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university:courses:electronics:switched-cap-power-supplies [10 Apr 2018 22:18] – Update Scopyshots. Add section breaks. Mark Thorenuniversity:courses:electronics:switched-cap-power-supplies [25 Jun 2020 22:07] (current) – external edit 127.0.0.1
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 ===== Circuit Construction and Testing ===== ===== Circuit Construction and Testing =====
 With the simulation understood, let's move on to actual components. Open the //LT1054_inverter.asc// schematic from the zip file in LTspice. Construct the circuit on a breadboard, following the LTspice schematic. With the simulation understood, let's move on to actual components. Open the //LT1054_inverter.asc// schematic from the zip file in LTspice. Construct the circuit on a breadboard, following the LTspice schematic.
 +
 +{{ :university:courses:electronics:sw_cap:lt1054_inverter_schematic.png?600 |}}
 +<WRAP centeralign> Figure 11. Inverter Breadboard circuit</WRAP>
  
 Build the following breadboard circuit for the voltage inverter. Build the following breadboard circuit for the voltage inverter.
  
-{{ :university:courses:electronics:sw_cap:lt1054_inverter_breadboard.png?600 |}} +{{ :university:courses:electronics:sw_cap:lt1054_inverter_breadboard.png |}} 
-<WRAP centeralign> Figure 11. Inverter Breadboard circuit</WRAP>+<WRAP centeralign> Figure 12. Inverter Breadboard circuit</WRAP>
  
 The circuit can also be soldered on a "Perma Proto" solderable breadboard from Adafruit, which matches the layout of typical solderless breadboards. The circuit can also be soldered on a "Perma Proto" solderable breadboard from Adafruit, which matches the layout of typical solderless breadboards.
  
 {{ :university:courses:electronics:sw_cap:lt1054_inverter.jpg?600 |}} {{ :university:courses:electronics:sw_cap:lt1054_inverter.jpg?600 |}}
-<WRAP centeralign> Figure 12. Inverter Circuit Soldered on PermaProto board</WRAP>+<WRAP centeralign> Figure 13. Inverter Circuit Soldered on PermaProto board</WRAP>
  
 Connect a voltmeter (or M2K in voltmeter mode) between circuit ground and the OUT pin of the LT1054, and Apply 5V to the IN pin. The voltmeter should read close to -5V. Connect a voltmeter (or M2K in voltmeter mode) between circuit ground and the OUT pin of the LT1054, and Apply 5V to the IN pin. The voltmeter should read close to -5V.
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 Set Scopy to Oscilloscope mode, with the following settings: Set Scopy to Oscilloscope mode, with the following settings:
  
-  * Timebase: 200us/div+  * Timebase: 250us/div
   * CH1, CH2: 1V/div   * CH1, CH2: 1V/div
   * Triggering: Ch1, -1V, Falling Edge, Single Shot mode.   * Triggering: Ch1, -1V, Falling Edge, Single Shot mode.
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 Momentarily short LT1054 pin 1 (FB) to ground. This disables the LT1054. Release FB; this allows the LT1054 to operate again, and produces a "clean" turn-on transient. You should see a waveform similar to the figure below: Momentarily short LT1054 pin 1 (FB) to ground. This disables the LT1054. Release FB; this allows the LT1054 to operate again, and produces a "clean" turn-on transient. You should see a waveform similar to the figure below:
  
-{{ :university:courses:electronics:sw_cap:lt1054_inverter_turn_on_scopy.png?800 |}} +{{ :university:courses:electronics:sw_cap:lt1054_inverter_turn_on_scopy.png |}} 
-<WRAP centeralign> Figure 13. LT1054 Inverter Startup Scopy Measurement</WRAP>+<WRAP centeralign> Figure 14. LT1054 Inverter Startup Scopy Measurement</WRAP>
  
 Run the LTspice simulation, and probe the corresponding nodes. You should see results similar to the figure below: Run the LTspice simulation, and probe the corresponding nodes. You should see results similar to the figure below:
  
 {{ :university:courses:electronics:sw_cap:lt1054_inverter_turn_on_ltspice2.png?600 |}} {{ :university:courses:electronics:sw_cap:lt1054_inverter_turn_on_ltspice2.png?600 |}}
-<WRAP centeralign> Figure 14. LT1054 Inverter Startup LTspice Simulation</WRAP>+<WRAP centeralign> Figure 15. LT1054 Inverter Startup LTspice Simulation</WRAP>
  
 This shows reasonable correlation between the simulation and actual measurements. This is a good thing, but it's always important to keep in mind that: This shows reasonable correlation between the simulation and actual measurements. This is a good thing, but it's always important to keep in mind that:
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 {{ :university:courses:electronics:sw_cap:lt1054_inverter_turn_on_ltspice_w_cap_current.png?600 |}} {{ :university:courses:electronics:sw_cap:lt1054_inverter_turn_on_ltspice_w_cap_current.png?600 |}}
-<WRAP centeralign> Figure 15. LT1054 Inverter Startup Simulation w/ Capacitor Current</WRAP>+<WRAP centeralign> Figure 16. LT1054 Inverter Startup Simulation w/ Capacitor Current</WRAP>
  
 If you built this circuit up on a PermaProto board, you can put it in a box and use it with your next project that requires a split (positive and negative) power supply. If you built this circuit up on a PermaProto board, you can put it in a box and use it with your next project that requires a split (positive and negative) power supply.
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 {{ :university:courses:electronics:sw_cap:switch_cap_pump_doubler_phase_0.png?500 |}} {{ :university:courses:electronics:sw_cap:switch_cap_pump_doubler_phase_0.png?500 |}}
-<WRAP centeralign> Figure 16. Doubler Phase 0</WRAP>+<WRAP centeralign> Figure 17. Doubler Phase 0</WRAP>
  
 **clk_bar** asserts, turning on S1. The lower terminal of C1 is driven to Vusb, and the Pump node is driven to Vusb plus another Vusb (minus a diode drop.) **clk_bar** asserts, turning on S1. The lower terminal of C1 is driven to Vusb, and the Pump node is driven to Vusb plus another Vusb (minus a diode drop.)
  
 {{ :university:courses:electronics:sw_cap:switch_cap_pump_doubler_phase_1.png?500 |}} {{ :university:courses:electronics:sw_cap:switch_cap_pump_doubler_phase_1.png?500 |}}
-<WRAP centeralign> Figure 17. Doubler Phase 1</WRAP>+<WRAP centeralign> Figure 18. Doubler Phase 1</WRAP>
  
 The result is that Vout is "pumped" to 2X Vusb, minus two diode drops. Probing Vout and Pump confirms this: The result is that Vout is "pumped" to 2X Vusb, minus two diode drops. Probing Vout and Pump confirms this:
  
 {{ :university:courses:electronics:sw_cap:switch_cap_pump_doubler_waveforms.png?600 |}} {{ :university:courses:electronics:sw_cap:switch_cap_pump_doubler_waveforms.png?600 |}}
-<WRAP centeralign> Figure 18. Doubler Startup LTspice Simulation</WRAP>+<WRAP centeralign> Figure 19. Doubler Startup LTspice Simulation</WRAP>
  
 As with the inverter circuit, the output takes several clock cycles to reach its final value due to charge sharing.  As with the inverter circuit, the output takes several clock cycles to reach its final value due to charge sharing. 
 ===== Circuit Construction and Testing ===== ===== Circuit Construction and Testing =====
 With the simulation understood, let's move on to actual components. Construct the LT1054 doubler circuit, following the LTspice schematic //LT1054_doubler.asc// from the zip file. With the simulation understood, let's move on to actual components. Construct the LT1054 doubler circuit, following the LTspice schematic //LT1054_doubler.asc// from the zip file.
 +
 +{{ :university:courses:electronics:sw_cap:lt1054_doubler_schematic.png?600 |}}
 +<WRAP centeralign> Figure 20. Doubler Schematic</WRAP>
  
 Build the following breadboard circuit for the voltage inverter. Build the following breadboard circuit for the voltage inverter.
  
-{{ :university:courses:electronics:sw_cap:lt1054_doubler_breadboard.png?600 |}} +{{ :university:courses:electronics:sw_cap:lt1054_doubler_breadboard.png |}} 
-<WRAP centeralign> Figure 19. Doubler Breadboard circuit</WRAP>+<WRAP centeralign> Figure 21. Doubler Breadboard circuit</WRAP>
  
 The circuit can also be soldered on a "Perma Proto" solderable breadboard from Adafruit, which matches the layout of typical solderless breadboards. The circuit can also be soldered on a "Perma Proto" solderable breadboard from Adafruit, which matches the layout of typical solderless breadboards.
  
 {{ :university:courses:electronics:sw_cap:lt1054_boost.jpg?600 |}} {{ :university:courses:electronics:sw_cap:lt1054_boost.jpg?600 |}}
-<WRAP centeralign> Figure 20. Doubler Circuit Soldered on PermaProto board</WRAP>+<WRAP centeralign> Figure 22. Doubler Circuit Soldered on PermaProto board</WRAP>
  
 Connect a voltmeter (or M2K in voltmeter mode) between circuit ground and the OUT pin of the LT1054, and Apply 5V to the IN pin. The voltmeter should read close to +8.6V. Connect a voltmeter (or M2K in voltmeter mode) between circuit ground and the OUT pin of the LT1054, and Apply 5V to the IN pin. The voltmeter should read close to +8.6V.
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 Set Scopy to Oscilloscope mode, with the following settings: Set Scopy to Oscilloscope mode, with the following settings:
  
-  * Timebase: 200us/div+  * Timebase: 250us/div
   * CH1, CH2: 1V/div   * CH1, CH2: 1V/div
   * Triggering: Ch1, +5V, Rising Edge, Single Shot mode.   * Triggering: Ch1, +5V, Rising Edge, Single Shot mode.
Line 228: Line 234:
 Momentarily short LT1054 pin 1 (FB) to ground. This disables the LT1054. Release FB; this allows the LT1054 to operate again, and produces a "clean" turn-on transient. You should see a waveform similar to the figure below: Momentarily short LT1054 pin 1 (FB) to ground. This disables the LT1054. Release FB; this allows the LT1054 to operate again, and produces a "clean" turn-on transient. You should see a waveform similar to the figure below:
  
-{{ :university:courses:electronics:sw_cap:lt1054_doubler_turn_on_scopy.png?800 |}} +{{ :university:courses:electronics:sw_cap:lt1054_doubler_turn_on_scopy.png |}} 
-<WRAP centeralign> Figure 21. LT1054 Doubler Startup Scopy Measurement</WRAP>+<WRAP centeralign> Figure 23. LT1054 Doubler Startup Scopy Measurement</WRAP>
  
  
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 {{ :university:courses:electronics:sw_cap:lt1054_doubler_turn_on_ltspice.png?600 |}} {{ :university:courses:electronics:sw_cap:lt1054_doubler_turn_on_ltspice.png?600 |}}
-<WRAP centeralign> Figure 22. LT1054 Doubler Startup LTspice Simulation</WRAP>+<WRAP centeralign> Figure 24. LT1054 Doubler Startup LTspice Simulation</WRAP>
  
-Note that there is a noticeable qualitative difference between the Scopy measurement and the LTspice simulation; the measured rampup appears more linear, while the LTspice rampup appears more exponential.+//Note that there is a noticeable qualitative difference between the Scopy measurement and the LTspice simulation; the measured rampup appears more linear, while the LTspice rampup appears more exponential.//
  
 ====== TBD: Activity 3: Voltage Divider ====== ====== TBD: Activity 3: Voltage Divider ======
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 ===== Questions: ===== ===== Questions: =====
  
 +<WRAP round download>
 +**Lab Resources:**
 +  * Fritzing files: [[downgit>education_tools/tree/master/m2k/fritzing/switch_cap_bb | switch_cap_bb]]
 +  * LTSpice files: [[downgit>education_tools/tree/master/m2k/ltspice/switched_cap_ltspice| switch_cap_ltspice]]
 +</WRAP>
  
 **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]** **Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]]**
  
university/courses/electronics/switched-cap-power-supplies.1523391496.txt.gz · Last modified: 10 Apr 2018 22:18 by Mark Thoren

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