Enable pin test
Current sense test
The new BTS load switch comes with built in current sense, to measure the output of said current sense the load switch output channel must be enabled. There are 2 ways to enable loadswitch output channel, 1.) solder jumper wire from 3v3 to enable pin or 2.) use firmware to enable desired load switch. Once either of the method are employed connect the board with power supply and e-load, once ready power the board using 13V~14.5V and turn on the e-load. In the board schematic there is an 1.21 kΩ resistor, measure the voltage drop across that and record it with the current draw.
RL = 1.21KΩ
BTS7200-2EPA
| Current (IL) [A] | IS Voltage (VIS ) [V] | IS Current (IIS) [A] |
|---|---|---|
| 0.5 | 0.9062 | 0.000749 |
| 0.6 | 1.084 | 0.000896 |
| 0.7 | 1.2619 | 0.001043 |
| 0.8 | 1.4398 | 0.00119 |
| 0.9 | 1.6278 | 0.001345 |
| 1 | 1.7971 | 0.001485 |
| 1.1 | 1.9752 | 0.001632 |
| 1.2 | 2.1532 | 0.00178 |
| 1.3 | 2.3311 | 0.001927 |
| 1.4 | 2.5095 | 0.002074 |
| 1.5 | 2.6878 | 0.002221 |
| 1.6 | 2.866 | 0.002369 |
| 1.7 | 3.0442 | 0.002516 |
| 1.8 | 3.2226 | 0.002663 |
| 1.9 | 3.4019 | 0.002811 |
| 2 | 3.5805 | 0.002959 |
| 2.1 | 3.7588 | 0.003106 |
| 2.2 | 3.9371 | 0.003254 |
| 2.3 | 4.1158 | 0.003401 |
| 2.4 | 4.2948 | 0.003549 |
| 2.5 | 4.4726 | 0.003696 |
| 2.6 | 4.6459 | 0.00384 |
| 2.7 | 4.8126 | 0.003977 |
| 2.8 | 4.9773 | 0.004113 |
| 2.9 | 5.1397 | 0.004248 |
| 3 | 5.3012 | 0.004381 |
Datasheet KILIS = 670
Experiment KILIS = 683.33
Current sense select test
Current sense resistor value selection
This resistor value will determine the voltage outputted to the gpio, therefore we want to limit the maximum voltage output to 3.3V or whatever the gpio is rated for.
1.2A loadswitch IS resistors (ratio constant on datasheet = 670) (ratio by expirement = 683.33)
-1708.325 for expiremented constant @ 1.2A
-1675 for datasheet constant @ 1.2A
-1600 choosen for 1.256A @ 3V for datasheet, and 1.281A @ 3V for expiremental
4.5A loadswitch IS resistors (ratio constant on datasheet = 1800)
-1200 for datasheet constant @ 4.5A
-1210 choosen 4.463A @ 3V