ISO-9001 CERTIFIED BY DSCC
M.S.KENNEDY CORP.
4707 Dey Road Liverpool, N.Y. 13088
7.5W
DC-DC
CONVERTER
DHD2805S
(315) 701-6751
FEATURES:
Typical Efficiency 70%
All Ceramic Capacitors
Surface Mount Magnetics
80 Volt Input Transient Tolerant
Operates to 12V Input at 5W
Wide Supply Range - 16V to 40V
High Isolation - 500V
Output Voltage Adjustment - Standard
Remote Shutdown
5V Output (See DHC Series for Other Voltages)
Replaces IR ASA2805S
Replaces Interpoint MSA2805S
MIL-PRF-38534 CERTIFIED
DESCRIPTION:
The DHD2805S DC-DC converter provides the ruggedness, reliability and features required to meet the
advanced design challenges of today's hi-rel market. The use of advanced substrate and reflow soldering
techniques during construction results in a rugged, cost-effective and completely solderable package.
DHD2805S hybrid converter utilizes all ceramic capacitors and surface mount magnetics to provide
reliable operation at all operating temperatures while surviving very high G forces.
DHD2805S standard features include output fault monitoring and/or turn on voltage point programming
via the shutdown pin. All three functions may be implemented simultaneously with a minimum of external
components. An output voltage adjustment/load compensation pin is also standard.
Fault tolerant design protects these converters from most external circuit faults. The output and output
adjust pins will withstand +35V while the shutdown pin will withstand +50V protecting the converters
from a variety of system or board faults i.e. solder bridges, etc. Unique load fault protection circuitry
allows this converter to pull up loads having difficult static load line characteristics and allows short term
load excursions significantly beyond ratings in most applications.
A transformer isolated forward converter topology operating at a switching frequency of 400kHz allows
operation over a wide input voltage range. Internal filtering of both input and output eliminates the need for
external capacitors in many applications.
The 8-pin DIP package is hermetically sealed and isolated from the internal circuits. Heat sinking is
recommended for full power operation at elevated ambient temperatures.
1
Rev. C 3/05
ELECTRICAL SPECIFICATIONS
Parameter
Test Conditions
1
Group A
Subgroup
1
2,3
DHD2805S H/E
Min.
4.95
4.80
120
120
-
-
-
-
-
-
-
-
65
60
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
16
12
10
-
-
-
-
-
100
1.6
375
±10
DHD2805S
Min.
4.90
-
120
-
-
-
-
-
-
-
-
-
63
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
16
12
10
-
-
-
-
-
100
1.5
350
±10
Units
Max.
5.10
-
1500
-
190
-
225
-
±30
-
±40
-
-
-
±500
-
300
-
±500
-
500
-
200
-
50
-
500
-
-
40
50
50
45
-
5
-
300
-
2.3
450
-
VDC
VDC
mA
mA
mVp-p
mVp-p
mAp-p
mAp-p
mV
mV
mV
mV
%
%
mV
mV
µS
µS
mV
mV
µS
µS
mV
mV
mS
mS
µS
µS
mS
V
V
V
mA
mA
mA
mA
µF
MΩ
A
KHz
%
Typ.
5.00
-
-
-
75
-
100
-
±9
-
±15
-
70
-
±300
-
90
-
±160
-
140
-
0
0
30
-
220
-
60
-
-
-
35
-
2
-
-
-
1.9
400
-
Max.
5.05
5.20
1500
1500
190
475
200
200
±25
±50
±35
±50
-
-
±500
±750
300
300
±500
±500
500
500
200
200
50
50
500
500
-
40
50
50
40
40
5
5
300
-
2.2
425
-
Typ.
5.00
-
-
-
75
-
100
-
±9
-
±15
-
70
-
±300
-
90
-
±160
-
140
-
0
-
30
-
220
-
60
-
-
-
35
-
2
-
-
-
1.9
400
-
Output Voltage
Output Current
2
16V≤V
IN
≤40V
BW=10KHz to 2MHz
1
2,3
1
2,3
Output Voltage Ripple
Input Current Ripple 2
BW=10KHz to 2MHz
1
2,3
Line Regulation
V
IN
=16V to 40V
V
IN
=28V
I
OUT
=120mA to/from 1500mA
1
2,3
Load Regulation
1
2,3
1
2,3
Efficiency
I
OUT
=500mA to/from 1000mA
Transition TIme=30µS
I
OUT
=500mA to/from 1000mA
Transition TIme=30µS
V
IN
=16V to/from 40V
Transition Time=30µS, I
OUT
=1A
V
IN
=16V to/from 40V
Transition Time=30µS, I
OUT
=1A
I
OUT
=1A
Step Load Response
4
5,6
4
5,6
4
5,6
4
5,6
4
5,6
Step Load Recovery
Step Line Response 2
Step Line Recovery 2
Start Up Overshoot
Start Up Delay
I
OUT
=0A and 1A
4
5,6
4
5,6
-
Shutdown Delay 2
Shutdown Recovery 2
P
OUT
=7.5W MAX.
Input Voltage Range 2
P
OUT
=5W MAX.
P
OUT
=2.5W MAX.
Enabled, I
OUT
=0mA
Quiescent Current
Disabled, I
OUT
=0mA
Capacitive Load 2
Isolation
Short Circuit Current Limit 7
Switching Frequency
VOUT Adjustment Range
R
POT
=50KΩ
No Effect on DC Performance
Input to output or any pin to case @ 500V
1,2,3
1,2,3
1,2,3
1
2,3
1
2,3
1,2,3
1
1
4
1
NOTES:
1
2
3
4
5
6
+V
IN
= 28V, I
OUT
= 1.5A, T
A
=T
C
=25°C unless otherwise specified.
Guaranteed by design but not tested. Typical parameters are representative of actual device performance but are for reference only.
Industrial grade and "E" suffix devices shall be tested to subgroups 1 and 4 unless otherwise specified.
Military grade devices ("H" suffix) shall be 100% tested to subgroups 1, 2, 3 and 4.
Subgroups 5 and 6 testing available upon request.
Subgroup 1, 4 T
A
=T
C
=+25°C
2, 5 T
A
=T
C
=+125°C
3, 6 T
A
=T
C
= -55°C
7 Device has internal shutdown feature that pulses the output with a low duty cycle during faults.
3
Rev. C 3/05
APPLICATION NOTES
POWER SUPPLIES
The output voltage of the DHD2805S may be adjusted from
90% to 110% of nominal value by the use of a 50KΩ potenti-
ometer as shown. Adjustment beyond this range is possible
however certain characteristics of the converter such as but
not limited to input voltage range, efficiency, ripple and tem-
perature performance will change. Characterization by the user
is recommended in such applications.
LOAD FAULT RESPONSE
Load fault conditions include short-circuit and severe over-
load conditions. The DHD2805S converter responds to load
faults by turning off all power conversion circuits for 250mS
and then attempting to restart for 10mS (typical). The net "on"
duty factor during a fault is very low resulting in low converter
dissipation and immunity from overheating at 125°C. Current
beyond rated can flow into the load at startup time. This al-
lows the converter to bring up capacitive and other difficult
load types more reliably than competing converters.
Adjust/comp (pin 3) may be driven by external circuitry refer-
enced to pin 2 (-output) if desired. Grounding pin 3 causes
voltage to increase (25% typically) while driving pin 3 above
1.3V causes output voltage to decrease. Pin 3 may be driven
through 10KΩ or more if connection of the comp function is
also required.
The comp function of pin 3 allows capacitive loads as large
as 1000µF to be accommodated on the DHD2805S without
loss of stability. This feature may be utilized by connecting a
10nF capacitor between pins 3 and 1. This is generally recom-
mended when low ESR load capacitances of 100µF or greater
are used.
SHUTDOWN PLUS
Pin 5 is used for remote shutdown, output fault detection,
and/or setting the input voltage point at which the converter
will turn on as shown in the typical application diagram. No
connection to pin 5 is necessary for normal operation of the
converter. Pin 5 is referenced to the -input (pin 7).
Shutdown may be implemented by simply connecting pin 5
to an open collector logic output or switch rated at 2.5mA,
25Vdc or higher.
Input voltage turn on point is programmed with a single resis-
tor from pin 5 to 7. An input turn on/off hysteresis (typically
3.5% of Vin) will be observed. This should be considered when
making or verifying set point adjustment. The value of the
setpoint resistor may be determined by the following:
R= 210·10³
E
TO
-9.5
(±10% accuracy at 25°C)
Set point temperature coefficient is typically +400ppm/°C.
Output fault monitoring is accomplished by observing pin 5
with a high impedance monitoring circuit. Pin 5 voltage drops
from over 10V to below 1V when a load fault causes the con-
verters fault protection circuitry to activate. It will remain low
for at least 100mS and return high. If the load fault is still
present pin 5 will return low and the cycle will repeat. A resis-
tor >400KΩ from pin 5 to 7 provides pull down for pin 5 if
there is no input setpoint programming resistor already in place.
4
Rev. C 3/05
Embedded System
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