07/24/02
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1
ADVANCED ANALOG
HIGH RELIABILITY
HYBRID DC/DC CONVERTERS
AFL270XXS SERIES
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
Description
demanding applications. Variations in electrical,
mechanical and screening can be accommo-
dated. Contact Advanced Analog for special re-
quirements.
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
Features
AFL
270V Input, Single Output
PD - 94435A
2
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AFL270XXS Series
For Notes to Specifications, refer to page 4
ABSOLUTE MAXIMUM RATINGS
Input Voltage
-0.5V to 500V
Soldering Temperature
300C for 10 seconds
Case Temperature
Operating
-55C to +125C
Storage
-65C to +135C
Static Characteristics
-55C
T
CASE
+125C, 160
V
IN
400 unless otherwise specified.
Parameter
Group A
Subgroups
Test Conditions
Min
Nom
Max
Unit
INPUT VOLTAGE
Note
6
160 270 400 V
OUTPUT VOLTAGE
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
1
1
1
1
1
1
2, 3
2, 3
2, 3
2, 3
2, 3
2, 3
VIN = 270 Volts, 100% Load
4.95
5.94
8.91
11.88
14.85
27.72
4.90
5.88
8.82
11.76
14.70
27.44
5.00
6.00
9.00
12.00
15.00
28.00
5.05
6.06
9.09
12.12
15.15
28.28
5.10
6.12
9.18
12.24
15.30
28.56
V
V
V
V
V
V
V
V
V
V
V
V
OUTPUT CURRENT
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
VIN = 160, 270, 400 Volts - Note 6
16.0
13.5
10.0
9.0
8.0
4.0
A
A
A
A
A
A
OUTPUT POWER
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
Note
6
80
81
90
108
120
112
W
W
W
W
W
W
MAXIMUM CAPACITIVE LOAD
Note
1
10,000
fd
OUTPUT VOLTAGE
TEMPERATURE COEFFICIENT
VIN = 270 Volts, 100% Load - Note 1, 6 -0.015 +0.015
%/C
OUTPUT VOLTAGE REGULATION
AFL27028S
Line
All Others
Line
Load
1, 2, 3
1, 2, 3
1, 2, 3
No Load, 50% Load, 100% Load
VIN = 160, 270, 400 Volts
-70.0
-10.0
-1.0
+70.0
+10.0
+1.0
mV
mV
%
OUTPUT RIPPLE VOLTAGE
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
VIN = 160, 270, 400 Volts, 100% Load,
BW = 10MHz
30
35
40
45
50
100
mVpp
mVpp
mVpp
mVpp
mVpp
mVpp
Specifications
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3
AFL270XXS Series
Static Characteristics
(Continued)
For Notes to Specifications, refer to page 4
Parameter
Group A
Subgroups
Test Conditions
Min
Nom
Max
Unit
INPUT CURRENT
No
Load
Inhibit
1
Inhibit
2
1
2, 3
1, 2, 3
1, 2, 3
VIN = 270 Volts
IOUT = 0
Pin 4 Shorted to Pin 2
Pin 12 Shorted to Pin 8
15
17
3.0
5.0
mA
mA
mA
mA
INPUT RIPPLE CURRENT
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
VIN = 270 Volts, 100% Load
B.W. = 10MHz
60
60
70
70
80
80
mApp
mApp
mApp
mApp
mApp
mApp
CURRENT LIMIT POINT
Expressed as a Percentage
of Full Rated Load
1
2
3
VOUT = 90% VNOM
Note 5
115
105
125
125
115
140
%
%
%
LOAD FAULT POWER DISSIPATION
Overload or Short Circuit
1, 2, 3
V
IN
= 270 Volts
30
W
EFFICIENCY
AFL27005S
AFL27006S
AFL27009S
AFL27012S
AFL27015S
AFL27028S
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
V
IN
= 270 Volts, 100% Load
78
79
80
82
83
82
82
83
84
85
87
85
%
%
%
%
%
%
ENABLE INPUTS (Inhibit Function)
Converter Off
Sink
Current
Converter
On
Sink
Current
1, 2, 3
1, 2, 3
Logical Low, Pin 4 or Pin 12
Note 1
Logical High, Pin 4 and Pin 12 - Note 9
Note 1
-0.5
2.0
0.8
100
50
100
V
A
V
A
SWITCHING FREQUENCY
1, 2, 3
500
550
600
KHz
SYNCHRONIZATION INPUT
Frequency Range
Pulse Amplitude, Hi
Pulse Amplitude, Lo
Pulse Rise Time
Pulse Duty Cycle
1, 2, 3
1, 2, 3
1, 2, 3
Note 1
Note 1
500
2.0
-0.5
20
700
10
0.8
100
80
KHz
V
V
nSec
%
ISOLATION
1
Input to Output or Any Pin to Case
(except Pin 3). Test @ 500VDC
100 M
DEVICE WEIGHT
Slight Variations with Case Style
85
gms
MTBF
MIL-HDBK-217F, AIF @ TC = 70C
300 KHrs
4
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AFL270XXS Series
Dynamic Characteristics
-55C
T
CASE
+125C, V
IN
=
270 Volts unless otherwise specified.
Parameter
Group A
Subgroup
s
Test Conditions
Min
Nom
Max
Unit
LOAD TRANSIENT RESPONSE
AFL27005S Amplitude
Recovery
Amplitude
Recovery
AFL27006S Amplitude
Recovery
Amplitude
Recovery
AFL27009S Amplitude
Recovery
Amplitude
Recovery
AFL27012S Amplitude
Recovery
Amplitude
Recovery
AFL27015S Amplitude
Recovery
Amplitude
Recovery
AFL27028S Amplitude
Recovery
Amplitude
Recovery
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
4, 5, 6
Note 2, 8
Load Step 50%
100%
Load Step 10%
50%
Load Step 50%
100%
Load Step 10%
50%
Load Step 50%
100%
Load Step 10%
50%
Load Step 50%
100%
Load Step 10%
50%
Load Step 50%
100%
Load Step 10%
50%
Load Step 50%
100%
Load Step 10%
50%
-450
-450
-450
-450
-600
-600
-750
-750
-900
-900
-1200
-1200
450
200
450
400
450
200
450
400
600
200
600
400
750
200
750
400
900
200
900
400
1200
200
1200
400
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
mV
Sec
LINE TRANSIENT RESPONSE
Amplitude
Recovery
Note 1, 2, 3
V
IN
Step = 160
400 Volts
-500
500
500
mV
Sec
TURN-ON CHARACTERISTICS
Overshoot
Delay
4, 5, 6
4, 5, 6
V
IN
= 160, 270, 400 Volts. Note 4
Enable 1, 2 on. (Pins 4, 12 high or
open)
50
75
250
120
mV
mSec
LOAD FAULT RECOVERY
Same as Turn On Characteristics.
LINE REJECTION
MIL-STD-461, CS101, 30Hz to 50KHz
Note 1
60 70 dB
Notes to Specifications:
1.
Parameters not 100% tested but are guaranteed to the limits specified in the table.
2.
Recovery time is measured from the initiation of the transient to where V
OUT
has returned to within
1% of V
OUT
at 50% load.
3.
Line transient transition time
100
Sec.
4.
Turn-on delay is measured with an input voltage rise time of between 100 and 500 volts per millisecond.
5.
Current limit point is that condition of excess load causing output voltage to drop to 90% of nominal.
6.
Parameter verified as part of another test.
7.
All electrical tests are performed with the remote sense leads connected to the output leads at the load.
8.
Load transient transition time
10
Sec.
9.
Enable inputs internally pulled high. Nominal open circuit voltage
4.0VDC.
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5
AFL270XXS Series
ERROR
AMP
& REF
OUTPUT
FILTER
INPUT
FILTER
OUTPUT RETURN
DC INPUT
INPUT RETURN
.*
CONTROL
1
2
4
3
5
6
SYNC INPUT
CURRENT
SENSE
+ SENSE
- SENSE
SENSE
AMPLIFIER
ENABLE 2
SHARE
SHARE
AMPLIFIER
7
11
10
9
12
8
+ OUTPUT
SYNC OUTPUT
ENABLE 1
CASE
PRIMARY
BIAS SUPPLY
AFL270XXS Circuit Description
Figure I. AFL Single Output Block Diagram
Connection of the + and - sense leads at a remotely locat-
led load permits compensation for resistive voltage drop
between the converter output and the load when they are
physically separated by a significant distance. This con-
nection allows regulation to the placard voltage at the point
of application. When the remote sensing features is not
Figure II. Enable Input Equivalent Circuit
Pin 4 or
Pin 12
1N4148
100K
290K
150K
2N3904
+5.6V
Disable
Pin 2 or
Pin 8
used, the sense leads should be connected to their respec-
tive output terminals at the converter. Figure III. illustrates a
typical application.
Circuit Operation and Application Information
The AFL series of converters employ a forward switched
mode converter topology. (refer to Figure I.) Operation of
the device is initiated when a DC voltage whose magnitude
is within the specified input limits is applied between pins 1
and 2. If pin 4 is enabled (at a logical 1 or open) the primary
bias supply will begin generating a regulated housekeeping
voltage bringing the circuitry on the primary side of the con-
verter to life. Two power MOSFETs used to chop the DC
input voltage into a high frequency square wave, apply this
chopped voltage to the power transformer. As this switch-
ing is initiated, a voltage is impressed on a second winding
of the power transformer which is then rectified and applied
to the primary bias supply. When this occurs, the input
voltage is shut out and the primary bias voltage becomes
exclusively internally generated.
The switched voltage impressed on the secondary output
transformer winding is rectified and filtered to provide the
converter output voltage. An error amplifier on the second-
ary side compares the output voltage to a precision refer-
ence and generates an error signal proportional to the dif-
ference. This error signal is magnetically coupled through
the feedback transformer into the controller section of the
converter varying the pulse width of the square wave sig-
nal driving the MOSFETs, narrowing the width if the output
voltage is too high and widening it if it is too low.
Remote Sensing
Inhibiting Converter Output
As an alternative to application and removal of the DC
voltage to the input, the user can control the converter
output by providing TTL compatible, positive logic signals
to either of two enable pins (pin 4 or 12). The distinction
between these two signal ports is that enable 1 (pin 4) is
referenced to the input return (pin 2) while enable 2 (pin 12)
is referenced to the output return (pin 8). Thus, the user
has access to an inhibit function on either side of the isola-
tion barrier. Each port is internally pulled "high" so that
when not used, an open connection on both enable
pins
permits normal converter operation. When their use is
desired, a logical "low" on either port will shut the
con-
verter down.
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