00:00 |
- An excellent feature that many PMUs have is being able to configure multiple output channels to operate in parallel.
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00:07 |
What this means is that you're able to connect a single device or load to multiple output channels and configure the PMU to always switch those output channels in response to the same input conditions.
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00:19 |
Essentially combining them into a single channel with an overall higher maximum current rating.
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00:24 |
The reason some PMUs include this feature is to increase their flexibility.
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00:28 |
Instead of having 4 20 amp capable outputs, the PMU can have 8 10 amp capable ouputs and if a device draws more than 10 amps, 2 of these channels can be parallel together.
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00:41 |
This gives more channels overall that can be controlled individually.
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00:45 |
High power MOSFETs are relatively expensive and by using 2 lower power units, the build cost of a PMU can also be reduced.
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00:54 |
The implementation of paralleling outputs like this varies with the PMU manufacturer and you need to make sure your PMU supports this feature.
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01:03 |
You can't simply configure two separate output channels to have the same input switching conditions and then just connect them to the same load.
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01:11 |
This will likely confuse the PMU current monitoring logic as there'll always be a slight delay between one channel turning on and the other.
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01:18 |
This delay might cause a current limit to be inadvertently tripped or other unexpected results.
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01:25 |
Related to output paralleling are PMUs that have a single output channel MOSFET connected to 2 physical pins on the connector.
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01:33 |
This is similar to paralleling 2 output channels but is a permanent connection, not something configurable in the software.
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01:41 |
The reason for this is that often the maximum output channel current is limited by the physical connector that's being used.
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01:48 |
It'll have a maximum continuous current rating per pin and the PMU shouldn't exceed this.
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01:53 |
By connecting the output channel to 2 physical pins, that available current can double.
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01:59 |
In either situation, whether you've configured outputs to operate in parallel or if you're using a PMU that has a single channel connected to 2 pins, you need to make sure that the load connected to each pin on that connector is as balanced as possible.
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02:14 |
If you're connecting just a single device to an output channel that has two physical pins, you can bring the wires from those pins together into a splice and then have the other side of that splice connect to the device with an appropriately sized larger gauge wire.
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02:29 |
If the output channel is supplying multiple devices like 8 injectors for example, you could have 4 injectors powered from each pin and this would ensure that that load is balanced.
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02:40 |
In this course module, we've looked at PMU output paralleling.
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02:43 |
This is a feature implemented in some PMUs to allow 2 or more channels to be combined into a single higher current channel.
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02:51 |
The PMU must support this feature specifically and it needs to be configured in the software.
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02:57 |
Some PMUs have single output channels connected to multiple connector pins permanently, allowing those channels to output a higher overall current than a single connector pin could handle.
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03:09 |
When paralleling output channels or using a single channel that has multiple pins, the current flowing through each connector pin must be kept as balanced as possible.
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