Part of the week: TI TPL5111

Stumbled on this interesting part from TI recently

TPL5111

TPL5111 solves a typical problem in low power wireless systems- things need to be off most of the time, and wake up periodically to transmit. The usual solution is to pick a microcontroller that can stay asleep in low power mode at a few uA, then wake up on RTC timer. That works most of the time, but sometimes even that is too much standby power. Imagine a system for example that has to work from a small coin cell for 5-10 years. Each uA of sleep current is an 8mAh a year. So in 10 years, 80mAh is wasted. (A typical CR2032 battery for example starts with only 220mAh)

TI’s solution is a timer that can stay on while drawing 35nA. Once set with a single resistor for a particular time interval, between 100ms  and 2 hours, it turns power on to the system, waits to hear back from the micro via “done” pin and then turns things back off. TI even provides a handy table of resistor values vs timer settings. Not bad for $0.45@1k, plus there are many other scenarios such an almost zero power scheduler may be handy.  

Datasheet:

 

Watchdog Water Alarm teardown

Today we have a somewhat vintage teardown. Even though you can still buy this Watchdog BWD-HWA Water Alarm in home stores and online, the design itself probably goes quite a few decades back as we’ll see below. We’ll also learn a few things about low power design. Rumor has it these last forever on a nine volt battery!

Front view

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1mm pitch flex cable passthrough

By popular demand, the breakout/passthrough combination boards family now includes a 1mm pitch variant:

This version handles up to 30 signals which seems to be a practical limit of most 1mm FPC connectors. Each signal is numbered and brought to a 0.1 in spacing header for easy connection to your favorite logger/analyzer/scope. Continue reading

Flex cable passthrough breakout- 0.5mm

Introduction

Front side

Front side

Here is a product whose origin lies in the pain and suffering of an actual development project. Imagine you have a shiny new display made somewhere out there in a world that comes with a demo board and some datasheets.  So you take a display, hook it up to your favorite development board and try to follow the documentation. Except nothing works. And yet a a demo next to you works well, but is very tiny, has no test points and not documented. So you poke at the fine pitch flex connector with a scope for a bit, and realize you need a better way to capture what’s going on. Off you go to the lab and cobble together what is essentially a pass-through: two FPC breakout boards back to back, with a 0.1″ header in between.

How it started

Now you can hook up your trusty Saleae Logic analyzer and look at what the demo board is actually sending down as opposed to what the datasheet says it should. This board is exactly that, but made into one neat package. It can handle standard 0.5mm pitch FPC connectors up to 40 pins wide.

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