POWER ELECTRONICS DIVISION
LSM2 Series
Single Output, Non-isolated, Selectable-Output POL DC/DC Converters
C&D’s miniature POL switching DC/DC converters are ideal regula-
tion and supply elements for distributed power and intermediate bus
architectures.
FEATURES
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PRODUCT OVERVIEW
They are fully compatible with the Distributed-
power Open Standards Alliance specification
(www.dosapower.com). LSM2’s can power CPU’s,
programmable logic and mixed voltage systems
with little heat and low noise. A typical application
uses a master isolated 2 or 5 Volt DC supply and
individual LSM2 converters for local .8 and 3.3
Volt DC supplies. All system isolation resides in the
SIMPLIFIED SCHEMATIC
central supply, leaving lower cost POL regula-
tion right at the load. Unlike linear regulators, the
LSM2’s can deliver very high power (up to 52
Watts) in a tiny area with no heat sinking and no
external components needed. They feature quick
transient response (to 25µsec) and very fast current
slew rates (to 20A/µsec).
Point-of-load (POL) converters for
distributed bus architectures
5V & 2V wide input ranges
6, 0 or 6 Amp maximum outputs
DOSA compatible SMT package
Double lead free to RoHS standards
Phased start up sequencing and tracking
Extensive self-protection
Starts up into pre-biased loads
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DC/DC CONVERTERS
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POWER ELECTRONICS DIVISION
LSM2 Series
Single Output, Non-isolated, Selectable-Output POL DC/DC Converters
Output
Input
Regulation
Line
±0.3%
±0.3%
±0.3%
±0.3%
±0.3%
±0.3%
PERFORMANCE SPECIFICATIONS AND ORDERING GUIDE
R/N (mVp-p)
Typ.
15
15
15
30
25
30
Model
LSM2-T/6-W3
LSM2-T/6-D12
LSM2-T/10-W3
LSM2-T/10-D12
LSM2-T/16-W3
LSM2-T/16-D12
V
OUT
(Volts)
0.75-3.3
0.75-5
0.75-3.3
0.75-5
0.75-3.3
0.75-5
I
OUT
(Amps)
6
6
10
10
16
16
Power
(Watts)
19.8
19.8
33.0
33.0
52.8
52.8
Max.
25
25
25
75
50
75
Load
±0.3%
±0.3%
±0.3%
±0.3%
±0.3%
±0.3%
V
IN
Nom.
(Volts)
5
12
5
12
5
12
Range
(Volts)
2.4-5.5
8.3-14
2.4-5.5
8.3-14
2.4-5.5
8.3-14
I
IN
(mA/A)
50/4.22
100/2.64
50/6.95
100/4.39
50/11.12
100/7.1
Efficiency
Min.
92%
93%
93%
93%
93%
92%
Typ.
94%
95%
95%
95%
95%
94%
Package
(Case/
Pinout)
C63, P67
C63, P67
C62, P66
C62, P66
C62, P66
C62, P66
Typical at T
A
= +25°C under nominal line voltage and full-load conditions, unless noted.
Ripple/Noise (R/N) is tested/specified over a 20MHz bandwidth and may be reduced with
external filtering. See I/O Filtering and Noise Reduction for details.
These devices have no minimum-load requirements and will regulate under no-load conditions.
Regulation specifications describe the output-voltage deviation as the line voltage or load is
varied from its nominal/midpoint value to either extreme.
Nominal line voltage, no-load/full-load conditions.
LSM2-T6-D2 efficiencies are shown at 5V
OUT
.
V
IN
must be
≥0.5V
greater than V
OUT
.
PART NUMBER STRUCTURE
L SM2
-
T
/
16
-
D12 N G
-
C
Output Configuration:
L
= Unipolar
Low Voltage
Non-Isolated SMT
Nominal Output Voltage:
0.75-3.3 Volts (W3)
0.75-5 Volts (D2)
Maximum Rated Output
Current in Amps
RoHS-6 compliant*
Power Good Output: **
Blank
= Omitted
G
= Installed
On/Off Polarity:
Blank
= Positive polarity
N
= Negative polarity
Input Voltage Range:
D12
= 8.3-4 Volts (2V nominal)
W3
= 2.4-5.5 Volts (5V nominal)
Note:
Not all model number combinations
are available. Contact DATEL.
* Contact C&D Technologies (DATEL)
for availability.
** The Power Good option is not
available for LSM2-T/0 and LSM2-T/6.
Models without Power Good do not install
pad 8.
DC/DC CONVERTERS
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POWER ELECTRONICS DIVISION
LSM2 Series
Single Output, Non-isolated, Selectable-Output POL DC/DC Converters
Short Circuit Duration
Prebias Startup
(5)
Sequencing
Slew Rate
Startup delay until sequence start
Tracking accuracy, rising input
Tracking accuracy, falling input
Sequence pin input impedance
Remote Sense to V
OUT
Power Good Output
(7)
(“G” suffix)
Power_Good Configuration
Continuous, no damage (output shorted
to ground)
Converter will start up if the external
output voltage is less than V
NOM
2V max. per millisecond
0 milliseconds
V
OUT
= ±00mV of Sequence In
V
OUT
= ±200mV of Sequence In
400kW to MW
0.5V max.
(7)
TRUE (OK) = open drain
FALSE (not OK) = Signal Ground to 0.4V
MOSFET to ground with external user
pullup, 0mA max. sink
Performance/Functional Specifications
()
INPUT
Input Voltage Range
Isolation
Start-Up Threshold
W3 Models
2V Models
Undervoltage Shutdown
W3 Models
2V Models
Overvoltage Shutdown
Reflected (Back) Ripple Current
(2)
Internal Input Filter Type
Reverse Polarity Protection
Input Current:
Full Load Conditions
Inrush Transient
Shutdown Mode (Off, UV, OT)
Output Short Circuit
No Load
W3 models
2V models
Low Line (V
IN
= V
MIN
)
LSM2-T/6-W3
LSM2-T/6-D2
LSM2-T/0-W3
LSM2-T/0-D2
LSM2-T/6-W3
LSM2-T/6-D2
Remote On/Off Control:
(5)
Positive Logic (no model suffix)
Negative Logic (“N” model suffix)
Current
See Ordering Guide
Not isolated, input and output commons
are internally connected
2.2 Volts
8 Volts
2.0 Volts
7.5 Volts
None
20-70mAp-p (model dependent)
Capacitive
See fuse information
See Ordering Guide
0.-0.4A
2
sec (model dependent)
5mA
60mA
50mA
00mA
5.54 Amps
3.79 Amps
9.4 Amps
6.3 Amps
4.63 Amps
0.2 Amps
OFF = ground pin to +0.3V max.
ON = open pin or +V
IN
max.
ON = ground pin to +0.3V max.
OFF = open pin to +V
IN
max.
mA max.
See Ordering Guide
No minimum load
±2% of V
NOM
(3)
DYNAMIC CHARACTERISTICS
Dynamic Load Response
25µsec to ±2% of final value
(50-00-50% load step, di/dt = 20A/msec)
Start-Up Time
7msec for V
OUT
= nominal
(V
IN
on to V
OUT
regulated or On/Off to V
OUT
)
Switching Frequency
LSM2-T/6 models
LSM2-T/0 and -T/6 models
35kHz
230kHz
TBC Hours
ENVIRONMENTAL
Calculated MTBF
(4)
Operating Temperature Range
(Ambient)
No derating, natural convection
–40 to +63°C
(9)
With derating
See Derating Curves
Operating PC Board TemUperature
Storage Temperature Range
Thermal Protection/Shutdown
Relative Humidity
–40 to +00°C max.
(2)
–55 to +25°C
+5°C
to 85% / +85°C, non-condensing
See Mechanical Specifications
Nylon 46
0.28 ounces (7.8 grams)
FCC part 5, class B, EN55022 (may
need external filter)
UL/cUL 60950 CSA-C22.2 No.234
IEC/EN 60950
PHYSICAL
Outline Dimensions
Removable Heat Shield
Weight
Electromagnetic Interference
(conducted and radiated)
Safety
OUTPUT
Voltage Output Range
Minimum Loading
Accuracy
(50% load)
Voltage Adjustment Range
Temperature Coefficient
Ripple/Noise
(20 MHz bandwidth)
Efficiency
Maximum Capacitive Loading:
LSM2-T/6 models:
Cap-ESR = 0.00 to 0.0W
Cap-ESR >0.0W
LSM2-T/0 and -T/6 models:
Cap-ESR = 0.00 to 0.0W
Cap-ESR >0.0W
(4)
See Ordering Guide
±0.02% of V
OUT
range per °C
See Ordering Guide and
(8)
See Ordering Guide
Line/Load Regulation
(See Tech Notes) See Ordering Guide and
(0)
ABSOLUTE MAXIMUM RATINGS
Input Voltage
(Continuous or transient)
W3 models
2V models
On/Off Control
Input Reverse Polarity Protection
Output Current
(7)
3000µF
5000µF
5000µF
0,000µF
+7 Volts
+5 Volts
–0.3V min. to +V
IN
max.
See Fuse section
Current-limited. Devices can
withstand sustained short circuit
without damage.
–55 to +25°C
Current Limit Inception:
(98% of V
OUT
)
LSM2-T/6 models
Amps (cold startup)
0 Amps (after warm up)
LSM2-T/0 models
8.75 Amps (cold startup)
6.75 Amps (after warm up)
LSM2-T/6 models
24 Amps (cold startup)
2 Amps (after warm up)
Short Circuit Mode
(6)
Short Circuit Current Output
Protection Method
(6)
600mA
Hiccup autorecovery on overload removal
Storage Temperature
Lead Temperature
(soldering 0 sec. max.) +280°C
These are stress ratings. Exposure of devices to any of these conditions may adversely affect
long-term reliability. Proper operation under conditions other than those listed in the Perfor-
mance/Functional Specifications Table is not implied.
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POWER ELECTRONICS DIVISION
LSM2 Series
Single Output, Non-isolated, Selectable-Output POL DC/DC Converters
Output noise may be further reduced by adding an external filter. See I/O Filtering and Noise
Reduction.
(9)
All models are fully operational and meet published specifications, including “cold start” at
–40°C.
(0)
Regulation specifications describe the deviation as the line input voltage or output load current is
varied from a nominal midpoint value to either extreme.
()
Other input or output voltage ranges are available under scheduled quantity special order.
(2)
Maximum PC board temperature is measured with the sensor in the center.
(3)
Do not exceed maximum power specifications when adjusting the output trim.
(4)
The maximum output capacitive loads depend on the the Equivalent Series Resistance (ESR) of
the external output capacitor.
(5)
Do not use Pre-bias startup and sequencing together. See Technical Notes below.
(6)
After short circuit shutdown, if the load is partially removed such that the load still exceeds the
overcurrent (OC) detection, the converter will remain in hiccup restart mode.
(7)
When Sequencing is not used, the Power Good output is TRUE at any time the output is within
approximately ±0% of the voltage set point. Power Good basically indicates if the converter is
in regulation. Power Good detects Over Temperature if the PWM has shut down due to OT. Power
Good does not directly detect Over Current.
If Sequencing is in progress, Power Good will falsely indicate TRUE (valid) before the output
reaches its setpoint. Ignore Power Good if Sequencing is in transition.
(8)
Performance/Functional Specification Notes:
()
(2)
(3)
(4)
(5)
(6)
(7)
All models are tested and specified with external || 0µF ceramic/tantalum output capacitors
and a 22µF external input capacitor. All capacitors are low ESR types. These capacitors are
necessary to accommodate our test equipment and may not be required to achieve specified
performance in your applications. All models are stable and regulate within spec under no-load
conditions.
General conditions for Specifications are +25°C, V
IN
= nominal, V
OUT
= nominal, full load. “Nomi-
nal” output voltage is +5V for D2 models and +3.3V for W3 models.
Input Back Ripple Current is tested and specified over a 5-20MHz bandwidth. Input filtering is C
IN
= 2 x 00µF tantalum, C
BUS
= 000µF electrolytic, L
BUS
= µH.
Note that Maximum Power Derating curves indicate an average current at nominal input voltage.
At higher temperatures and/or lower airflow, the DC/DC converter will tolerate brief full current
outputs if the total RMS current over time does not exceed the derating curve.
Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method , Case 3,
ground fixed conditions, T
PCBOARD
= +25°C, full output load, natural air convection.
The On/Off Control may be driven with external logic or by applying appropriate external voltages
which are referenced to –Input Common. The On/Off Control Input should use either an open
collector/open drain transistor or logic gate which does not exceed +V
IN
. A 68KW external pullup
resistor to +V
IN
will cause the “ON” state for negative logic models.
Short circuit shutdown begins when the output voltage degrades approximately 2% from the
selected setting.
If Sense is connected remotely at the load, up to 0.5 Volts difference is allowed between the
Sense and +V
OUT
pins to compensate for ohmic voltage drop in the power lines. A larger voltage
drop may cause the converter to exceed maximum power dissipation.
TECHNICAL NOTES
I/O Filtering and Noise Reduction
All models in the LSM2 Series are tested and specified with external
|| 0µF ceramic/tantalum output capacitors and a 22µF tantalum input ca-
pacitor. These capacitors are necessary to accommodate our test equipment
and may not be required to achieve desired performance in your application.
The LSM2's are designed with high-quality, high-performance internal I/O
caps, and will operate within spec in most applications with no additional
external components.
In particular, the LSM2's input capacitors are specified for low ESR and are
fully rated to handle the units' input ripple currents. Similarly, the internal out-
put capacitors are specified for low ESR and full-range frequency response.
In critical applications, input/output ripple/noise may be further reduced using
filtering techniques, the simplest being the installation of external I/O caps.
External input capacitors serve primarily as energy-storage devices. They
minimize high-frequency variations in input voltage (usually caused by IR
drops in conductors leading to the DC/DC) as the switching converter draws
pulses of current. Input capacitors should be selected for bulk capacitance
(at appropriate frequencies), low ESR, and high rms-ripple-current ratings.
The switching nature of modern DC/DC's requires that the dc input voltage
source have low ac impedance at the frequencies of interest. Highly inductive
source impedances can greatly affect system stability. Your specific system
configuration may necessitate additional considerations.
Output ripple/noise (also referred to as periodic and random deviations or
PARD) may be reduced below specified limits with the installation of additional
external output capacitors. Output capacitors function as true filter elements
and should be selected for bulk capacitance, low ESR, and appropriate fre-
quency response. Any scope measurements of PARD should be made directly
at the DC/DC output pins with scope probe ground less than 0.5" in length.
All external capacitors should have appropriate voltage ratings and be located
as close to the converters as possible. Temperature variations for all relevant
parameters should be taken into consideration.
The most effective combination of external I/O capacitors will be a function
of your line voltage and source impedance, as well as your particular load
and layout conditions. Our Applications Engineers can recommend potential
solutions and discuss the possibility of our modifying a given device’s internal
filtering to meet your specific requirements. Contact our Applications Engineer-
ing Group for additional details.
Input Fusing
Most applications and or safety agencies require the installation of fuses at
the inputs of power conversion components. The LSM2 Series are not inter-
nally fused. Therefore, if input fusing is mandatory, either a normal-blow or a
fast-blow fuse with a value no greater than twice the maximum input current
should be installed within the ungrounded input path to the converter.
As a rule of thumb however, we recommend to use a normal-blow or slow-
blow fuse with a typical value of about twice the maximum input current,
calculated at low line with the converter's minimum efficiency.
Safety Considerations
LSM2 SMT's are non-isolated DC/DC converters. In general, all DC/DC's
must be installed, including considerations for I/O voltages and spacing/sepa-
ration requirements, in compliance with relevant safety-agency speci-
fications (usually UL/IEC/EN60950).
In particular, for a non-isolated converter's output voltage to meet SELV (safety
extra low voltage) requirements, its input must be SELV compliant.
If the output needs to be ELV (extra low voltage), the input must be ELV.
Input Overvoltage and Reverse-Polarity Protection
LSM2 SMT Series DC/DC's do not incorporate either input overvoltage or input
reverse-polarity protection. Input voltages in excess of the specified absolute
maximum ratings and input polarity reversals of longer than "instantaneous"
duration can cause permanent damage to these devices.
Start-Up Time
The V
IN
to V
OUT
Start-Up Time is the interval between the time at which a
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POWER ELECTRONICS DIVISION
LSM2 Series
Single Output, Non-isolated, Selectable-Output POL DC/DC Converters
it is not a low-impedance point and must be treated with care in layout and
cabling. Sense lines should be run adjacent to signals (preferably ground), and
in cable and/or discrete-wiring applications, twisted-pair or similar techniques
should be used. To prevent high frequency voltage differences between V
OUT
and Sense, we recommend installation of a 000pF capacitor close to the
converter.
The sense function is capable of compensating for voltage drops between the
+Output and +Sense pins that do not exceed 0% of V
OUT
.
[V
OUT
(+) – Common] – [Sense(+) – Common]
≤
0%V
OUT
Power derating (output current limiting) is based upon maximum output
current and voltage at the converter's output pins. Use of trim and sense
functions can cause the output voltage to increase, thereby increasing output
power beyond the LSM2's specified rating. Therefore:
(V
OUT
at pins) x (I
OUT
)
≤
rated output power
The internal 0.5W resistor between +Sense and +Output (see Figure )
serves to protect the sense function by limiting the output current flowing
through the sense line if the main output is disconnected. It also prevents
output voltage runaway if the sense connection is disconnected.
Note: If the sense function is not used for remote regulation, +Sense
must be tied to +Output at the DC/DC converter pins.
Sense Input
Figure 2. Measuring Input Ripple Current
ramping input voltage crosses the lower limit of the specified input voltage
range and the fully loaded output voltage enters and remains within its speci-
fied accuracy band. Actual measured times will vary with input source imped-
ance, external input capacitance, and the slew rate and final value of the input
voltage as it appears to the converter.
+SENSE
+OUTPUT
6
4
COPPER STRIP
C1
C2
SCOPE
R
LOAD
Use the Sense input with caution. Many applications do not need the Sense
connection. Sense is intended to correct small output accuracy errors caused
by the resistive ohmic drop in output wiring as output current increases. This
output drop (the difference between Sense and V
OUT
when measured at the
converter) should not be allowed to exceed 0.5V. Consider using heavier wire
if this drop is excessive.
Sense is connected at the load and corrects for resistive errors only. Be careful
where it is connected. Any long, distributed wiring and/or significant inductance
introduced into the Sense control loop can adversely affect overall system sta-
bility. If in doubt, test the application, and observe the DC/DC's output transient
response during step loads. There should be no appreciable ringing or oscilla-
tion. You may also adjust the output trim slightly to compensate for voltage loss
in any external filter elements. Do not exceed maximum power ratings.
On/Off Control
The On/Off Control pin may be used for remote on/off operation. Positive logic
LSM2 Series DC/DC converters are designed so that they are enabled when
the control pin is left open (open collector) and disabled when the control pin
is pulled low (to less than +0.3V relative to Common). As shown in Figure 4,
all models have an internal pull-up current source to V
IN
(+Input).
Dynamic control of the on/off function is best accomplished with a mechani-
cal relay or open-collector/open-drain drive circuit (optically isolated if
appropriate). The drive circuit should be able to sink appropriate current when
activated and withstand appropriate voltage when deactivated.
Applying an external voltage to the On/Off Control pin when no input power is
applied to the converter can cause permanent damage to the converter. The
on/off control function, however, is designed such that the converter can be
disabled (control pin pulled low) while input voltage is ramping up and then
"released" once the input has stabilized (see also power-up sequencing).
COMMON
3
COPPER STRIP
C1 = NA
C2 = 22µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 3. Measuring Output Ripple/Noise (PARD)
The On/Off to V
OUT
Start-Up Time assumes the converter is turned off via the
On/Off Control with the nominal input voltage already applied to the converter.
The specification defines the interval between the time at which the converter
is turned on and the fully loaded output voltage enters and remains within its
specified accuracy band. See Typical Performance Curves.
Remote Sense
LSM2 Series offer an output sense function. The sense function enables point-
of-use regulation for overcoming moderate IR drops in conductors and/or ca-
bling. Since these are non-isolated devices whose inputs and outputs usually
share the same ground plane, sense is provided only for the +Output.
The remote sense line is part of the feedback control loop regulating the
DC/DC converter’s output. The sense line carries very little current and
consequently requires a minimal cross-sectional-area conductor. As such,
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