Was done enjoying Friday afternoon
"hackathon" at WIN Enterprises Inc.
This is the logical continuation of simple dc-dc converter that has been described here. The same idea, only the current consumption of converter is reduced to 10uA due to the 'standby' state.
When at the input "ON/Sleep" level is low (0,8V or less), the output voltage Vout = ~1,9V. A high voltage (>1,5V) at this input forces output to ~3,1V.
The output voltage is controlled by software. When an increased voltage is required, the MSP430F2xx raises the signal at "ON/Sleep" input.
Both white LEDs are connected to Vout through 1k resistors and show when the output is above 2,4 volts.
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17.28.4. How it works.
According to the datasheet, MSP430F2xx operates in the voltage range 1,8V-3,6V. In the active mode, when software do something useful, the required voltage will depend on clock frequency.
For an example, for a 1MHz frequency, it suffices 1,8V (enough to run a 32.768kHz crystals). The voltage >1,8V will lead to the useless current consumption.
Another story is when you need to run analog-to-digital converter (ADC) or write to nonvolatile memory (flash memory). Flash requires at least 2,2V, ADC - 2,8V. Short-term switching to 3,1V will make these processes reliable.
In most cases, the MSP430 spends 99.9% of the time in the sleep. If this is not a case, then you are doing a very large number of calculations or the programmer was too lazy, which would put the microcontroller into Low-Power mode. In any case, even in this mode, voltage less than 1,8V (on the RESET pin) may lead to unpredictable stop or restart of MSP430.
Let's stop here. Any questions by e-mail.
* 3. Solar Garden Lights based on Integrated Circuits, schematics here
* X A simple dc-dc converter has been described here
* Y MSP430 for fun (not ready,yet)
* All schematics for reference, only.