Continuous
Operating Temperature Please refer to Fig. 18 For measuring point -40 110 °C
Storage Temperature
Input/Output Isolation Voltage 2250 Vdc
INPUT CHARACTERISTICS
Operating Input Voltage
Input Under-Voltage Lockout
Turn-On Voltage Threshold
Turn-Off Voltage Threshold
Lockout Hysteresis Voltage
Maximum Input Current 100% Load, 18Vin 2.2 A
No-Load Input Current 50 mA
Off Converter Input Current 7
Inrush Current(I2t) 0.01 A2s
Input Reflected-Ripple Current P-P thru 12µH inductor, 5Hz to 20MHz 5 mA
Input Voltage Ripple Rejection 120 Hz 50 dB
OUTPUT CHARACTERISTICS
Output Voltage Set Point
Output Voltage Regulation
Over Load Io=Io,min to Io,max ±2 ±10 mV
Over Line Vin=18V to36V ±2 ±5 mV
Over Temperature
Total Output Voltage Range Over sample load, line and temperature 1.73 1.87 V
Output Voltage Ripple and Noise 5Hz to 20MHz bandwidth
Peak-to-Peak Full Load, 1µF ceramic, 10µF tantalum 20 50 mV
RMS Full Load, 1µF ceramic, 10µF tantalum 5 15 mV
Operating Output Current Range 0 12 A
Output DC Current-Limit Inception Output Voltage 10% Low 13.2 18 A
DYNAMIC CHARACTERISTICS
Output Voltage Current Transient 24V, 10µF Tan & 1µF Ceramic load cap, 0.1A/µs
Positive Step Change in Output Current 50% Io,max to 75% Io,max 30 75 mV
Negative Step Change in Output Current 75% Io,max to 50% Io.max 30 75 mV
Settling Time to 1% of Final value 200 µs
Turn-On Transient
Start-Up Time, From On/Off Control 12 ms
Start-Up Time, From Input 12
Maximum Output Capacitance Full load; 5% overshoot of Vout at startup 2200 µF
EFFICIENCY
100% Load
ISOLATION CHARACTERISTICS
Isolation Voltage 2250 V
Isolation Resistance 10 MΩ
Isolation Capacitance 1500 pF
FEATURE CHARACTERISTICS
Switching Frequency 330 kHz
ON/OFF Control, (Logic Low-Module ON)
Logic Low Von/off at Ion/off=1.0mA 0 0.8 V
Logic High Von/off at Ion/off=0.0 µA 15 V
ON/OFF Current Ion/off at Von/off=0.0V 1 mA
Leakage Current Logic High, Von/off=15V50 u
Output Voltage Trim Range
Output Over-Voltage Protection(Hiccup) Over full temp range; % of nominal Vout 115 160 %
GENERAL SPECIFICATIONS
Calculated MTBF Io=80% of Io, max; Ta=25°C, Airflow=200LFM 5.7 M hours
Weight 18 grams
Over-Temperature Shutdown Please refer to Fig.18 For measuring point 115 °C
87.5 %
NOTES and CONDITIONS S24SA1R812NRFA
Min. Typ. Max. Units Units
Vin=24V, Io=50%Io.max, Ta=25℃
Ta=-40℃ to 85℃
cross Trim Pin & +Vo or –Vo, Pout≦max rated
-0.3 50 Vdc
-55 125 °C
18 24 36 V
17 18 V
13 15 V
1 2 3 V
1.77 1.80 1.83
100 300
-10+10 %
m
V
m/℃
ms
DS_S24SA1R812_05092006
2
ELECTRICAL CHARACTERISTICS CURVES
95
90
85
EFFICIENCY (%)
80
75
70
65
60
55
50
18Vin24Vin36Vin
0.124681012
OUTPUT CURRENT (A)
POWER DISSIPATION (W)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
18Vin24Vin36Vin
0.124681012
OUT PUT CURRENT (A)
Figure 1: Efficiency vs. load current for minimum, nominal, and
maximum input voltage at 25
°C.
1.60
1.40
INPUT CURRENT (A)
1.20
1.00
0.80
0.60
0.40
0.20
0.00
1520253035
Io= 12AIo= 7.2AIo= 1.2A
INPUT VOLTAGE (V)
Figure 2: Power dissipation vs. load current for minimum,
nominal, and maximum input voltage at 25
°C.
Figure 3: Typical input characteristics at room temperature. Figure 4: Turn-on transient at full rated load current (2 ms/div).
Top Trace: Vout (1V/div); Bottom Trace: ON/OFF Control
(5V/div).
DS_S24SA1R812_05092006
3
ELECTRICAL CHARACTERISTICS CURVES
)
Figure5: Turn-on transient at zero load current (2 ms/div). Top
Trace: Vout (1mV/div); Bottom Trace: ON/OFF Control
(5V/div).
Figure 7: Output voltage response to step-change in load
current (75%-50% of Io, max; di/dt = 0.1A/µs). Load cap:
10µF, 100 m
capacitor. Top Trace: Vout (50mV/div), Bottom Trace: Iout
5A/div).
Ω
ESR tantalum capacitor and 1µF ceramic
Figure 6: Output voltage response to step-change in load
current (50%-75% of Io, max; di/dt = 0.1A/µs). Load cap: 10µF,
100 m
Ω
ESR tantalum capacitor and 1µF ceramic capacitor.
Top Trace: Vout (50mV/div), Bottom Trace: Iout (5A/div).
Figure 8: Test set-up diagram showing measurement points
for Input Reflected Ripple Current (Figure 9).
Note: Measured input reflected-ripple current with a simulated
source Inductance (L
possible battery impedance.
ΩΩ
@20 100KHZ
℃
of 12 µH. Capacitor Cs offset
TEST
Vi (-)
DS_S24SA1R812_05092006
4
ELECTRICAL CHARACTERISTICS CURVES
E
StripCopper
Vo(+)
Figure 9: Input Reflected Ripple Current, i
current and nominal input voltage with 12
and 100
µF electrolytic capacitor (2 mA/div).
, at full rated output
s
µH source impedance
10u
Vo(-)
SCOPERESISTIV
1u
LOAD
Figure 10: Output voltage noise and ripple measurement test
setup. 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.
2.0
1.8
1.6
1.4
OUTPUT VOLTAGE (V)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Vin=24V
0.05.010.015.020.0
Figure 11: Output voltage ripple at nominal input voltage and
rated load current (10 mV/div). Load capacitance: 1
capacitor and 10
µF tantalum capacitor. Bandwidth: 20 MHz.
DS_S24SA1R812_05092006
µF ceramic
LOA D CURRENT (A)
Figure 12: Output voltage vs. load current showing typical
current limit curves and converter shutdown points.
5
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 10 to 100 µF
electrolytic capacitor (ESR < 0.7 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 enduser’s safety agency standard if the system in which the
power module is to be used must meet safety agency
requirements.
When the input source is 60Vdc or below, 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 any
hazardous voltages, including the ac mains, with
reinforced insulation.
One Vi pin and one Vo pin are grounded, or all the
input and output pins are kept floating.
The input terminals of the module are not operator
accessible.
A SELV reliability test is conducted on the system
where the module is used to ensure that under a
single fault, hazardous voltage does not appear at
the module’s output.
Do not ground one of the input pins without grounding
one of the output pins. This connection may allow a
non-SELV voltage to appear between the output pin
and ground.
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 5A 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_S24SA1R812_05092006
6
n
FEATURES DESCRIPTIONS
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 overvoltage set point, the module will shut down (Hiccup
mode). The modules will try to restart after shutdown. If
the fault condition still exists, the module will shut down
again. This restart trial will continue until the fault
condition is corrected.
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 overtemperature 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
The remote on/off feature on the module can be either
negative or positive logic. Negative logic turns the
module on during a logic low and off during a logic high.
Positive logic turns the modules on during a logic high
and off during a logic low.
Remote on/off can be controlled by an external switch
between the on/off terminal and the Vi(-) terminal. The
switch can be an open collector or open drain.
For negative logic if the remote on/off feature is not
used, please short the on/off pin to Vi(-). For positive
logic if the remote on/off feature is not used, please
leave the on/off pin floating.
Vo(+)Vi(+)
Sense(+)
ON/OFF
Sense(-)
Vi(-)
Vo(-)
Figure 13: Remote on/off implementation
Remote Sense (Optional)
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:
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
Figure 14: 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.
Vo(-)
Contact and Distributio
Losses
7
DS_S24SA1R812_05092006
]
FEATURES DESCRIPTIONS (CON.)
utput Voltage Adjustment (TRIM)
O
o increase or decrease the output voltage set point, the
T
modules may be connected with an external resistor
between the TRIM pin and either the Vo+ or Vo -. The
TRIM pin should be left open if this feature is not used.
Figure 15: Circuit configuration for trim-down (decrease output
voltage)
the external resistor is connected between the TRIM
If
and Vo- pins, the output voltage set point decreases.
The external resistor value required to obtain a
percentage of output voltage change △Vo% is defined
as:
Rtrim
Ex. When trim-down –10% (1.8V X 0.9 = 1.62V)
down
downRtrim
∆
1089
%Vo
1089
=−104
10
[]
ΚΩ−
[]
ΚΩ9.4104
=−=−
=−104
upRtrim
∆
−∆+1089%)100(8.23Vo
%Vo
[]
ΚΩ−
Ex. When trim-up +10% (1.8V X 1.1 = 1.98V)
1089)10100(8.23
upRtrim
−+
[
ΚΩ=−=−9.48104
10
Care should be taken to ensure that the maximum
output power of the module remains at or below the
maximum rated power.
Figure 16: Circuit configuration for trim-up (increase output
voltage)
the external resistor is connected between the TRIM
If
and Vo+ pins, the output voltage set point increases.
The external resistor value required to obtain a
percentage output voltage change △Vo% is defined as:
DS_S24SA1R812_05092006
8
THERMAL CONSIDERATIONS
A
Y
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 or a heat sink is
6.35mm (0.25”).
Thermal Derating
Heat can be removed by increasing airflow over the
module. The module’s maximum hot spot temperature is
110℃. 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.
FACING PWB
PWB
THERMAL CURVES
Figure 18: Hot spot temperature measured point
*
The allowed maximum hot spot temperature is defined at 110
S24SA1R812NR (Standard) Output Current vs. Ambient Temperature and Air Velocity
Output Current(A)
12
10
Natural
7
5
2
0
5055606570758085
Convection
100LFM
200LFM
300LFM
400LFM
500LFM
Figure 19: Output current vs. ambient temperature and air velocity
(Either Orientation)
(Either Orientation)
Ambient Temperature (℃)
℃
AIR VELOCIT
AND AMBIENT
TEMPERATURE
MEASURED BELOW
THE MODULE
Note: Wind Tunnel Test Setup Figure Dimensions are in millimeters and (Inches)
Figure 17: Wind tunnel test setup figure
DS_S24SA1R812_05092006
MODULE
50.8 (2.0”)
IR FLOW
10 (0.4”)
9
PICK AND PLACE LOCATION SURFACE-MOUNT TAPE & REEL
RECOMMENDED PAD LAYOUT (SMD)
DS_S24SA1R812_05092006
10
℃
LEADED (Sn/Pb) PROCESS RECOMMEND TEMP. PROFILE
Peak temp.
210~230°C 5sec.
Cooling down rate <3°C /sec.
250
150
Ramp-up temp.
0.5~3.0°C /sec.
2nd Ramp-up temp.
Pre-heat temp.
140~180°C 60~120 sec.
1.0~3.0°C /sec.
Temperature (°C )
100
50
Time ( sec. )
Over 200°C
40~50sec.
300 60 0 120 180 240
Note: The temperature refers to the pin of S24SA, measured on the pin +Vout joint.
LEAD FREE (SAC) PROCESS RECOMMEND TEMP. PROFILE
217℃
200
150
25℃
.
Peak Temp. 240 ~ 245
℃
℃
Ramp up
max. 3℃/sec.
Preheat time
100~140 sec.
Time Limited 90 sec.
above 217
℃
Time
Ramp down
max. 4℃/sec.
Temp
Note: The temperature refers to the pin of S24SA, measured on the pin +Vout joint.
DS_S24SA1R812_05092006
11
MECHANICAL DRAWING
Surface-mount module Through-hole module
Pin No. Name Function
1 +Vout Positive output voltage
2 -Vout Negative output voltage
6 Trim Output voltage trim
8 ON/OFF ON/OFF logic
11 -Vin Negative input voltage
12 +Vin Positive input voltage
Telephone:
East Coast: (888) 335 8201
West Coast: (888) 335 8208
Fax: (978) 656 3964
Email: DCDC@delta-corp.com
WARRANTY
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