IRF AFL2803R3SZES High reliability hybrid dc/dc converter Datasheet

PD - 94462F
AFL27003R3S
270V Input, 3.3V 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 +28V or +270V inputs with
output power ranging from 80W to 120W. For applications
requiring higher output power, multiple converters can
be operated in parallel. The internal current sharing
circuits assure equal current distribution among the
paralleled converters. This series incorporates
International Rectifier’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 550KHz. Multiple
converters can be synchronized to a system clock in
the 500KHz to 700KHz range or to the synchronization
output of one converter. Under voltage 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 International Rectifier’s
rugged ceramic lead-to-package seal assuring long
term hermeticity in the most harsh environments.
AFL
Features
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
160V To 400V Input Range
3.3V Output
High Power Density - 46W/in3
66W Output Power
Parallel Operation with Stress and Current
Sharing
Low Profile (0.380") Seam Welded Package
Ceramic Feed thru Copper Core Pins
High Efficiency - to 74%
Full Military Temperature Range
Continuous Short Circuit and Overload
Protection
Remote Sensing Terminals
Primary and Secondary Referenced
Inhibit Functions
Line Rejection > 60dB - DC to 50KHz
External Synchronization Port
Fault Tolerant Design
Dual Output Versions Available
Standard Microcircuit Drawing Available
Manufactured in a facility fully qualified to MIL-PRF38534, these converters are fabricated utilizing DSCC
qualified processes. For available screening options,
refer to device screening table in the data sheet. Variations
in electrical, mechanical and screening can be
accommodated. Contact IR Santa Clara for special
requirements.
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1
12/04/06
AFL27003R3S
Specifications
Absolute Maximum Ratings
Input voltage
Soldering temperature
Operating case temperature
Storage case temperature
-0.5V to +500VDC
300°C for 10 seconds
-55°C to +125°C
-65°C to +135°C
Electrical Performance Characteristics -55°C < TCASE < +125°C, 160V< VIN < 400V unless otherwise specified.
Group A
Subgroups
Parameter
Test Conditions
Note 6
INPUT VOLTAGE
OUTPUT VOLTAGE
1
VIN = 270 Volts, 100% Load
2, 3
Min
Nom
Max
Unit
160
270
400
V
3.27
3.30
3.33
V
3.37
3.23
OUTPUT CURRENT
VIN = 160, 270, 400 Volts, Note 6
20
A
OUTPUT POWER
Note 6
66
W
%/°C
MAXIMUM CAPACITIVE LOAD
4
10,000
-0.015
+0.015
No Load, 50% Load, 100% Load
VIN = 160, 270, 400 Volts
-10.0
+10.0
1, 2, 3
-35.0
+35.0
mV
1, 2, 3
VIN = 160, 270, 400 Volts, 100% Load,
BW = 10MHz
30
mVpp
OUTPUT VOLTAGE
TEMPERATURE COEFFICIENT
OUTPUT VOLTAGE REGULATION
Line
Load
1, 2, 3
OUTPUT RIPPLE VOLTAGE
INPUT CURRENT
No Load
Inhibit 1
Inhibit 2
EFFICIENCY
SWITCHING FREQUENCY
ISOLATION
MTBF
15.0
17.0
3.00
5.00
Pin 4 Shorted to Pin 2
Pin 12 Shorted to Pin 8
1, 2, 3
VIN = 270 Volts, 100% Load
B.W. = 10MHz
VOUT = 90% VNOM
CURRENT LIMIT POINT
LOAD FAULT POWER
DISSIPATION
Overload or Short Circuit
VIN = 270 Volts
IOUT = 0
1
2, 3
1, 2, 3
1, 2, 3
INPUT RIPPLE CURRENT
Expressed as a
Percentage
of Full Rated Load
µF
Note 1
VIN = 270 Volts, 100% Load - Note 1, 6
1, 2, 3
115
105
125
VIN = 270 Volts
VIN = 270 Volts, 100% Load
1, 2, 3
1
60
mApp
125
115
140
%
30
W
Note 5
1
2
3
1, 2, 3
mA
72
74
500
550
%
600
KHz
Input to Output or Any Pin to Case
(except Pin 3). Test @ 500VDC
100
MΩ
MIL-HDBK-217F, AIF @ TC = 40°C
300
KHrs
For Notes to Specifications, refer to page 3
2
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AFL27003R3S
Elecrical Performance Characteristics (Continued)
Parameter
ENABLE INPUTS (Inhibit Function)
Converter Off
Sink Current
Converter On
Sink Current
SYNCHRONIZATION INPUT
Frequency Range
Pulse Amplitude, Hi
Pulse Amplitude, Lo
Pulse Rise Time
Pulse Duty Cycle
Group A
Subgroups
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
1, 2, 3
Test Conditions
Logical Low, Pin 4 or Pin 12
Note 1
Logical High, Pin 4 and Pin 12 - Note 9
Note 1
Note 1
Note 1
Min
Nom
-0.5
2.0
500
2.0
-0.5
20
Max
Unit
0.8
100
50
100
V
µA
V
µA
700
10
0.8
100
80
KHz
V
V
ns
%
Note 2, 8
LOAD TRANSIENT RESPONSE
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-450
450
200
mV
µs
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
-450
450
400
mV
µs
-500
500
500
mV
µs
250
120
mV
ms
Note 1, 2, 3
LINE TRANSIENT RESPONSE
VIN Step = 160 ⇔ 400 Volts
Amplitude
Recovery
TURN-ON CHARACTERISTICS
Overshoot
Delay
4, 5, 6
4, 5, 6
VIN = 160, 270, 400 Volts. Note 4
Enable 1, 2 on. (Pins 4, 12 high or open)
LOAD FAULT RECOVERY
Same as Turn On Characteristics.
LINE REJECTION
MIL-STD-461, CS101, 30Hz to 50KHz
Note 1
50
75
60
70
dB
Notes to Specifications:
1.
2.
3.
4.
5.
6.
7.
8.
9.
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 ±1.0% of
VOUT at 50% load.
Line transient transition time ≥ 100µs.
Turn-on delay is measured with an input voltage rise time of between 100V and 500V 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 the remote sense leads connected to the output leads at the load.
Load transient transition time ≥ 10µs.
Enable inputs internally pulled high. Nominal open circuit voltage ≈ 4.0VDC.
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3
AFL27003R3S
Block Diagram
Figure I. AFL Single Output
+ INPUT
1
ENABLE 1
4
INPUT
FILTER
OUTPUT
FILTER
PRIMARY
BIAS SUPPLY
7
+ OUTPUT
10
+ SENSE
11
SHARE
12
ENABLE 2
9
RETURN SENSE
8
OUTPUT RETURN
CURRENT
SENSE
SYNC OUTPUT
5
SYNC INPUT
6
CASE
3
SHARE
CONTROL
INPUT RETURN
ERROR
AMP
& REF
SENSE
AMPLIFIER
2
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 house keeping
voltage bringing the circuitry on the primary side of the
converter 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
switching 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 secondary
side compares the 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 controller section of the
converter varying the pulse width of the square wave signal
driving the MOSFETs, narrowing the width if the output
voltage is too high and widening it if it is too low.
not used, the sense leads should be connected to their
respective output terminals at the converter. Figure III.
illustrates a typical application.
Inhibiting Converter Output (Enable)
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
Pin 4 or
Pin 12
Connection of the + and - sense leads at a remotely located
load permits compensation for resistive voltage drop
between the converter output and the load when they are
physically separated by a significant distance. This
connection allows regulation to the placard voltage at the
point of application.When the remote sensing features is
1N4148
100K
Disable
290K
Remote Sensing
4
AMPLIFIER
2N3904
150K
Pin 2 or
Pin 8
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AFL27003R3S
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).
high level of +2.0V. 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 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 ±50KHz, with a duty cycle of 15 ±5.0%. 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 100ns and the low level output impedance is
less than 50Ω. This signal is active when the DC input
voltage is within the specified operating range and the
converter is not inhibited. This output has adequate drive
reserve to synchronize at least five additional converters.
A typical synchronization connection option is illustrated in
Figure III.
Synchronization of Multiple Converters
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 500KHz and 700KHz. This input signal
should be referenced to the input return and have a 10% to
90% duty cycle. Compatibility requires transition times less
than100ns, maximum low level of +0.8V and a minimum
Figure III. Preferred Connection for Parallel Operation
Power
Input
12
1
Vin
Enable 2
Rtn
Share
Case
Enable 1
Optional
Synchronization
Connection
AFL
+ Sense
- Sense
Sync Out
Return
Sync In
+ Vout
7
6
Share Bus
12
1
Enable 2
Vin
Share
Rtn
Case
Enable 1
AFL
+ Sense
- Sense
Sync Out
Return
Sync In
+ Vout
6
1
to Load
7
12
Vin
Enable 2
Rtn
Share
Case
Enable 1
AFL
+ Sense
- Sense
Sync Out
Return
Sync In
+ Vout
6
7
(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
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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
provides to the load will be reduced as compensation for
the temperature induced stress on that device.
5
AFL27003R3S
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 sense leads from each converter 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 outputs and sense pins
connected at a star point which is located close as possible
to the load.
As a consequence of the topology utilized in the current
sharing circuit, the share pin may be used for other functions.
In applications requiring a single converter, the voltage
appearing on the share pin may be used as a “current
monitor”. The share pin open circuit voltage is nominally
+1.00V at no load and increases linearly with increasing
output current to +2.20V at full load. The share pin voltage is
referenced to the output return pin.
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.
Because 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
transferance 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 dissipator thereby compensating
for minor variations of either surface. While other available
types of heat conductive materials and compounds may
provide similar performance, these alternatives are often
less convinient and are frequently messy to use.
A conservative aid to estimating the total heat sink surface
area (A HEAT SINK ) required to set the maximum case
temperature rise (∆T) above ambient temperature is given
by the following expression:
.
⎧ ∆T ⎫ −143
⎬
A HEAT SINK ≈ ⎨
− 3.0
⎩ 80P 0.85 ⎭
where
∆T = Case temperature rise above ambient
⎧ 1
⎫
− 1⎬
P = Device dissipation in Watts = POUT ⎨
⎩ Eff
⎭
As an example, it is desired to maintain the case temperature
of this device at ≤ +85°C in an area where the ambient
temperature is held at a constant +25°C; then
∆T = 85 - 25 = 60°C
From the Specification Table, the worst case full load
efficiency for this device is 83%; therefore the power
dissipation at full load is given by
⎧ 1
⎫
P = 120 • ⎨
− 1⎬ = 120 • ( 0.205) = 24.6W
⎩ .83 ⎭
and the required heat sink area is
⎫ −1.43
⎧
60
⎬
− 3.0 = 71 in2
A HEAT SINK = ⎨
⎩ 80 • 24.6 0.85 ⎭
Thus, a total heat sink surface area (including fins, if any) of
71 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 9" (36 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 ambient air.
1Sil-Pad is a registered Trade Mark of Bergquist, Minneapolis, MN
6
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AFL27003R3S
Input Filter
The AFL270XXS series converters incorporate a LC input
filter whose elements dominate the input load impedance
characteristic at turn-on. The input circuit is as shown in
Figure IV.
Figure IV. Input Filter Circuit
Finding a resistor value for a particular output voltage, is
simply a matter of substituting the desired output voltage
and the nominal device voltage into the equation and solving
for the corresponding resistor value.
Figure V. Connection for VOUT Adjustment
Enable 2
8.4µH
Share
Pin 1
AFL270xxS
+ Sense
RADJ
- Sense
0.54µfd
Return
To Load
+ Vout
Pin 2
Caution: Do not set Radj < 500Ω
Undervoltage Lockout
A minimum voltage is required at the input of the converter
to initiate operation. This voltage is set to 150V± 5.0V. To
preclude the possibility of noise or other variations at the
input falsely initiating and halting converter operation, a
hysteresis of approximately 10V is incorporated in this circuit.
Thus if the input voltage droops to 140V ± 4.0V, the converter
will shut down and remain inoperative until the input voltage
returns to ≈ 150V.
Output Voltage Adjust
In addition to permitting close voltage regulation of remotely
located loads, it is possible to utilize the converter sense
pins to incrementally increase the output voltage over a
limited range. The adjustments made possible by this method
are intended as a means to “trim” the output to a voltage
setting for some particular application, but are not intended
to create an adjustable output converter. These output
voltage setting variations are obtained by connecting an
appropriate resistor value between the +sense and -sense
pins while connecting the -sense pin to the output return pin
as shown in Figure V. below. The range of adjustment and
corresponding range of resistance values can be determined
by use of the following equation.
⎧
⎫
VNOM
⎬
Radj = 100 • ⎨
⎩VOUT - VNOM -.025 ⎭
Where
Attempts to adjust the output voltage to a value greater than
120% of nominal should be avoided because of the potential
of exceeding internal component stress ratings and
subsequent operation to failure. Under no circumstance
should the external setting resistor be made less than 500Ω.
By remaining within this specified range of values, completely
safe operation fully within normal component derating limits
is assured.
Examination of the equation relating output voltage and
resistor value reveals a special benefit of the circuit topology
utilized for remote sensing of output voltage in the
AFL270XXS series of converters. It is apparent that as the
resistance increases, the output voltage approaches the
nominal set value of the device. In fact the calculated limiting
value of output voltage as the adjusting resistor becomes
very large is ≈ 25mV above nominal device voltage.
The consequence is that if the +sense connection is
unintentionally broken, an AFL270XXS has a fail-safe output
voltage of Vout + 25mV, where the 25mV is independent of
the nominal output voltage. It can be further demonstrated
that in the event of both the + and - sense connections
being broken, the output will be limited to Vout + 440mV.
This 440mV is also essentially constant independent of the
nominal output voltage. While operation in this condition is
not damaging to the device, not at all performance
parameters will be met.
VNOM = device nominal output voltage, and
VOUT = desired output voltage
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7
AFL27003R3S
Mechanical 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
0.200 Typ
Non-cum
6
7
1.260 1.500
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
0.380
Max
Case Y
Case Z
Pin Variation of Case Y
1.150
0.300
ø 0.140
0.25 typ
0.050
0.050
1
12
0.250
0.250
1.000
Ref
6
1.750
1.000
Ref
0.200 Typ
Non-cum
7
1.500 1.750 2.00
Pin
ø 0.040
0.375
Pin
ø 0.040
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
8
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AFL27003R3S
Pin Designation
Pin #
Designation
1
+ Input
2
Input Return
3
Case Ground
4
Enable 1
5
Sync Output
6
Sync Input
7
+ Output
8
Output Return
9
Return Sense
10
+ Sense
11
Share
12
Enable 2
Standard Microcircuit Drawing Equivalence Table
Standard Microcircuit
IR Standard
Drawing Number
Part Number
5962-99553
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AFL27003R3S
9
AFL27003R3S
Device Screening
Requirement
MIL-STD-883 Method
Temperature Range
No Suffix
ES
d
-20°C to +85°C -55°C to +125°C
Element Evaluation
HB
e -55°C to +125°C
CH
-55°C to +125°C
MIL-PRF-38534
N/A
N/A
N/A
Class H
2023
N/A
N/A
N/A
N/A
Internal Visual
2017
c
Yes
Yes
Yes
Temperature Cycle
1010
N/A
Cond B
Cond C
Cond C
Constant Acceleration
2001, Y1 Axis
N/A
500 Gs
3000 Gs
3000 Gs
PIND
2020
N/A
N/A
N/A
N/A
48 hrs@hi temp
Non-Destructive
Bond Pull
Burn-In
1015
N/A
Final Electrical
MIL-PRF-38534
25°C
( Group A )
& Specification
25°C
d
160 hrs@125°C 160 hrs@125°C
-55°C, +25°C,
-55°C, +25°C,
+125°C
+125°C
PDA
MIL-PRF-38534
N/A
N/A
N/A
10%
Seal, Fine and Gross
1014
Cond A
Cond A, C
Cond A, C
Cond A, C
Radiographic
2012
N/A
External Visual
2009
c
N/A
N/A
N/A
Yes
Yes
Yes
Notes:
 Best commercial practice
‚ Sample tests at low and high temperatures
ƒ -55°C to +105°C for AHE, ATO, ATW
Part Numbering
Model
AFL 270 03R3 S X /CH
Screening Level
(Please refer to Screening Table)
Input Voltage
No suffix, ES, HB, CH
28 = 28V
50 = 50V
120 = 120V
270 = 270V
Case Style
Output Voltage
W, X, Y, Z
Output
S = Single
03R3 = 3.3V
WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 252-7105
IR SANTA CLARA: 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. 12/2006
10
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