EYE on NPI - ABLIC S-35710/20 Series Convenience Timer ICs #EYEonNPI @ADI_News @DigiKey @Adafruit
Channel: Adafruit Industries
Date: 21/07/2022

This week's EYE ON NPI is OK with you going back to sleep...shhh! Rest up, it'll wake you up when it's time to go...we're reviewing the new ABLIC S-35710/20 Series Convenience Timer ICs (https://www.digikey.com/en/product-highlight/a/ablic/s-35710-20-series-convenience-timer-ics). These are a great solution for when you need to turn a non-low-power system into something that sips power.

When we first started on our embedded electronics journey, with boards like the Arduino, power management wasn't a high priority: you'd plug something into DC or USB power and it would sit there blinking lights or moving servos. Even if you did have a battery-powered project, those same LEDs or motors would be so high-power consuming that trying to optimize power wouldn't be a great use of time: anyways the regulator and chip are just not designed to be low power (https://analysisnorth.com/articles/arduino-for-a-year.html) and would need replacing, something that would add significant cost.

For many years, folks were basically ok with this arrangement! Chips did start having sleep modes, but it was not surprising that one would have to re-design or spend more just to get low power performance. Then, with the proliferation of low cost and low-power-optimized WiFi (https://www.digikey.com/en/supplier-centers/espressif-systems) and BLE chipsets (https://www.digikey.com/en/supplier-centers/nordic-semiconductor) plus low cost LiPo batteries, the demand for devices that can last for days or weeks on a rechargeable battery became a roar. Now it's expected that any design can become a low power one.

OK cool - but what if you're dealing with a chip or module that does not have ultra low sleep - say you want to use the cool new Pico W from Raspberry Pi - but the RP2040 chip's sleep current is 0.2mA (https://forums.raspberrypi.com/viewtopic.php?t=316458). That's low but perhaps not low enough for your needs. The ESP32 series, by comparison, can hibernate at 0.005mA / 50uA, 1/25th the current. But perhaps even that is considered too much! Or perhaps it's the regulator that is drawing more current - 50uA or more is pretty normal for an LDO.

That's where the ABLIC S-353710/20 Series Convenience Timer ICs comes in! (https://www.digikey.com/short/z952dntf)  If your use case has consistent and periodic wake-ups, these chips can be programmed via I2C to wake up every 'n' seconds with a 24 bit counter. That means you can go from 1 second to 2^24 seconds, 194 days! The output can control a power transistor or enable-pin for your power system, to give you the lowest-possible current draw: since the chip can run from 2 to 5V, just power it directly from your battery input. Current draw is about 0.2uA, which beats even the lowest-power microcontrollers or LDOs.

There are three versions of this family, the S-353720 (https://www.digikey.com/short/r797trjn) which uses two pins to set fixed wake-times of 1, 10, 30 and 60 seconds. We recommend the MSOP version of the S-353710 (https://www.digikey.com/short/f2j7dhqp) which is I2C programmable up to 194 days. Finally, there's also the SOIC version of the S-353710 (https://www.digikey.com/short/dj9tzz1q) which is basically the same as the MSOP one, but has a built in crystal for simpler assembly but higher cost.

No matter which version you choose, all types of ABLIC S-353710/20 Series Convenience Timer ICs (https://www.digikey.com/short/z952dntf) are in stock at Digi-Key for immediate shipment! Order today and they will not snooze even 1 second before packing your order and sending it to you, so you can get working on optimizing your design to the lowest power possible by tomorrow afternoon.