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university:courses:alm1k:alm-lab-16 [22 Jul 2016 21:30]
Doug Mercer created
university:courses:alm1k:alm-lab-16 [05 Nov 2021 15:21] (current)
Doug Mercer [Activity: Capacitor Based DC-DC Converters]
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-======Activity ​16: Capacitor Based DC-DC Converters======+======Activity:​ Capacitor Based DC-DC Converters ​- ADALM1000======
  
 =====Objective:​===== =====Objective:​=====
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 Scope traces are similarly referred to by channel and voltage / current. Such as CA-V , CB-V for the voltage waveforms and CA-I , CB-I for the current waveforms. Scope traces are similarly referred to by channel and voltage / current. Such as CA-V , CB-V for the voltage waveforms and CA-I , CB-I for the current waveforms.
  
-The circuits used in this Lab activity while generally low current can produce voltages beyond the 0 to 5 V analog input range of the ALM1000. Input voltage divider techniques as discussed in the document on ALM1000 analog inputs will be required. Refer to the document and construct and use input dividers before preforming any of these experiments with the ALM1000.+The circuits used in this Lab activity while generally low current can produce voltages beyond the 0 to 5 V analog input range of the ALM1000. ​[[university:​courses:​alm1k:​circuits1:​alm-measure-outside-0-5-range|Input voltage divider techniques]] as discussed in the document on ALM1000 analog inputs will be required. Refer to the document and construct and use input dividers before preforming any of these experiments with the ALM1000.
  
 =====Concept:​===== =====Concept:​=====
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 Solder-less breadboard and jumper wire kit\\ Solder-less breadboard and jumper wire kit\\
 1 – 1 MΩ resistor\\ 1 – 1 MΩ resistor\\
-1 – 470 KΩ resistor\\ 
 1 – 200 KΩ resistor\\ 1 – 200 KΩ resistor\\
-1 – AD8541 rail-to-rail CMOS op-amp ​or ½ dual AD8542 ​)\\ +1 – ZVN2110A NMOS FET 2N7000 ​)\\ 
-2 – ZVN2110A ​NMOS FET ( 2N7000 )\\+2 – ZVN3310 ​NMOS FET ( 2N7000 )\\ 
 +1 – ZVP2110A PMOS FET\\
 2 – 74HC04 HEX CMOS Inverters ( CD4007, CD4069 )\\ 2 – 74HC04 HEX CMOS Inverters ( CD4007, CD4069 )\\
 +1 – LT1054\\
 2 – 10uF capacitors\\ 2 – 10uF capacitors\\
 1 – 220uF capacitor\\ 1 – 220uF capacitor\\
-2 – 1N914 small signal ​diodes+2 – 1N914 diodes ​(1N4001 or 1N5819 Schottky diodes)
  
 //​Additional Equipment://​ //​Additional Equipment://​
  
 Small handheld DMM ( optional )\\ Small handheld DMM ( optional )\\
-+5 V bench power supply or 4.5 V battery ( 3 x AA cells )++5 V bench power supply or 4.5 V battery ( optional ​)
  
 ====Directions:​==== ====Directions:​====
  
-Before we build any of the DC-DC converter circuits we need to build an input voltage divider circuit to attenuate or reduce the voltages being measured to a low enough value to fit safely within the 0V to +5V range allowed for the ALM1000 ​analog inputs. Build the simple voltage divider ​and voltage follower op-amp buffer ​shown in figure 3 on one end of your solder-less ​breadboard. ​The op-amp can be powered from the fixed +5 V supply on the ALM1000. The input offset voltage is supplied from the ALM1000 ​fixed +2.5 V supply.+Before we build any of the DC-DC converter circuits we need to build an input voltage divider circuit to attenuate or reduce the voltages being measured to a low enough value to fit safely within the 0V to +5V range allowed for the ADALM1000 ​analog inputs. Build the simple voltage divider shown in figure 3 on one end of your solderless ​breadboard. ​A DC offset voltage is supplied from the fixed 5 V supply ​to allow the ability to measure both positive and negative voltages.
  
-{{ :​university:​courses:​alm1k:​alm-lab16_f3.png?​550 |}}+{{ :​university:​courses:​alm1k:​alm-lab16_f3.png?​600 |}}
  
 <WRAP centeralign>​Figure 3, Input voltage divider with buffer op-amp follower</​WRAP>​ <WRAP centeralign>​Figure 3, Input voltage divider with buffer op-amp follower</​WRAP>​
  
-Use the ALICE desk-top input attenuator gain and offset entry widgets ( figure ​) to calibrate the displayed voltage level by connecting the divider input ( end of R<​sub>​1</​sub>​ ) to ground and the fixed +2.5 V and +5 V supplies ​on the ALM1000. Adjust the offset value such that the scope trace displays 0 V with the input grounded. Next adjust the gain value so that the trace displays as +5 V with the input connected to +5 V supply. With R<​sub>​2</​sub>​ = 470 KΩ the gain factor should be around 3, with R<​sub>​2</​sub>​ = 200 KΩ the gain factor should be around 6. You can double check your settings by connecting the input to the +2.5 V supply and the trace should read as 2.5V. You can now safely measure ​voltage ​within the ranges ​shown in figure 3. Be sure to only use the voltage divider input when measuring voltages in this Lab.+Use the ALICE Desk-top input attenuator gain and offset entry widgets ( figure ​4A ) to calibrate the displayed voltage level by connecting the divider input ( end of R<​sub>​1</​sub>​ ) to ground and the fixed +5 V supply ​on the ADALM1000. Adjust the offset value such that the scope trace displays 0 V with the input grounded. Next adjust the gain value so that the trace displays as +5 V with the input connected to +5 V supply. With R<​sub>​2</​sub>​ = 200 KΩ the gain factor should be around 6 but is actually 7.2 due to the internal 1 MΩ input resistance of the input. You can double check your settings by connecting the input to the +2.5 V supply and the trace should read as 2.5V. You can now safely measure ​voltages ​within the range shown in figure 3. Be sure to only use the voltage divider input when measuring voltages in this Lab.
  
 {{ :​university:​courses:​alm1k:​alm-lab16_f4.png?​150 |}} {{ :​university:​courses:​alm1k:​alm-lab16_f4.png?​150 |}}
  
-<WRAP centeralign>​Figure ​Input Attenuator settings</​WRAP>​+<WRAP centeralign>​Figure ​4A Input Attenuator settings</​WRAP>​
  
-If  a dual version of the op-amp is used  (AD8542) or a second AD8541 single is available then two copies ​of the input voltage ​divider can be build, one for CHA and the second for CHB scope input.+For this lab you will be mainly making DC measurements but the frequency response ​of the input divider can also be adjusted. To adjust the compensation settings open the Change Settings screen. Set CHA to SVMI mode and Shape Square. Set Min value to 0.5 and Max to 4.5. Set the Frequency to 500 Hz. With CHB in Hi-Z mode and connected to the voltage divider connect CHA output to the input of the divider. Adjust the CHB compensation TC1, A1 and TC2, A2 until the CHB wave shape is a flat top square wave just like CHA. Something like the settings shown in Figure 4B. 
 + 
 +{{ :​university:​courses:​alm1k:​alm-lab16_f4b.png?​300 |}} 
 + 
 +<WRAP centeralign>​Figure 4B Frequency compensation settings</​WRAP>​ 
 + 
 +The software should now be calibrated for using the input divider with CHB.
  
 **First DC-DC converter** **First DC-DC converter**
  
-The breadboard connections for the first version are as shown in figure 5 below. The voltage divider circuit should be connected to measure the voltage at V<​sub>​Boost</​sub>​. ( or DMM could be used ). The +5V bench power supply or 4.5 V battery should be connected to the Vin node. The digital pulse output drives the input of the first Inverter gate at pin 1. Scope input CA-H through the external resistor divider (see figure 3 ) is connected to the drain terminal of M<​sub>​1</​sub>​ and scope input CB-H through an external resistor divider is connected to the drain terminal of M<​sub>​2</​sub>​. ​+The breadboard connections for the first version are as shown in figure 5 below. The voltage divider circuit should be connected to measure the voltage at VBoost. (or DMM could be used). The +5V bench power supply or 4.5 V battery should be connected to the Vin node. The digital pulse output drives the input of the first Inverter gate at pin 1. Scope input CA-H through the external resistor divider (see figure 3) is connected to the drain terminal of M<​sub>​1</​sub>​ and scope input CB-H through an external resistor divider is connected to the drain terminal of M<​sub>​2</​sub>​. ​
  
 {{ :​university:​courses:​alm1k:​alm-lab16_f5.png?​550 |}} {{ :​university:​courses:​alm1k:​alm-lab16_f5.png?​550 |}}
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 ====Hardware Setup:==== ====Hardware Setup:====
  
-The digital pulse source ( details below ) output ​should generate a 50% duty cycle square wave at least 20 KHz output frequency. The input of scope channel ​CA-V with an external resistor divider is used to measure the waveform seen at the drain of M<​sub>​1</​sub>​ and the second scope channel CB-V with an external resistor divider can be used to measure the waveform seen at the drain of M<​sub>​2</​sub>​.+The V<​sub>​Clock</​sub>​ pulse can be supplied from the Channel A output or the digital pulse source ​circuit ​(details below in figure 8and should generate a 50% duty cycle square wave with at least 20 KHz output frequency. The input of scope channel ​CB-V with the external resistor divider is used to measure the waveform seen at the drain of M<​sub>​1</​sub>​ and to measure the waveform seen at the drain of M<​sub>​2</​sub> ​and to measure the V<​sub>​Boost</​sub>​ output voltage.
  
 ====Procedure:​==== ====Procedure:​====
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 ====Directions:​==== ====Directions:​====
  
-The breadboard connections for another version are as shown in figure 6 below. A second ​package of CMOS inverters is used for the upper set of switches (INV3 and INV4) rather than the discrete FETs and diodes. The ground connection of the second ​74HC04 is connected to the V<​sub>​IN</​sub> ​node and the supply connection at pin 14 becomes the V<​sub>​Boost</​sub>​ node. The DMM should be connected to measure the voltage at V<​sub>​Boost</​sub>​. The +5V bench power supply should be connected to the V<​sub>​IN</​sub>​ node. The digital pulse source output drives the input of the first Inverter ​gate at pin 1.+The breadboard connections for another version are as shown in figure 6 below. A one package of CMOS inverters is used for the upper set of switches (INV1 and INV2) rather than the discrete FETs and diodes. The ground connection of the 74HC04 ​at pin 7 is connected to the VIN node and the supply connection at pin 14 becomes the V<​sub>​Boost</​sub>​ node. The voltage divider input should be connected to measure the voltage at V<​sub>​Boost</​sub>​. The +5V power supply should be connected to the V<​sub>​IN</​sub>​ node. The LT1054 is used as both the clock digital pulse source ​and first driver ​output ​for capacitor C<​sub>​1</​sub>​ and drives the input of the Inverter at the gates of NMOS M<​sub>​1</​sub>​ and PMOS M<​sub>​2</​sub>​.
  
 {{ :​university:​courses:​alm1k:​alm-lab16_f6.png?​550 |}} {{ :​university:​courses:​alm1k:​alm-lab16_f6.png?​550 |}}
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 <WRAP centeralign>​Figure 6 All CMOS Inverter configuration</​WRAP>​ <WRAP centeralign>​Figure 6 All CMOS Inverter configuration</​WRAP>​
  
-Figure 7 shows an inverting DC-DC configuration that produces V<​sub>​Boost</​sub>​ equal to –V<​sub>​IN</​sub>​. The second ​74HC04 is connected below ground as shown to produce a V<​sub>​Boost</​sub>​ that is equal to –V<​sub>​IN</​sub>​.+Figure 7 shows an inverting DC-DC configuration that produces V<​sub>​Boost</​sub>​ equal to –V<​sub>​IN</​sub>​. The 74HC04 is connected below ground as shown to produce a V<​sub>​Boost</​sub>​ that is equal to –V<​sub>​IN</​sub>​.
  
 {{ :​university:​courses:​alm1k:​alm-lab16_f7.png?​550 |}} {{ :​university:​courses:​alm1k:​alm-lab16_f7.png?​550 |}}
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 **For further reading:** **For further reading:**
  
 +[[adi>​en/​analog-dialogue/​articles/​the-interleaved-inverting-charge-pump-part-1.html|The Interleaved Inverting Charge Pump—Part 1: A New Topology for Low Noise Negative Voltage Supplies]]\\
 http://​en.wikipedia.org/​wiki/​DC-to-DC_converter\\ http://​en.wikipedia.org/​wiki/​DC-to-DC_converter\\
 http://​en.wikipedia.org/​wiki/​Charge_pump\\ http://​en.wikipedia.org/​wiki/​Charge_pump\\
-http://​www.analog.com/​static/​imported-files/​data_sheets/​ADM660_8660.pdf+[[adi>static/​imported-files/​data_sheets/​ADM660_8660.pdf|ADM660,​8660 Data Sheet]]
  
 ====Appendix:​==== ====Appendix:​====
university/courses/alm1k/alm-lab-16.1469215857.txt.gz · Last modified: 22 Jul 2016 21:30 by Doug Mercer