AMF28XXD Datasheet, PDF (5/7 Pages) International Rectifier – 28V Input, Dual Output, ADVANCED ANALOG RADIATION TOLERANT DC/DC CONVERTERS

AMF28XXD Series
Notes to Specifications
1. Applicable to positive and negative outputs.
2. Maximum combined output is 12 watts. 10.8 watts (max.) is available from either output (90%).
3. Load current split equally between +VOUT and –VOUT.
4. 1.2 watt load on output under test, 1.2 watt to 10.8 watt load change on other output.
5. Capacitive value may be any value from 0 to the maximum limit without compromising DC performance. A
capacitive load in excess of the maximum limit will not disturb loop stability but may interfere with the operation
of the load fault detection circuitry, appearing as a short circuit during turn-on.
6. Parameter shall be tested as part of design characterization and after design or process changes. Thereafter,
parameters shall be guaranteed to the limit specified.
7. Load step transition time between 2 and 10 microseconds.
8. Recovery time is measured from initiation of the transient to where Vout has returned to within ±1% of Vout at
50% load.
9. Input step transient time between 1 and 10 microseconds.
10. Turn-on delay time measurement is for either a step application of power at the input or the removal of a ground
signal from the inhibit pin while power is applied to the input.
AMF28XXD Block Diagram
8
+Input
1
E n a b le
EMI
F ilte r
Prim ary
H o u s e k e e p in g
S u p p ly
3 _+Vout
4 _Return
5 -Vout
6
Case
2
Sync
D rive
P ulse W idth
M odulator ^FB
CS
Error
Amp &
Ref
Input
R e tu rn
7
Application Information
Inhibit Function
Connecting the enable input (Pin 1) to input common
(Pin 7) will cause the converter to shut down. It is
recommended that the enable pin be driven by an
open collector device capable of sinking at least 400
µA of current. If the user chooses not to use the inhibit
function, it may be left open and the converter will
function normally. Because it is internally pulled up,
the open circuit voltage of the inhibit input is 10.0
+1V_DC.
EMI Filter
An optional EMI filter is available (AFH461) that will
reduce the input ripple current to levels below the
limits imposed by MIL-STD-461 CE03.
Device Synchronization
When multiple DC/DC converters are utilized in a
single system, significant low frequency noise may
be generated due to a small difference in the switch-
ing frequency of the converters (beat frequency
noise). Because of the low frequency nature of this
noise (typically less than 10 KHz), it is difficult to
filter out and may interfere with proper operation of
sensitive systems (communication, radar or telem-
etry). Advanced Analog provides synchronization
of multiple AMF type converters to match switching
frequency of the converter to the frequency of the
system clock, thus eliminating this type of noise.
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