Q54SG Datasheet, PDF (21/26 Pages) Delta Electronics, Inc. – Industry standard, DOSA compliant pin out

FEATURES DESCRIPTIONS (CON.)
Output Voltage Adjustment (TRIM)
To increase or decrease the output voltage set point,
connect an external resistor between the TRIM pin and
either the Vo(+) or Vo(-). The TRIM pin should be left
open if this feature is not used. Below Trim equation is
only adapt to the module without droop current sharing
option code; For the module with droop current sharing
option code, please contact Delta’s technical support
team.
Figure 20: Circuit configuration for trim-down (decrease
output voltage)
If the external resistor is connected between the TRIM
and Vo (-) pins, the output voltage set point decreases
(Fig. 19). The external resistor value required to obtain
a percentage of output voltage change △% is defined
as:
Rtrim

down



511

10.2^{}K
Ex. When Trim-down -10% (12V×0.9=10.8V)
Rtrim

down



511
10

10.2^{}K

40.9K
Figure 21: Circuit configuration for trim-up (increase output
voltage)
If the external resistor is connected between the TRIM
and Vo (+) the output voltage set point increases (Fig.
20). The external resistor value required to obtain a
percentage output voltage change △% is defined as:
Rtrim  up  ^{5.11Vo (100   )}  ⁵¹¹ 10.2K
1.225

Ex. When Trim-up +10% (12V×1.1=13.2V)
Rtrim  up  ^{5.1112  (100  10)}  ⁵¹¹ 10.2  489.3K
1.225 10
10
DS_Q54SG12050_09092016
Care should be taken to ensure that the maximum
output power of the module remains at or below the
maximum rated power.
Parallel and Droop Current Sharing
The module has voltage droop function is capable of
parallel operation. There is a 250mV output voltage
droop when output current varies from 0A to full load
current, so the maximum ±25mV set point variation will
guarantee the current sharing accuracy at room
temperature within 10%. By connecting the Vin pin and
the Vo pin of the parallel module together, the current
sharing can be realized automatically.
Vin+
Vo+
On/off Module I
Vin
Vin-
Vo-
Load
Vin+
Vo+
On/off Module II
Vin-
Vo-
Figure 21: Parallel and droop current sharing configuration for
no redundancy requirement system
If system has no redundancy requirement, the module
can be parallel directly without adding external oring-fet;
whereas, if the redundancy function is required, external
oring-fets are needed.
To ensure normal parallel operation, the following
precautions must be observed:
1. The current sharing accuracy equation is:
X% = | Io – ( Itotal / N ) | / Irated, Where,
Io is the output current of each module;
Itotal is the total load current;
N is parallel module numbers;
Irated is the rated full load current of per module.
2. To ensure a better current sharing accuracy, below
design guidelines should be followed:
a) The inputs of the converters must be connected to the
same voltage source; and the PCB trace resistance from
Input voltage source to Vin+ and Vin- of each converter
should be equalized as much as possible.
b) The PCB trace resistance from each converter’s
output to the load should be equalized as much as
possible.
c) For accurate current sharing accuracy test, the
module should be soldered in order to avoid the
unbalance of the contact resistance between the
modules to the test board.
21