LAMBDA ADVANCED ANALOG INC.
λ
PRELIMINARY
AFL2803.3S Series
Single Output, Hybrid - High Reliability
DC/DC Converter
DESCRIPTION
The AFL Series of DC/DC converters feature high
power density with no derating over the full military
temperature range. This series is offered as part of
a complete family of converters providing single and
dual output voltages and operating from nominal
+28, +50, +120 or +270 volt inputs with output
power ranging from 80 to 120 watts.
For
applications requiring higher output power,
individual converters can be operated in parallel.
The internal current sharing circuits assure accurate
current distribution among the paralleled converters.
This series incorporates Lambda Advanced Analog's
proprietary magnetic pulse feedback technology
providing optimum dynamic line and load regulation
response. This feedback system samples the output
voltage at the pulse width modulator fixed clock
frequency, nominally 550 KHz. Multiple converters
can be synchronized to a system clock in the 500
KHz to 700 KHz range or to the synchronization
output of one converter. Undervoltage lockout,
primary and secondary referenced inhibit, soft-start
and load fault protection are provided on all models.
These converters are hermetically packaged in two
enclosure variations, utilizing copper core pins to
minimize resistive DC losses. Three lead styles are
available, each fabricated with Lambda Advanced
Analog's rugged ceramic lead-to-package seal
assuring long term hermeticity in the most harsh
environments.
Manufactured in a facility fully qualified to MIL-PRF-
38534, these converters are available in four
screening grades to satisfy a wide range of
requirements. The CH grade is fully compliant to
the requirements of MIL-PRF-38534 for class H.
The HB grade processed and screened to the class
H requirement, may not necessarily meet all of the
other MIL-PRF-38534 requirements, e.g., element
evaluation and Periodic Inspections (P.I.) not
required. Both grades are tested to meet the
complete group "A" test specification over the full
military temperature range without output power
deration. Two grades with more limited screening
are also available for use in less demanding
applications. Variations in electrical, mechanical
and screening can be accommodated. Contact
Lambda Advanced Analog for special requirements.
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FEATURES
16 To 40 Volt Input Range
3.3 Volt Output
High Power Density - 50 W / in
3
66 Watt Output Power
Parallel Operation with Stress and Current
Sharing
Low Profile (0.380") Seam Welded Package
Ceramic Feedthru Copper Core Pins
High Efficiency - 72%
Full Military Temperature Range
Continuous Short Circuit and Overload
Protection
Remote Sensing Terminals
Primary and Secondary Referenced Inhibit
Functions
Line Rejection > 40 dB - DC to 50KHz
External Synchronization Port
Fault Tolerant Design
Dual Output Versions Available
Standard Military Drawings Available
AFL2803.3S
TABLE I. Electrical Performance Characteristics - Continued.
Test
Symbol
Conditions
-55°C
≤
T
C
≤
+125°C
V
IN
=28 V dc
±5%,
C= 0
unless otherwise specified
Group A
subgroups
Device
type
Limits
Unit
Min
Max
Power dissipation load fault
P
D
Overload 6/
Short circuit
1,2,3
01
33
33
W
Current Limit Point 5/
I
CL
V
OUT
= 90% V
NOM
V
IN
= 28 V
1
2
3
01
115
105
125
125
%
115
140
600
700
+450
KHz
KHz
mV pk
Switching frequency
Sync frequency range
Output response to step
transient load changes 2/ 8/
F
S
I
OUT
= 20 A
1,2,3
4,5,6
4,5,6
01
01
01
500
500
-450
F
sync
VO
TLOAD
I
OUT
= 20 A
50% to/from 100%
10% to/from 50%
Recovery time, step
transient load changes 2/ 8/
TT
LOAD
50% to/from 100%
4,5,6
01
-450
+450
200
µs
10% to/from 50%
Input step 16 V to/from 40 V dc,
I
OUT
= 20 A
Input step 16 V to/from 40 V dc,
I
OUT
= 20 A
I
OUT
= 0 and 20 A
I
OUT
= 0 and 20 A
4,5,6
01
400
mV pk
Output response to transient
step line changes 1/ 2/ 3/
Recovery time transient step
line changes 1/ 2/ 3/
Turn on overshoot 4/
Turn on delay
4/
VO
TLINE
-500
500
TT
LINE
4,5,6
01
500
µs
VTon
OS
Ton
D
Tr
LF
4,5,6
4,5,6
4,5,6
01
01
01
250
10
10
mV pk
ms
ms
Load fault recovery
Notes:
1/
2/
3/
4/
5/
6/
7/
8/
9/
Parameters not tested but are guaranteed to the limits specified in the table.
Recovery time is measured from the initiation of the transient to where V
OUT
has returned to within
±
1 percent of V
OUT
at 50 percent load.
Line transient transition time
≥10
microseconds.
Turn on delay is measured with an input voltage rise time of between 100 and 500 volts per millisecond.
Current limit point is that condition of excess load causing output voltage to drop to 90% of nominal.
Parameter verified as part of another test.
All electrical tests are performed with remote sense leads connected to the output lead at the load.
Input step transition time
≥100
microseconds.
Enable inputs internally pulled high. Nominal open circuit voltage = 4.0V
DC
.
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