Vicor VI Chip PRM Evaluation Board - Manual (Page 26)

UG:013 vicorpower.com Applications Engineering: 800 927.9474 Page 26
Slave operating mode (Arrays)
Mode select switch S10 setting: keep the switch S10 setting at all positions as shown in
following illustration.
Slave operation is required for constructing arrays of parallel devices as described
in the next section. Switch at position 1 is ON and switch at rest of the positions are
OFF. When switch at position 1 is ON, TRIM pin of the PRM is shorted to SGND and
PRM is configured as a slave. When a PRM is configured as slave, the internal voltage
and current sensing circuitry are disabled and slave PRMs receive their control signal
(SHARE) from a master PRM or external remote sense circuit.
For Remote Sense operation parallel array where all PRMs are configured as slave,
switch at position 3 should be ON to enable the constant output current limit.
Paralleling
The paralleling and current sharing capability of the devices can be demonstrated by
stacking multiple evaluation board and interconnecting the inputs and outputs with
standoffs of sufficient current rating to create a parallel array. See Figure 16 below. One
board should be configured normally for Adaptive Loop or Remote Sense operation
and placed on top for easy access to control circuitry. The remaining PRMs should be
configured as Slaves and placed underneath.
When paralleling PRMs, the ENABLE, SHARE and SGND pins should be connected
together. Dual paralleling wire to board connectors (J17 and J18) are used for
transferring signal pins (ENABLE, SHARE and SGND) in parallel operation from board
to board. These connectors provide simple strip and insert option and accept 18-24AWG
solid wires. SHARE and SGND wires can be twisted to minimize noise pick-up. Note that
when using J17 and J18, SGND pins will be connected together through an on board
1 OHM series resistors to decouple signal grounds.
VTM boards can also be connected in parallel to create high power PRM-VTM arrays.
VTM input and outputs need to be connected in parallel using same size standoffs.
Each VTM requires a VC signal from a PRM in order to start and it is recommended to
connect one PRM VC to one VTM VC using the connector J13 when possible. If needed
a single PRM VC can be used to drive up to two VTMs (will require additional off
board connections).
ON
OFF
1 2 3 4 5 6 7 8 9 10
Postion
number
Slave configuration for
Adaptive Loop Master.
Master/Slave configured
PRM parallel arrays
Slave configuration for
Remote Sense Operation.
Slave configured
PRM parallel arrays
ON
OFF
1 2 3 4 5 6 7 8 9 10
Postion
number