PQ60280HZX22 Datasheet, PDF (12/16 Pages) SynQor Worldwide Headquarters – High efficiency, 94% at full rated load current

Applications Section
Input: 35-75V
Output: 28V
Current: 21.5A
Package: Half-brick
APPLICATION CONSIDERATIONS
Input System Instability: This condition can occur because any
DC-DC converter appears incrementally as a negative resistance
load. A detailed application note titled “Input System Instability” is
available on the SynQor website which provides an understanding
of why this instability arises, and shows the preferred solution for
correcting it.
Application Circuits: A typical circuit diagram, Figure D below
details the input filtering and voltage trimming.
Input Filtering and External Input Capacitance: Figure
E below shows the internal input filter components. This filter
dramatically reduces input terminal ripple current, which otherwise
could exceed the rating of an external electrolytic input capacitor.
The recommended external input capacitance is specified in the
Input Characteristics section of the Electrical Specifications. More
detailed information is available in the application note titled “EMI
Characteristics” on the SynQor website.
Output Filtering and External Output Capacitance: The
internal output filter components are shown in Figure E below. This
filter dramatically reduces output voltage ripple. Some minimum
external output capacitance is required, as specified in the Output
Characteristics area of the Electrical Characteristics section. No
damage will occur without this capacitor connected, but peak
output voltage ripple will be much higher.
Thermal Considerations: For baseplated and encased versions,
the max operating baseplate temperature, TB, is 100ºC. Refer to
the Thermal Derating Curves in the Technical Figures section to
see the available output current at baseplate temperatures below
100ºC.
A power derating curve can be calculated for any heatsink that is
attached to the base-plate of the converter. It is only necessary to
determine the thermal resistance, RTHBA, of the chosen heatsink
between the baseplate and the ambient air for a given airflow rate.
This information is usually available from the heatsink vendor. The
following formula can the be used to determine the maximum
power the converter can dissipate for a given thermal condition if
its base-plate is to be no higher than 100ºC.
Pmax
diss
=
100ºC - TA
RTHBA
This value of maximum power dissipation can then be used in
conjunction with the data shown in the Power Dissipation Curves
in the Technical Figures section to determine the maximum load
current (and power) that the converter can deliver in the given
thermal condition.
For convenience, Thermal Derating Curves are provided in the
Technical Figures section.
Vin(+)
Vout(+)
Electrolytic
Vsense(+)
External
Capacitor
R
trim-up
Vin
Input
ON/OFF
Trim
or
Filter
Vsense(^_)
R_trim-down
C
load
I
load
Vin(^_)
Vout(^_)
Figure D: Typical Application Circuit (negative logic unit, permanently enabled).
Vin(+)
C₁
Vin(^_)
L_in
C₂
Regulation
Stage
Current
Sense
Isolation
Stage
Figure E: Internal Input and Output Filter Diagram (component values listed in Electrical Characteristics section)
Product # PQ60280HZx22
Phone [phone]
www.synqor.com
Doc.# 005-0005788 Rev. D
12/26/13
Vout(+)
Vout(-)
Page 12