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AFL270XXS Schematic ( PDF Datasheet ) - International Rectifier

Teilenummer AFL270XXS
Beschreibung ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS
Hersteller International Rectifier
Logo International Rectifier Logo 




Gesamt 16 Seiten
AFL270XXS Datasheet, Funktion
www.DataSheet4U.com
PD - 94435A
ADVANCED ANALOG
HIGH RELIABILITY
HYBRID DC/DC CONVERTERS
AFL270XXS SERIES
270V Input, Single Output
Description
The AFL Series of DC/DC converters feature high power
density with no derating over the full military tempera-
ture range. This series is offered as part of a complete
family of converters providing single and dual output
voltages and operating from nominal +28 or +270 volt
inputs with output power ranging from 80 to 120 watts.
For applications requiring higher output power, multiple
converters can be operated in parallel. The internal cur-
rent sharing circuits assure equal current distribution
among the paralleled converters. This series incorpo-
rates 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 con-
verters 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 en-
closure variations, utilizing copper core pins to mini-
mize resistive DC losses. Three lead styles are avail-
able, each fabricated with 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 is fully processed and
screened to the class H requirement, but does not have
material element evaluated to the class H requirement.
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
AFL
Features
n 160 To 400 Volt Input Range
n 5, 6, 9, 12, 15 and 28 Volt Outputs Available
n High Power Density - up to 84 W /in3
n Up To 120 Watt Output Power
n Parallel Operation with Stress and Current
Sharing
n Low Profile (0.380") Seam Welded Package
n Ceramic Feedthru Copper Core Pins
n High Efficiency - to 87%
n Full Military Temperature Range
n Continuous Short Circuit and Overload
Protection
n Remote Sensing Terminals
n Primary and Secondary Referenced
Inhibit Functions
n Line Rejection > 60 dB - DC to 50KHz
n External Synchronization Port
n Fault Tolerant Design
n Dual Output Versions Available
n Standard Military Drawings Available
demanding applications. Variations in electrical,
mechanical and screening can be accommo-
dated. Contact Advanced Analog for special re-
quirements.
www.irf.com
1
07/24/02






AFL270XXS Datasheet, Funktion
AFL270XXS Series
Internally, these ports differ slightly in their function. In use,
a low on Enable 1 completely shuts down all circuits in the
converter while a low on Enable 2 shuts down the second-
ary side while altering the controller duty cycle to near zero.
Externally, the use of either port is transparent save for
minor differences in idle current. (See specification table).
Synchronization of Multiple Converters
When operating multiple converters, system requirements
often dictate operation of the converters at a common fre-
quency. To accommodate this requirement, the AFL series
converters provide both a synchronization input and out-
put.
The sync input port permits synchronization of an AFL co-
nverter to any compatible external frequency source oper-
ating between 500 and 700 KHz. This input signal should
be referenced to the input return and have a 10% to 90%
duty cycle. Compatibility requires transition times less th an
100 ns, maximum low level of +0.8 volts and a minimum high
level of +2.0 volts. The sync output of another converter
which has been designated as the master oscillator pro-
vides a convenient frequency source for this mode of op-
eration. When external synchronization is not required, the
sync in pin should be left unconnected thereby permitting
the converter to operate at its’ own internally set frequency.
The sync output signal is a continuous pulse train set at 550
±50 KHz, with a duty cycle of 15 ±5%. This signal is refer-
enced to the input return and has been tailored to be com-
patible with the AFL sync input port. Transition times are
less than 100 ns and the low level output impedance is less
than 50 ohms. This signal is active when the DC input
voltage is within the specified operating range and the con-
verter is not inhibited. This output has adequate drive re-
serve to synchronize at least five additional converters. A
typical synchronization connection option is illustrated in
Figure III.
Figure III. Preferred Connection for Parallel Operation
Power
Input
Optional
Synchronization
Connection
1
Vin
Rtn
Case
Enable 1
Sync Out
Sync In
6
AFL
Enable 2
Share
+ Sense
- Sense
Return
+ Vout
12
7
1
Vin
Rtn
Case
Enable 1
Sync Out
Sync In
6
AFL
Enable 2
Share
+ Sense
- Sense
Return
+ Vout
12
7
Share Bus
1
Vin
Rtn
Case
Enable 1
Sync Out
Sync In
6
AFL
Enable 2
Share
+ Sense
- Sense
Return
+ Vout
12
7
to Load
(Other Converters)
Parallel Operation-Current and Stress Sharing
Figure III. illustrates the preferred connection scheme for
operation of a set of AFL converters with outputs operating
in parallel. Use of this connection permits equal sharing of
a load current exceeding the capacity of an individual AFL
among the members of the set. An important feature of the
AFL series operating in the parallel mode is that in addition
to sharing the current, the stress induced by temperature
will also be shared. Thus if one member of a paralleled set
is operating at a higher case temperture, the current it pro-
vides to the load will be reduced as compensation for the
temperature induced stress on that device.
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6 Page









AFL270XXS pdf, datenblatt
AFL270XXS Series
Typical Performance Characteristics - AFL27015S
Output Load = 100%, Vin = 270VDC unless otherwise specified.
Turn-on Time, No Load
18
18
16 16
14 14
12 12
10 10
88
66
44
22
00
-2
50 55 60 65 70 75 80
Time from Application of Input Power ( msec )
-2
50
Output Ripple Voltage
8
40
Turn-on Time, Full Load
55 60 65 70 75
Time from Application of Input Power ( msec )
Input Ripple Current
80
20
4
00
-4 -20
-8
0 2 4 6 8 10
Time ( usec )
Output Load Transient Response
50% Load to/from 100% Load
800
-40
0 2 4 6 8 10
Time ( usec )
Output Load Transient Response
10% Load to/from 50% Load
800
400 400
00
-400
-400
-800
0
12
200 400 600 800 1000
Time ( usec )
-800
0
200 400 600 800 1000
Time ( usec )
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