MQFL-270-05S Datasheet, PDF (11/16 Pages) SynQor Worldwide Headquarters – HIGH RELIABILITY DC-DC CONVERTER

Technical Specification
MQFL-270-05S
Output: _{5.0 V}
Current: _{24 A}
Since the SHARE pin is monitored with respect to the OUTPUT
RETURN (pin 8) by each converter, it is important to connect all of
the converters’ OUTPUT RETURN pins together through a low DC
and AC impedance. When this is done correctly, the converters
will deliver their appropriate fraction of the total load current to
within +/- 10% at full rated load.
Whether or not converters are paralleled, the voltage at the
SHARE pin could be used to monitor the approximate average
current delivered by the converter(s). A nominal voltage of 1.0V
represents zero current and a nominal voltage of 2.2V represents
the maximum rated total current, with a linear relationship in
between. The internal source resistance of a converter’s SHARE
pin signal is 2.5 kW.
During an input voltage fault or primary disable event, the SHARE
pin outputs a power failure warning pulse. The SHARE pin will
go to 3V for approximately 14ms as the output voltage falls.
During a current limit auto-restart event, the SHARE pin outputs a
startup synchronization pulse. The SHARE pin will go to 5V for
approximately 2ms before the converter restarts.
NOTE: Converters operating from separate input filters with
reverse polarity protection (such as the MQME-270-R filter) with
their outputs connected in parallel may exhibit auto-restart opera-
tion at light loads. Consult factory for details.
OUTPUT VOLTAGE TRIM: If desired, it is possible to increase
the MQFL converter’s output voltage above its nominal value. To
do this, use the +SENSE pin (pin 10) for this trim function instead
of for its normal remote sense function, as shown in Figure D.
In this case, a resistor connects the +SENSE pin to the –SENSE
pin (which should still be connected to the output return, either
remotely or locally). The value of the trim resistor should be cho-
sen according to the following equation or from Figure E:
[ ] ^{Rtrim = 100 x}
Vnom
Vout – Vnom – 0.025
100,000
10,000
1,000
100
0
0.1
0.2
0.3
0.4
0.5
0.6
Increase in Vout (V)
Figure E: Output Voltage Trim Graph
where:
Vnom = the converter’s nominal output voltage,
Vout = the desired output voltage (greater than Vnom), and
Rtrim is in Ohms.
As the output voltage is trimmed up, it produces a greater voltage
stress on the converter’s internal components and may cause the
converter to fail to deliver the desired output voltage at the low
end of the input voltage range at the higher end of the load cur-
rent and temperature range. Please consult the factory for details.
Factory trimmed converters are available by request.
INPUT UNDER-VOLTAGE LOCKOUT: The MQFL converter
has an under-voltage lockout feature that ensures the converter
will be off if the input voltage is too low. The threshold of input
voltage at which the converter will turn on is higher that the thresh-
old at which it will turn off. In addition, the MQFL converter will
not respond to a state of the input voltage unless it has remained
in that state for more than about 200µs. This hysteresis and the
delay ensure proper operation when the source impedance is
high or in a noisy environment.
270Vdc
+
–
open
means
on
1
+VIN
2
IN RTN
3
CASE
4
ENA 1
5
SYNC OUT
6
SYNC IN
12
ENA 2
11
SHARE
10
+ SNS
9
– SNS
8
OUT RTN
7
+VOUT
Rtrim
–
Load
+
Figure D: Typical connection for output voltage trimming.
Product # MQFL-270-05S
Phone [phone]
www.synqor.com
Doc.# 005-MQ2750S Rev. B 08/08/08
Page 11