I’m using the HD4 for a design and I have it powered from a regulated 12V supply nominally. I wanted to check what the minimum voltage is on the 12V that is acceptable for proper operation.
For my supply, it’s 12V +/-2% worse case from a DC/continuous perspective and then there is a transient response which can dip as low as 10V for <1ms durations depending on the load conditions. Is this acceptable from a design perspective?
The reason I ask is the spec is 12V - 56V and a 12V nominal brick is provided but no tolerance for the lower margin. The current will increase since the wattage is roughly constant is understood and we have sized the 12V for 45W in this case.
The voltage dips 10V for <1ms should be fine as internal power circuits have capacitors and they will smooth voltage ripples if they happen from time to time.
If your power supply is 12V +/-2%, then there will be no problems. Typically the upper and lower margins for power supply are ±10%.
This is a vehicle related project so we have the main battery cleaned up with a DC/DC and avoiding all of the transients of the main line. This is what we need to know in terms of designing a regulator upstream for the 12V that isn’t going to cause the system to brownout or cause failures.
The upstream voltage can swing from ~10V to 33V but we’re regulating and protecting that down to 12V+/-2% DC, with the transients it’s closer to 5%. if we use 10% as a design target then that should give us enough wiggle room to not have to overkill the upstream design.
One more thing to add about the upper range. If the Maximum voltage is 56V, it would be better not to exceed 57-58V as the over-voltage clamping will start to work. In other words upper range for this particular case is not +10%.