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Deep Sleep Mode on Microchip PIC18F and PIC24F MCUs

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To provide an overview of Deep Sleep mode in PIC MCUs

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Deep Sleep Mode on Microchip PIC18F and PIC24F MCUs

  1. 1. Deep Sleep Mode on Microchip PIC18F and PIC24F MCUs <ul><li>Source: M ICROCHIP </li></ul>
  2. 2. Introduction <ul><li>Purpose </li></ul><ul><ul><li>To provide an overview of Deep Sleep mode in PIC MCUs </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>Overview deep sleep feature </li></ul></ul><ul><ul><li>Average current consumption in a typical deep sleep application </li></ul></ul><ul><ul><li>Various wake-up sources </li></ul></ul><ul><ul><li>A typical Deep Sleep firmware flow diagram </li></ul></ul><ul><ul><li>Microchip PIC18F & PIC24F families </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>26 pages </li></ul></ul>
  3. 3. Vocabulary <ul><li>RTCC – Real-Time Clock/Calendar </li></ul><ul><li>DSWDT – Deep Sleep Watchdog Timer </li></ul><ul><li>ULPWU – Ultra Low-Power Wake-Up </li></ul><ul><li>DSBOR – Deep Sleep Brown-Out Reset </li></ul>
  4. 4. What is Deep Sleep? <ul><li>Core, Peripherals and SRAM Powered-Off </li></ul><ul><li>Lowest Power Mode: </li></ul><ul><ul><li>Deep Sleep as low as ~20 nA! </li></ul></ul><ul><ul><li>Deep Sleep with RTCC as low as ~500 nA </li></ul></ul><ul><li>External Switches Not Required </li></ul><ul><li>I/Os Remain Powered, Certain Peripherals Still Operable </li></ul>
  5. 5. Battery Power <ul><li>Most of microcontrollers require extra battery or dedicated pins for RTCC </li></ul><ul><li>RTCC can operate in Deep Sleep, powered by V DD </li></ul><ul><li>Deep Sleep can run off of battery power for years! </li></ul>
  6. 6. How is This Different Than Sleep? <ul><li>Consumes 90% Less Current! </li></ul><ul><li>Context Saving </li></ul><ul><ul><li>Two Deep Sleep registers for context save will retain data </li></ul></ul><ul><ul><li>Rest of SRAM data not retained </li></ul></ul><ul><ul><li>Self-programmed FLASH or EEPROM could also be used </li></ul></ul><ul><li>Internal Core Voltage Regulator Shut Down </li></ul><ul><li>Wake-Up Causes a Power-On Reset </li></ul><ul><ul><li>Execution resumes at the Reset vector </li></ul></ul><ul><ul><li>Most SFRs reset to default values </li></ul></ul>Active Sleep Deep Sleep Current Consumption
  7. 7. When to Use Deep Sleep? <ul><li>Great for applications that are inactive for long periods of time </li></ul><ul><ul><li>Remote Controls · Input Devices </li></ul></ul><ul><ul><li>Sensors · Digital Thermometers </li></ul></ul><ul><li>Ideal for applications that require accurate timekeeping while consuming minimum power </li></ul><ul><ul><li>Sprinkler Timers </li></ul></ul><ul><ul><li>Thermostats </li></ul></ul><ul><ul><li>Watches </li></ul></ul><ul><ul><li>Digital Clocks </li></ul></ul>
  8. 8. What Defines Low Power? Current Operation Time Device Running 1.5 mA @ 4 MHz
  9. 9. What Defines Low Power? Current Operation Time Device Running 1.5 mA @ 4 MHz Powers Down
  10. 10. What Defines Low Power? Current Operation Time Device Running 1.5 mA @ 4 MHz Powers Down Deep Sleep 20 nA
  11. 11. What Defines Low Power? Current Operation Time Deep Sleep 20 nA Device Running 1.5 mA @ 4 MHz Powers Down
  12. 12. What Defines Low Power? Current Operation Time Wake-up Time 50 µs Device Running 1.5 mA @ 4 MHz Powers Down Deep Sleep 20 nA
  13. 13. What Defines Low Power? Current Operation Time Device Running 1.5 mA @ 4 MHz Device Running 1.5 mA @ 4 MHz Powers Down Deep Sleep 20 nA Wake-up Time 50 µs
  14. 14. What Defines Low Power? Current Operation Time Lowest Average Current Device Running 1.5 mA @ 4 MHz Powers Down Deep Sleep 20 nA Device Running 1.5 mA @ 4 MHz Wake-up Time 50 µs
  15. 15. What Can Remain Operating? <ul><li>RTCC Continues To Keep Time </li></ul><ul><ul><li>RTCC pin can output seconds clock </li></ul></ul><ul><li>I/O Pins Maintain State </li></ul><ul><li>Special Deep Sleep Registers Retain Values (DSGPR0, DSGPR1, RTCC date/time) </li></ul><ul><li>DSBOR </li></ul>
  16. 16. Waking Up From Deep Sleep <ul><li>INT0 </li></ul><ul><li>Deep Sleep Watchdog Timer </li></ul><ul><li>RTCC Alarm </li></ul><ul><li>Ultra Low-Power Wake-Up </li></ul><ul><li>MCLR </li></ul><ul><li>(power off / power on) </li></ul>
  17. 17. Waking Up by INT0 <ul><li>INT0 </li></ul>
  18. 18. Waking Up by DSWDT <ul><li>Deep Sleep Watchdog Timer (DSWDT) </li></ul><ul><li>No external circuit required for internal RC oscillator </li></ul><ul><ul><li>Use to guard against crystal failures </li></ul></ul><ul><li>Secondary Oscillator Can Be Used Optionally as Clock Source </li></ul><ul><li>16 Different Timeout Settings Available </li></ul><ul><ul><li>2.1 ms, 8.3 ms, 33 ms, 132 ms, </li></ul></ul><ul><ul><li>528 ms, 2.1s, 8.5s, 34s, </li></ul></ul><ul><ul><li>135s, 9m, 36m, 2.4h, </li></ul></ul><ul><ul><li>9.6h, 38.5h, 6.4d, 25.7d </li></ul></ul>
  19. 19. Waking Up by RTCC Alarm <ul><li>RTCC Alarm </li></ul><ul><li>Alarm resolution from seconds up through days, years </li></ul><ul><li>Can Use the Same Clock Sources as DSWDT </li></ul><ul><ul><li>Save power: avoid using two different clock sources </li></ul></ul><ul><li>Optionally Output a Seconds Clock or Alarm Pulse on RTCC Pin During Deep Sleep </li></ul>
  20. 20. RTCC/DSWDT Clock Sources 31 kHz Internal RC Secondary Oscillator
  21. 21. Waking Up by ULPWU <ul><li>Ultra Low-Power Wake-Up </li></ul>
  22. 22. Waking Up by ULPWU <ul><li>Ultra Low-Power Wake-Up </li></ul>Voltage Time ~0.5V threshold reached, device wakes up ULPWU enabled Deep Sleep entered I/O pin output high, capacitor charges Small pull-down current discharges capacitor
  23. 23. Firmware Overview Release State Enter Deep Sleep Reset Vector Enable Secondary Osc Set Deep Sleep registers Read Deep Sleep registers & restore context Y Perform Application Tasks N Woke from Deep Sleep? Wake-Up
  24. 24. Family Roadmap 3.5 µA at 2.15V 80 nA at 1.8V 1.2 µA at 2.15V Typical Sleep Current at 25C 25 µs 5 µs 275 µs Typical Sleep Wake-Up Time Yes No Yes Power Needed to Recharge VDDCORE Capacitor on Wake-Up 2x16-bit DSGPR FLASH 2x16-bit DSGPR FLASH EEPROM 2x8-bit DSGPR FLASH Context Saving ULPWU Support Other Family Features 1-2 ms 50 µs 1-2 ms Typical Deep Sleep Wake-Up Time 500 nA at 2.15V 500 nA at 1.8V 500 nA at 2.15V Typical Deep Sleep Current with RTCC at 25C 24 nA at 2.15V 20 nA at 1.8V 24 nA at 2.15V Typical Deep Sleep Current at 25C Yes No Deep Sleep when VREG disabled No Yes No Deep Sleep when VREG disabled (LF parts) Core Voltage Regulator PIC24FJ64GA104 PIC24F16KA102 PIC18F46J50/11
  25. 25. Deep Sleep Summary <ul><li>Use for devices that have long periods of inactivity </li></ul><ul><li>Deep Sleep is the lowest power mode </li></ul><ul><li>RTCC can keep time during Deep Sleep </li></ul><ul><li>Several wake-up sources available </li></ul><ul><li>Special registers available to save state information </li></ul>
  26. 26. Additional Resource <ul><li>For ordering PIC18 & PIC24 MCUs, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li>www.microchip.com/lowpower </li></ul></ul><ul><li>Visit Element 14 to post your question </li></ul><ul><ul><li> www.element-14.com </li></ul></ul><ul><li>For additional inquires contact our technical service hotline or even use our “Live Technical Chat” online facility </li></ul>

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