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dc2023afa
DEMO MANUAL DC2023A
aDvanceD Demo BoarD operations
pin when another device drives it low (input). Because all
FAULT pins are wire OR’d on the DC2023A, this hardware
configuration allows one to program each device’s fault
settings on a channel-by-channel basis. By default, the
LTM2987 is configured to shut down all channels if other
devices fault and to broadcast its own fault via the FAULT
pins. A fault on these channels will cause only that channel
to fault off. You can think of the “Response” switches as
“shut this channel down when another channel faults”, and
the “Propagate” switches as “drive a fault pin to broadcast
to other channels that this channel faulted”.
Fault Configuration Example
Let’s explore two different examples. Suppose we do not
want channel U0:0 (CH0 1.0V rail) to propagate its fault
to the other channels when it faults. And suppose we do
not want channel U0:1 (CH1 1.1V rail) to shut down in
response to another channel’s fault. We can configure the
switches as shown in Figure 11. Simply click the switches
to open/close. Click OK to close the dialog box. Click the
“PC->RAM” icon to write the changes to the DC2023A.
We can now create a fault on U0:0 (CH0) by shorting
the output to ground. You may use a coin or a jumper
to temporarily connect CH0 to the GND turret. You will
notice that the channel shuts off but the other channels
remain powered up because its fault is not propagated to
the other channels. After the retry period, channel U0:0
(CH0) will power back up. We can now observe the effect
of changing the response setting on U0:1 (CH1). If you
short U0:2 (CH2 1.2V rail) to ground, notice that all rails
shut down except U0:1 (CH1). This is an example of a
keep-alive channel that remains powered up independent
of faults on other channels.
Multiple DC2023A boards can be combined to control up
to 128 independent power supplies. Eight boards may
be cascaded. The number of boards is limited by an I/O
expander chip that has three address pins, allowing eight
different combinations. This setup demonstrates the co-
ordinated fault responses and accurate time base shared
across multiple LTM2987 modules.
Figure 10. Fault Sharing Utility in LTpowerPlay GUI
Figure 11. Updated Fault Sharing Configuration
