SLVAFG5 November   2022 TPS929240-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Device Overview
    2. 1.2 BCI Test Method
  4. 2PCB Design Recommendation
    1. 2.1 Schematic Design
    2. 2.2 Layout Design
  5. 3BCI Test
    1. 3.1 Test Set-up
    2. 3.2 Test Results
  6. 4Summary
  7. 5References

1.2 BCI Test Method

Buck Current Injection (BCI) is a method of carrying out immunity tests by inducting disturbance signals directly into the wiring harness by means of a current injection probe. In an automotive exterior lighting application, due to the long cables that connect the battery to a LED module, the noise generated by RF electromagnetic fields frequently degrades the performance of the electronic device. To simulate the effect of noise in vehicle environment, the international standard ISO11452-4 defines BCI test methods for evaluating the immunity levels of electronic devices.

The TPS929240-Q1 testing was done according to the ISO11452-4:2011 standard. Substitution method is used and the applicable frequency range is 1MHz to 400MHz. As shown in Table 1-1, according to the example of test severity levels for BCI from the standard, based on the test level Ⅳ, the highest 200mA current is injected during testing. The detailed test requirements are shown in Table 1-2.

Table 1-1 Example of Test Severity Levels (BCI)
Frequency Band (MHz) Test Level I (mA) Test Level II (mA) Test Level III (mA) Test Level IV (mA) Test Level V (mA)
1 to 3 60 × F M H z   /   3 100 × F M H z   /   3 150 × F M H z   /   3 200 × F M H z   /   3 Specific values agreed between the users of this part of ISO 11452
3 to 200 60 100 150 200
200 to 400 60 × 200 /   F M H z 100 × 200 /   F M H z 150 × 200 /   F M H z 200 × 200 /   F M H z
Table 1-2 Test Requirements
Frequency (MHz) Frequency Step Size (MHz) Dwell Time (s) Text Level (mA) Working Voltage (V) Probe Type Probe Distance to DUT Modulation
1 to 3 0.1 2 200 × F M H z   /   3 12 Open Loop 150 mm
450 mm
750 mm		 CW
AM
3 to 200 5 2 200 12 Open Loop 150 mm
450 mm
750 mm		 CW
AM
200 - 400 10 2 200 × 200 /   F M H z 12 Open Loop 150 mm
450 mm
750 mm		 CW
AM

As defined in the Function Performance Status Classification (FPSC), four function performance status of the device functions are divided by whether the function can perform as designed during and after the test. So two key parameters, including supply current and LED status were monitored to measure the function performance during the whole test. The general acceptance criteria are shown in Table 1-3.

Table 1-3 Acceptance Criteria
Monitoring Parameters Acceptance Test Level
Supply current Changes < ±20% IV
LED No flicker IV