEB pin, which I don't know what they are or how do I use them and there is no example of such circuit in the datasheet.

How can I configure this module to consume less power?

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    \$\begingroup\$ Do realize that if you power down the receiver it will not receive anything while in power down. So when you transmit a signal, it has to be present long enough for the receiver to receive it in the short time that it is enabled. \$\endgroup\$ Commented Sep 21, 2020 at 9:58
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    \$\begingroup\$ WAKEB pin, which I don't know what they are or how do I use them Read the datasheet: "Wakeup (Digital Output): Active-low output that indicates detection of an incoming RF signal" So it is an output that turns low when a signal is received (the received RF signal has more power than a certain level). This will only work when the receiver is powered on so for saving power consumption of the SYN470, the WAKEB pin doesn't help. \$\endgroup\$ Commented Sep 21, 2020 at 10:04
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    \$\begingroup\$ That takes 3.9 mA. Find the current, or find a different approach. Like the polled approach I outlined above. \$\endgroup\$
    – user16324
    Commented Sep 21, 2020 at 10:04
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    \$\begingroup\$ Define: "any moment". Do you need a response within 1 us or is 100ms also OK? If you want an "immediate" response (as fast as possible) then the receiver needs to be on continuously. There is no way around that. So be specific in what you actually need because there lies the "design space" that can be used to lower the power consumption. \$\endgroup\$ Commented Sep 21, 2020 at 10:08
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    \$\begingroup\$ @ElectronSurf well, then, my answer hits exactly the right point: the 500ms is a typical inter-wakeup time, and "as long as it's received whenever its sent" isn't a given with such a simple receiver without any error correction. \$\endgroup\$ Commented Sep 21, 2020 at 10:14

1 Answer 1


Only skimmed through the datasheet, but as usual:

You can simply shut down the receiver for as long as you're not using it. Then, wake it up every e.g. 0.5 s, listen for a couple milliseconds, see whether there's a preamble going on, and else go back to sleep.

It requires, however, that the transmitter sends a preamble for 0.5s. That shifts the power demand from the receiver to the transmitter.

That happens to be exactly the thing that the emergency pagers for firemen do.

I have an answer where I explained why receiving needs much energy; there's really no way around it. You can make your receiver less hungry by turning it off and on, but that requires a fast "turn on" time.

Also, your receiver should use as little watt per (bit per second) as possible. Your 470R seems to be pretty terrible at that – 2.5 mA for 1 kbit/s, where other receivers (example, see page 35, 36) do much more data with only a little more power. The quicker your reception is finished, the more you can turn off the receiver again, the less energy you used.

By the way, this is really a very basic receiver. You'll definitely have to add error correction, unless you can live with the 1% bit errors that the datasheet says all measurements were made with. And you usually can't. So, there's a microcontroller somewhere that takes the data coming out of your receiver, and decoding them, correcting errors on the way. You'll have to factor in the extra bits you need to transmit to be able to correct errors, and also the computational effort to correct the errors at the receiver, into your power design.

  • \$\begingroup\$ What interval do you think works the best? 1 sec ON and 500ms OFF? \$\endgroup\$ Commented Sep 21, 2020 at 10:15
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    \$\begingroup\$ That is impossible to tell without knowing your application in detail. It's up to you to define. \$\endgroup\$ Commented Sep 21, 2020 at 10:16
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    \$\begingroup\$ Also, you have an incredible broad range of interests: yesterday you were trying to build a buck converter from 555, today you're doing a digital receiver: Are you a whole group of engineers? \$\endgroup\$ Commented Sep 21, 2020 at 10:18
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    \$\begingroup\$ I'm a hobbyist, I do something everyday to keep my self busy. sometimes I do several projects simultaneously. it's fun ;) \$\endgroup\$ Commented Sep 21, 2020 at 10:32
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    \$\begingroup\$ Also consider that some of these illegal alibabas might be wideband, sending a several MHz wide signal, spilling out beyond the allowed band etc. Great efficiency then, kind of like driving two cars in both lanes at once, instead of one car in a single lane. Works fine until you crash or the police notices you... \$\endgroup\$
    – Lundin
    Commented Sep 21, 2020 at 10:52

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