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AN-1209 Constant Current RGB LED Driver

Contents

References

For related documents and software, please visit:

https://www.dialog-semiconductor.com/products/greenpak

Download our free GreenPAK™ Designer software to open the .gp files and view the proposed circuit design. Use the GreenPAK development tools to freeze the design into your own customized IC in a matter of minutes. Dialog Semiconductor provides a complete library of application notes featuring design examples as well as explanations of features and blocks within the Dialog IC.

  1. GreenPAK Designer Software, Software Download and User Guide, Dialog Semiconductor
  2. AN-1209 Constant Current RGB LED Driver.gp, GreenPAK Design File, Dialog Semiconductor
  3. GreenPAK Development Tools, GreenPAK Development Tools Webpage, Dialog Semiconductor
  4. GreenPAK Application Notes, GreenPAK Application Notes Webpage, Dialog Semiconductor
  5. SLG46580, Datasheet, Dialog Semiconductor

Author: Craig Cary

Abstract

This application note describes how to create a constant current RGB LED driver using the SLG46580V [5]. By enabling and disabling the GreenPAK’s internal power switches, the designer can regulate the current flow through the individual LEDs of an RGB LED. This system is based on ACMP feedback that measures the voltage across current limiting resistors for each of the LEDs. The constant current levels can be adjusted through I2C for each LED.

Basic Idea and Circuit Layout

Figure 1 shows the circuit schematic for this design. The current regulation is achieved by monitoring R1, R2, and R3 with analog comparators (ACMPs) to enable and disable the GreenPAK’s internal power switches.

When enabled, these switches charge up the output capacitors which increases the voltage across them. Assuming the forward voltage drop of the LEDs stays constant, increasing the output capacitor voltage will increase the voltage across the resistor and, as a result, will increase the current through the LED.

When disabled, the charge stored on the output capacitors will be used to source the current through the LEDs. As current is drawn from the capacitors (C1, C2, and C3), their voltages will begin to drop and the current through the LEDs will decrease. When the voltage across the current limiting resistors falls bellows the acceptable threshold, the power switches are re-enabled.

Figure 1: Constant Current RGB Driver Circuit Schematic

The enabling and disabling of the power switches makes up the feedback loop of this regulatory system. Since the power switch is periodically turning on and off, there will be a ripple voltage present across the resistors as shown in Figure 2. The magnitude and frequency of this ripple voltage depends on the strength of the input voltage source, the current drawn by the LED, the capacitive load size, and the internal delays of the GreenPAK design.

Figure 2: Constant Current Functional Waveform

By changing the ACMP’s IN- reference voltage, the constant current level can be changed. Table 1 shows the register values and respective current levels associated with each of the internal reference voltages.

Table 1: ACMP VREF Relation to LED Current

Register Value

ACMP VREF
(mV)

IBLUE/GREEN
(mA)

IRED
(mA)

0x00

50

1.3

2.3

0x01

100

2.6

4.5

0x02

150

3.8

6.8

0x03

200

5.1

9.1

0x04

250

6.4

11.4

0x05

300

7.7

13.6

0x06

350

9.0

15.9

0x07

400

10.2

18.2

0x08

450

11.5

20.4

0x09

500

12.8

22.7

0x0A

550

14.1

25.0

0x0B

600

15.4

27.3

0x0C

650

16.7

29.5

0x0D

700

17.9

31.8

0x0E

750

19.2

34.1

0x0F

800

20.6

36.4

0x10

850

21.8

38.6

0x11

900

23.1

40.9

0x12

950

24.3

43.2

0x13

1000

25.6

45.4

0x14

1050

26.9

47.7

0x15

1100

28.2

50.0

0x16

1150

29.5

52.3

0x17

1200

30.8

54.5

GreenPAK Design

Figure 3 shows the SLG46580V GreenPAK design for this constant current RGB Driver. This figure shows the ACMP SENSE pins on the left-hand side which monitor the voltages across the current limiting resistors. When the SENSE pin voltages drop below the internal threshold voltages, the power switches close. As the output capacitors are connected to 5V, the capacitor voltages increase quickly and cause a voltage jump on the SENSE pins. This voltage jump results in higher current flow through the LEDs. The delay blocks force the power switches to be disabled for an additional 1µs before allowing the power switches to turn on. This helps create a more accurate average current by accommodating for the increased current when the power switch is enabled. The 3-bit LUTs act as inverters when either their GPIO or I2C enables are set high; otherwise, these LUTs disable the power switches.

Figure 3: GreenPAK Constant Current RGB Driver Design

I2C Features

By using I2C, the user can alter the ACMP IN- reference voltages to change the constant current settings. In addition, the LEDs can be enabled using the I2C virtual inputs. Table 2 shows the register locations of these features.

Table 2: I2C Registers

ACMP0

ACMP1

ACMP2

ACMP3

I2C Virtual Input

Register

Reg<1628:1624>

Reg<1636:1632>

Reg<1644:1640>

Reg<1652:1648>

Reg<1959:1952:>

For more I2C information, please check out AN-1090 (Simple I2C IO Controllers with SLG46531V) and AN-1091 (How to change a GreenPAK comparator’s threshold voltage using I2C). Please reference the SLG46580V datasheet for more register information.

Component Selection

RGB LED Selection:

I’ve selected a Kingbright RGB LED. (PN: AAAF5060QBFSURZGS) It is important to note that this LED isn’t a common anode or a common cathode LED, but rather, it contains 3 individual red, green, and blue LEDs. Table 3 lists some of the important specifications for this LED.

Table 3: Kingbright RGB LED Specifications

Blue

Red

Green

Units

Material

InGaN

AlGaInP

InGaN

--

DC Forward Current

30

50

30

mA

Peak Forward Current

150

185

150

mA

Forward Voltage (typ, max)*

3.3, 4

1.9, 2.5

3.3, 4.1

V

Dominant Wavelength*

465

630

525

nm

Luminous Intensity (min, typ)**

280, 400

500, 800

500, 1000

mcd

Notes:

* - IF = 20mA

** - IF = 30mA for Blue and Green, 50mA for Red

Since the average DC forward current of the Kingbright LED is 30 and 50 mA, we are well within the SLG46580V’s 150mA power switch limitation. For this design, we are planning to run off a 5V supply. Given the typical 3.3V forward voltage of these LEDs, we have sufficient headroom for use in our ACMP feedback system as will be described in the current limiting resistor section.

Current Limiting Resistor Selection: (R1, R2, R3)

When selecting the resistors for the RGB LEDs, we must perform a couple simple calculations to estimate the proper size. First, we need to know that the maximum reference voltage of the SLG46580V’s ACMP is 1.2V. Since the IN- reference voltages of the ACMPs are in 50mV increments, we want to select the largest resistor value to obtain the best current resolution whilst staying under the 1.2V limitation of the ACMP and the 5V power supply limit.

Equation 1 calculates the maximum current limiting resistor voltage to be 1.7V. Since the ACMP input reference is limited to a maximum of 1.2V without an input resistive divider, we should aim to have 1.2V across the current limiting resistors at the maximum current draw.

Equation 1: Maximum Current Limiting Resistor Voltage Calculation

Once we’ve selected the maximum current limiting resistor voltage, we can use Equation 2 to select the appropriate resistor value for both the 30mA and 50mA cases. Since 40Ω and 24Ω are not standard resistor values, we will select 39Ω and 22Ω respectively as shown in Figure 1.

Equation 2: Current Limiting Resistor Calculation

We could increase the range from 1.2V to 1.7V if we use a resistive divider on the ACMP inputs, but we would decrease the current resolution of the ACMP. For example, if we used an input divide by 2, the voltage change across the resistors would be in 100mV steps instead of 50mV steps. We would get 17 steps using the 1.7V limit with the input divide by 2, but we get 24 steps if we use 1.2V without an input divider.

Power Switch Output Capacitor Selection: (C1, C2, C3)

The output capacitor selection impacts a couple factors including the average current accuracy and the initial turn on time of the LEDs. If the power switch is closed, the input sources current to charge the output capacitor. As the output voltage exceeds the ACMP IN- reference, the power switch turns off and the output capacitor begins to source the charge for the LED until the output voltage drops below the ACMP’s IN- reference. This charge cycle creates an output ripple voltage across the current limiting resistor that translates directly into current ripple.

Over time, this current ripple can be averaged to determine the brightness of the LED. The size of the capacitor impacts the accuracy of the averaged current.

For larger capacitors, the charge and discharge cycles in Figure 2 take longer. As a result, the ripple voltage is minimized and the average current matches closely with the ideal current calculations. With the increase in output capacitance, the initial turn on time of the LED is increased.

The capacitor’s charge is much more fluid for smaller capacitors in that they charge and discharge more quickly. This results in voltage ripples that are larger than those measured with bigger capacitors. The average current differs significantly at low current levels because the charge and discharge cycles can be fast compared to the minimum 1µs delay times of the GreenPAK’s DLY blocks. For smaller capacitors, the initial turn on time is quicker than that of larger capacitors.

Experimental Results

I tested this constant current LED driver design with four capacitive loads: 1µF, 10µF, 47µF, and 94µF. The next couple paragraphs will address the results with the Green LED inside the RGB LED package. The Red and Blue LEDs produced similar results, so I’ve skipped their waveforms for brevity’s sake. Please see Appendix A for the raw data. I’ve also included the raw data using a 47µF input capacitor instead of a 94µF capacitor.

Figure 4 plots the constant current drive level through the green LED vs the ACMP reference voltages for various capacitive loads. The deviation from the calculated current level is caused by the voltage jump across the current sense resistor as the power switch is enabled. This design tries to counteract this behavior by keeping the power switch disabled for an additional 1µs.

Figure 4: ACMP Reference Voltage vs Constant Current Level for Various Capacitive Loads (Green LED)

The percent error of the drive current can be used to see how far off the measured current levels are from the theoretical current levels. Equation 3 shows the calculation used to obtain the data in Figure 5.

Equation 3: Percent Error Equation

By looking at Figure 5, we can see that the 94µF capacitor performs more accurately than the other capacitive loads. Due to excessive charging at low current levels, the 1µF capacitor reaches 100% error. This may not be problematic for an application if the desired current levels do not need to be precise.

Figure 5: Percent Error vs Constant Current Level for Various Capacitive Loads (Green LED)

On the surface, selecting large output capacitors appears to be the best solution, but by selecting a large capacitance, the inrush current and the turn on time of the LEDs increase. The designer needs to pay attention to this inrush current as it can cause the input voltage rail to droop. The input voltage droop can be minimized by having a larger capacitor to pull charge from when the power switch is initially enabled. Note that the strength of your drive source will also impact the amount of input voltage droop. Weaker sources will experience more voltage droop than stronger sources.

For this design, there are two startup times to consider: partially and fully discharged. When the LED is disabled for a long time (10-20 seconds), the output capacitors discharge significantly by leaking through the LED. Fully discharged capacitors can take 10µs to 150µs to charge up before being able to supply 30mA of current as shown in Figure 6.

Figure 6: Startup Time for Fully Discharged Capacitive Loads (94µF Input Capacitors)

If the LEDs are being cycled at a quicker rate, the initial turn on times decrease for each of the capacitive loads. For partially discharged capacitive loads, the turn on time can range from 5µs to 50µs as seen in Figure 7.

Figure 7: Startup Time for Partially Discharged Capacitive Loads (94µF Input Capacitors)

Figure 8 shows the steady-state, periodic behavior of this design for various loads. This figure shows the previously described voltage jump when the LDO is enabled or disabled and should match the functional waveform shown in Figure 2.

Figure 8: Periodic Behavior of the Various Capacitive Loads (94µF Input Capacitors)

The waveforms above show the performance of this design for applications with varying capacitive loads. The capacitive load size selection depends entirely on the application. For this application note, these results show that the startup time for the LED is about 140µs for a 94µF load capacitor. In addition, the actual current will not deviate more than ±5% from the calculated current levels.

Going Further

This design demonstrates the process of creating a constant current LED driver using the SLG46580V. If one wanted to expound upon this idea, the designer could use an I2C script to create various patterns and colors for the RGB LED.

This design could also be used with an external DAC to provide more reference voltage steps for the ACMP. This would create finer current control for the RGB LEDs.

This design can support constant current designs for LEDs with DC forward currents greater than the 30mA and 50mA examples used in this application note. Table 4 shows the available GreenPAK devices with the corresponding power switch quantity and maximum current limitation.

Table 4: Power Switch Availability

GreenPAK

# of Power Switches

IMAX Limitation per Switch

SLG46580V

4

150mA

SLG46582

2

300mA

SLG46583

1

600mA

Conclusion

This constant current driver can be used in conjunction with a microcontroller to source current for LEDs in many different applications. By regulating the current flow through an external current limiting resistor, the designer can control the brightness of each of the LEDs in his or her circuit. The component selection process outlined in this application note will help create a constant current LED driver with the maximum number of current steps using the GreenPAK’s internal reference voltages. By extending these principles, this design can become the foundation for creating a simple constant current LED driver for many applications.

Appendix A: Raw Measurement Data
Table 5: Raw Data for 47uF Input / 1uF Output Capacitor

1µF

Green

Red

Blue

Meas

Calc

% Error

Meas

Calc

% Error

Meas

Calc

% Error

0x00

50

0.10379247

2.66

1.28

107.58

0.11537794

5.24

2.27

130.76

0.12175323

3.12

1.28

143.51

0x01

100

0.16615782

4.26

2.56

66.16

0.17511562

7.96

4.55

75.12

0.1817855

4.66

2.56

81.79

0x02

150

0.21896942

5.61

3.85

45.98

0.22550583

10.25

6.82

50.34

0.23340979

5.98

3.85

55.61

0x03

200

0.26772105

6.86

5.13

33.86

0.2725134

12.39

9.09

36.26

0.28182527

7.23

5.13

40.91

0x04

250

0.3138484

8.05

6.41

25.54

0.31727374

14.42

11.36

26.91

0.32801675

8.41

6.41

31.21

0x05

300

0.35858112

9.19

7.69

19.53

0.36042987

16.38

13.64

20.14

0.37283955

9.56

7.69

24.28

0x06

350

0.40275658

10.33

8.97

15.07

0.40293702

18.32

15.91

15.12

0.4173867

10.70

8.97

19.25

0x07

400

0.44640148

11.45

10.26

11.60

0.44465317

20.21

18.18

11.16

0.46106654

11.82

10.26

15.27

0x08

450

0.48936079

12.55

11.54

8.75

0.48620648

22.10

20.45

8.05

0.50447927

12.94

11.54

12.11

0x09

500

0.53081713

13.61

12.82

6.16

0.52495704

23.86

22.73

4.99

0.54678054

14.02

12.82

9.36

0x0A

550

0.57271651

14.69

14.10

4.13

0.56565032

25.71

25.00

2.85

0.58792907

15.08

14.10

6.90

0x0B

600

0.61412511

15.75

15.38

2.35

0.60513991

27.51

27.27

0.86

0.6312687

16.19

15.38

5.21

0x0C

650

0.65496818

16.79

16.67

0.76

0.64342316

29.25

29.55

-1.01

0.67258659

17.25

16.67

3.47

0x0D

700

0.69520097

17.83

17.95

-0.69

0.68253692

31.02

31.82

-2.49

0.71408606

18.31

17.95

2.01

0x0E

750

0.7373418

18.91

19.23

-1.69

0.72365938

32.89

34.09

-3.51

0.75455878

19.35

19.23

0.61

0x0F

800

0.77610465

19.90

20.51

-2.99

0.76254207

34.66

36.36

-4.68

0.79664259

20.43

20.51

-0.42

0x10

850

0.81736643

20.96

21.79

-3.84

0.79704787

36.23

38.64

-6.23

0.83789071

21.48

21.79

-1.42

0x11

900

0.85988201

22.05

23.08

-4.46

0.85224812

38.74

40.91

-5.31

0.87721843

22.49

23.08

-2.53

0x12

950

0.90766286

23.27

24.36

-4.46

0.89109791

40.50

43.18

-6.20

0.91915932

23.57

24.36

-3.25

0x13

1000

0.95431436

24.47

25.64

-4.57

0.93842265

42.66

45.45

-6.16

0.96359729

24.71

25.64

-3.64

0x14

1050

0.97544291

25.01

26.92

-7.10

0.9848529

44.77

47.73

-6.20

1.00784423

25.84

26.92

-4.01

0x15

1100

1.00983025

25.89

28.21

-8.20

1.02724296

46.69

50.00

-6.61

1.05466384

27.04

28.21

-4.12

0x16

1150

1.06286018

27.25

29.49

-7.58

1.06923613

48.60

52.27

-7.02

1.10590202

28.36

29.49

-3.83

0x17

1200

1.13698422

29.15

30.77

-5.25

1.15238756

52.38

54.55

-3.97

1.15924573

29.72

30.77

-3.40

Table 6: Raw Data for 94uF Input / 1uF Output Capacitor

1µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.10544961

2.70

1.28

110.90

0.11658766

5.30

2.27

133.18

0.1219656

3.13

1.28

143.93

0x01

100

0.16841484

4.32

2.56

68.41

0.17639123

8.02

4.55

76.39

0.18184723

4.66

2.56

81.85

0x02

150

0.22148852

5.68

3.85

47.66

0.22719944

10.33

6.82

51.47

0.23398508

6.00

3.85

55.99

0x03

200

0.2702408

6.93

5.13

35.12

0.27413039

12.46

9.09

37.07

0.28203652

7.23

5.13

41.02

0x04

250

0.31681257

8.12

6.41

26.73

0.31912763

14.51

11.36

27.65

0.32829134

8.42

6.41

31.32

0x05

300

0.36179645

9.28

7.69

20.60

0.36242803

16.47

13.64

20.81

0.37359763

9.58

7.69

24.53

0x06

350

0.40594958

10.41

8.97

15.99

0.40480821

18.40

15.91

15.66

0.41828879

10.73

8.97

19.51

0x07

400

0.44921564

11.52

10.26

12.30

0.44608536

20.28

18.18

11.52

0.46164798

11.84

10.26

15.41

0x08

450

0.49196858

12.61

11.54

9.33

0.48733012

22.15

20.45

8.30

0.50514277

12.95

11.54

12.25

0x09

500

0.53404017

13.69

12.82

6.81

0.52701476

23.96

22.73

5.40

0.54771031

14.04

12.82

9.54

0x0A

550

0.57546574

14.76

14.10

4.63

0.60427355

27.47

25.00

9.87

0.58997701

15.13

14.10

7.27

0x0B

600

0.61666606

15.81

15.38

2.78

0.60719107

27.60

27.27

1.20

0.63178835

16.20

15.38

5.30

0x0C

650

0.65797972

16.87

16.67

1.23

0.64528342

29.33

29.55

-0.73

0.67298954

17.26

16.67

3.54

0x0D

700

0.69866542

17.91

17.95

-0.19

0.6833907

31.06

31.82

-2.37

0.71545727

18.35

17.95

2.21

0x0E

750

0.7402992

18.98

19.23

-1.29

0.72499195

32.95

34.09

-3.33

0.75650091

19.40

19.23

0.87

0x0F

800

0.77923443

19.98

20.51

-2.60

0.76366601

34.71

36.36

-4.54

0.79802829

20.46

20.51

-0.25

0x10

850

0.819662

21.02

21.79

-3.57

0.79876461

36.31

38.64

-6.03

0.83916501

21.52

21.79

-1.27

0x11

900

0.86193967

22.10

23.08

-4.23

0.85408488

38.82

40.91

-5.10

0.87845455

22.52

23.08

-2.39

0x12

950

0.9106347

23.35

24.36

-4.14

0.88793466

40.36

43.18

-6.53

0.92064209

23.61

24.36

-3.09

0x13

1000

0.95426373

24.47

25.64

-4.57

0.93464328

42.48

45.45

-6.54

0.96424275

24.72

25.64

-3.58

0x14

1050

0.99187168

25.43

26.92

-5.54

0.98019999

44.55

47.73

-6.65

1.00857849

25.86

26.92

-3.94

0x15

1100

1.02673933

26.33

28.21

-6.66

1.02636925

46.65

50.00

-6.69

1.05540592

27.06

28.21

-4.05

0x16

1150

1.07916886

27.67

29.49

-6.16

1.07175653

48.72

52.27

-6.80

1.10651142

28.37

29.49

-3.78

0x17

1200

1.14910569

29.46

30.77

-4.24

1.15607567

52.55

54.55

-3.66

1.16008577

29.75

30.77

-3.33

Table 7: Raw Data for 47uF Input / 10uF Output Capacitor

10µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.05696687

1.46

1.28

13.93

0.0608695

2.77

2.27

21.74

0.06364242

1.63

1.28

27.28

0x01

100

0.11190378

2.87

2.56

11.90

0.1167021

5.30

4.55

16.70

0.11729143

3.01

2.56

17.29

0x02

150

0.16386559

4.20

3.85

9.24

0.16933401

7.70

6.82

12.89

0.16829089

4.32

3.85

12.19

0x03

200

0.21452406

5.50

5.13

7.26

0.22096825

10.04

9.09

10.48

0.21900129

5.62

5.13

9.50

0x04

250

0.26469255

6.79

6.41

5.88

0.27264091

12.39

11.36

9.06

0.26849579

6.88

6.41

7.40

0x05

300

0.31427045

8.06

7.69

4.76

0.32385321

14.72

13.64

7.95

0.31903935

8.18

7.69

6.35

0x06

350

0.36356466

9.32

8.97

3.88

0.37505051

17.05

15.91

7.16

0.36874841

9.46

8.97

5.36

0x07

400

0.41306167

10.59

10.26

3.27

0.42597334

19.36

18.18

6.49

0.41871936

10.74

10.26

4.68

0x08

450

0.46215197

11.85

11.54

2.70

0.47648217

21.66

20.45

5.88

0.46798635

12.00

11.54

4.00

0x09

500

0.51098743

13.10

12.82

2.20

0.53380787

24.26

22.73

6.76

0.51768896

13.27

12.82

3.54

0x0A

550

0.55960619

14.35

14.10

1.75

0.58261136

26.48

25.00

5.93

0.56683641

14.53

14.10

3.06

0x0B

600

0.60814478

15.59

15.38

1.36

0.62860522

28.57

27.27

4.77

0.61631691

15.80

15.38

2.72

0x0C

650

0.65656522

16.84

16.67

1.01

0.68043583

30.93

29.55

4.68

0.66513055

17.05

16.67

2.33

0x0D

700

0.7053916

18.09

17.95

0.77

0.73217776

33.28

31.82

4.60

0.71416908

18.31

17.95

2.02

0x0E

750

0.75526266

19.37

19.23

0.70

0.78485439

35.68

34.09

4.65

0.76372485

19.58

19.23

1.83

0x0F

800

0.80548788

20.65

20.51

0.69

0.83361132

37.89

36.36

4.20

0.81248002

20.83

20.51

1.56

0x10

850

0.85543585

21.93

21.79

0.64

0.88269354

40.12

38.64

3.85

0.86449548

22.17

21.79

1.71

0x11

900

0.90548148

23.22

23.08

0.61

0.89966919

40.89

40.91

-0.04

0.91472816

23.45

23.08

1.64

0x12

950

0.92975533

23.84

24.36

-2.13

0.91862285

41.76

43.18

-3.30

0.96463776

24.73

24.36

1.54

0x13

1000

0.94440475

24.22

25.64

-5.56

0.94529897

42.97

45.45

-5.47

1.01494303

26.02

25.64

1.49

0x14

1050

0.9652224

24.75

26.92

-8.07

0.98863585

44.94

47.73

-5.84

1.06544166

27.32

26.92

1.47

0x15

1100

0.99919215

25.62

28.21

-9.16

1.05643345

48.02

50.00

-3.96

1.11603657

28.62

28.21

1.46

0x16

1150

1.0515009

26.96

29.49

-8.57

1.15793781

52.63

52.27

0.69

1.16646977

29.91

29.49

1.43

0x17

1200

1.12696417

28.90

30.77

-6.09

1.25019887

56.83

54.55

4.18

1.21734881

31.21

30.77

1.45

Table 8: Raw Data for 94uF Input / 10uF Output Capacitor

10µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.05667659

1.45

1.28

13.35

0.06039193

2.75

2.27

20.78

0.0631777

1.62

1.28

26.36

0x01

100

0.1114737

2.86

2.56

11.47

0.11675404

5.31

4.55

16.75

0.11677163

2.99

2.56

16.77

0x02

150

0.16397112

4.20

3.85

9.31

0.16956418

7.71

6.82

13.04

0.16766698

4.30

3.85

11.78

0x03

200

0.21453605

5.50

5.13

7.27

0.22109595

10.05

9.09

10.55

0.21866362

5.61

5.13

9.33

0x04

250

0.26449718

6.78

6.41

5.80

0.27298962

12.41

11.36

9.20

0.2687388

6.89

6.41

7.50

0x05

300

0.31443697

8.06

7.69

4.81

0.3239341

14.72

13.64

7.98

0.31862643

8.17

7.69

6.21

0x06

350

0.36373456

9.33

8.97

3.92

0.37484507

17.04

15.91

7.10

0.36824002

9.44

8.97

5.21

0x07

400

0.41308802

10.59

10.26

3.27

0.4258419

19.36

18.18

6.46

0.41829517

10.73

10.26

4.57

0x08

450

0.46216109

11.85

11.54

2.70

0.47643272

21.66

20.45

5.87

0.46777219

11.99

11.54

3.95

0x09

500

0.51139605

13.11

12.82

2.28

0.53307068

24.23

22.73

6.61

0.51733506

13.27

12.82

3.47

0x0A

550

0.56013487

14.36

14.10

1.84

0.58359091

26.53

25.00

6.11

0.56672071

14.53

14.10

3.04

0x0B

600

0.60853462

15.60

15.38

1.42

0.62771951

28.53

27.27

4.62

0.61568856

15.79

15.38

2.61

0x0C

650

0.65709471

16.85

16.67

1.09

0.68043057

30.93

29.55

4.68

0.66477022

17.05

16.67

2.27

0x0D

700

0.70591019

18.10

17.95

0.84

0.73302461

33.32

31.82

4.72

0.71382589

18.30

17.95

1.98

0x0E

750

0.75570922

19.38

19.23

0.76

0.78416394

35.64

34.09

4.56

0.76305229

19.57

19.23

1.74

0x0F

800

0.80650331

20.68

20.51

0.81

0.83453021

37.93

36.36

4.32

0.81203826

20.82

20.51

1.50

0x10

850

0.85541153

21.93

21.79

0.64

0.88538484

40.24

38.64

4.16

0.86357862

22.14

21.79

1.60

0x11

900

0.90564218

23.22

23.08

0.63

0.9121895

41.46

40.91

1.35

0.91405471

23.44

23.08

1.56

0x12

950

0.93859806

24.07

24.36

-1.20

0.93358964

42.44

43.18

-1.73

0.96344014

24.70

24.36

1.41

0x13

1000

0.95464993

24.48

25.64

-4.54

0.96179225

43.72

45.45

-3.82

1.01358792

25.99

25.64

1.36

0x14

1050

0.97648599

25.04

26.92

-7.00

1.00526445

45.69

47.73

-4.26

1.06392257

27.28

26.92

1.33

0x15

1100

1.01062508

25.91

28.21

-8.12

1.07413981

48.82

50.00

-2.35

1.11461595

28.58

28.21

1.33

0x16

1150

1.06282538

27.25

29.49

-7.58

1.17652837

53.48

52.27

2.31

1.16496896

29.87

29.49

1.30

0x17

1200

1.13744593

29.17

30.77

-5.21

1.24881434

56.76

54.55

4.07

1.21599284

31.18

30.77

1.33

Table 9: Raw Data for 47uF Input / 47uF Output Capacitor

47µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.05284997

1.36

1.28

5.70

0.05572375

2.53

2.27

11.45

0.05597801

1.44

1.28

11.96

0x01

100

0.10446982

2.68

2.56

4.47

0.10880488

4.95

4.55

8.80

0.10849779

2.78

2.56

8.50

0x02

150

0.15602785

4.00

3.85

4.02

0.1627258

7.40

6.82

8.48

0.16003556

4.10

3.85

6.69

0x03

200

0.20705548

5.31

5.13

3.53

0.21487117

9.77

9.09

7.44

0.21083247

5.41

5.13

5.42

0x04

250

0.25767828

6.61

6.41

3.07

0.26757125

12.16

11.36

7.03

0.26153132

6.71

6.41

4.61

0x05

300

0.308024

7.90

7.69

2.67

0.31904542

14.50

13.64

6.35

0.312157

8.00

7.69

4.05

0x06

350

0.35835892

9.19

8.97

2.39

0.37227837

16.92

15.91

6.37

0.36272472

9.30

8.97

3.64

0x07

400

0.40828701

10.47

10.26

2.07

0.42390311

19.27

18.18

5.98

0.41316941

10.59

10.26

3.29

0x08

450

0.45843415

11.75

11.54

1.87

0.47591661

21.63

20.45

5.76

0.46369158

11.89

11.54

3.04

0x09

500

0.50819755

13.03

12.82

1.64

0.53043107

24.11

22.73

6.09

0.51395828

13.18

12.82

2.79

0x0A

550

0.55824129

14.31

14.10

1.50

0.58225828

26.47

25.00

5.87

0.56444652

14.47

14.10

2.63

0x0B

600

0.60809776

15.59

15.38

1.35

0.63292883

28.77

27.27

5.49

0.61435939

15.75

15.38

2.39

0x0C

650

0.65889063

16.89

16.67

1.37

0.68554104

31.16

29.55

5.47

0.6645481

17.04

16.67

2.24

0x0D

700

0.7096786

18.20

17.95

1.38

0.73836305

33.56

31.82

5.48

0.7146985

18.33

17.95

2.10

0x0E

750

0.75915353

19.47

19.23

1.22

0.79074113

35.94

34.09

5.43

0.76616247

19.65

19.23

2.15

0x0F

800

0.80958737

20.76

20.51

1.20

0.84278624

38.31

36.36

5.35

0.81768077

20.97

20.51

2.21

0x10

850

0.8598852

22.05

21.79

1.16

0.88893407

40.41

38.64

4.58

0.86730782

22.24

21.79

2.04

0x11

900

0.91044416

23.34

23.08

1.16

0.91066016

41.39

40.91

1.18

0.91824571

23.54

23.08

2.03

0x12

950

0.92981981

23.84

24.36

-2.12

0.93188495

42.36

43.18

-1.91

0.96880778

24.84

24.36

1.98

0x13

1000

0.94497926

24.23

25.64

-5.50

0.9607309

43.67

45.45

-3.93

1.01981203

26.15

25.64

1.98

0x14

1050

0.96604538

24.77

26.92

-8.00

1.0042516

45.65

47.73

-4.36

1.07105886

27.46

26.92

2.01

0x15

1100

1.00018289

25.65

28.21

-9.07

1.07300547

48.77

50.00

-2.45

1.12235726

28.78

28.21

2.03

0x16

1150

1.05221671

26.98

29.49

-8.50

1.17405224

53.37

52.27

2.09

1.17247753

30.06

29.49

1.95

0x17

1200

1.12718062

28.90

30.77

-6.07

1.26327698

57.42

54.55

5.27

1.22272863

31.35

30.77

1.89

Table 10: Raw Data for 94uF Input / 47uF Output Capacitor

47µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.05291514

1.36

1.28

5.83

0.05539243

2.52

2.27

10.78

0.05601921

1.44

1.28

12.04

0x01

100

0.10462567

2.68

2.56

4.63

0.10912348

4.96

4.55

9.12

0.10843575

2.78

2.56

8.44

0x02

150

0.1564698

4.01

3.85

4.31

0.1625579

7.39

6.82

8.37

0.15990617

4.10

3.85

6.60

0x03

200

0.20741859

5.32

5.13

3.71

0.21504034

9.77

9.09

7.52

0.21036629

5.39

5.13

5.18

0x04

250

0.25806276

6.62

6.41

3.23

0.26746106

12.16

11.36

6.98

0.26173763

6.71

6.41

4.70

0x05

300

0.30814908

7.90

7.69

2.72

0.31994793

14.54

13.64

6.65

0.31229453

8.01

7.69

4.10

0x06

350

0.35868465

9.20

8.97

2.48

0.37261995

16.94

15.91

6.46

0.36260267

9.30

8.97

3.60

0x07

400

0.40914515

10.49

10.26

2.29

0.42412714

19.28

18.18

6.03

0.41311657

10.59

10.26

3.28

0x08

450

0.45877138

11.76

11.54

1.95

0.47657509

21.66

20.45

5.91

0.46399478

11.90

11.54

3.11

0x09

500

0.50855585

13.04

12.82

1.71

0.53012237

24.10

22.73

6.02

0.51392322

13.18

12.82

2.78

0x0A

550

0.55900969

14.33

14.10

1.64

0.5829086

26.50

25.00

5.98

0.56458547

14.48

14.10

2.65

0x0B

600

0.60911462

15.62

15.38

1.52

0.63359852

28.80

27.27

5.60

0.61437464

15.75

15.38

2.40

0x0C

650

0.65890609

16.90

16.67

1.37

0.68622949

31.19

29.55

5.57

0.66458817

17.04

16.67

2.24

0x0D

700

0.71044378

18.22

17.95

1.49

0.73885477

33.58

31.82

5.55

0.71513022

18.34

17.95

2.16

0x0E

750

0.76011529

19.49

19.23

1.35

0.79096045

35.95

34.09

5.46

0.76657382

19.66

19.23

2.21

0x0F

800

0.81060667

20.78

20.51

1.33

0.84223802

38.28

36.36

5.28

0.81806824

20.98

20.51

2.26

0x10

850

0.86115742

22.08

21.79

1.31

0.8937373

40.62

38.64

5.15

0.86766599

22.25

21.79

2.08

0x11

900

0.91173149

23.38

23.08

1.30

0.92951703

42.25

40.91

3.28

0.91850303

23.55

23.08

2.06

0x12

950

0.93476316

23.97

24.36

-1.60

0.95465707

43.39

43.18

0.49

0.96900081

24.85

24.36

2.00

0x13

1000

0.95066682

24.38

25.64

-4.93

0.98530644

44.79

45.45

-1.47

1.0201794

26.16

25.64

2.02

0x14

1050

0.97236449

24.93

26.92

-7.39

1.03180084

46.90

47.73

-1.73

1.07079682

27.46

26.92

1.98

0x15

1100

1.00661917

25.81

28.21

-8.49

1.10290594

50.13

50.00

0.26

1.12191533

28.77

28.21

1.99

0x16

1150

1.05867592

27.15

29.49

-7.94

1.20250549

54.66

52.27

4.57

1.17251081

30.06

29.49

1.96

0x17

1200

1.13346901

29.06

30.77

-5.54

1.26252175

57.39

54.55

5.21

1.22278686

31.35

30.77

1.90

Table 11: Raw Data for 47uF Input / 94uF Output Capacitor

94µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.05196736

1.33

1.28

3.93

0.05478907

2.49

2.27

9.58

0.05419975

1.39

1.28

8.40

0x01

100

0.103065

2.64

2.56

3.07

0.10768332

4.89

4.55

7.68

0.1058245

2.71

2.56

5.82

0x02

150

0.15412767

3.95

3.85

2.75

0.16099784

7.32

6.82

7.33

0.1572915

4.03

3.85

4.86

0x03

200

0.20490047

5.25

5.13

2.45

0.21394376

9.72

9.09

6.97

0.20848153

5.35

5.13

4.24

0x04

250

0.25549392

6.55

6.41

2.20

0.26762751

12.16

11.36

7.05

0.25987667

6.66

6.41

3.95

0x05

300

0.30603438

7.85

7.69

2.01

0.31921234

14.51

13.64

6.40

0.31047097

7.96

7.69

3.49

0x06

350

0.3565531

9.14

8.97

1.87

0.37237293

16.93

15.91

6.39

0.36143307

9.27

8.97

3.27

0x07

400

0.40703449

10.44

10.26

1.76

0.42561601

19.35

18.18

6.40

0.41235934

10.57

10.26

3.09

0x08

450

0.45719809

11.72

11.54

1.60

0.47891979

21.77

20.45

6.43

0.46312996

11.88

11.54

2.92

0x09

500

0.50785377

13.02

12.82

1.57

0.53177389

24.17

22.73

6.35

0.51383347

13.18

12.82

2.77

0x0A

550

0.55790184

14.31

14.10

1.44

0.58490111

26.59

25.00

6.35

0.5641612

14.47

14.10

2.57

0x0B

600

0.60806349

15.59

15.38

1.34

0.63761642

28.98

27.27

6.27

0.61527414

15.78

15.38

2.55

0x0C

650

0.65926581

16.90

16.67

1.43

0.69060046

31.39

29.55

6.25

0.66692751

17.10

16.67

2.60

0x0D

700

0.70934843

18.19

17.95

1.34

0.74316386

33.78

31.82

6.17

0.71791896

18.41

17.95

2.56

0x0E

750

0.76007223

19.49

19.23

1.34

0.79570772

36.17

34.09

6.09

0.76877243

19.71

19.23

2.50

0x0F

800

0.81059966

20.78

20.51

1.32

0.84789002

38.54

36.36

5.99

0.81975618

21.02

20.51

2.47

0x10

850

0.86228285

22.11

21.79

1.45

0.88138006

40.06

38.64

3.69

0.87071806

22.33

21.79

2.44

0x11

900

0.91005099

23.33

23.08

1.12

0.90063212

40.94

40.91

0.07

0.92183687

23.64

23.08

2.43

0x12

950

0.93013376

23.85

24.36

-2.09

0.92022659

41.83

43.18

-3.13

0.97296767

24.95

24.36

2.42

0x13

1000

0.94551178

24.24

25.64

-5.45

0.94770514

43.08

45.45

-5.23

1.02425197

26.26

25.64

2.43

0x14

1050

0.9666595

24.79

26.92

-7.94

0.99105021

45.05

47.73

-5.61

1.07558602

27.58

26.92

2.44

0x15

1100

1.00054072

25.65

28.21

-9.04

1.05860334

48.12

50.00

-3.76

1.12305367

28.80

28.21

2.10

0x16

1150

1.05244688

26.99

29.49

-8.48

1.15948375

52.70

52.27

0.82

1.17836679

30.21

29.49

2.47

0x17

1200

1.12710175

28.90

30.77

-6.07

1.27185882

57.81

54.55

5.99

1.22905678

31.51

30.77

2.42

Table 12: Raw Data for 94uF Input / 94uF Output Capacitor

94µF

Green

Red

Blue

 

 

Meas

 

Calc

% Error

Meas

 

Calc

% Error

Meas

 

Calc

% Error

0x00

50

0.05200697

1.33

1.28

4.01

0.05436706

2.47

2.27

8.73

0.05426098

1.39

1.28

8.52

0x01

100

0.10356678

2.66

2.56

3.57

0.10741029

4.88

4.55

7.41

0.10632832

2.73

2.56

6.33

0x02

150

0.1542082

3.95

3.85

2.81

0.16045634

7.29

6.82

6.97

0.15769801

4.04

3.85

5.13

0x03

200

0.20524837

5.26

5.13

2.62

0.21290037

9.68

9.09

6.45

0.20863386

5.35

5.13

4.32

0x04

250

0.25610078

6.57

6.41

2.44

0.26618547

12.10

11.36

6.47

0.25931849

6.65

6.41

3.73

0x05

300

0.30645528

7.86

7.69

2.15

0.31828622

14.47

13.64

6.10

0.3099029

7.95

7.69

3.30

0x06

350

0.3572653

9.16

8.97

2.08

0.36985684

16.81

15.91

5.67

0.36067985

9.25

8.97

3.05

0x07

400

0.40774651

10.46

10.26

1.94

0.42234751

19.20

18.18

5.59

0.41182698

10.56

10.26

2.96

0x08

450

0.45800112

11.74

11.54

1.78

0.47483759

21.58

20.45

5.52

0.46222067

11.85

11.54

2.72

0x09

500

0.50869042

13.04

12.82

1.74

0.52873399

24.03

22.73

5.75

0.51296907

13.15

12.82

2.59

0x0A

550

0.55827629

14.31

14.10

1.50

0.58164023

26.44

25.00

5.75

0.56320472

14.44

14.10

2.40

0x0B

600

0.60854326

15.60

15.38

1.42

0.63388916

28.81

27.27

5.65

0.61428574

15.75

15.38

2.38

0x0C

650

0.65988213

16.92

16.67

1.52

0.68597037

31.18

29.55

5.53

0.66513881

17.05

16.67

2.33

0x0D

700

0.71048667

18.22

17.95

1.50

0.73909677

33.60

31.82

5.59

0.7169713

18.38

17.95

2.42

0x0E

750

0.76074182

19.51

19.23

1.43

0.79136279

35.97

34.09

5.52

0.76812468

19.70

19.23

2.42

0x0F

800

0.8112982

20.80

20.51

1.41

0.84310076

38.32

36.36

5.39

0.81840901

20.98

20.51

2.30

0x10

850

0.86227747

22.11

21.79

1.44

0.89487317

40.68

38.64

5.28

0.86932097

22.29

21.79

2.27

0x11

900

0.91322673

23.42

23.08

1.47

0.92747895

42.16

40.91

3.05

0.91998515

23.59

23.08

2.22

0x12

950

0.94056779

24.12

24.36

-0.99

0.95254878

43.30

43.18

0.27

0.97092654

24.90

24.36

2.20

0x13

1000

0.95720689

24.54

25.64

-4.28

0.98313275

44.69

45.45

-1.69

1.02202162

26.21

25.64

2.20

0x14

1050

0.97886934

25.10

26.92

-6.77

1.02896735

46.77

47.73

-2.00

1.07298488

27.51

26.92

2.19

0x15

1100

1.01336698

25.98

28.21

-7.88

1.0986225

49.94

50.00

-0.13

1.12462839

28.84

28.21

2.24

0x16

1150

1.06548863

27.32

29.49

-7.35

1.19693633

54.41

52.27

4.08

1.17503361

30.13

29.49

2.18

0x17

1200

1.14029463

29.24

30.77

-4.98

1.26581559

57.54

54.55

5.48

1.22561547

31.43

30.77

2.13