Technical Specification
Brick
a release of a short-circuit condition, or 3) a release of a cur-
rent limit condition. Load capacitance determines exactly how
high the output voltage will rise in response to these conditions.
After 200 ms the converter will automatically restart.
Over-Temperature Shutdown:
A temperature sensor on
the converter senses the average temperature of the module.
The thermal shutdown circuit is designed to turn the converter
off when the temperature at the sensed location reaches the
Over-Temperature Shutdown value. It will allow the converter to
turn on again when the temperature of the sensed location falls
by the amount of the Over-Temperature Shutdown Restart
Hysteresis value.
ming.
Input Filtering and External Capacitance:
Figure E
below provides a diagram showing the internal input filter
components. This filter dramatically reduces input terminal rip-
ple current, which otherwise could exceed the rating of an
external electrolytic input capacitor. The recommended exter-
nal input capacitance is specified in the “Input Characterisitcs”
section. More detailed information is available in the applica-
tion note titled “EMI Characteristics” on the SynQor website.
Half
48Vin 3.3Vout 50A
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 web site
(www.synqor.com) which provides an understanding of why
this instability arises, and shows the preferred solution for
correcting it.
Application Circuits:
Figure D below provides a typical cir-
cuit diagram which details the input filtering and voltage trim-
Electrolytic
Capacitor
V
in(+)
V
out(+)
V
sense(+)
R
trim-up
or
V
in
External
Input
Filter
33µF
ESR
≅1Ω
ON/OFF
Trim
V
sense(
_
)
V
in(
_
)
V
out(
_
)
R
trim-down
C
load
I
load
Figure D:
Typical application circuit (negative logic unit, permanently enabled).
L
V
in(+)
C
1
V
in(
_
)
C
2
Figure E:
Internal Input Filter Diagram
(component values listed on page 3)
.
Product # PQ60033HTA50
Phone 1-888-567-9596
Doc.# 005-2HT633F Rev. A
4/11/03
Page 11
SYNQOR [ SYNQOR WORLDWIDE HEADQUARTERS ]
