10.3.3 Application Curves

When the device receives a rising edge on the ENx pulse the output will turn on as shown in Figure 53. After the turn-on delay time, the device V_OUT goes to the V_BB supply and begins outputting the steady state resistive current.

Figure 53. Turn On Waveform

When the device turns off on a falling edge of ENx, the channel I_OUT will go to zero and the V_OUT will drop to zero as well as shown in Figure 54.

Figure 54. Turn-Off Waveform

While enabled, it is important to measure the output current through both channels. Figure 55 shows this behavior when toggling the SELx pins. The image shows that when SEL2 toggles high to low, the SNS pin toggles between representing I_OUT1 and I_OUT2. When SEL2 is low SNS represents I_OUT1 and when SEL2 is high SNS represents I_OUT2. This image shows that channel 2 is currently outputting twice the output current as channel 1.

Figure 55. Toggling Between CH1 and CH2 Current Measurement

Figure 56 shows the SNS current behavior when there is a load step. The image shows the output current temporarily increase from 1 A to 5 A and then return to 1 A. In this situation, the output current is accurately modeled throughout the pulse by the voltage on the SNS pin allowing for accurate diagnostics.

Figure 56. SNS Settling Time

If the output of the TPS2HB16-Q1 is short-circuited, the device will protect the system from failure. shows the device turning off the output at a set current limit when the output is short circuited. (Note: shows a case with a higher R_ILIM than calculated in this example, so the current limit is higher than ).

Figure 57. TPS2HB16B-Q1 Short Circuit Waveform