10.2.5 Detailed Design Procedure

The another typical bulb test is to have the bulbs at room temperature (25°C) and the device heated up to 105°C. This test is designed see if the device can drive the bulbs without hitting thermal shutdown due to the current draw of the bulbs. The passing criteria is that the bulb illuminates when the device enables the channels and the device does not go into thermal shutdown. Figure 51 shows the current waveform of this test and as it can be seen the bulb comes on and stays on without hitting thermal shutdown. Notice that the current is lower in this condition than the inrush condition. This is due to the bulbs effective capacitance being lower at higher temperatures as expected.