Output voltage and pwm modulation captured fig
| Robust DCDC Converter for Automotive Applications | 293 | |
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| IL AV G max =VE RR CL P | (9) | |
itation to 2 A, while during the VERR CLP slope (see Fig. 26), the current limitation In our case, Rs = 0.25 � and ACSA = 6. This sets the steady state current lim- |
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| Vin_min | ||
| Lfilt |
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HF ceramic Cap |
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Vin | VH | |||
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| ESR |
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EMC filter
9.1 I-V Characteristics
The DCDC I-V characteristics for each particular mode are displayed in the figures below. In the actual application, a coil with saturation current of 1 A is used. The impact is clearly seen in Figs. 28 and 29. In the moment the coil current exceeds 1 A, VO abruptly declines. From Fig. 29 it is obvious that in the buck mode the coil current is always below 1 A if the load current is below 1 A as well. In this case, VO is flat with respect to the output current while the load current easy reaches 1 A. Using a coil with higher saturation current, the overall DCDC load performance improves accordingly.
The next most important test required for automotive field is a periodical short and release on the DCDC output voltage. Such captured waveforms are displayed in Fig. 31. Reliable start-up, no uncontrolled current spikes nor thermal shut down are a must for automotive application.
9.4 EMC – Susceptibility and Radiation Results
