ETC AFL2812DZ/CH

PD - 94458B
AFL28XXD SERIES
28V Input, Dual Output
ADVANCED ANALOG
HIGH RELIABILITY
HYBRID DC/DC CONVERTERS
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 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 equal current distribution among the paralleled converters. This series incorporates 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 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-PRF38534, 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-H38534 for class H. The HB grade is processed and
screened to the class H requirement, but may not necessarily meet all of the other MIL-PRF-38534 requirements, e.g., element evaluation and Periodic Inspection
(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 avail-
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AFL
Features
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16 To 40 Volt Input Range
±5, ±12, and ±15 Volts Outputs Available
High Power Density - up to 70 W / in3
Up To 100 Watt Output Power
Parallel Operation with Power Sharing
Low Profile (0.380") Seam Welded Package
Ceramic Feedthru Copper Core Pins
High Efficiency - to 87%
Full Military Temperature Range
Continuous Short Circuit and Overload
Protection
Output Voltage Trim
Primary and Secondary Referenced
Inhibit Functions
Line Rejection > 40 dB - DC to 50KHz
External Synchronization Port
Fault Tolerant Design
Single Output Versions Available
Standard Military Drawings Available
able for use in less demanding applications. Variations in electrical, mechanical and screening can
be accommodated. Contact Advanced Analog for
special requirements.
1
09/11/02
AFL28XXD Series
Specifications
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Soldering Temperature
-0.5V to 50V
300°C for 10 seconds
Case Temperature
Operating
Storage
-55°C to +125°C
-65°C to +135°C
Static Characteristics -55°C < TCASE < +125°C, 16V< VIN < 40V unless otherwise specified.
Group A
Subgroups
Parameter
INPUT VOLTAGE
OUTPUT VOLTAGE
AFL2805D
1
1
AFL2812D
1
1
AFL2815D
1
1
AFL2805D
2, 3
2, 3
AFL2812D
2, 3
2, 3
AFL2815D
2, 3
2, 3
Test Conditions
Min
Nom
Max
Unit
Note 6
16
28
40
V
VIN = 28 Volts, 100% Load
Positive Output
Negative Output
4.95
-5.05
5.00
-5.00
5.05
-4.95
V
V
11.88
-12.12
12.00
-12.00
12.12
-11.88
V
V
14.85
-15.15
15.00
-15.00
15.15
-14.85
V
V
4.90
-5.10
5.10
-4.90
V
V
11.76
-12.24
12.24
-11.76
V
V
14.70
-15.30
15.30
-14.70
V
V
Positive Output
Negative Output
Positive Output
Negative Output
Positive Output
Negative Output
Positive Output
Negative Output
Positive Output
Negative Output
VIN = 16, 28, 40 Volts - Notes 6, 11
Either Output
OUTPUT CURRENT
AFL2805D
12.8
A
AFL2812D
Either Output
6.4
A
AFL2815D
Either Output
5.3
A
OUTPUT POWER
Total of Both Outputs. Notes 6,11
AFL2805D
80
W
AFL2812D
96
W
AFL2815D
100
W
10,000
µfd
MAXIMUM CAPACITIVE LOAD
Each Output Note 1
OUTPUT VOLTAGE
TEMPERATURE COEFFICIENT
VIN = 28 Volts, 100% Load - Notes 1, 6
OUTPUT VOLTAGE REGULATION
Line
Load
1, 2, 3
1, 2, 3
Cross
-0.015
+0.015
%/°C
-0.5
-1.0
+0.5
+1.0
%
%
VIN = 16, 28, 40 Volts. Note 12
Positive Output
Negative Output
-1.0
-8.0
+1.0
+8.0
%
%
Note 10
No Load, 50% Load, 100% Load
VIN = 16, 28, 40 Volts.
AFL2805D
1, 2, 3
AFL2812D
1, 2, 3
Positive Output
Negative Output
-1.0
-5.0
+1.0
+5.0
%
%
AFL2815D
1, 2, 3
Positive Output
Negative Output
-1.0
-5.0
+1.0
+5.0
%
%
For Notes to Specifications, refer to page 4
2
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AFL28XXD Series
Static Characteristics (Continued)
Parameter
Group A
Subgroups
OUTPUT RIPPLE VOLTAGE
Test Conditions
Min
Nom
VIN = 16, 28, 40 Volts, 100% Load,
BW = 10MHz
Max
Unit
AFL2805D
1, 2, 3
60
mVpp
AFL2812D
1, 2, 3
80
mVpp
AFL2815D
1, 2, 3
80
mVpp
80.0
100.0
mA
mA
5.0
mA
50.0
30.0
mA
mA
INPUT CURRENT
No Load
1
2, 3
Inhibit 1
1, 2, 3
Inhibit 2
AFL2805D
AFL2812D, 15D
VIN = 28 Volts
IOUT = 0
Pin 4 Shorted to Pin 2
Pin 12 Shorted to Pin 8
1, 2, 3
1, 2, 3
VIN = 28 Volts, 100% Load
INPUT RIPPLE CURRENT
AFL2805D
1, 2, 3
60
mApp
AFL2812D
1, 2, 3
60
mApp
AFL2815D
1, 2, 3
60
mApp
125
115
140
%
%
%
33
W
CURRENT LIMIT POINT
Expressed as a percentage
of Full Rated Load
LOAD FAULT POWER DISSIPATION
Overload or Short Circuit
1
2
3
115
105
125
VIN = 28 Volts
1, 2, 3
VIN = 28 Volts, 100% Load
EFFICIENCY
AFL2805D
AFL2812D
AFL2815D
ENABLE INPUTS (Inhibit Function)
Converter Off
Sink Current
Converter On
Sink Current
SWITCHING FREQUENCY
SYNCHRONIZATION INPUT
Frequency Range
Pulse Amplitude, Hi
Pulse Amplitude, Lo
Pulse Rise Time
Pulse Duty Cycle
ISOLATION
VOUT = 90% VNOM , Equal current on
positive and negative outputs. Note 5
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
78
82
81
Logical Low on Pin 4 or Pin 12
Note 1
Logical High on Pin 4 and Pin 12 - Note 9
Note 1
-0.5
2.0
1, 2, 3
500
1, 2, 3
1, 2, 3
1, 2, 3
500
2.0
-0.5
Note 1
Note 1
1
Input to Output or Any Pin to Case
(except Pin 3). Test @ 500VDC
DEVICE WEIGHT
Slight Variations with Case Style
MTBF
MIL-HDBK-217F, AIF @ TC = 70°C
550
20
100
0.8
100
50
100
V
µA
V
µA
600
KHz
700
10
0.8
100
80
KHz
V
V
nSec
%
MΩ
85
300
%
%
%
81
84
85
gms
KHrs
For Notes to Specifications, refer to page 4
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3
AFL28XXD Series
Dynamic Characteristics -55°C < TCASE < +125°C, VIN=28V unless otherwise specified.
Parameter
Group A
Subgroups
AFL2812D
Either Output
AFL2815D
Either Output
Min
Nom
Max
Unit
Note 2, 8
LOAD TRANSIENT RESPONSE
AFL2805D
Either Output
Test Conditions
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-450
450
200
mV
µSec
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
10% ⇒ 50%
50% ⇒ 10%
-450
450
200
400
mV
µSec
µSec
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-750
750
200
mV
µSec
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
10% ⇒ 50%
50% ⇒ 10%
-750
750
200
400
mV
µSec
µSec
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-750
750
200
mV
µSec
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
10% ⇒ 50%
50% ⇒ 10%
-750
750
200
400
mV
µSec
µSec
-500
500
500
mV
µSec
250
10
mV
mSec
Note 1, 2, 3
LINE TRANSIENT RESPONSE
VIN Step = 16 ⇔ 40 Volts
Amplitude
Recovery
VIN = 16, 28, 40 Volts. Note 4
TURN-ON CHARACTERSTICS
Overshoot
Delay
4, 5, 6
4, 5, 6
Enable 1, 2 on. (Pins 4, 12 high or
open)
LOAD FAULT RECOVERY
Same as Turn On Characteristics.
LINE REJECTION
MIL-STD-461D, CS101, 30Hz to
50KHz
Note 1
0
4
40
50
dB
Notes to Specifications:
1.
2.
Parameters not 100% tested but are guaranteed to the limits specified in the table.
Recovery time is measured from the initiation of the transient to where Vout has returned to within ±1% of Vout
at 50% load.
3. Line transient transition time ≥ 100 µSec.
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 µSec.
9. Enable inputs internally pulled high. Nominal open circuit voltage ≈ 4.0VDC.
10. Load current split equally between +Vout and -Vout.
11. Output load must be distributed so that a minimum of 20% of the total output power is being provided by one of
the outputs.
12. Cross regulation measured with load on tested output at 20% of maximum load while changing the load on
other output from 20% to 80%.
4
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AFL28XXD Series
AFL28XXD Circuit Description
Figure I. AFL Dual Output Block Diagram
DC Input
1
Enable 1 4
Input
Filter
Output
Filter
7 + Output
Current
Sense
Primary
Bias Supply
8 Output Return
Output
Filter
Sync Output
5
Sync Input
6
Share
Amplifier
Control
Case
3
Input Return
2
Circuit Operation and Application Information
The AFL series of converters employ a forward switched
mode converter topology. (refer to the block diagram in
Figure I.) Operation of the device is initiated when a DC
voltage whose magnitude is within the specified input voltage 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 converter to life. A power
MOSFET is used to chop the DC input voltage into a high
frequency square wave, applying this chopped voltage to
the power transformer at the nominal converter switching
frequency. By maintaining a DC voltage within specified
operating range at the input, continuous generation of the
bias voltage is assured.
The switched voltage impressed on the secondary output
transformer windings is rectified and filtered to provide the
positive and negative converter output voltages. An error
amplifier on the secondary side compares the positive output voltage to a precision reference and generates an error
signal proportional to the difference. This error signal is
magnetically coupled through the feedback transformer into
the control section of the converter varying the pulse width
of the square wave signal driving the MOSFETs, narrowing
the pulse width if the output voltage is too high and widening
it if it is too low. These pulse width variations provide the
necessary corrections to regulate the magnitude of output
voltage within its’ specified limits.
Error
Amp
& Ref
9
-Output
11 Share
12 Enable 2
10 Trim
series can be initiated by simply applying an input voltage to
pins 1 and 2 and connecting the appropriate loads between
pins 7, 8, and 9. As is the case with any high power density
converter, operation should not be initiated before secure
attachment to an appropriate heat dissipator. (See Thermal
Considerations, page 7) Additional application information
is provided in the paragraphs following.
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 isolation
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 converter down.
Figure II. Enable Input Equivalent Circuit
+5.6V
100K
Pin 4 or
Pin 12
1N4148
Disable
200K
Because the primary portion of the circuit is coupled to the
secondary side with magnetic elements, full isolation from
input to output is maintained.
2N3904
220K
Although incorporating several sophisticated and useful
ancilliary features, basic operation of the AFL28XXD series
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Pin 2 or
Pin 8
5
AFL28XXD 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 secondary side while altering the controller duty cycle to near zero.
Externally, the use of either port is transparent to the user
save for minor differences in idle current. (See specification
table).
level of +2.0 volts. The sync output of another converter
which has been designated as the master oscillator provides a convenient frequency source for this mode of operation. When external synchronization is not indicted, the
sync in pin should be left open (unconnected )thereby permitting the converter to operate at its’ own internally set
frequency.
Synchronization of Multiple Converters
The sync output signal is a continuous pulse train set at
550 ±50 KHz, with a duty cycle of 15 ±5%. This signal is
referenced to the input return and has been tailored to be
compatible 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 converter is not inhibited. This synch output has adequate
drive reserve to synchronize at least five additional converters. A typical synchronization connection option is illustrated in Figure III.
When operating multiple converters, system requirements
often dictate operation of the converters at a common frequency. To accommodate this requirement, the AFL series
converters provide both a synchronization input and output.
The sync input port permits synchronization of an AFL converter to any compatible external frequency source operating 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
Figure III. Preferred Connection for Parallel Operation
Power
Input
1
12
Vin
Enable 2
Rtn
Share
Case
Enable 1
AFL
Trim
- Output
Return
Sync Out
Sync In
Optional
Synchronization
Connection
+ Output
7
6
Share Bus
1
12
Enable 2
Vin
Rtn
Share
Case
Enable 1
AFL
Trim
to Negative Load
- Output
Return
Sync Out
Sync In
to Positive Load
+ Output
7
6
1
12
Vin
Enable 2
Rtn
Share
Case
Enable 1
AFL
Trim
- Output
Return
Sync Out
+ Output
Sync In
7
6
(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 current sharing among the members of a set whose load current exceeds the capacity of an individual AFL. An important fea-
6
ture 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 temperature, the
current it provides to the load will be reduced as compensation for the temperature induced stress on that device.
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AFL28XXD Series
When operating in the shared mode, it is important that
symmetry of connection be maintained as an assurance of
optimum load sharing performance. Thus, converter outputs should be connected to the load with equal lengths of
wire of the same gauge and should be connected to a common physical point, preferably at the load along with the
converter output and return leads. All converters in a paralleled set must have their share pins connected together.
This arrangement is diagrammatically illustrated in Figure
III. showing the output and return pins connected at a star
point which is located close as possible to the load.
A conservative aid to estimating the total heat sink surface
area (AHEAT SINK) required to set the maximum case temperature rise (∆T) above ambient temperature is given by
the following expression:
.
 ∆T −143

− 3.0
A HEAT SINK ≈ 
 80P 0.85 
where
∆T = Case temperature rise above ambient
As a consequence of the topology utilized in the current
sharing circuit, the share pin may be used for other functions. In applications requiring only a single converter, the
voltage appearing on the share pin may be used as a “total
current monitor”. The share pin open circuit voltage is nominally +1.00v at no load and increases linearly with increasing total output current to +2.20v at full load. Note that the
current we refer to here is the total output current, that is,
the sum of the positive and negative outout currents.
Thermal Considerations
Because of the incorporation of many innovative technological concepts, the AFL series of converters is capable of
providing very high output power from a package of very
small volume. These magnitudes of power density can only
be obtained by combining high circuit efficiency with effective methods of heat removal from the die junctions. This
requirement has been effectively addressed inside the device; but when operating at maximum loads, a significant
amount of heat will be generated and this heat must be
conducted away from the case. To maintain the case temperature at or below the specified maximum of 125°C, this
heat must be transferred by conduction to an appropriate
heat dissipater held in intimate contact with the converter
base-plate.
Since the effectiveness of this heat transfer is dependent
on the intimacy of the baseplate/heatsink interface, it is
strongly recommended that a high thermal conductivity heat
transferring medium is inserted between the baseplate and
heatsink. The material most frequently utilized at the factory during all testing and burn-in processes is sold under
the trade name of Sil-Pad 4001 . This particular product is
an insulator but electrically conductive versions are also
available. Use of these materials assures maximum surface contact with the heat dissipater thereby compensating
for any minor surface variations. While other available types
of heat conductive materials and thermal compounds provide similar effectiveness, these alternatives are often less
convenient and can be somewhat messy to use.
 1

P = Device dissipation in Watts = POUT 
− 1
 Eff

As an example, assume that it is desired to operate an
AFL2815D in a still air environment where the ambient temperature is held to a constant +25°C while holding the case
temperature at TC ≤ +85°C; then case temperature rise is
∆T = 85 - 25 = 60°C
From the Specification Table, the worst case full load efficiency for AFL2815D is 83% at 100 watts: thus, power dissipation at full load is given by
 1

− 1 = 100 • ( 0.205) = 20.5W
P = 100 • 
 .83 
and the required heat sink area is
60


A HEAT SINK = 
0.85 
 80 • 20.5

−1.43
− 3.0 = 56.3 in 2
Thus, a total heat sink surface area (including fins, if any) of
56 in2 in this example, would limit case rise to 60°C above
ambient. A flat aluminum plate, 0.25" thick and of approximate dimension 4" by 7" (28 in2 per side) would suffice for
this application in a still air environment. Note that to meet
the criteria in this example, both sides of the plate require
unrestricted exposure to the +25°C ambient air.
1Sil-Pad is a registered Trade Mark of Bergquist, Minneapolis, MN
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7
AFL28XXD Series
Input Filter
Table 1. Output Voltage Trim Values and Limits
The AFL28XXD series converters incorporate a two stage
LC input filter whose elements dominate the input load impedance characteristic during the turn-on sequence. The
input circuit is as shown in Figure IV.
Figure IV. Input Filter Circuit
900nH
130nH
Pin 1
6 µfd
11.2 µfd
Pin 2
Undervoltage Lockout
A minimum voltage is required at the input of the converter
to initiate operation. This voltage is set to 14.0 ± 0.5 volts. To
preclude the possibility of noise or other variations at the
input falsely initiating and halting converter operation, a hysteresis of approximately 1.0 volts is incorporated in this
circuit. Thus if the input voltage droops to 13.0 ± 0.5 volts,
the converter will shut down and remain inoperative until the
input voltage returns to ≈14.0 volts.
Output Voltage Adjust
By use of the trim pin (10), the magnitude of output voltages
can be adjusted over a limited range in either a positive or
negative direction. Connecting a resistor between the trim
pin and either the output return or the positive output will
raise or lower the magnitude of output voltages. The span
of output voltage adjustment is restricted to the limits shown
in Table I.
Figure V. Connection for VOUT Adjustment
12
Enable 2
Share
R ADJ
AFL28xxD
Trim
+
- Vout
To
Loads
Return
+ Vout
7
Connect Radj to + to increase, - to decrease
8
AFL2805D
AFL2812D
AFL2815D
Vout
Radj
Vout
Radj
Vout
5.5
0
12.5
0
15.5
0
5.4
5.3
12.5K
33.3K
12.4
12.3
47.5K
127K
15.4
15.3
62.5K
167K
5.2
75K
12.2
285K
15.2
375K
5.1
200K
∞
12.1
760K
∞
15.1
1.0M
∞
5.0
4.9
190K
12.0
11.7
4.8
65K
11.3
4.7
23K
4.6
4.583
2.5K
0
Radj
975K
15.0
14.6
1.2M
288K
14.0
325K
10.8
72.9K
13.5
117K
10.6
10.417
29.9K
0
13.0
12.917
12.5K
0
Note that the nominal magnitude of output voltage resides in
the middle of the table and the corresponding resistor value
is set to ∞. To set the magnitude greater than nominal, the
adjust resistor is connected to output return. To set the
magnitude less than nominal, the adjust resistor is connected to the positive output. (Refer to Figure V.)
For output voltage settings that are within the limits, but
between those listed in Table I, it is suggested that the
resistor values be determined empirically by selection or by
use of a variable resistor. The value thus determined can
then be replaced with a good quality fixed resistor for permanent installation.
When use of this adjust feature is elected, the user should
be aware that the temperature performance of the converter output voltage will be affected by the temperature
performance of the resistor selected as the adjustment
element and therefore, is advised to employ resistors with a
tight temperature coefficient of resistance.
General Application Information
The AFL28XXD series of converters are capable of providing large transient currents to user loads on demand.
Because the nominal input voltage range in this series is
relatively low, the resulting input current demands will be
correspondingly large. It is important therefore, that the line
impedance be kept very low to prevent steady state and
transient input currents from degrading the supply voltage
between the voltage source and the converter input. In
applications requiring high static currents and large transients, it is recommended that the input leads be made of
adequate size to minimize resistive losses, and that a good
quality capacitor of approximately100µfd be connected directly across the input terminals to assure an adequately
low impedance at the input terminals. Table I relates nominal resistance values and selected wire sizes.
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AFL28XXD Series
Table 1. Nominal Resistance of Cu Wire
Wire Size, AWG
Resistance per ft
24 Ga
25.7 mΩ
22 Ga
16.2 mΩ
20 Ga
10.1 mΩ
18 Ga
6.4 mΩ
16 Ga
4.0 mΩ
14 Ga
2.5 mΩ
12 Ga
1.6 mΩ
Another potential problem resulting from parasitically induced voltage drop on the input lines is with regard to the
operation of the enable 1 port. The minimum and maximum operating levels required to operate this port are
specified with respect to the input common return line at
the converter. If a logic signal is generated with respect to
a ‘common’ that is distant from the converter, the effects of
the voltage drop over the return line must be considered
when establishing the worst case TTL switching levels.
These drops will effectively impart a shift to the logic levels. In Figure VI, it can be seen that referred to system
ground, the voltage on the input return pin is given by
eRtn = IRtn • RP
As an example of the effects of parasitic resistance, consider an AFL2815D operating at full power of 100 W. From
the specification sheet, this device has a minimum efficiency of 83% which represents an input power of more
than 120 W. If we consider the case where line voltage is at
its’ minimum of 16 volts, the steady state input current
necessary for this example will be slightly greater than 7.5
amperes. If this device were connected to a voltage source
with 10 feet of 20 gauge wire, the round trip (input and
return) would result in 0.2 Ω of resistance and 1.5 volts of
drop from the source to the converter. To assure 16 volts
at the input, a source closer to 18 volts would be required.
In applications using the paralleling option, this drop will be
multiplied by the number of paralleled devices. By choosing 14 or 16 gauge wire in this example, the parasitic resistance and resulting voltage drop will be reduced to 25% or
31% of that with 20 gauge wire.
Therefore, the logic signal level generated in the system
must be capable of a TTL logic high plus sufficient additional amplitude to overcome eRtn. When the converter is
inhibited, IRtn diminishes to near zero and eRtn will then be at
system ground.
Incorporation of a 100 µfd capacitor at the input terminals
is recommended as compensation for the dynamic effects of the parasitic resistance of the input cable reacting
with the complex impedance of the converter input, and to
provide an energy reservoir for transient input current
requirements.
Figure VI. Problems of Parasitic Resistance in input Leads
Rp
I in
Vin
100
µfd
e source
Rp
I Rtn
e Rtn
Rtn
Case
System Ground
Enable 1
Sync Out
Sync In
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9
AFL28XXD Series
AFL28XXD Case Outlines
Case X
Case W
Pin Variation of Case Y
3.000
ø 0.128
2.760
0.050
0.050
1
12
0.250
0.250
1.260 1.500
0.200 Typ
Non-cum
6
7
1.000
Ref
1.000
Pin
ø 0.040
Pin
ø 0.040
0.220
2.500
0.220
2.800
2.975 max
0.525
0.238 max
0.42
0.380
Max
* per
0.380
Max
Case Y
Case Z
Pin Variation of Case Y
0.300
1.150
ø 0.140
0.25 typ
0.050
0.050
1
12
0.250
0.250
1.500 1.750 2.00
1.000
Ref
0.200 Typ
Non-cum
6
7
1.000
Ref
Pin
ø 0.040
Pin
ø 0.040
1.750
0.375
0.220
0.220
0.36
2.500
2.800
2.975 max
0.525
0.238 max
0.380
Max
0.380
Max
Tolerances, unless otherwise specified:
.XX
.XXX
=
=
±0.010
±0.005
BERYLLIA WARNING: These converters are hermetically sealed; however they contain BeO substrates and should not be ground or subjected to any other
operations including exposure to acids, which may produce Beryllium dust or fumes containing Beryllium
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AFL28XXD Series
Available Screening Levels and Process Variations for AFL28XXD Series.
MIL-STD-883
Method
Requirement
Temperature Range
No
Suffix
ES
Suffix
HB
Suffix
CH
Suffix
-20°C to +85°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
Element Evaluation
MIL-PRF-38534
Internal Visual
2017
¬
ü
ü
ü
Temperature Cycle
1010
Cond B
Cond C
Cond C
Constant Acceleration
2001
500g
Cond A
Cond A
Burn-in
1015
48hrs @ 85°C
48hrs @ 125°C
160hrs @ 125°C
160hrs @ 125°C
MIL-PRF-38534
& Specification
25°C
25°C
-55, +25, +125°C
-55, +25, +125°C
Seal, Fine & Gross
1014
Cond A
Cond A, C
Cond A, C
Cond A, C
External Visual
2009
¬
ü
ü
ü
Final Electrical (Group A)
* per Commercial Standards
Part Numbering
AFL28XXD Pin Designation
Pin No.
1
AFL 28 05 D X / CH
Designation
Positive Input
Model
Input Voltage
28 = 28V
270 = 270V
Screening
Case Style
2
Input Return
3
Case
4
Enable 1
5
Sync Output
6
Sync Input
7
Positive Output
AFL2805D
5962-9579501
8
Output Return
AFL2812D
5962-9579601
9
Negative Output
AFL2815D
5962-9472401
10
Output Voltage Trim
11
Share
12
Enable 2
Output Voltage
05 = 5V, 12 = 12V,
15 = 15V
–
, ES
HB, CH
W, X, Y, Z
Outputs
S = Single
D = Dual
AFL28XXD to Standard Military Drawing Equivalence Table
WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 322 3331
ADVANCED ANALOG: 2270 Martin Av., Santa Clara, California 95050, Tel: (408) 727-0500
Visit us at www.irf.com for sales contact information.
Data and specifications subject to change without notice. 09/02
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