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Power Management ICs

Tobbera
Level 1
First question asked Welcome!
Level 1

I'm experimenting with the BTS50010-1TAD high side smart switch. However I'm experiencing very scattered values on the current feedback pin. I have connectedb the BTS to a ESP32 MCU.

I also don't understand how the dkILIS vs Rsense is calculated, because the values that is being read is not what I expected. With a 10K Rsense I was expecting 18500 µV per Amp = 18,5 mV per Amp = 0,05 Amp per mV. But what I get is notthis, and with a very inconsistent ratio between Vsense and the actual current measured thru the MOSFET.

Also the Vsense value can easily rise above any commonly available ADC Vmax value, usually 3V3 or 5V. But there is no zener or any other protection circuit recommended in the datasheet for the BTS50010-1TAD. What is the idea here?

This is my circuit:

Tobbera_0-1643230803845.png

 

Results from Vsense measured at IS versus actual mA flowing:

µV mA Ratio
2851941 13700 208.17
1883296 11400 165.20
1755164 10700 164.03
1802710 11000 163.88
1766447 10800 163.56
1774505 10900 162.80
1704395 10700 159.29
1693113 10750 157.50
1220073 8000 152.51
1061318 7000 151.62
1095970 7500 146.13
917875 6300 145.69
986373 6800 145.05
826813 5800 142.55
948498 6700 141.57
875970 6200 141.29
904175 6500 139.10
828425 6000 138.07
832454 6100 136.47
747838 5500 135.97
730915 5400 135.35
697069 5200 134.05
743809 5600 132.82
647912 4900 132.23
617289 4700 131.34
641465 5000 128.29
567326 4500 126.07
535091 4300 124.44
564908 4600 122.81
531062 4400 120.70
461758 4000 115.44
383589 3500 109.60
413406 3800 108.79
277216 3000 92.41
251428 2800 89.80
218388 2700 80.88
199047 2500 79.62
173260 2350 73.73
137802 2150 64.09
112820 2000 56.41
88644 1900 46.65
75750 1800 42.08
68498 1700 40.29
59633 1600 37.27
52380 1500 34.92
41904 1400 29.93
30622 1300 23.56
16923 1000 16.92
15311 1150 13.31
12087 1100 10.99
5641 1000 5.64
4029 1000 4.03
800 900 0.89
0 800 0.00
0 700 0.00
0 600 0.00

 

Thank you in advance.

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1 Solution
Meghana
Moderator
Moderator 25 likes received 100 sign-ins 25 solutions authored
Moderator

Hello Tobbera,

Thank you for posting on Infineon Community.

dkILIS is not exactly a function of Rsense. It mainly depends on Vs, difference between Vs & Vis, and Tj. A typical value of 1kohm is recommended for Rsense value in the datasheet. With this the measured Vsense can be kept below the uC measurement range.

The current through Is pin is given by below formula:

IIS =IL/dkILIS+ IIS0  

The wide variation in the ratio is contributed by the tolerance of both dkILIS & IIS0. IISO values at different Tj is given in "Table 6 Electrical Characteristics: BTS50010-1TAD"  and dkILIS vs Tj is provided in the section 6.2.

Kindly consider all these tolerance while analyzing the accuracy of Sense.

Request you to repeat your experiment with Rsense of 1kohm and let us know your observation.  Also please share the specifications of input and output voltage to analyze the behavior further. 

Thanks,

Meghana R

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Meghana
Moderator
Moderator 25 likes received 100 sign-ins 25 solutions authored
Moderator

Hello Tobbera,

Thank you for posting on Infineon Community.

dkILIS is not exactly a function of Rsense. It mainly depends on Vs, difference between Vs & Vis, and Tj. A typical value of 1kohm is recommended for Rsense value in the datasheet. With this the measured Vsense can be kept below the uC measurement range.

The current through Is pin is given by below formula:

IIS =IL/dkILIS+ IIS0  

The wide variation in the ratio is contributed by the tolerance of both dkILIS & IIS0. IISO values at different Tj is given in "Table 6 Electrical Characteristics: BTS50010-1TAD"  and dkILIS vs Tj is provided in the section 6.2.

Kindly consider all these tolerance while analyzing the accuracy of Sense.

Request you to repeat your experiment with Rsense of 1kohm and let us know your observation.  Also please share the specifications of input and output voltage to analyze the behavior further. 

Thanks,

Meghana R

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Meghana
Moderator
Moderator 25 likes received 100 sign-ins 25 solutions authored
Moderator

Hello Tobbera,

Do you have any further query regarding this topic? If there are no questions, can we close this thread?

Regards

Meghana 

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