AHP2800D [INFINEON]
HIGH RELIABILITY HYBRID DC/DC CONVERTERS;
| 型号： | AHP2800D |
| 厂家： | 
Infineon |
| 描述： | HIGH RELIABILITY HYBRID DC/DC CONVERTERS |
| 文件： | 总11页 (文件大小：236K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PD-97389
AHP28XXD SERIES
28V Input, Dual Output
HIGH RELIABILITY
HYBRID DC/DC CONVERTERS
Description
The AHP 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
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 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. Also included
is input over-voltage protection, a new protection feature
unique to the AHP.
AHP
Features
n 16 To 40 Volt Input Range
±5, ±12, and ±15 Volts Outputs Available
n
3
n High Power Density - up to 70 W / in
n Up To 100 Watt Output Power
n Parallel Operation with Stress and Current Sharing
n Input Over-Voltage Protection
n High Efficiency - to 85%
n Continuous Short Circuit and Overload
Protection
n External Synchronization Port
n Remote Sensing Terminals
n Primary and Secondary Referenced
Inhibit Functions
n Line Rejection > 40 dB - DC to 50KHz
n Fault Tolerant Design
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.
n Full Military Temperature Range
n Ceramic Feedthru Copper Core Pins
n Low Profile (0.380") Seam Welded Package
n Single Output Versions Available
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 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-able for use in less
demanding applications. Variations in electrical,
mechanical and screening can be accommodated.
Contact IR Santa Clara for special requirements.
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1
04/16/09
AHP28XXD Series
Specifications
ABSOLUTE MAXIMUM RATINGS
Input Voltage
-0.5V to 50V
Soldering Temperature
300°C for 10 seconds
Case Temperature - Operating
Case Temperature - 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
Test Conditions
Min
Nom
Max
Unit
Note 6
V = 28V, 100% Load
16
28
40
V
OUTPUT VOLTAGE
IN
AHP2805D
AHP2812D
AHP2815D
AHP2805D
AHP2812D
AHP2815D
1
1
1
1
1
1
2, 3
2, 3
2, 3
2, 3
2, 3
2, 3
4.95
5.00
5.05
Positive Output
Negative Output
Positive Output
Negative Output
Positive Output
Negative Output
Positive Output
Negative Output
-5.05
-5.00
-4.95
11.88
-12.12
14.85
-15.15
4.90
-5.10
11.76
-12.24
12.00
-12.00
15.00
-15.00
12.12
-11.88
15.15
-14.85
5.10
-4.90
12.24
-11.76
V
Positive Output
Negative Output
Positive Output
Negative Output
14.70
-15.30
15.30
-14.70
OUTPUT CURRENT
OUTPUT POWER
V
= 16, 28, 40V - Notes 6, 11
Either Output
IN
AHP2805D
AHP2812D
AHP2815D
12.8
6.4
5.3
Either Output
Either Output
A
Total of Both Outputs - Notes 6,11
AHP2805D
AHP2812D
AHP2815D
80
96
100
W
µF
MAXIMUM CAPACITIVE LOAD
Each Output - Note 1
10,000
-0.015
OUTPUT VOLTAGE
V
= 28V, 100% Load - Notes 1, 6
IN
TEMPERATURE COEFFICIENT
+0.015
%/°C
OUTPUT VOLTAGE REGULATION
Note 10
-0.5
-1.0
+0.5
+1.0
Line
Load
1, 2, 3
1, 2, 3
No Load, 50% Load, 100% Load
V
V
= 16, 28, 40V
IN
Cross
= 16, 28, 40V - Note 12
IN
AHP2805D
1, 2, 3
1, 2, 3
1, 2, 3
Positive Output
Negative Output
-1.0
-9.0
+1.0
+9.0
%
AHP2812D
AHP2815D
Positive Output
Negative Output
-1.0
-5.0
+1.0
+5.0
Positive Output
Negative Output
-1.0
-5.0
+1.0
+5.0
For Notes to Specifications, refer to page 4
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AHP28XXD Series
Static Characteristics (Continued)
Group A
Subgroups
Parameter
Test Conditions
Min
Nom
Max
Unit
OUTPUT RIPPLE VOLTAGE
V
= 16, 28, 40V, 100% Load,
IN
BW = 10MHz
AHP2805D
AHP2812D
AHP2815D
1, 2, 3
1, 2, 3
1, 2, 3
60
80
80
mV
pp
V
= 28V
INPUT CURRENT
IN
1
2, 3
80
100
No Load
I
= 0
OUT
Inhibit 1
Inhibit 2
1, 2, 3
Pin 4 Shorted to Pin 2
Pin 12 Shorted to Pin 8
5.0
mA
1, 2, 3
1, 2, 3
1, 2, 3
50
30
30
AHP2805D
AHP2812D
AHP2815D
INPUT RIPPLE CURRENT
AHP2805D
V
V
= 28V, 100% Load
IN
1, 2, 3
1, 2, 3
1, 2, 3
60
60
60
mA
pp
AHP2812D
AHP2815D
CURRENT LIMIT POINT
= 90% V , Equal current on
NOM
OUT
Expressed as a percentage
of Full Rated Load
positive and negative outputs - Note 5
1
2
3
115
105
105
125
125
125
%
LOAD FAULT POWER DISSIPATION
V
= 28V
IN
Overload or Short Circuit
1, 2, 3
33
W
%
EFFICIENCY
AHP2805D
AHP2812D
AHP2815D
V
= 28V, 100% Load
IN
1, 2, 3
1, 2, 3
1, 2, 3
78
82
81
81
84
85
ENABLE INPUTS
(Inhibit Function)
Converter Off
Sink Current
Converter On
Sink Current
1, 2, 3
1, 2, 3
Logical Low on Pin 4 or Pin 12
Note 1
Logical High on Pin 4 and Pin 12 - Note 9 2.0
-0.5
0.8
100
50
V
µA
V
Note 1
100
µA
SWITCHING FREQUENCY
1, 2, 3
500
550
600
KHz
SYNCHRONIZATION INPUT
Frequency Range
1, 2, 3
1, 2, 3
1, 2, 3
500
2.0
-0.5
700
10
0.8
100
80
KHz
V
V
ns
%
Pulse Amplitude, Hi
Pulse Amplitude, Lo
Pulse Rise Time
Note 1
Note 1
20
Pulse Duty Cycle
ISOLATION
1
Input to Output or Any Pin to Case
(except Pin 3). Test @ 500VDC
100
MΩ
DEVICE WEIGHT
MTBF
Slight Variations with Case Style
85
g
MIL-HDBK-217F, AIF @ T = 40°C
300
KHrs
C
For Notes to Specifications, refer to page 4
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3
AHP28XXD Series
Dynamic Characteristics -55°C < TCASE < +125°C, VIN=28V unless otherwise specified.
Group A
Subgroups
Parameter
Test Conditions
Min
Nom
Max
Unit
LOAD TRANSIENT RESPONSE
Notes 2, 8
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-450
-450
450
200
mV
µs
AHP2805D
Either Output
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
10% ⇒ 50%
450
200
400
mV
µs
µs
Amplitude
Recovery
50% ⇒ 10%
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-750
-750
750
200
mV
µs
AHP2812D
Either Output
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
10% ⇒ 50%
750
200
400
mV
µs
µs
Amplitude
Recovery
50% ⇒ 10%
4, 5, 6
4, 5, 6
Load Step 50% ⇔ 100%
-750
-750
750
200
mV
µs
AHP2815D
Either Output
Amplitude
Recovery
4, 5, 6
4, 5, 6
Load Step 10% ⇔ 50%
750
200
400
mV
µs
µs
Amplitude
Recovery
10%
50% ⇒ 10%
⇒ 50%
LINE TRANSIENT RESPONSE
Notes 1, 2, 3
-500
500
500
mV
µs
Amplitude
Recovery
V
Step = 16 ⇔ 40V
IN
TURN-ON CHARACTERISTICS
V
= 16, 28, 40V - Note 4
IN
Overshoot
Delay
4, 5, 6
4, 5, 6
Enable 1, 2 on. (Pins 4, 12 high or
open)
12
10
%
ms
0
4.0
50
LOAD FAULT RECOVERY
LINE REJECTION
Same as Turn On Characteristics.
MIL-STD-461D, CS101, 30Hz to 50KHz
Note 1
40
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 VOUT has returned to within ±1% of V
at 50% load.
out
3. Line transient transition time ≥ 100 µs.
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 µs.
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 30% of maximum load while changing the load on
other output from 30% to 70%.
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AHP28XXD Series
AHP28XXD Circuit Description
Figure I. AFL Dual Output Block Diagram
Input
Filter
Output
Filter
1
4
+ Output
DC Input
Enable 1
7
Current
Sense
Primary
Bias Supply
Output Return
-Output
8
9
Output
Filter
Sync Output
5
Share
Amplifier
Control
Share
11
Error
Amp
& Ref
Sync Input
Case
6
3
2
12 Enable 2
Trim
10
Input Return
Circuit Operation and Application Information
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.
The AHP 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
Inhibiting Converter Output
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.
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.
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.
Figure II. Enable Input Equivalent Circuit
+5.6V
100K
1N4148
Pin 4 or
Pin 12
Disable
270K
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
200K
Pin 2 or
Pin 8
Although incorporating several sophisticated and useful
ancilliary features, basic operation of the AHP28XXD
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5
AHP28XXD Series
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 indicated, the sync in
pin should be left open (unconnected )thereby permitting
the converter to operate at its’ own internally set frequency.
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).
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.
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 AHP
series converters provide both a synchronization input and
output.
The sync input port permits synchronization of an AHP
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 than
100 ns, maximum low level of +0.8 volts and a minimum high
Figure III. Preferred Connection for Parallel Operation
1
12
Power
Input
Enable 2
Vin
Rtn
Share
Trim
Case
AHP
AHP
Enable 1
Sync Out
Sync In
- Output
Return
+ Output
7
6
1
Optional
Synchronization
Connection
Share
Bus
12
Enable 2
Vin
Rtn
Share
Trim
Case
Enable 1
Sync Out
Sync In
- Output
Return
to Negative Load
to Positive Load
+ Output
7
6
1
12
Enable 2
Share
Vin
Rtn
Case
Trim
AHP
Enable 1
Sync Out
Sync In
- Output
Return
+ Output
7
6
(Other Converters)
Parallel Operation-Current and Stress Sharing
feature of the AHP 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
Figure III. illustrates the preferred connection scheme for
operation of a set of AHP 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 AHP. An important
6
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AHP28XXD Series
device. When operating in the shared mode, it is important A conservative aid to estimating the total heat sink surface
that symmetry of connection be maintained as an assurance area (AHEAT SINK) required to set the maximum case temp-
of optimum load sharing performance. Thus, converter erature rise (∆T) above ambient temperature is given by
outputs should be connected to the load with equal lengths the following expression:
of wire of the same gauge and should be connected to a
common physical point, preferably at the load along with the
−1.43
⎧
⎨
⎩
⎫
⎬
⎭
∆T
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 as close as possible to the load.
A
HEAT SINK
≈
− 3.0
0.85
80P
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.
⎧
⎨
⎫
⎭
1
⎬
−1
P = Device dissipation in Watts = P
OUT⎩Eff
As an example, assume that it is desired to operate an
AHP2815D 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
Thermal Considerations
∆T = 85 - 25 = 60°C
Because of the incorporation of many innovative
technological concepts, the AHP 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.
From the Specification Table, the worst case full load
efficiency for AHP2815D is 83% at 100 watts: thus, power
dissipation at full load is given by
1
⎧
⎨
⎩
⎫
⎭
P = 100•
−1 = 100• 0.205 = 20.5W
(
)
⎬
.83
and the required heat sink area is
−1.43
60
⎧
⎨
⎩
⎫
⎬
⎭
A
HEAT SINK
=
− 3.0 = 56.3 in2
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
80•20.50.85
Thus, a total heat sink surface area (including fins, if any) of
2
56 in in this example, would limit case rise to 60°C above
ambient. A flat aluminum plate, 0.25" thick and of
1
trade name of Sil-Pad® 400 . This particular product is an
2
approximate dimension 4" by 7" (28 in per side) would
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.
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.
1
Sil-Pad is a registered Trade Mark of Bergquist, Minneapolis, MN
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7
AHP28XXD Series
Input Filter
Figure V. Connection for VOUT Adjustment
The AHP28XXD series converters incorporate a single 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.
12
Enable 2
Share
RADJ
-
Trim
+
AHP28xxD
Figure IV. Input Filter Circuit
- Vout
To
Loads
Return
3.5µH
+ Vout
7
Pin 1
11.2 µfd
Connect Radj to + to increase, - to decrease
Pin 2
Table 1. Output Voltage Trim Values and Limits
AHP2805D AHP2812D AHP2815D
Vout Radj Vout Radj Vout Radj
Input Over-Voltage Protection
5.5
5.4
0
12.5
12.4
12.3
12.2
12.1
12.0
11.7
11.3
10.8
10.6
10.417
0
15.5
15.4
15.3
15.2
15.1
15.0
14.6
14.0
13.5
13.0
12.917
0
One additional protection feature is incorporated into the
AHP input circuit. It is an input over-voltage protection. The
output will shutdown and restart at approximately 110% of
the maximum rated input voltage. This protection feature is
unique to the AHP.
12.5K
33.3K
75K
200K
∞
190K
65K
23K
2.5K
0
47.5K
127K
285K
760K
∞
975K
288K
72.9K
29.9K
0
62.5K
167K
375K
1.0M
∞
1.2M
325K
117K
12.5K
0
5.3
5.2
5.1
5.0
Undervoltage Lockout
4.9
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.
4.8
4.7
4.6
4.583
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.)
Output VoltageAdjust
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
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.
in Table I.
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.
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AHP28XXD Series
General Application Information
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.
The AHP28XXD 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 2 relates
nominal resistance values and selected wire sizes.
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,
Table 2. Nominal Resistance of Cu Wire
Wire Size, AWG
Resistance per ft
24 Ga
22 Ga
20 Ga
18 Ga
16 Ga
14 Ga
12 Ga
25.7 mΩ
16.2 mΩ
10.1 mΩ
6.4 mΩ
4.0 mΩ
2.5 mΩ
1.6 mΩ
the voltage on the input return pin is given by
eRtn = IRtn • RP
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
As an example of the effects of parasitic resistance,
consider an AHP2815D 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
Amps.
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
Iin
Vin
100
µfd
esource
Rtn
eRtn
IRtn
Rp
Case
Enable 1
Sync Out
Sync In
System Ground
www.irf.com
9
AHP28XXD Series
AHP28XXD Case Outlines
Case X
Case W
Pin Variation of Case Y
3.000
ø 0.128
2.760
0.050
0.050
0.250
0.250
1.000
1.000
Ref
1.260 1.500
0.200 Typ
Non-cum
Pin
ø 0.040
Pin
ø 0.040
0.220
2.500
0.220
0.525
2.800
2.975 max
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
0.250
0.250
1.000
Ref
1.500 1.750 2.00
1.000
Ref
0.200 Typ
Non-cum
Pin
ø 0.040
Pin
ø 0.040
0.220
0.220
1.750
2.500
0.375
0.36
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
10
www.irf.com
AHP28XXD Series
Available Screening Levels and Process Variations for AHP28XXD Series.
MIL-STD-883
Method
No
ES
HB
CH
Requirement
Temperature Range
Element Evaluation
Internal Visual
Suffix
Suffix
Suffix
Suffix
-20°C to +85°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
MIL-H-38534
2017
1010
Temperature Cycle
Constant Acceleration
Burn-in
Cond B
500g
Cond C
3000g
Cond C
3000g
2001, Y1 Axis
1015
48hrs @ 85°C
48hrs @ 125°C
25°C
160hrs @ 125°C
160hrs @ 125°C
Final Electrical (Group A)
MIL-PRF-38534
Specification
25°C
-55, +25, +125°C -55, +25, +125°C
Seal, Fine & Gross
External Visual
1014
2009
Cond C
Cond A, C
Cond A, C
Cond A, C
* per Commercial Standards
AHP28XXD Pin Designation
Part Numbering
AHP 28 05 D X / CH
Pin No.
Designation
Positive Input
Input Return
Case
Screening Level
ES, HB, CH
Blank = min screening
Model
1
2
Input Voltage
28 = 28V
270 = 270V
Case Style
W, X, Y, Z
3
Output Voltage
05 = 5V, 12 = 12V
15 = 15V
Outputs
S = Single
D = Dual
4
Enable 1
5
Sync Output
Sync Input
6
7
Positive Output
Output Return
Negative Output
Output Voltage Trim
Share
8
9
10
11
12
Enable 2
WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 322 3331
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. 04/2009
www.irf.com
11
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