Data Sheet
JNW350R Power Modules; DC-DC Converters
36 – 75 Vdc Input; 28Vdc Output; 350W Output
July 27, 2009
R
TUNE and CTUNE for different values of ceramic output
conduction, convection, and radiation to the
surrounding environment. Proper cooling can be
verified by measuring the case temperature. Peak
temperature (TREF) occurs at the position indicated in
Figure 15.
capacitors up to 8000μF that might be needed for an
application to meet output ripple and noise
requirements. Selecting RTUNE and CTUNE according to
Table 2 will ensure stable operation of the module
In applications with tight output voltage limits in the
presence of dynamic current loading, additional
output capacitance will be required. Table 2 lists
recommended values of RTUNE and CTUNE in order to
meet 2% output voltage deviation limits for some
common output voltages in the presence of a 6A to
12A step change (50% of full load), with an input
voltage of 48V.
Considerations include ambient temperature, airflow,
module power dissipation, and the need for increased
reliability. A reduction in the operating temperature of
the module will result in an increase in reliability. The
thermal data presented here is based on physical
measurements taken in a wind tunnel.
For reliable operation this temperature should not
exceed 100ºC at TREF 1 for cold plate applications or
exceed 112ºC at TREF 2 for applications using forced
convection airflow. The output power of the module
should not exceed the rated power for the module as
listed in the ordering Information table. Although the
maximum TREF temperature of the power modules is
discussed above, you can limit this temperature to a
lower value for extremely high reliability.
Table 1. General recommended values of of RTUNE
and CTUNE for Vout=28V and various external
ceramic capacitor combinations.
Cout(µF)
RTUNE(kΩ)
CTUNE(pF)
1100
348
2200
200
4400
6600
8000
51.1
36.5
40.2
1500
6800
10,000 15,000 15,000
Table 2. Recommended values of RTUNE and CTUNE
to obtain transient deviation of 2% of Vout for a
6A step load with Vin=48V.
Vo
Co(uF)
RTUNE(kΩ)
32V
880
1000
28V
880
402
25V
1100 1320 1320 1540
348 221 84.5 61.9
22V
19V 16.8V
CTUNE(pF) 820
1500 1500 2200 3300 6800
500 530 420 370 317
530
ΔV
Please contact your Lineage Power technical
representative to obtain more details of this feature as
well as for guidelines on how to select the right value
of external R-C to tune the module for best transient
performance and stable operation for other output
capacitance values.
Over Temperature Protection
Figure 19. Case (TREF ) Temperature Measurement
Location (top view).
The JNW350R module provides with non-latching
over temperature protection. A temperature sensor
monitors the operating temperature of the converter. If
the reference temperature exceeds a threshold of 110
ºC (typical) at the center of the baseplate, the
converter will shut down and disable the output. When
the baseplate temperature has decreased by
approximately 20 ºC the converter will automatically
restart.
Thermal Derating
Thermal derating is presented for two different
applications: 1) Figure 20, the JNW350R module is
thermally coupled to a cold plate inside a sealed
clamshell chassis, without any internal air circulation;
and 2) Figure 21 and 22, the JNW350R module is
mounted in a traditional open chassis or cards with
forced air flow. In application 1, the module is cooled
entirely by conduction of heat from the module
primarily through the top surface to a coldplate, with
some conduction through the module’s pins to the
power layers in the system board. For application 2,
the module is cooled by heat removal into a forced
airflow that passes through the interior of the module
and over the top baseplate and/or attached heatsink.
The module can be restarted by cycling the dc input
power for at least one second or by toggling the
remote on/off signal for at least one second.
Thermal Considerations
The power modules operate in a variety of thermal
environments; however, sufficient cooling should be
provided to help ensure reliable operation of the unit.
Heat-dissipating components inside the unit are
thermally coupled to the case. Heat is removed by
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11
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