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A SUBSIDIARY OF C&D TECHNOLOGIES

LSM-16A D12 Models

Single Output

Non-Isolated, 12V

, 0.75-5V

OUT

16 Amp DC/DC’s in SMT Packages

Features

■

Step-down buck regulators for new

distributed 12V power architectures

12V input (10-14V range)

0.75/1/1.2/1.5/1.8/2/2.5/3.3/5V

OUT

@16A

Non-isolated, ﬁxed-frequency,

synchronous-rectiﬁer topology

Tape and reel SMT package

±1.25% setpoint accuracy

Efﬁciencies to 96% @ 16 Amps

Noise as low as 50mVp-p

Stable no-load operation

Remote on/off control

Sense pin and output voltage trim

No derating to +65°C with 200 lfm

UL/IEC/EN60950 certiﬁed

EMC compliant

■

LSM Series D12 SMT's (surface-mount packages) are ideal building blocks for

emerging, on-board power-distribution schemes in which isolated 12V buses deliver

power to any number of non-isolated, step-down buck regulators. LSM D12 DC/

DC's accept a 12V input (10V to 14V input range) and convert it, with the highest

efﬁciency in the smallest space, to a 0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volt output

fully rated at 16 Amps.

LSM D12's are ideal point-of-use/load power processors. They typically require

no external components. Their surface-mount packages occupy a mere 1.3" x 0.53"

(33.0 x 13.5mm), and are only 0.34 inches (8.6mm) high.

The LSM's best-in-class power density is achieved with a fully synchronous,

ﬁxed-frequency, buck topology that also delivers: high efﬁciency (95% for 5V

OUT

models), low noise (50mVp-p typ.), tight line/load regulation (±0.1%/±0.25% max.),

quick step response (100µsec), stable no-load operation, and no output reverse

conduction.

The fully functional LSM’s feature output overcurrent detection, continuous

short-circuit protection, over-temperature protection, a remote on/off control pin

(pull low to disable), an output-voltage trim function, and a sense pin. High efﬁciency

enables the LSM D12's to deliver rated output currents of 16 Amps at ambient tem-

peratures to +65°C with 100 lfm air ﬂow.

If your new system boards call for ½multiple supply voltages, check out the

economics of on-board 12V distributed power. If you don't need to pay for multiple

isolation barriers, DATEL's non-isolated LSM D12 SMT's will save you money.

+INPUT

(2)

+OUTPUT

(4)

+SENSE

(6)

COMMON

(3)

CURRENT

SENSE

ON/OFF

CONTROL

(1)

COMMON

(3)

PWM

CONTROLLER

REFERENCE &

ERROR AMP

OUT

TRIM

(5)

Figure 1. Simpliﬁed Schematic

DATEL, Inc., Mansﬁeld, MA 02048 (USA) · Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 · Email: sales@datel.com · Internet: www.datel.com

LSM-16A D12 Series

Performance Speciﬁcations and Ordering Guide

Output

Model

LSM-0.75/16-D12

LSM-1/16-D12

LSM-1.2/16-D12

LSM-1.5/16-D12

LSM-1.8/16-D12

LSM-2/16-D12

LSM-2.5/16-D12

LSM-3.3/16-D12

LSM-5/16-D12

LSM-T/16-D12

N O N - I S O L AT E D , 1 3 - 8 0 W S M T D C / D C C O N V E R T E R S

➀

Input

Efﬁciency ( Full load)

= nom.

= min.

OUT

(Volts)

0.75

1.2

1.5

1.8

2.5

3.3

0.75-5

OUT

(Amps)

R/N (mVp-p)

➁

Typ.

Max.

100

Regulation (Max.)

➂

Line

Load

±0.1%

±0.375%

±0.25%

Nom.

(Volts)

Range

(Volts)

10-14

➃

(mA/A)

35/1.26

35/1.57

40/1.84

50/2.26

55/2.67

55/2.93

60/3.62

70/4.68

85/7.06

85/7.02

Min.

83%

85%

86.5%

88%

89%

90%

92%

92.5%

93%

Typ.

85%

87%

88.5%

90%

91%

92%

94%

94.5%

95%

Typ.

86%

88%

89.5%

91%

91.5%

94.5%

95.5%

Package

(Case,

Pinout)

C45, P63

➀

Typical at T

= +25°C under nominal line voltage and full-load conditions, 200 lfm air ﬂow for

extended operation, unless otherwise noted. All models are tested and speciﬁed with external

22µF tantalum input and output capacitors. These capacitors are necessary to accommodate

our test equipment and may not be required to achieve speciﬁed performance in your

applications. See I/O Filtering and Noise Reduction.

➁

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.

➂

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.

➃

Nominal line voltage, no-load/full-load conditions.

M E C H A N I C A L

S P E C I F I C A T I O N S

P A R T

N U M B E R

S T R U C T U R E

L SM

1.8

D12

Output

Conﬁguration:

= Unipolar

Low Voltage

Non-Isolated SMT

Nominal Output Voltage:

0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3

or 5 Volts

Input Voltage Range:

D12

= 10 to 14 Volts

(12V nominal)

Maximum Rated Output

Current in Amps

Note: Not all model number combinations

are available. Contact DATEL.

1.30

(33.02)

0.34

(8.64)

SMT COPPER LEADS

COPLANAR 0.004

0.310

(7.87)

0.570 (14.48)

3 EQ. SP. @

0.190 (4.83)

0.085

(2.16)

1.36

(34.54)

0.062

(1.57)

TYP.

Case C45

0.05

(1.27)

0.53

0.48

(12.19)

(13.46)

0.55

(13.97)

0.112

(2.84)

TYP.

BOTTOM VIEW

0.075

(1.91)

0.048

(1.22)

0.010

(0.254)

0.570 (14.48)

3 EQ. SP. @

0.190 (4.83)

0.60

(15.24)

1.177

(29.90)

0.570 (14.48)

3 EQ. SP. @

0.190 (4.83)

0.310

(7.87)

0.375

(9.53)

0.052

(1.32)

0.297

(7.54)

0.310

(7.87)

DIMENSIONS ARE IN INCHES (MM)

0.062

(1.57)

0.405

(10.29)

0.430

(10.92)

RECOMMENDED PAD LAYOUT

0.112 TYP.

(2.84)

0.049

(1.24)

0.047

(1.19)

Recommended Pad Size: 0.15 x 0.10 (3.81 x 2.54)

BOTTOM VIEW

0.052

(1.32)

LSM WITH REMOVEABLE HEAT SHIELD

FOR HIGH TEMPERATURE SOLDER

Refer to the last page for

Tape and Reel information.

CAUTION

PRESS TO REMOVE

THE HEAT SHIELD

AFTER THE SOLDER

PROCESS

NOTCH IN SHELL

INDICATES

PIN ONE.

I/O Connections

Function P63

On/Off Control

+Input

Common

+Output

OUT

Trim

+Sense

N O N - I S O L AT E D , 1 3 - 8 0 W S M T D C / D C C O N V E R T E R S

LSM-16A D12 Models

Performance/Functional Speciﬁcations

Typical @ T

= +25°C under nominal line voltage and full-load conditions unless noted.

➀

Absolute Maximum Ratings

Input Voltage:

Continuous or transient

On/Off Control

(Pin 1)

Input Reverse-Polarity Protection

Output Overvoltage Protection

Output Current

15 Volts

None

Current limited. Devices can

withstand sustained output short

circuits without damage.

–55 to +125°C

See Reﬂow Solder Proﬁle

Input Voltage Range

Startup Voltage

Input

10-14 Volts (12V nominal)

8.5-9.2 Volts (model dependent)

Input Current:

Normal Operating Conditions

See Ordering Guide

Inrush Transient

0.08A

sec

Standby/Off Mode

1.5mA

12-40mA average (model dependent)

Output Short-Circuit Condition

➁

Input Reﬂected Ripple Current

➁ ➅

20-50mAp-p, model dependent

Input Filter Type

Capacitive

Overvoltage Protection

None

Reverse-Polarity Protection

None

Undervoltage Shutdown

7.5-8 Volts (model dependent)

On = open (internal pull-up to +V

)

On/Off Control

➁ ➂

Off = 0 to +0.4V (1mA max.)

Storage Temperature

Lead Temperature

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

Performance/Functional Speciﬁcations Table is not implied.

Output

OUT

Accuracy

(50% load)

±1.25% maximum

No load

Minimum Loading

➀

Maximum Capacitive Load

1000µF (low ESR, OSCON)

OUT

Trim Range

±10%

Ripple/Noise

(20MHz BW)

➀ ➁ ➃

See Ordering Guide

Total Accuracy

3% over line/load/temperature

Efﬁciency

See Ordering Guide

Overcurrent Detection and Short-Circuit Protection:

➁

Current-Limiting Detection Point

21-31 Amps (model dependent)

Short-Circuit Detection Point

98% of V

OUT

set

SC Protection Technique

Hiccup with auto recovery

Short-Circuit Current

125-420mA average (model dependent)

Dynamic Characteristics

Transient Response

(50% load step) 30-135µsec to ±2% of ﬁnal value

(model dependent)

Start-Up Time:

➁

60msec for V

OUT

= 1V and 0.75V

to V

OUT

and On/Off to V

OUT

40msec for V

OUT

= 1.2V to 5V

Switching Frequency

260kHz ±10%

T E C H N I C A L

N O T E S

I/O Filtering and Noise Reduction

All models in the LSM D12 Series are tested and speciﬁed with external

22µF tantalum input and output capacitors. These capacitors are necessary

to accommodate our test equipment and may not be required to achieve

desired performance in your application. The LSM D12'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 LSM D12's input capacitors are speciﬁed for low ESR

and are fully rated to handle the units' input ripple currents. Similarly, the

internal output capacitors are speciﬁed for low ESR and full-range frequency

response. As shown in the Performance Curves, removal of the external 22µF

tantalum output caps has minimal effect on output noise.

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.

½½½

½½½½½½½½½½½½

Environmental

Calculated MTBF

➄

TBD

Operating Temperature:

(Ambient)

➁

Without Derating (Natural convection) –40 to +33/64°C (model dependent)

With Derating

See Derating Curves

Thermal Shutdown

Dimensions

Pin Dimensions/Material

Weight

Flamability Rating

+115°C (110 to 125°C)

Physical

1.3" x 0.53" x 0.34" (33.03 x 13.46 x 8.64)

0.112" x 0.062" (2.84 x 1.57mm) rectangular

copper with gold plate over nickel underplate

0.28 ounces (7.8g)

UL94V-0

➀

All models are tested and speciﬁed with external 22µF tantalum input and output capacitors.

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.

➁

See Technical Notes and Performance Curves for details.

➂

The On/Off Control (pin 1) is designed to be driven with open-collector logic or the appli-

cation of appropriate voltages (referenced to Common, pin 3). Applying a voltage to On/Off

Control when no input voltage is applied to the converter may cause permanent damage.

➃

Output noise may be further reduced with the installation of additional external output

ﬁltering. See I/O Filtering and Noise Reduction.

➄

MTBF’s are calculated using Telcordia SR-332(Bellcore), ground ﬁxed, T

= +25°C, full

power, natural convection, +67°C pcb temperature.

➅

Input Ripple Current is tested/speciﬁed over a 5Hz-20MHz bandwidth with an external 2 x

100µF input capacitor and a simulated source impedance of 1000µF and 1µH. See I/O

Filtering, Input Ripple Current and Output Noise for details.

½½½½½½½

½½½½½

½½½

½½½½½½

½½

½½½

½½

½½½½½½

½½

½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½

½½½

½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½

½½½

½½½½½½

Figure 2. Measuring Input Ripple Current

LSM-16A D12 Series

N O N - I S O L AT E D , 1 3 - 8 0 W S M T D C / D C C O N V E R T E R S

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 appro-

priate frequency 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.

Input Overvoltage and Reverse-Polarity Protection

LSM D12 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 "instan-

taneous" duration can cause permanent damage to these devices.

Start-Up Time

The V

to V

OUT

Start-Up Time is the interval between the time at which a

ramping input voltage crosses the lower limit of the speciﬁed input voltage

range (10 Volts) and the fully loaded output voltage enters and remains within

its speciﬁed accuracy band. Actual measured times will vary with input source

impedance, external input capacitance, and the slew rate and ﬁnal value of

the input voltage as it appears to the converter.

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

LSM D12 SMT Series DC/DC converters offer an output sense function on

pin 6. The sense function enables point-of-use regulation for overcoming

moderate IR drops in conductors and/or cabling. 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, 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 tech-

niques should be used. To prevent high frequency voltage differences between

OUT

and Sense, we recommend installation of a 1000pF 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 10% of V

OUT

(+) – Common] – [Sense(+) – Common]

≤

10%V

OUT

Power derating (output current limiting) is based upon maximum output cur-

rent and voltage at the converter's output pins. Use of trim and sense func-

tions can cause the output voltage to increase, thereby increasing output

power beyond the LSM's speciﬁed rating. Therefore:

OUT

at pins) x (I

OUT

)

≤

rated output power

The internal 10.5Ω resistor between +Sense and +Output (see Figure 1)

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

(pin 6) must be tied to +Output (pin 4) at the DC/DC converter pins.

+SENSE

+OUTPUT

COPPER STRIP

SCOPE

LOAD

COMMON

COPPER STRIP

C1 = NA

C2 = 22µF TANTALUM

LOAD 2-3 INCHES (51-76mm) FROM MODULE

Figure 3. Measuring Output Ripple/Noise (PARD)

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 solu-

tions and discuss the possibility of our modifying a given device’s internal ﬁlter-

ing to meet your speciﬁc requirements. Contact our Applications Engineering

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 LSM D12 Series are not

internally 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 cur-

rent 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 converters minimum efﬁciency.

Safety Considerations

LSM D12 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/

separation 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.

N O N - I S O L AT E D , 1 3 - 8 0 W S M T D C / D C C O N V E R T E R S

LSM-16A D12 Models

On/Off Control

The On/Off Control pin may be used for remote on/off operation. LSM D12

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 +0.4V relative to Common). As shown in Figure 4, all

models have an internal pull-up current source to V

(+Input).

Dynamic control of the on/off function is best accomplished with a mechanical

relay or open-collector/open-drain drive circuit (optically isolated if appropri-

ate). The drive circuit should be able to sink appropriate current when

activated and withstand appropriate voltage when deactivated.

½½½½½½

½½½½

½½½½½

½½

½½½½½½½

½½½½½½½½

½½½½½½

½½½½½½½

½½½½½½

½½½½½½½½

½½½½½½½½½½

Figure 5. Inverting On/Off Control With An External CMOS Gate

½½½½½½

½½½½½½½½½½½

½½½½½½½½½½½½½½½½

½½½½½½½½

½½

½½½½½

½½½½½½

½½½½½½½½½½

½½½½½½½½

½½½½½½½

½½½½½½

½½½½½½½

½½½½½½

½½½½½½½½

Output Overcurrent Detection

Overloading the power converter's output for an extended time will invariably

cause internal component temperatures to exceed their maximum ratings and

eventually lead to component failure. High-current-carrying components such

as inductors, FET's and diodes are at the highest risk. LSM D12 SMT Series

DC/DC converters incorporate an output overcurrent detection and shutdown

function that serves to protect both the power converter and its load.

If the output current exceeds it maximum rating by typically 70% (27 Amps)

or if the output voltage drops to less than 98% of it original value, the LSM

D12's internal overcurrent-detection circuitry immediately turns off the

converter, which then goes into a "hiccup" mode. While hiccupping, the

converter will continuously attempt to restart itself, go into overcurrent, and

then shut down. Under these conditions, the average output current will be

approximately 400mA, and the average input current will be approximately

40mA. Once the output short is removed, the converter will automatically

restart itself.

Output Voltage Trimming

Allowable trim ranges for each model in the LSM D12 SMT Series are ±10%.

Trimming is accomplished with either a trimpot or a single ﬁxed resistor. The

trimpot should be connected between +Output and Common with its wiper

connected to the Trim pin as shown in Figure 6 below.

A trimpot can be used to determine the value of a single ﬁxed resistor

which can then be connected, as shown in Figure 7, between the Trim pin

and +Output to trim down the output voltage, or between the Trim pin and

Common to trim up the output voltage. Fixed resistors should have absolute

TCR’s less than 100ppm/°C to ensure stability.

The equations below can be starting points for selecting speciﬁc trim-resistor

values. Recall, untrimmed devices are guaranteed to be ±1.25% accurate.

Adjustment beyond the speciﬁed ±10% adjustment range is not recommended.

When using trim in combination with Remote Sense, the maximum rated power

must not be exceeded (see Remote Sense).

½½½½½½½½½½

Figure 4. On/Off Control Using An External Open Collector Driver

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).

Power-up sequencing

If a controlled start-up of one or more LSM D12 Series DC/DC converters

is required, or if several output voltages need to be powered-up in a given

sequence, the On/Off control pin can be driven with an external open collec-

tor device as per Figure 4.

Leaving the input of the on/off circuit closed during power-up will have the

output of the DC/DC converter disabled. When the input to the external open

collector is pulled high, the DC/DC converter's output will be enabled.

Output Overvoltage Protection

LSM D12 SMT Series DC/DC converters do not incorporate output overvolt-

age protection. In the extremely rare situation in which the device’s feedback

loop is broken, the output voltage may run to excessively high levels (V

OUT

). If it is absolutely imperative that you protect your load against any and

all possible overvoltage situations, voltage limiting circuitry must be provided

external to the power converter.