1476 - Power Manager II: Can I use an ispPAC-POWR1220 for -48V hot-swap control?

1476 - Power Manager II: Can I use an ispPAC-POWR1220 for -48V hot-swap control?

Although most of our applications literature shows the ispPAC-POWR607 in -48V hot-swap applications, it is possible to also use an ispPAC-POWR1220. It is generally not preferable to the ispPAC-POWR607 for the following reasons:

  1. It is physically larger.
  2. It is more expensive.
  3. It has more logic and I/O resources than are typically needed just for hot swap.
  4. It draws more current and this current must be drawn from ground down to -48V, resulting in higher than necessary power dissipation.

Of the above, item number 3 above is probably the most compelling reason not to use the ispPAC-POWR1220 for -48V hot swap. Although the device has lots of resources and I/O, it will be referenced to the -48V rail. This will make it very difficult if not impossible to interface to other circuitry referenced to ground, especially voltage monitoring functions. In a -48V hot swap application many of the device's resources may end up being unused.