ISO-9001 CERTIFIED BY DSCC
M.S.KENNEDY CORP.
30W TRIPLE
DC-DC
CONVERTERS
QCH28515T/
RCH28515T
4707 Dey Road Liverpool, N.Y. 13088
(315) 701-6751
HI-REL DESIGN
REPLACES APEX DT28515T/F
WAVE SOLDERABLE PACKAGE
ALL CERAMIC CAPACITORS
NO OPTOCOUPLERS
SURFACE MOUNT MAGNETICS
WITHSTANDS 3000 G Y1 AXIS
OVER-VOLTAGE PROTECTION (OVP) OPTION
OTHER FEATURES TRIPLE OUTPUT
NO DERATING 55°C TO +125°C
WIDE SUPPLY RANGE 16 TO 40 VOLTS
QCH28515T
RCH28515T
HIGH ISOLATION 500V
HIGH POWER DENSITY 23 W/in3
REMOTE SHUTDOWN
BLOCK DIAGRAM
EXTERNAL SYNCH INPUT (FULLY TTL COMPATIBLE
OPTION)
DESCRIPTION
The QCH28515T/RCH28515T series of DC-DC convert-
ers provides the ruggedness, reliability and features re-
quired to meet the advanced challenges of today's hi-rel
market. This family of converters uses all surface-mounted
hybrid components including magnetics, all ceramic capaci-
tors and ultrasonic wirebonds to give long life in full tempera-
ture range and high acceleration environments. There is no
power derating anywhere in the –55°C to 125°C operating
range.
This product family is tolerant of many types of faults
including load short, load overload, loss of voltage feedback,
large forward and reverse voltages applied to the synchroniza-
tion pin and input overvoltage. This converter family will
operate during input transients to 80 volts. The output voltages
have little overshoot during the input voltage transient such
that typical logic and linear parts on the outputs will stay well
within data sheet absolute maximums.
Other operational features include low duty factor current
limit and dynamic current limit threshold. The current limit
operates in a cyclic on-off mode with an on time of about 2
milliseconds and an off time of 20 milliseconds for a duty factor
of about 10 percent. This limits the converter dissipation to
about 1 watt, so there is no danger of overheating during an
output fault at 125° C. The dynamic current limit threshold
allows over 50 percent more current to flow for a short time
INPUT
MAGNETICS
AND
FILTER
Vin
PUSH–PULL
PWM
PRIMARY
SIDE
FAILSAFES
POWER
MAGNETICS
FEED–BACK
MAGNETICS
EXTERNAL CONNECTIONS
POSITIVE
INPUT
+5 OUT
1
10
2
9
± 15 V
LINEAR
REGS
+Aux
–Aux
OUTPUT
MAGNETICS
AND
FILTER
MAIN
OUTPUT
SECONDARY
SIDE
FAILSAFES
INPUT
COMMON
SYNCH
after power application, release from shutdown or recovery
from previous current limit allowing large load capacitances to
OUT COMMON
3
8
INHIBIT
be charged during turn-on.
This converter family is a push-pull 400 kHz forward con-
verter with full isolation between the input side, output side and
–15 OUT
4
7
CASE GND
case. This isolation is achieved without optocouplers for an
even greater margin of reliability. The converter is housed in
+15 OUT
5
6
CASE GND
a power DIP package and is hermetically sealed. The
RCH28515T has tabs for bolting the device down.
TOP VIEW
1
PRELIMINARY Rev. - 5/01