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Mikkel C. Simonsen
06/09/13 13:58
Read: 2433 times

#189891 - Low-power MCU needed
For a current project, I chose the Atmel AT89LP214 based on datasheet data. Low power consumption was one of the requirements.

The MCU spends most of the time in idle mode with a timer running. Then when the timer overflows, a port pin is flipped, the timer registers are reloaded, and idle mode is entered again. Based on the datasheet, I chose a 2MHz ceramic resonator. The current should be about 2.7mA in active mode and about 0.6mA in idle mode. The actual current is 2.7mA all the time - not what I expected. Using the internal 8MHz oscillator, the current should be 6/2mA, and it's actually the same 2.7mA, with the software running at 4x speed. If I change the software to work correctly at 8MHz, the consumption drops to 2.55mA. Better, but not great.

Are there better alternatives?

The requirements are quite simple:

- 5V operation
- 4 available push/pull output pins
- 1kB flash
- small(ish) size

I chose the LP214 because of the DIL-14 house also. A DIL-device is easy to program in a ZIF socket, and there isn't space for a DIL-14 and a programming header on the board. The IC shouldn't be too small either, as the boards have to be hand-assembled. A narrow SOIC-14 -20 would be ideal. The IC + programming header would be the same size as the DIL-14.

A device with an internal precision clock would be nice - provided it can be divided to be slow enough. A 12-clock device running at 4MHz is fast enough, so much "power" isn't needed...


List of 44 messages in thread
Low-power MCU needed      Mikkel C. Simonsen      06/09/13 13:58      
   OK, but wrong      Erik Malund      06/09/13 15:33      
      Wrong how?      Mikkel C. Simonsen      06/09/13 16:30      
         Silabs options      Jim Granville      06/09/13 16:53      
            C8051F99x      Maarten Brock      06/10/13 13:06      
               Silabs      Mikkel C. Simonsen      06/10/13 17:17      
                  look it up      Erik Malund      06/10/13 19:28      
                     Looked up      Mikkel C. Simonsen      06/11/13 16:26      
                        f53, no      Erik Malund      06/11/13 17:37      
                        C8051F537A is OK      Jim Granville      06/11/13 19:31      
         the current in active mode is not the issue      Erik Malund      06/10/13 05:30      
            Inactive current      Mikkel C. Simonsen      06/10/13 16:41      
         re: wrong      Jacob Boyce      06/10/13 06:56      
            Consumers      Mikkel C. Simonsen      06/10/13 09:54      
   Zilog Z51F0410       Jim Granville      06/09/13 16:46      
      Zilog      Mikkel C. Simonsen      06/10/13 17:01      
   Check you are entering idle ?      Jim Granville      06/09/13 16:48      
   idle current      Jan Waclawek      06/09/13 22:27      
      Idle test      Mikkel C. Simonsen      06/10/13 10:57      
         re:      Jacob Boyce      06/10/13 13:10      
            It floats! It floats!      Mikkel C. Simonsen      06/10/13 14:18      
               re:floats      Jacob Boyce      06/10/13 14:52      
               re:floats      Jacob Boyce      06/10/13 15:10      
                  Timers      Mikkel C. Simonsen      06/10/13 15:27      
         More idle tests      Jim Granville      06/10/13 19:33      
            Better regulator?      Mikkel C. Simonsen      06/11/13 18:19      
               LR8K4 450V regulator       Jim Granville      06/11/13 19:53      
         also try CLKREG      Jim Granville      06/10/13 19:47      
            Clk Dividers are a good idea      Jim Granville      06/11/13 01:03      
               No dividers      Mikkel C. Simonsen      06/11/13 18:11      
                  LP52 is cheaper too...      Jim Granville      06/11/13 20:04      
                     LP52      Mikkel C. Simonsen      06/17/13 20:24      
                        No GND pin?      Maarten Brock      06/18/13 11:34      
         re:idle      Jacob Boyce      06/11/13 13:30      
         Totally idle      Mikkel C. Simonsen      06/11/13 16:22      
            Checks      Jim Granville      06/11/13 16:33      
               More checks      Mikkel C. Simonsen      06/11/13 18:00      
                  Power Down ?      Jim Granville      06/11/13 18:59      
                  test setup      Jacob Boyce      06/12/13 08:33      
   STC      Mikkel C. Simonsen      08/17/13 18:22      
      C8051F86x/85x ?      Jim Granville      08/17/13 23:32      
      Maybe not such a good choice, after all?      Andy Neil      08/28/13 14:21      
         Support?      Mikkel C. Simonsen      08/28/13 14:31      
            '51 support      Erik Malund      08/28/13 15:49      

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