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I. Preface
This is a PDA5927 four-quadrant photocell. It has four photocells encapsulated together. It is often used for position sensors. The following is a preliminary test of its characteristics to provide a basis for future applications.
2. Make an adapter board
On the Jialichuang website, there are PDF5927 devices, export them, design the test board, use a 5-pin interface to lead out, draw a single-sided board, after a minute, get the test board, place it on a breadboard, and perform a preliminary test of its port characteristics below.
First, the forward conduction voltage of the four quadrant diodes is measured using a multimeter diode range, which is all around 0.53V and is reversed to cut off.
Use a multimeter to measure the voltage at both ends of the photocell. In normal indoor light, the voltage is about 235mV. A flashlight is used to irradiate the photocell. It can be seen that the photocell voltage can go up to 360mV.
3. Measurement of metal box
To avoid the effects of external ambient light, the photocell is placed inside a metal box that can be sealed. There's a breadboard inside that leads its leads through the Q9 socket on the metal box. Cover the metal box and keep it dark inside. Measure the output voltage of the photocell, and you can see that the output voltage is reduced to about 0V.
Place a red LED above the photocell, the LED luminous intensity is basically proportional to the passing current, and the relationship between the photocurrent of the LED and the voltage at the end of the photocell is measured, and this relationship is also the relationship between the light intensity and the voltage of the photocell. The DH1766 is used to provide LED voltage power supply. The LED current is obtained by measuring the voltage on the series resistance of the LED. According to the test results, there is a nonlinear saturation relationship between the voltage and the light intensity of the photocell.
▲ Figure 1.3.1 LED current and photocell voltage
#!/usr/local/bin/python
# -*- coding: gbk -*-
#******************************
# TEST1.PY - by Dr. ZhuoQing 2024-04-30
#
# Note:
#******************************
from headm import *
from tsmodule.tsvisa import *
from tsmodule.tsstm32 import *
dm3068open()
vdim = linspace(0, 5, 100)
idim = []
odim = []
dh1766volt1(vdim[0])
time.sleep(5)
R = 220
for v in vdim:
dh1766volt1(v)
time.sleep(2)
vi = dm3068vdc()
i = vi / R
idim.append(i)
meter = meterval()
odim.append(meter[0])
tspsave('current', vdim=vdim, idim=idim, odim=odim)
printff(v, i, meter)
plt.plot(idim, odim, lw=3)
plt.xlabel("Current(A)")
plt.ylabel("Voltage(V)")
plt.grid(True)
plt.tight_layout()
plt.show()
#------------------------------------------------------------
# END OF FILE : TEST1.PY
#******************************
vdim=[0.0000,0.0505,0.1010,0.1515,0.2020,0.2525,0.3030,0.3535,0.4040,0.4545,0.5051,0.5556,0.6061,0.6566,0.7071,0.7576,0.8081,0.8586,0.9091,0.9596,1.0101,1.0606,1.1111,1.1616,1.2121,1.2626,1.3131,1.3636,1.4141,1.4646,1.5152,1.5657,1.6162,1.6667,1.7172,1.7677,1.8182,1.8687,1.9192,1.9697,2.0202,2.0707,2.1212,2.1717,2.2222,2.2727,2.3232,2.3737,2.4242,2.4747,2.5253,2.5758,2.6263,2.6768,2.7273,2.7778,2.8283,2.8788,2.9293,2.9798,3.0303,3.0808,3.1313,3.1818,3.2323,3.2828,3.3333,3.3838,3.4343,3.4848,3.5354,3.5859,3.6364,3.6869,3.7374,3.7879,3.8384,3.8889,3.9394,3.9899,4.0404,4.0909,4.1414,4.1919,4.2424,4.2929,4.3434,4.3939,4.4444,4.4949,4.5455,4.5960,4.6465,4.6970,4.7475,4.7980,4.8485,4.8990,4.9495,5.0000]
idim=[-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0001,0.0001,0.0002,0.0003,0.0005,0.0006,0.0008,0.0010,0.0011,0.0013,0.0015,0.0017,0.0019,0.0021,0.0023,0.0025,0.0026,0.0028,0.0030,0.0032,0.0034,0.0036,0.0038,0.0040,0.0042,0.0044,0.0046,0.0048,0.0050,0.0052,0.0054,0.0055,0.0057,0.0059,0.0061,0.0063,0.0065,0.0067,0.0069,0.0071,0.0073,0.0075,0.0077,0.0079,0.0081,0.0083,0.0085,0.0087,0.0089,0.0091,0.0093,0.0095,0.0097,0.0099,0.0101,0.0103,0.0105,0.0107,0.0109,0.0110,0.0112,0.0114,0.0116,0.0118,0.0120,0.0122,0.0124,0.0126,0.0128,0.0130]
odim=[-0.0044,-0.0017,-0.0005,-0.0002,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0000,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,-0.0001,0.0000,0.0004,0.0017,0.0050,0.0182,0.0569,0.1166,0.1459,0.1666,0.1817,0.1931,0.2023,0.2099,0.2163,0.2219,0.2267,0.2310,0.2349,0.2384,0.2416,0.2445,0.2472,0.2498,0.2521,0.2544,0.2565,0.2585,0.2604,0.2622,0.2639,0.2655,0.2671,0.2686,0.2700,0.2714,0.2727,0.2740,0.2752,0.2764,0.2776,0.2787,0.2798,0.2808,0.2819,0.2828,0.2838,0.2847,0.2857,0.2865,0.2874,0.2882,0.2891,0.2899,0.2907,0.2914,0.2922,0.2929,0.2936,0.2943,0.2950,0.2957,0.2963,0.2970,0.2976,0.2982,0.2988,0.2994,0.3000,0.3006,0.3011,0.3017,0.3022,0.3028,0.3033,0.3038]
Therefore, the reaction light intensity cannot use the port voltage of the photocell, and the light intensity needs to be reacted according to the reverse current. Next, a multimeter is used to measure the relationship between the short-circuit current of the photocell and the photocurrent irradiating the LED.
Next, a multimeter is used to measure the relationship between the short-circuit current of the photocell and the light intensity. DH1766 is still used to supply current to the LED in the metal box, and the test results show that the working current of the LED and the short-circuit current of the photocell are approximately linear. This also shows that there is a linear relationship between the photocell short-circuit current and the light intensity. Therefore, the op amp is used to convert the output photocurrent of the photocell into voltage, and the light intensity obtained by the photocell can be reflected.
▲ LED current and photocell short-circuit current
vdim=[0.0000,0.0505,0.1010,0.1515,0.2020,0.2525,0.3030,0.3535,0.4040,0.4545,0.5051,0.5556,0.6061,0.6566,0.7071,0.7576,0.8081,0.8586,0.9091,0.9596,1.0101,1.0606,1.1111,1.1616,1.2121,1.2626,1.3131,1.3636,1.4141,1.4646,1.5152,1.5657,1.6162,1.6667,1.7172,1.7677,1.8182,1.8687,1.9192,1.9697,2.0202,2.0707,2.1212,2.1717,2.2222,2.2727,2.3232,2.3737,2.4242,2.4747,2.5253,2.5758,2.6263,2.6768,2.7273,2.7778,2.8283,2.8788,2.9293,2.9798,3.0303,3.0808,3.1313,3.1818,3.2323,3.2828,3.3333,3.3838,3.4343,3.4848,3.5354,3.5859,3.6364,3.6869,3.7374,3.7879,3.8384,3.8889,3.9394,3.9899,4.0404,4.0909,4.1414,4.1919,4.2424,4.2929,4.3434,4.3939,4.4444,4.4949,4.5455,4.5960,4.6465,4.6970,4.7475,4.7980,4.8485,4.8990,4.9495,5.0000]
idim=[-0.0001,-0.0006,0.0002,-0.0006,-0.0008,-0.0016,-0.0006,-0.0006,-0.0009,-0.0006,-0.0022,-0.0010,-0.0020,-0.0007,-0.0021,-0.0010,-0.0015,-0.0027,-0.0009,-0.0004,-0.0002,0.0002,-0.0006,-0.0021,-0.0006,-0.0011,-0.0009,-0.0013,-0.0015,-0.0014,0.0062,0.0265,0.0782,0.1707,0.3007,0.4594,0.6475,0.8582,1.0850,1.3241,1.5755,1.8389,2.1075,2.3860,2.6680,2.9584,3.2467,3.5435,3.8467,4.1513,4.4597,4.7718,5.0851,5.4010,5.7195,6.0385,6.3594,6.6824,6.9981,7.3245,7.6498,7.9753,8.3015,8.6278,8.9571,9.2856,9.6127,9.9439,10.2699,10.5917,10.9222,11.2512,11.5789,11.9101,12.2370,12.5638,12.8936,13.2186,13.5469,13.8726,14.1935,14.5220,14.8477,15.1709,15.4973,15.8185,16.1423,16.4662,16.7903,17.1087,17.4260,17.7377,18.0566,18.3773,18.6940,19.0114,19.3286,19.6423,19.9570,20.2704]
ridim=[-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,0.0000,0.0000,0.0000,0.0001,0.0002,0.0004,0.0010,0.0027,0.0071,0.0185,0.0471,0.1076,0.2072,0.3383,0.4913,0.6548,0.8304,1.0127,1.1993,1.3896,1.5826,1.7773,1.9743,2.1723,2.3716,2.5719,2.7689,2.9708,3.1728,3.3760,3.5795,3.7833,3.9875,4.1916,4.3967,4.6045,4.8086,5.0141,5.2155,5.4223,5.6282,5.8350,6.0418,6.2486,6.4559,6.6632,6.8705,7.0782,7.2855,7.4891,7.6968,7.9050,8.1127,8.3209,8.5286,8.7368,8.9450,9.1532,9.3618,9.5700,9.7745,9.9827,10.1918,10.4000,10.6091,10.8177,11.0268,11.2350,11.4445,11.6532,11.8618,12.0668,12.2759,12.4850,12.6932,12.9023,13.1114,13.3205,13.5295,13.7382]
#!/usr/local/bin/python
# -*- coding: gbk -*-
#******************************
# TEST1.PY - by Dr. ZhuoQing 2024-04-30
#
# Note:
#******************************
from headm import *
from tsmodule.tsvisa import *
from tsmodule.tsstm32 import *
dm3068open()
vdim = linspace(0, 5, 100)
idim = []
ridim = []
dh1766volt1(vdim[0])
time.sleep(5)
R = 220
for v in vdim:
dh1766volt1(v)
time.sleep(2)
ii = dm3068cdc()*1e6
idim.append(ii)
meter = meterval()
ridim.append(meter[0]/R*1e3)
tspsave('current', vdim=vdim, idim=idim, ridim=ridim)
printff(v, ii, meter)
plt.plot(ridim, idim, lw=3)
plt.xlabel("LED Current(mA)")
plt.ylabel("EC(uA)")
plt.grid(True)
plt.tight_layout()
plt.show()
#------------------------------------------------------------
# END OF FILE : TEST1.PY
#******************************
In the following case, a lithium battery is used to apply a bias voltage of -4.2V to the photocell, and the relationship between the photocell's reverse conduction current and light intensity is re-measured. Controlling the LED current from 0 to 15mA, measuring the reverse conduction current of the photocell, you can see that this current is almost the same as the short-circuit current with 0V bias. Plot them together, except that when the photocurrent is relatively large, the reverse current with the reverse bias voltage is slightly larger. This shows that the reverse current of the photocell is basically a saturation constant current characteristic.
▲ Figure 1.3.3 Reverse conduction current with bias
vdim=[0.0000,0.0505,0.1010,0.1515,0.2020,0.2525,0.3030,0.3535,0.4040,0.4545,0.5051,0.5556,0.6061,0.6566,0.7071,0.7576,0.8081,0.8586,0.9091,0.9596,1.0101,1.0606,1.1111,1.1616,1.2121,1.2626,1.3131,1.3636,1.4141,1.4646,1.5152,1.5657,1.6162,1.6667,1.7172,1.7677,1.8182,1.8687,1.9192,1.9697,2.0202,2.0707,2.1212,2.1717,2.2222,2.2727,2.3232,2.3737,2.4242,2.4747,2.5253,2.5758,2.6263,2.6768,2.7273,2.7778,2.8283,2.8788,2.9293,2.9798,3.0303,3.0808,3.1313,3.1818,3.2323,3.2828,3.3333,3.3838,3.4343,3.4848,3.5354,3.5859,3.6364,3.6869,3.7374,3.7879,3.8384,3.8889,3.9394,3.9899,4.0404,4.0909,4.1414,4.1919,4.2424,4.2929,4.3434,4.3939,4.4444,4.4949,4.5455,4.5960,4.6465,4.6970,4.7475,4.7980,4.8485,4.8990,4.9495,5.0000]
idim=[0.0002,0.0002,-0.0006,0.0005,-0.0004,0.0007,0.0007,0.0012,0.0010,0.0002,0.0002,0.0007,0.0020,0.0002,-0.0002,-0.0008,0.0008,0.0014,0.0011,0.0003,0.0016,0.0006,0.0010,0.0007,0.0010,0.0003,0.0004,0.0020,0.0013,0.0021,0.0081,0.0305,0.0849,0.1853,0.3252,0.4958,0.6960,0.9196,1.1620,1.4177,1.6871,1.9657,2.2548,2.5497,2.8507,3.1602,3.4651,3.7837,4.1056,4.4297,4.7578,5.0873,5.4204,5.7556,6.0916,6.4318,6.7725,7.1138,7.4491,7.7939,8.1381,8.4831,8.8288,9.1773,9.5223,9.8702,10.2163,10.5619,10.9115,11.2511,11.5986,11.9450,12.2927,12.6403,12.9848,13.3322,13.6770,14.0224,14.3680,14.7130,15.0495,15.3912,15.7336,16.0750,16.4162,16.7576,17.0995,17.4383,17.7762,18.1141,18.4525,18.7804,19.1166,19.4507,19.7833,20.1173,20.4484,20.7768,21.1062,21.4345]
ridim=[-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,-0.0000,0.0000,0.0000,0.0001,0.0002,0.0004,0.0011,0.0028,0.0073,0.0191,0.0484,0.1113,0.2151,0.3521,0.5125,0.6835,0.8675,1.0584,1.2538,1.4532,1.6555,1.8594,2.0657,2.2731,2.4821,2.6920,2.8983,3.1099,3.3216,3.5345,3.7477,3.9613,4.1752,4.3892,4.6077,4.8205,5.0350,5.2514,5.4623,5.6782,5.8950,6.1114,6.3282,6.5450,6.7623,6.9795,7.1968,7.4145,7.6323,7.8455,8.0632,8.2814,8.4995,8.7173,8.9350,9.1532,9.3718,9.5905,9.8086,10.0273,10.2418,10.4605,10.6791,10.8982,11.1173,11.3364,11.5555,11.7745,11.9936,12.2123,12.4318,12.6464,12.8655,13.0850,13.3041,13.5236,13.7427,13.9618,14.1818,14.4014]
▲ Figure 1.3.4 The relationship between the light current with 4V backpressure and the 0V backpressure and the current illuminating the LED
※Summary※
In this paper, the characteristics of a four-quadrant photocell are tested, and the relationship between the reverse current and the light intensity is approximately linear. The reverse current is about 20 microamperes, and this current can be converted into a voltage using an op amp and then a signal can be acquired.
Resources
[1]
PDA5927 Four-quadrant photodiode: http://szsgir.com/data/PDA5927_CN.PDF