I'm trying to design a wireless temperature sensor powered by one (or maybe two) rechargeable NiMH AA cell(s). The sensor should read and transmit the temperature every couple of seconds and remain in low power consumption mode the rest of the time.
I'd like the sensor to be built with the following components:
- ATtiny85-20PU or ATmega328P-PU as MCU (1.8-2.7 to 5.5V)
- TWS-DS-6 433.92MHz RF Transmitter (1.5 to 12V)
- The obsolete LM35DZ Precision Centigrade Temperature Sensor (4 to 30V)
To power these components with the batteries I chose, I suppose I'll need a boost converter that generates 4 to 5V out of 1.2 to 1.5V input (or 2.4 to 3V if I use two cells).
My problem is that I can't find the right boost converter that is simple and cheap enough for me to build, and that I can easily get parts for. For example, I've found these really cool resources online:
- Maxim's Switching Regulators for Battery-Powered Applications - a quick guide to choosing switching regulators for battery powered applications, with links to parametric searches on Maxim's site.
- Linear's App Note 30 - Switching Regulator Circuit Collection
From App Note 30 above, I could select a couple of circuits that I think could meet my requirements, such as:
- Figure 9. Boost Converter (1.5V to 5V)
- Figure 11. Single Cell Up Converter (1.5V to 5V)
The problems I have with those circuits is that I don't have easy access to some of the components, such as the LT1018, LM10 or the TRIAD SP-29 (I don't even know what that is), for example.
So, my question is what would be an appropriate boost voltage regulator circuit for my specs?