DESCRIPTION
The QCH28515T/RCH28515T series of DC-DC converters provides the ruggedness, reliability and features required 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 capacitors and ultrasonic wirebonds to give long life in full temperature 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 synchronization 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
after power application, release from shutdown or recovery
from previous current limit allowing large load capacitances to
be charged during turn-on.
This converter family is a push-pull 400 kHz forward converter with full isolation between the input side, output side and
case. This isolation is achieved without optocouplers for an
even greater margin of reliability. The converter is housed in
a power DIP package and is hermetically sealed. The
RCH28515T has tabs for bolting the device down.
EXTERNAL CONNECTIONS
BLOCK DIAGRAM
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
HIGH ISOLATION 500V
HIGH POWER DENSITY 23 W/in
3
REMOTE SHUTDOWN
EXTERNAL SYNCH INPUT (FULLY TTL COMPATIBLE
OPTION)
110
29
38
47
56
POSITIVE
INPUT
+5 OUT
OUT COMMON
–15 OUT
+15 OUT
INPUT
COMMON
SYNCH
INHIBIT
CASE GND
CASE GND
TOP VIEW
INPUT
MAGNETICS
AND
FILTER
PUSH–PULL
PWM
PRIMARY
SIDE
FAILSAFES
OUTPUT
MAGNETICS
AND
FILTER
POWER
MAGNETICS
FEED–BACK
MAGNETICS
SECONDARY
SIDE
FAILSAFES
± 15 V
LINEAR
REGS
V
in
+Aux
–Aux
MAIN
OUTPUT
4707 Dey Road Liverpool, N.Y. 13088
M.S.KENNEDY CORP.
(315) 701-6751
QCH28515T/
RCH28515T
ISO-9001 CERTIFIED BY DSCC
30W TRIPLE
DC-DC
CONVERTERS
PRELIMINARY Rev. - 5/01
1
QCH28515T
RCH28515T
SPECIFICATIONS
INPUT VOLTAGE V
IN
No load 1, 2, 3 0 28 50 Vdc Normal
to full load 16 40 Operating
1
50 80 Vpk Transient
UVLO V
UVLO
1, 2, 3 10 12.5 14 Vdc
INPUT CURRENT I
IN
NoLoad 1, 2, 3 0.12 Adc
Full load
2
1.25 1.57 1.65
Inhibited 0.0001 0.002 0.005
OUTPUT CURRENT
3
I
MAIN
1 4.00 6.00 Adc
2, 3
I
+AUX
1 0.33 0.66
2, 3
I
-AUX
1 -0.33 -0.66
2,3
OUTPUT VOLTAGE
2,4
V
MAIN
1 4.95 5.0 5.05 Vdc
2,3
V
+AUX
1 14.85 15.00 15.15
2, 3
V
-AUX
1 -14.85 -15.00 -15.15
2, 3
OVP
4
V
OVP
1 5.3 5.6 5.9 Vdc
2, 3 5.14 6.10
OUTPUT POWER P
OUT
P
MAIN
1, 2, 3 0 20 30 W
P±
AUX
01020
P
TOT
030
P
OVERLOAD
30 35 65
(5)
EFFICIENCY
2
η 163%
2, 3
LINE REGULATION VR
LINE
V
IN
1 5 10 mV Main
16-40V 2, 3 10 50
1 50 75 Aux
2, 3 120 150
LOAD REGULATION VR
LOAD
I
MAIN
1 5 20 mV Main
0↔4A 2, 3 20 50
±I
AUX
1 50 75 Aux
0↔0.33A 2, 3 150 250
INPUT VOLTAGE RANGE 0 to 50 VDC
INPUT VOLTAGE TRANSIENT RANGE 80V@50mS
OUTPUT WITHSTAND VOLTAGE 25 VDC
STORAGE TEMPERATURE –65 to +150°C
OPERATING TEMPERATURE –55 to +125°C
TEMPERATURE, pin soldering 10 seconds 300 °C MAX
ABSOLUTE MAXIMUM RATINGS
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONSQCH28515T/RCH28515T
TEST GROUP A
12
PARAMETER SYMBOL CONDITIONS SUBGROUP MIN TYPICAL MAX UNITS COMMENT
Unless noted: –55°C ≤ T
CASE
≤ 125°C, 16Vdc ≤ VIN ≤ 40Vdc, P
MAIN
= 20W, P+
AUX
= P-
AUX
= 5W.
2
PRELIMINARY Rev. - 5/01
CROSS REGULATION VR
CROSS
±I
AUX
1 5 20 mV Main
0↔0.33A 2, 3 20 50
I
MAIN
1 50 75 ±Aux
0↔4A 2, 3 150 250
CURRENT LIMIT I
LIM
1 115 125 %
2, 3
LOAD FAULT POWER P
D
Overload
6
1, 2, 3 14 25 W
Short Ckt. 6
INHIBIT PIN VOLTAGE
7
V
ENH
Enabled 1, 2, 3 12 16.8 V dc
V
ENL
Inhibited 0 5
INHIBIT PIN CURRENT
7
I
ENH
Enabled 1, 2, 3 0 10 µA dc
I
ENL
Inhibited 650 1200 1800
ISOLATION R
ISO
500V dc 1, 2, 3 100 Meg Ω Primary
to Secondary to Case
CAPACITIVE LOAD C
L
1, 2, 3 330 500 µF Main
10 22 ±Aux
INPUT CURRENT RIPPLE2I
RIP
1 100 mA rms
2, 3 120 250
OUTPUT VOLTAGE RIPPLE V
RIP
1 15 45 mV rms Main
2, 3 30 90
1 12 36 ±Aux
2 ,3 25 75
SWITCHING FREQUENCY F
SW
4, 5, 6 350 400 450 kHz
SYNC. FREQUENCY F
SYNC
4, 5, 6 300 650 kHz
SYNC. PIN VOLTAGE
8
V
HI
1, 2, 3 2.4 – V dc
V
LO
– 0.4
SYNC. PIN CURRENT I
SYN
H 1, 2, 3 -400 µA dc
I
SYN
L -500 -750
TURN ON TIME
9
T
ON
448mS
TURN ON OVERSHOOT VT
ON
CL=0 4 0 300 mVdc Main
4 900 ±Aux
STEP LOAD TRANSIENT, VT
LOADCL
=0, I
MAIN
=50↔100% 1 -800 +800 mVdc Main
RESPONSE CL=0, I
AUX
=50↔100% 1 500 750 ±Aux
SPECIFICATIONS
QCH28515T/RCH28515T
TEST GROUP A
12
PARAMETER SYMBOL CONDITIONS SUBGROUP MIN TYPICAL MAX UNITS COMMENT
Unless noted: –55°C ≤ T
CASE
≤ 125°C, 16Vdc ≤ VIN ≤ 40Vdc, P
MAIN
= 20W, P+
AUX
= P-
AUX
= 5W.
3
PRELIMINARY Rev. - 5/01