Continous Mode High Side Switch

[Eva]

Why can't you just disable the full bridge? I don't think that an additional switch is required.

[peranders]

Have you checked Intersil HIP4082 with disable?

[N-Channel]

Originally posted by Eva
Why can't you just disable the full bridge? I don't think that an additional switch is required..........

........Like using the disable pin(s) of the HV Driver ICs.

[TechGuy]

Why can't you just disable the full bridge? I don't think that an additional switch is required.

I will be using the High Side switch for a startup test in case one or more MOSFETs of the H-bridge fail. The H-Bridge will be controlled by a microcontroller which will permit some basic in-circuit testing. I need a way to limit the current going into the H-bridge to avoid a potential shoot-through if one of the MOSFET is fused.

[Eva]

By the time the microcontroller notices the overcurrent caused by a single MOSFET blowing, you will already have a total of three MOSFETs blown with a dead short between drain and source, including the main high side switch...

[peranders]

TechGuy, a HIP4082 is pretty nice and also safe. I have personal experience of this IC and here we talk 475 A in a pcb!

[TechGuy]

By the time the microcontroller notices the overcurrent caused by a single MOSFET blowing, you will already have a total of three MOSFETs blown with a dead short between drain and source, including the main high side switch...

I am going to use a separate analog circuit to shutdown in an overload condition. The microcontroller just controls the bridge switching and performs a self startup test. Its very possible that I won't be able shutdown in time to prevent the other mosfets from being blown. The overall idea is to run a start up test on the circuit to test for failed devices, which could be use to reduce manual diagnostics. I will probably include funtionally to shutdown the bridge during an overload condition using a comparor (no ADC) and and interrupt input to minimize latency as backup overload shutdown system.

TechGuy, a HIP4082 is pretty nice and also safe. I have personal experience of this IC and here we talk 475 A in a pcb!

Thanks, but I wish to do something different than an off the self controller. I could go the easier route, but were is the fun in that! I plan to include:

1. Multiple Discrete switching frequencies depending on the load. At low loads, the switching frequency is lower and higher frequencies during higher loads to maximum efficiency while using a small transformer core.

2. ZVS switch and possibly micro switching (at low loads).

3. Synchronous Rectification.

4. Thermal monitoring and shutdown

5. Low input voltage detection (and shutdown).

6. Start up self-test.

Thanks for your interest