Single Output
LQN D12 Models
Features
Non Isolated, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick DC/DC Converters
Figure 1. Simplified Schematic
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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
The LQN D12 Series of non-isolated quarter bricks 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. LQN D12 DC/DC's
accept a 12V input (10.2V to 13.8V input range) and convert it, with the highest
efficiency in the smallest space, to a 0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volt output
fully rated at 45-50 Amps.
LQN D12's are ideal POLPP's (point-of-use/load power processors) and they
typically require no external components. They occupy the standard quarter brick
board space (1.45" x 2.3") and come in either through-hole packages or surface-
mount packages with a profile of only 0.4" (0.5" including heatsink).
The LQN's best-in-class power density is achieved with a fully synchronous,
fixed-frequency, 3-phase buck topology that delivers extremely high efficiency (95%
for 5VOUT models), low noise (20mVp-p typ.), tight line/load regulation (±0.25%
max.), quick step response (70µsec), stable no-load operation, and no output
reverse conduction.
The fully functional LQN's feature input over/undervoltage lockout, output over-
voltage and overcurrent detection, continuous short-circuit protection, overtempera-
ture protection, an output-voltage trim function, a remote on/off control pin, a sense
pin and a current share function (optional). High efficiency enables the LQN D12's to
deliver rated output currents of 50 Amps at high ambient temperatures and minimal
air flow�.
If your new system boards call for multiple 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 LQN D12 brick's will save you money.
3-phase buck regulators for new
distributed 12V power architectures
12V input (10.2-13.8V range)
0.8/1/1.2/1.5/1.8/2/2.5/3.3/5VOUT @ 45-50A
Non-isolated, fixed-frequency,
synchronous-rectifier topology
¼-brick size, through hole or SMT
Current share/N+1 redundancy
±1% setpoint accuracy
Efficiencies to 94% @ 45 Amps
Noise as low as 20mVp-p
Stable no-load operation
On/Off control, trim & sense functions
Output Overvoltage Protection
Input Over/Undervoltage lockout
Thermal shutdown
Designed to meet UL/EN/IEC60950
EMC compliant
➀ Only one phase of three shown.
➀
PRELIMINARY
®®
A SUBSIDIARY OF C&D TECHNOLOGIES
LXN D12 Series N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
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LQN-0.8/50-D12 0.8 50 30 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 83% 83% C41,C42, P62
LQN-1/50-D12 1 50 30 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 85% 86% C41,C42, P62
LQN-1.2/50-D12 1.2 50 30 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 87% 87.5% C41,C42, P62
LQN-1.5/50-D12 1.5 50 20 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 88% 88% C41,C42, P62
LQN-1.8/50-D12 1.8 50 20 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 89.5% 89.5% C41,C42, P62
LQN-2/50-D12 2 50 20 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 90% 90% C41,C42, P62
LQN-2.5/45-D12 2.5 45 20 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 91.5% 92% C41,C42, P62
LQN-3.3/45-D12 3.3 45 30 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 93% 93.5% C41,C42, P62
LQN-5/45-D12 5 45 30 50 ±0.25% ±0.25% 12 10.2-13.8 TBD TBD% 95% 95.5% C41,C42, P62
➀ Typical at TA = +25°C under nominal line voltage and full-load conditions, unless otherwise
noted. All models are tested and specified with external 33µF input capacitor and 470µF
poscap output capacitor paralleled with a 100µF ceramic output capacitor.
➁ Ripple/Noise (R/N) is tested/specified over a 20MHz bandwidth.
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.
MECHANICAL SPECIFICATIONS
➃ Nominal line voltage, no-load/full-load conditions.
➄ The operating input voltage is 10.2V to 13.8V. However, 10.8VIN is required for the DC/DC
to properly start up under all line, load and temperature conditions. The 10.8V potential must be
maintained across the inputs until the output is up and regulating. After the output is regulating,
the operating input range is 10.2V to 13.8V.
Performance Specifications and Ordering Guide ➀
Package
VOUT IOUT VIN Nom. Range ➄ IIN ➃ (Case,
Model (Volts) (Amps) Typ. Max. Line Load (Volts) (Volts) (mA/A) Min. Typ. Typ. Pinout)
Output Input
R/N (mVp-p) ➁ Regulation (Max.) ➂
Efficiency
Full Load ½ Load
Pin Function P62 Pin Function P62
1 Input Common 6 Output Common
2 VOUT Trim 7 +Output
3 N.C.* 8 Output Common
4 On/Off Control 9 +Output
5 +Input 10 +Sense In
I/O Connections
C41 Through-Hole Package C42 Surface-Mount Package
See page 9 for Part Number Structure.
* A "Power Good" output is available
on pin 3 under special order.
Contact DATEL.
LQN D12 Models
N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
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Input
Input Voltage Range 10.2-13.8 Volts (12V nominal) [13]
Start-Up Threshold 9.7 Volts typical
Overvoltage Shutdown 14.3 Volts typical
Undervoltage Shutdown 9.5 Volts typical
Input Current:
Normal Operating Conditions See Ordering Guide
Standby Mode (Off, Under Voltage) TBD mA
Inrush transient TBD A2sec
Output Short-Circuit Condition 350mA
Low Line Voltage (VIN = VMIN):
LQN-1/50-D12 5.63 Amps
LQN-1.8/50-D12 9.64 Amps
LQN-2.5/45-D12 11.26 Amps
LQN-3.3/45-D12 15.57 Amps
Input Reflected Ripple Current [2] 40mAp-p
Input Filter Type Capacitive, 88µF
Overvoltage Protection None
Reverse-Polarity Protection See external fuse information
No-load Input Current 240mA
Remote On/Off Control [5] Off = +2.5V to +VIN max.
On = open pin to +2V max.
Remote Control On/Off Current 1mA pulldown
Remote Sense Input Range +10% of VOUT nominal
Output
Total Output Power (VOUT x IOUT must not exceed maximum power) [3]
LQN-1/50-D12 50.75 Watts
LQN-1.8/50-D12 91.35 Watts
LQN-2.5/45-D12 112.5 Watts
LQN-3.3/45-D12 150 Watts
Voltage Output Accuracy [11]
Initial ±1% of VNOMINAL
Temperature Coefficient ±0.02% of VOUT per °C
Extreme [12] ±3% of VNOMINAL
Minimum Loading [1] No minimum load
Ripple/Noise (20 MHz bandwidth) [8] See Ordering Guide
Line/Load Regulation [10] See Ordering Guide
Efficiency See Ordering Guide
Maximum Capacitive Loading 10,000µF (low ESR ≤0.004Ω)
Vout Trim Range ±10% of VNOMINAL
Current Limit Inception (98% of VOUT)
1 & 1.8V models 82A (cold start), 60A (warmed up)
2.5 & 3.3V models 85A (cold start), 70A (warmed up)
Short Circuit Detection See Note 6
Short Circuit Protection Method Hiccup with autorecovery
See Technical Notes
Short Circuit Current
LQN-1/50-D12 TBD Amps
LQN-1.8/50-D12 TBD Amps
LQN-2.5/45-D12 TBD Amps
LQN-3.3/45-D12 22 Amps
Short Circuit Duration Continuous, output shorted to ground
Overvoltage Protection 120% of VOUT
Method: comparator feedback
Dynamic Characteristics
Dynamic Load Response (50% - 75% - 50% load step to ±2% of VOUT final value)
LQN-1/50-D12 70µsec
LQN-1.8/50-D12 70µsec
LQN-2.5/45-D12 50µsec
LQN-3.3/45-D12 80µsec
Start-Up Time
(On/Off or VIN on to VOUT regulated) 10msec for VOUT = nominal
Switching Frequency 690 kHz ±30kHz
Environmental
Calculated MTBF [4] TBC Hours
Operating Temperature Range (Ambient) [9]
No derating, natural convection, –40 to +TBD °C
With derating See Derating Curves
Storage Temperature Range –40 to +125 °C
Thermal Protection/Shutdown +115°C (PC board)
Density Altitude 0 to 10,000 feet
Relative Humidity 0% to 90%, non-condensing
Physical
Outline Dimensions See Mechanical Specifications
Pin Material [11] Round copper with tin-lead solder
(through-hole models) plate over nickel underplate
Weight (no heatsink) 0.6 ounces (17 grams)
Flammability Rating UL94V-0
Electromagnetic Interference
(conducted or radiated) FCC Part 15, EN55022, Class A
Safety UL/cUL 60950, CSA-C22.2 No.234
IEC/EN 60950
Performance/Functional Specifications
Typical at TA = +25°C under nominal input line voltage, nominal output voltage,
natural convection, external caps and full-load conditions unless otherwise noted. [1]
1] All models are tested and specified with an external 33µF tantalum input capacitor,
470µF Poscap output cap paralled with a 100µF ceramic output capacitor. 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.
[2] Input Ripple Current is tested and specified over a 5-20MHz bandwidth. Input filter-
ing is CIN = 200µF tantalum (100 || 100), CBUS = 1000µF electrolytic, LBUS = 1µH.
[3] 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 shorter full current outputs if the total RMS current over time does not
exceed the Derating curve.
[4] Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method
1, Case 3, ground fixed conditions, TPCBOARD = +25°C, full output load, natural air
convection.
[5] The On/Off Control (pin 4) may be driven with external logic or by applying appropri-
ate external voltages which are referenced to Common, pin 1. The On/Off Control
Input should use either an open collector/open drain transistor or logic gate which
does not exceed +VIN.
The On/Off Control may be supplied with positive logic (LO = off, HI = on) under
special quantity order.
[6] Short circuit shutdown begins when the output voltage degrades approximately 2%
from the selected setting.
[7] The outputs are not intended to sink appreciable reverse current. If the outputs are
forced to sink excessive current, damage may result.
[8] 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.
[10] Regulation specifications describe the deviation as the line input voltage or output
load current is varied from a nominal midpoint value to either extreme.
[11] Alternate pin length and/or other output voltages available under special quantity order.
[12] Extreme accuracy refers to all combinations of trim adjustment, temperature, airflow
and load current.
[13] See Performance Specifications note 5.
LXN D12 Series N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
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Input Fusing
Certain applications and/or safety agencies may require the installation of
fuses at the inputs of power conversion components. Fuses should also be
used if the possibility of sustained, non-current-limited, input-voltage polarity
reversals exists. For DATEL LQN series DC/DC converters, we recommend
the use of a time delay fuse, installed in the ungrounded input supply line,
with a value no greater than the following:
Model Fuse Value
LQN-1/50-D12 12.5 Amps
LQN-1.8/50-D12 15 Amps
LQN-2.5/45-D12 25 Amps
LQN-3.3/45-D12 30 Amps
As a rule of thumb however, we recommend the use of a normal-blow or
slow-blow fuse with a typical value about twice the maximum input current,
calculated at low line with the converter's minimum efficiency.
All relevant national and international safety standards and regulations must
be observed by the installer. For system safety agency approvals, the con-
verters must be installed in compliance with the requirements of the end-use
safety standard, i.e. IEC/EN/UL60950.
Input Reverse-Polarity Protection
If the input voltage polarity is accidentally reversed, an internal diode will
become forward biased and likely draw excessive current from the power
source. If this source is not current limited or the circuit appropiately fused, it
could cause permanent damage to the converter.
Start-Up Time
The VIN to VOUT Start-Up Time is the time interval between the point at which
the ramping input voltage crosses the Start-Up Threshold 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 capaci-
tance, and the slew rate and final value of the input voltage as it appears at
the converter. The LQN Series implements a soft start circuit to limit the duty
cycle of its PWM controller at power up, thereby limiting the input inrush current.
The On/Off Control to VOUT start-up time assumes the converter has its
nominal input voltage applied but is turned off via the On/Off Control pin. The
specification defines the interval between the point at which the converter is
turned on (released) and the fully loaded output voltage enters and remains
within its specified accuracy band.
Similar to the VIN to VOUT start-up, the On/Off Control to VOUT start-up time is
also governed by the internal soft start circuitry and external load capaci-
tance. The difference in start up time from VIN to VOUT and from On/Off
Control to VOUT is therefore insignificant.
Input Undervoltage Shutdown and Start-Up Threshold
Under normal start-up conditions, devices will not begin to regulate properly
until the ramping-up input voltage exceeds the Start-Up Threshold Voltage.
Once operating, devices will not turn off until the input voltage drops below
the Undervoltage Shutdown limit. Subsequent re-start will not occur until the
input is brought back up to the Start-Up Threshold. This built in hysteresis
prevents any unstable on/off situations from occurring at a single input voltage.
Input Overvoltage Shutdown
All LQN DC/DC's are equipped with input overvoltage protection. Input
voltages exceeding the input overvoltage shutdown specification listed in the
Performance/Functional Specifications will cause the device to shut down.
A built-in hysterisis for all models will not allow the converter to restart until
the input voltage is sufficiently reduced.
Input Source Impedance
The input of LQN converters must be driven from a low ac-impedance
source. The DC/DC's performance and stability can be compromised by the
use of highly inductive source impedances. The input circuit shown in Figure
2 is a practical solution that can be used to minimize the effects of induc-
tance in the input traces. For optimum performance, components should be
mounted close to the DC/DC converter.
I/O Filtering, Input Ripple Current, and Output Noise
All LQN Series models are tested/specified for input reflected ripple current
and output noise using the specified external input/output components/cir-
cuits and layout as shown in the following two figures. External input capaci-
tors (CIN in Figure 2) serve primarily as energy-storage elements, minimizing
line voltage variations caused by transient IR drops in conductors from
backplane to the DC/DC. Input caps should be selected for bulk capacitance
(at appropriate frequencies), low ESR, and high rms-ripple-current ratings.
TECHNICAL NOTES
Figure 2. Measuring Input Ripple Current
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Absolute Maximum Ratings
Input Voltage
Continuous or Transient 15.5 Volts maximum
On/Off Control (pin 4) +VIN maximum
Input Reverse Polarity Protection See Fuse section
Output Overvoltage Protection VOUT +20% maximum
Output Current Current-limited (See note 7).
Devices can withstand
sustained short circuit without
damage.
Storage Temperature –55 to +125°C.
Lead Temperature (soldering 10 sec. max.) +300°C. Refer to solder profile.
Absolute maximums 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 nor recommended.
LQN D12 Models
N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
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The switching nature of DC/DC converters requires that dc voltage sources
have low ac impedance as highly inductive source impedance can affect
system stability. In Figure 2, CBUS and LBUS simulate a typical dc voltage bus.
Your specific system configuration may necessitate additional considerations.
Minimum Output Loading Requirements
LQN converters employ a synchronous-rectifier design topology and all
models regulate within spec and are stable under no-load to full load condi-
tions. Operation under no-load conditions however might slightly increase the
output ripple and noise.
Thermal Shutdown
The LQN converters are equipped with thermal-shutdown circuitry. If envi-
ronmental conditions cause the temperature of the DC/DC converter to rise
above the designed operating temperature, a precision temperature sensor
will power down the unit. When the internal temperature decreases below the
threshold of the temperature sensor, the unit will self start. See Performance/
Functional Specifications.
Output Overvoltage Protection
The LQN output voltage is monitored for an overvoltage condition using a
comparator. The signal is optically coupled to the primary side and if the
output voltage rises to a level which could be damaging to the load, the sens-
ing circuitry will power down the PWM controller causing the output voltage
to decrease. Following a time-out period the PWM will restart, causing the
output voltage to ramp to its appropriate value. If the fault condition persists,
and the output voltage again climbs to excessive levels, the overvoltage
circuitry will initiate another shutdown cycle. This on/off cycling is referred to
as "hiccup" mode.
The LQN Series will withstand higher external sources several volts above
the nominal output. However, if there is a chance of consistent overvoltage,
users should provide an external voltage clamp or other protection.
Figure 4. Trim Connections Using Fixed Resistors
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. LQN 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 40% or if the
output voltage drops to less than 98% of it original value, the LQN'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, both the average output current and the average input current will
be kept extremely low. Once the output short is removed, the converter will
automatically restart itself.
Output Voltage Trimming
Allowable trim ranges 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 3 below.
A trimpot can be used to determine the value of a single fixed resistor
which can then be connected, as shown in Figure 4, between the Trim pin
Figure 3. Trim Connections Using a Trimpot
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Note:
Install either a fixed
trim-up resistor
or a fixed trim-down
resistor depending upon
desired output voltage.
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 used as starting points for selecting specific trim-
resistor values. Recall, untrimmed devices are guaranteed to be ±1% accurate.
Adjustment beyond the specified adjustment range is not recommended. If trim
is not desired, leave the Trim pin open.
Trim Equations
Note: Resistor values are in kΩ. Accuracy of adjustment is subject to
tolerances of resistors and factory-adjusted, initial output accuracy.
VO = desired output voltage. VONOM = nominal output voltage.
Note: LQN-0.8/50-D12 is not trimmable.
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LXN D12 Series N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
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Return Current Paths
The LQN D12 are non-isolated DC/DC converters. Their Common pins
(pins 1, 6 and 8) are connected to each other internally (see Figure 1). To
the extent possible (with the intent of minimizing ground loops), input return
current should be directed through pin 1 (also referred to as –Input or Input
Return), and output return current should be directed through pin 6 and 8
(also referred to as –Output or Output Return). Any on/off control signals
applied to pin 4 (On/Off Control) should be referenced to Common
(specifically pin 1).
Safety Considerations
LQN D12'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.
On/Off Control
The On/Off Control pin may be used for remote on/off operation. LQN D12
Series DC/DC converters are designed so that they are enabled when the
control pin is left open (or pulled low to 0 to +0.4V) and disabled when the
control pin is pulled high (+2.8V to +VIN). As shown in Figure 5, all models
have an internal 20kΩ pull-down resistor to Common (ground).
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 appro-
priate). The drive circuit should be able to sink appropriate current when
activated and withstand appropriate voltage when deactivated.
Figure 5. Driving the On/Off Control Pin
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The on/off control can be driven using a circuit comparable to that shown in
Figure 5. Leaving the On/Off control pin open or applying a voltage between
0V and +0.4V will turn on the converter. Applied voltages between +2.8V and
+VIN will disable the converter.
ON/OFF pin open: Logic Low = DC/DC converter On
ON/OFF pin >2.8V: Logic High = DC/DC converter Off
Figure 6. Driving The Power-Up With An External Pull-up Resistor
External Input Open: On/Off pin High = DC/DC converter Off
External Input Low: On/Off pin Low = DC/DC converter On
Power-up sequencing
If a controlled start-up of one or more LQN 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 pulled high to +VIN with an external
5.6kΩ restistor. While input voltage and/or other converters are ramping up,
the control pin is pulled high and the converter remains disabled. To enable
the output voltage, the control pin needs to be pulled low in the configuration
shown in Figure 6.
Remote Sense
Note: The Sense and VOUT lines are internally connected through low-value
resistors. Nevertheless, if the sense function is not used for remote regulation
the user should connect the +Sense to +VOUT at the DC/DC converter pins.
LQN series converters employ a sense feature to provide point of use regula-
tion, thereby overcoming moderate IR drops in pcb conductors or cabling.
The remote sense line carries very little current and therefore require minimal
cross-sectional-area conductors. As such, they are not low impedance
points and must be treated with care in layouts and cabling. Sense lines
on a pcb should be run adjacent to dc signals, preferably ground. In cables
and discrete wiring applications, twisted pair or other techniques should be
implemented.
Figure 7. Remote Sense Circuit Configuration
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LQN D12 Models
N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
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To prevent high frequency voltage differences between VOUT 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 VOUT.
[VOUT(+) – Common] – [Sense(+) – Common] ≤ 10%VOUT
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 converter's specified rating. Therefore:
(VOUT at pins) x (IOUT) ≤ 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 devices have the +Sense pin (pin 10) installed (no part-number
suffix) and the sense function is not used for remote regulation, +Sense
(pin 10) must be tied to +Output (pin 7, 9) at the DC/DC converter pins.
Output overvoltage protection is monitored at the output voltage pin, not the
Sense pin. Therefore, excessive voltage differences between VOUT and Sense
in conjunction with trim adjustment of the output voltage can cause the
overvoltage protection circuitry to activate (see Performance Specifications
for overvoltage limits). Power derating is based on maximum output current
and voltage at the converter's output pins.
Temperature/power derating is based on maximum output current and volt-
age at the converter's output pins.
The Trim pin (pin 2) is a relatively high impedance node that can be suscep-
tible to noise pickup when connected to long conductors in noisy environ-
ments. In such cases, a 0.22µF capacitor to ground can be added to reduce
this long lead effect.
LXN D12 Series N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
Typical Performance Curves
8
–40 0 30 40 50 60 70 80 90 100
LQN-3.3/45-D12
Maximum Output Current vs. Ambient Temperature
(With heatsink, air flow direction from input to output pins, VIN = VNOM)
Output Current (Amps)
Ambient Temperature (°C)
60
50
40
30
20
10
0
400 lfm
200 lfm
100 lfm
Natural
Convection
–40 0 30 40 50 60 70 80 90 100
LQN-1.8/50-D12
Maximum Output Current vs. Ambient Temperature
(With heatsink, air flow direction from input to output pins, VIN = VNOM)
Output Current (Amps)
Ambient Temperature (°C)
60
50
40
30
20
10
0
400 lfm
200 lfm
100 lfm
Natural
Convection
95
93
91
89
87
85
83
81
LQN-3.3/45-D12
Efficiency vs. Line Voltage and Load Current @ 25°C
5 9.4 13.9 18.3 22.8 27.2 31.7 36.1 40.6 45
Load Current (Amps)
Efficiency (%)
V
IN
= 10.2V
V
IN
= 12V
V
IN
= 13.8V
95
93
91
89
87
85
83
81
LQN-1.8/50-D12
Efficiency vs. Line Voltage and Load Current @ 25°C
8 14 20 26 32 38 44 50
Load Current (Amps)
Efficiency (%)
V
IN
= 10.2V
V
IN
= 12V
V
IN
= 13.8V
94
93
92
91
90
89
88
87
86
85
84
83
LQN-2.5/45-D12
Efficiency vs. Line Voltage and Load Current @ 25°C
6.8 11.6 16.3 21.1 25.9 30.7 35.4 40.2 45
Load Current (Amps)
Efficiency (%)
V
IN
= 10.2V
V
IN
= 12V
V
IN
= 13.8V
12
10
8
6
4
2
LQN-2.5/45-D12
Internal Power Dissipation vs. Load Current
2 6.8 11.6 16.3 21.1 25.9 30.7 35.4 40.2 45
Load Current (Amps)
Power Dissipation (Watts)
V
IN
= 10.2V
V
IN
= 12V
V
IN
= 13.8V
LQN D12 Models
N O N - I S O L A T E D , 4 5 - 5 0 A Q U A R T E R B R I C K , D C / D C C O N V E R T E R S
8
PART NUMBER STRUCTURE
Maximum Rated Output
Current in Amps
Non-Isolated Quarter Brick
Output
Configuration:
L = Unipolar
Low Voltage
Nominal Output Voltage:
0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3
or 5 Volts
Input Voltage Range:
D12 = 10.2 to 13.8 Volts
(12V nominal)
L QN 50-/D12-1.8 MB
Mounting Method:
Blank = Through-hole package
M = Surface-Mount Package
Heat Transfer:
Blank = No heatsink or baseplate
B = Basplate installed
H = Heat sink installed
Model Options
Note:
Not all model number combinations
are available. Contact DATEL.
9
DS-0522 07/04
DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein
do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. The DATEL logo is a registered DATEL, Inc. trademark.
DATEL (UK) LTD. Tadley, England Tel: (01256)-880444
Internet: www.datel-europe.com E-mail: datel.ltd@datel.com
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Internet: www.datel-europe.com E-mail: datel.sarl@datel.com
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Internet: www.datel-europe.com E-mail: datel.gmbh@datel.com
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Internet: www.datel.co.jp Email: salestko@datel.co.jp, salesosa@datel.co.jp
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E-mail: davidx@datel.com
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Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
www.datel.com Email: sales@datel.com
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