PARAMETER NOTES and CONDITIONSF48SA28025 (Standard)
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Continuous 80 Vdc
Transient (100ms) 100ms 100 Vdc
Operating Temperature Please refer to Fig 20 for measuring point -40 95 °C
Storage Temperature -55 125 °C
Input/Output Isolation Voltage 2250 Vdc
INPUT CHARACTERISTICS
Operating Input Voltage 36 48 75 Vdc
Input Under-Voltage Lockout
Turn-On Voltage Threshold 33 34.5 36 Vdc
Turn-Off Voltage Threshold 31 32.5 34 Vdc
Lockout Hysteresis Voltage
Input Over-Voltage Lockout
Turn-On Voltage Threshold 76 78 80 Vdc
Turn-Off Voltage Threshold 78 80 82 Vdc
Lockout Hysteresis Voltage 2 Vdc
Maximum Input Current 100% Load, 36Vin 23 A
Inrush Current(I2t) 1 A2s
Input Reflected-Ripple Current P-P thru 15µH inductor, 5Hz to 20MHz 20 mA
Input Voltage Ripple Rejection 120 Hz 50 dB
OUTPUT CHARACTERISTICS
Output Voltage Set Point Vin=48V, Io=Io.max, Tc=25°C 27.44 28.00 28.56
Output Voltage Regulation
Over Load Io=Io,min to Io,max 28 56 mV
Over Line Vin=36V to 75V 28 56 mV
Over Temperature Tc=-40°C to 100°C 100 300 mV
Total Output Voltage Range over all load, line and temperature 27.25 28.00 28.75 V
Output Voltage Ripple and Noise 5Hz to 20MHz bandwidth
Peak-to-Peak Full Load, 1µF ceramic, 10µF Low ESR cap 200 mV
RMS Full Load, 1µF ceramic, 10µF Low ESR cap 65 mV
Operating Output Current Range 2 25 A
Output DC Current-Limit Inception Output Voltage 10% Low 120 150 %
DYNAMIC CHARACTERISTICS
Output Voltage Current Transient
Positive Step Change in Output Current 50% Io.max to 75% Io.max 450 mV
Negative Step Change in Output Current 75% Io.max to 50% Io.max 450 mV
Settling Time (within 1% Vout nominal) 500 us
Turn-On Transient
Start-Up Time, From On/Off Control 20 35 ms
Start-Up Time, From Input 20 35
Output Capacitive Load 470 6000 µF
EFFICIENCY
100% Load
60% Load 91.5 %
ISOLATION CHARAC TERISTICS
Input to Output 2250 Vdc
Input to Case
Output to Case 1500 Vdc
Isolation Resistance 10 MΩ
Isolation Capacitance 1800 pF
FEATURE CHARACTERISTICS
Switching Frequency 300 kHz
t Volt
Power good pin max applied voltage Max sink current 5mA 35 V
Auxiliary output voltage
Output Voltage Trim Range
Output Voltage Remote Sense Range
Output Over-Voltage Protection Over full temp range; % of nominal Vout 115 140 %
GENERAL SPECIFICATIONS
MTBF Io=80% of Io, max; Ta=25°C 1.14 M hours
Weight 168 grams
Over-Temperature Shutdown Please refer to Fig.20 for measuring point 100 °C
Min. Typ. Max. Units
48V, Tested with a 10µF, a 1µF Ceramic cap and a
470uF low ESR aluminum load cap,
ΔIo/Δt=1A/µs
ring start up
Aux pin source current <=20mA
Referenced to Sense(-) pin
Pout ≦ max rated power
Pout ≦ max rated power
2 Vdc
Vdc
ms
91.5 %
1500 Vdc
7 10 13 V
-15 +10 %
0.5 V
DS_F48SA28025_12072007
2
ELECTRICAL CHARACTERISTICS CURVES
95
EFFICIENCY (%)
90
85
80
75
70
051015202530
36Vin48Vi n75Vin
OUT PUT CURRENT (A)
Figure 1: Efficiency vs. load current for minimum, nominal, and
maximum input voltage at 25°C.
Figure 2: Power dissipation vs. load current for minimum,
nominal, and maximum input voltage at 25°C.
DS_F48SA28025_12072007
3
ELECTRICAL CHARACTERISTICS CURVES
For Negative Remote On/Off Logic
Figure 3: Turn-on transient at full rated load current (resistive
Figure 4: Turn-on transient at minimum load current
. CH3: Vout: 5V/div; CH1: ON/OFF input:5V/div
Figure 6: Turn-on transient at minimum load current
(10ms/div). Top Trace: Vout: 5V/div; Bottom Trace: ON/OFF
input: 2V/div
DS_F48SA28025_12072007
4
ELECTRICAL CHARACTERISTICS CURVES
A
Figure 7: Output voltage response to step-change in load
current (75%-50% of Io, max; di/dt = 1A/µs). Load cap: 470µF
aluminum ,10uF Low ESR capacitor and 1µF ceramic
capacitor. Top Trace: Vout (200mV/div), Bottom Trace: Iout
(10A/div). Scope measurement should be made using a BNC
cable (length shorter than 20 inches). Position the load
between 51 mm to 76 mm (2 inches to 3 inches) from the
module.
Figure 8: Output voltage response to step-change in load
current (50%-75% of Io, max; di/dt = 1A/µs). Load cap: 470µF
aluminum,10uF Low ESR capacitor and 1µF ceramic capacitor.
Top Trace: Vout (200mV/div), Bottom Trace: Iout (10
Scope measurement should be made using a BNC cable
(length shorter than 20 inches). Position the load between 51
mm to 76 mm (2 inches to 3 inches) from the module.
/div).
Figure 9: Test set-up diagram showing measurement points for
Input Terminal Ripple Current and Input Reflected Ripple
Current.
Note: Measured input reflected-ripple current with a simulated
source Inductance (L
possible battery impedance. Measure current as shown above.
) of 15 μH. Capacitor Cs offset
TEST
DS_F48SA28025_12072007
5
ELECTRICAL CHARACTERISTICS CURVES
E
Figure 10: Input Terminal Ripple Current, i
current and nominal input voltage with 15µH source impedance
and 220µF electrolytic capacitor (1A/div).
, at full rated output
c
Copper Strip
Vo(+)
10u1u
Vo(-)
Figure 12: Output voltage noise and ripple measurement test
setup
SCOPERESISTIV
LOAD
Figure 11: Input reflected ripple current, i
source inductor at nominal input voltage and rated load current
(10 mA/div)
, through a 15µH
s
DS_F48SA28025_12072007
6
ELECTRICAL CHARACTERISTICS CURVES
Figure 13: Output voltage ripple at nominal input voltage and
rated load current (100 mV/div). Load capacitance:470uF
aluminum, 1µF ceramic capacitor and 10µFlow ESR capacitor.
Bandwidth: 20 MHz. Scope measurement should be made
using a BNC cable (length shorter than 20 inches). Position the
load between 51 mm to 76 mm (2 inches to 3 inches) from the
module.
Figure 14: Output voltage vs. load current showing typical
current limit curves and converter shutdown points.
DS_F48SA28025_12072007
7
DESIGN CONSIDERATIONS
Input Source Impedance
The impedance of the input source connecting to the
DC/DC power modules will interact with the modules
and affect the stability. A low ac-impedance input source
is recommended. If the source inductance is more than
a few μH, we advise adding a 220 to 470 μF electrolytic
capacitor (ESR < 0.1 Ω at 100 kHz) mounted close to
the input of the module to improve the stability.
Layout and EMC Considerations
Delta’s DC/DC power modules are designed to operate
in a wide variety of systems and applications. For design
assistance with EMC compliance and related PWB
layout issues, please contact Delta’s technical support
team. An external input filter module is available for
easier EMC compliance design. Application notes to
assist designers in addressing these issues are pending
release.
Safety Considerations
The power module must be installed in compliance with
the spacing and separation requirements of the
end-user’s safety agency standard, i.e., UL60950,
CAN/CSA-C22.2 No. 60950-00 and EN60950:2000 and
IEC60950-1999, if the system in which the power
module is to be used must meet safety agency
requirements.
Basic insulation based on 75 Vdc input is provided
between the input and output of the module for the
purpose of applying insulation requirements when the
input to this DC-to-DC converter is identified as TNV-2
or SELV. An additional evaluation is needed if the
source is other than TNV-2 or SELV.
When the input source is SELV, the power module meets
SELV (safety extra-low voltage) requirements. If the
input source is a hazardous voltage which is greater than
60 Vdc and less than or equal to 75 Vdc, for the module’s
output to meet SELV requirements, all of the following
must be met:
The input source must be insulated from the ac
mains by reinforced or double insulation.
The input terminals of the module are not operator
accessible.
If the metal baseplate is grounded, one Vi pin and
one Vo pin shall also be grounded.
A SELV reliability test is conducted on the system
where the module is used, in combination with the
module, to ensure that under a single fault,
hazardous voltage does not appear at the module’s
output.
When installed into a Class II equipment (without
grounding), spacing consideration should be given to
the end-use installation, as the spacing between the
module and mounting surface have not been evaluated.
The power module has extra-low voltage (ELV) outputs
when all inputs are ELV.
This power module is not internally fused. To achieve
optimum safety and system protection, an input line fuse
is highly recommended. The safety agencies require a
normal-blow fuse with 20A maximum rating to be
installed in the ungrounded lead. A lower rated fuse can
be used based on the maximum inrush transient energy
and maximum input current.
Soldering and Cleaning Considerations
Post solder cleaning is usually the final board assembly
process before the board or system undergoes electrical
testing. Inadequate cleaning and/or drying may lower the
reliability of a power module and severely affect the
finished circuit board assembly test. Adequate cleaning
and/or drying is especially important for un-encapsulated
and/or open frame type power modules. For assistance
on appropriate soldering and cleaning procedures,
please contact Delta’s technical support team.
DS_F48SA28025_12072007
8
FEATURES DESCRIPTIONS
n
Over-Current Protection
The modules include an internal output over-current
protection circuit, which will endure current limiting for
an unlimited duration during output overload. If the
output current exceeds the OCP set point, the modules
will automatically shut down (hiccup mode).
The modules will try to restart after shutdown. If the
overload condition still exists, the module will shut down
again. This restart trial will continue until the overload
condition is corrected.
Over-Voltage Protection
The modules include an internal output over-voltage
protection circuit, which monitors the voltage on the
output terminals. If this voltage exceeds the over-voltage
set point, the module will shut down and latch off. The
over-voltage latch is reset by either cycling the input
power or by toggling the on/off signal for one second.
Over-Temperature Protection
The over-temperature protection consists of circuitry
that provides protection from thermal damage. If the
temperature exceeds the over-temperature threshold
the module will shut down.
The module will try to restart after shutdown. If the
over-temperature condition still exists during restart, the
module will shut down again. This restart trial will
continue until the temperature is within specification.
Remote On/Off
+Vin
-Vin
+On/Off
-On/Off
Input side on off control
DS_F48SA28025_12072007
Aux
-Sense
+On/Off
-On/Off
Output side on off control
Figure 15: Remote on/off implementation
Remote Sense
Remote sense compensates for voltage drops on the
output by sensing the actual output voltage at the point
of load. The voltage between the remote sense pins
and the output terminals must not exceed the output
voltage sense range given here:
[Vo(+) – Vo(–)] – [SENSE(+) – SENSE(–)] ≤ 10% × Vo ut
This limit includes any increase in voltage due to
remote sense compensation and output voltage set
point adjustment (trim).
Vi(+)
Vo(+)
Sense(+)
Sense(-)
Vi(-)
Contact
Resistance
Vo(-)
Contact and Distributio
Losses
Figure 16: Effective circuit configuration for remote sense
operation
If the remote sense feature is not used to regulate the
output at the point of load, please connect SENSE(+) to
Vo(+) and SENSE(–) to Vo(–) at the module.
The output voltage can be increased by both the
remote sense and the trim; however, the maximum
increase is the larger of either the remote sense or the
trim, not the sum of both.
When using remote sense and trim, the output voltage
of the module is usually increased, which increases the
power output of the module with the same output
current.
Care should be taken to ensure that the maximum
output power does not exceed the maximum rated
power.
9
FEATURES DESCRIPTIONS (CON.)
⎛⎝⎞
⎠
(
)
⎡
⎣
Output Voltage Adjustment (TRIM)
To increase or decrease the output voltage set point,
the modules may be connected with an external
resistor between the TRIM pin and either the
SENSE(+) or SENSE(-). The TRIM pin should be left
open if this feature is not used.
Figure 17: Circuit configuration for trim-down (decrease
output voltage)
If the external resistor is connected between the TRIM
and SENSE (-) pins, the output voltage set point
decreases (Fig. 18). The external resistor value
required to obtain a percentage of output voltage
change △% is defined as:
Figure 18: Circuit configuration for trim-up (increase output
voltage)
If the external resistor is connected between the TRIM
and SENSE (+) the output voltage set point increases
(Fig. 19). The external resistor value required to obtain
a percentage output voltage change △% is defined
The output voltage can be increased by both the remote
sense and the trim, however the maximum increase is
the larger of either the remote sense or the trim, not the
sum of both.
When using remote sense and trim, the output voltage
of the module is usually increased, which increases the
power output of the module with the same output
current.
Care should be taken to ensure that the maximum
output power of the module remains at or below the
maximum rated power.
DS_F48SA28025_12072007
10
THERMAL CONSIDERATIONS
A
B
Y
E
E
Thermal management is an important part of the system
design. To ensure proper, reliable operation, sufficient
cooling of the power module is needed over the entire
temperature range of the module. Convection cooling is
usually the dominant mode of heat transfer.
Hence, the choice of equipment to characterize the
thermal performance of the power module is a wind
tunnel.
Thermal Testing Setup
Delta’s DC/DC power modules are characterized in
heated vertical wind tunnels that simulate the thermal
environments encountered in most electronics
equipment. This type of equipment commonly uses
vertically mounted circuit cards in cabinet racks in which
the power modules are mounted.
The following figure shows the wind tunnel
characterization setup. The power module is mounted
on a test PWB and is vertically positioned within the
wind tunnel. The space between the neighboring PWB
and the top of the power module is constantly kept at
6.35mm (0.25’’).
FACI NG PW
PWB
MODULE
Thermal Derating
Heat can be removed by increasing airflow over the module.
The module’s maximum case temperature is
95℃. To
enhance system reliability, the power module should always
be operated below the maximum operating temperature. If
the temperature exceeds the maximum module
temperature, reliability of the unit may be affected.
THERMAL CURVES
Figure 20: Temperature measurement location viewed from the
IMS side
The allowed maximum hot spot temperature is defined at 95
Output Power (W)
750
700
F48SA28025(Standard) Output Power vs. Hot Spot Temperature
(Either Orientation)
℃
AIR VELOCIT
AN
D AMBIENT
TEMPERATUR
MEASURED BELOW
THE MODUL
IR FLOW
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
50.8 (2.0”)
12.7 (0.5”)
Figure 19: Wind tunnel test setup
650
600
550
500
450
400
350
2535455565758595
Hot spot Temperature(℃)
Figure 21: Output power vs. hot spot temperature (Either
Orientation)
DS_F48SA28025_12072007
11
MECHANICAL DRAWING
Pin No.
1
2
3
4
5
6
7
8
9
10
Pin S ecificatio
pn:
Pins 3-4, 11-16
Pins 1-2, 6-10
All pins are coppen plating.
DS_F48SA28025_12072007
NameFunction
-Vin
+Vin
-ON/OFF
+ON/OFF
+Vout
+Vout
+Vout
-Vout
-Vout
-Vout
r with Ti
gative input volt
Neage
Pooltage
sitive input v
Negative Remote ON/O
Positive Remote ON/OFF
Positive output voltage
Positive output voltage
Positive output voltage
Negative output voltage
Negative output voltage
Negative output voltage
1.00mm (0.040”) diameter
2.00mm (0.0
79”) diameter
FF
12
PART NUMBERING SYSTEM
F 48 S A 280 25 P R F A
Form
Factor
F- Full Brick 48V S- Single A- Advanced 280- 28V25- 25AP- PositiveR- 0.170”
Input
Voltage
Number of
Outputs
Product
Series
Output
Voltage
Output
Current
ON/OFF
Logic
Pin
Length
Option Code
F- RoHS 6/6
(Lead Free)
Space - RoHS 5/6
A - Standard
Functions
B - No thread in
heatsink mounting
hole
MODEL LIST
MODEL NAME INPUT OUTPUT EFF @ 100% LOAD
F48SA28025PRFA 36V~75V 21.4A 28V 25A 91.5 %
For different remote on/off logic and pin length options, please contact Delta local sales
CONTACT: www.delta.com.tw/dcdc
USA:
Telephone:
East Coast: (888) 335 8201
West Coast: (888) 335 8208
Fax: (978) 656 3964
Email: DCDC@delta-corp.com
Delta offers a two (2) year limited warranty. Complete warranty information is listed on our web site or is available upon
request from Delta.
Information furnished by Delta is believed to be accurate and reliable. However, no responsibility is assumed by Delta for its
use, nor for any infringements of patents or other rights of third parties, which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of Delta. Delta reserves the right to revise these specifications
at any time, without notice