Isolated bias supply start-up and shutdown
waveforms are shown in this section. The focus of these tests was on proper ramp up
and ramp down of outputs with abrupt and noisy loading and with a noisy and bouncing
enable signal.
![Isolated DC/DC Turn On by Rising Enable Signal GUID-20220322-SS0I-WVKW-4SCM-5GMCXBFFGMLR-low.jpg](/ods/images/TIDT256A/GUID-20220322-SS0I-WVKW-4SCM-5GMCXBFFGMLR-low.jpg)
24 VDC into isolated DC/DC:
75-mA load between +15-V and –5-V output
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output with 0.5-V overshoot
Scope channel 3 (blue) is the enable signal
Scope channel 4 (green) is the –5-V output.
Figure 3-13 Isolated DC/DC Turn On by Rising Enable Signal![Isolated DC/DC Turn On by Rising Enable Signal With Switch Bounce GUID-20220322-SS0I-ZGKW-P5XT-TGXGTGCSTQTD-low.jpg](/ods/images/TIDT256A/GUID-20220322-SS0I-ZGKW-P5XT-TGXGTGCSTQTD-low.jpg)
24 VDC into isolated DC/DC:
75-mA load between +15-V and –5-V output
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output with 0.5-V overshoot
Scope channel 3 (blue) is the enable signal
Scope channel 4 (green) is the –5-V output
Figure 3-15 Isolated DC/DC Turn On by Rising Enable Signal With Switch Bounce![Isolated DC/DC Turn Off by Falling Enable Signal GUID-20220322-SS0I-97NB-VHWS-KBPSLL98KMKN-low.jpg](/ods/images/TIDT256A/GUID-20220322-SS0I-97NB-VHWS-KBPSLL98KMKN-low.jpg)
24 VDC into isolated DC/DC:
75-mA load between +15-V and –5-V output
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output
Scope channel 3 (blue) is the enable signal
Scope channel 4 (green) is the –5-V output.
Figure 3-14 Isolated DC/DC Turn Off by Falling Enable Signal![Isolated DC/DC Turn On by Rising Main VIN to 24 V GUID-20220322-SS0I-FHVZ-MXDF-74B2XVW62FMK-low.jpg](/ods/images/TIDT256A/GUID-20220322-SS0I-FHVZ-MXDF-74B2XVW62FMK-low.jpg)
24 VDC ramped up into isolated DC/DC:
75-mA load between +15-V and –5-V output. Enable is always high.
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output with 0.5-V overshoot
Scope channel 3 (blue) is ramping up main VIN
Scope channel 4 (green) is the –5-V output.
Figure 3-16 Isolated DC/DC Turn On by Rising Main VIN to 24 V