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LQN D12 Models
www.murata-ps.com
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
FEATURES
„
3-phase buck regulators for new
distributed 12V power architectures
„
12V input (10.2-13.8V range)
OBSOLETE PRODUCT
„
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
Typical unit
„
±1% setpoint accuracy
„
Efficiencies to 93.5% @ 45 Amps
„ Noise as low as 20mVp-p
„
Stable no-load operation
„
On/Off control, trim & sense functions
PRODUCT OVERVIEW
„
Output overvoltage protection
„
Input Over/Undervoltage lockout
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/DCs
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 D12s are ideal POLPPs (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 LQNs best-in-class power density is
achieved with a fully synchronous, fixed-frequency,
3-phase buck topology that delivers extremely
„
Thermal shutdown
„
Designed to meet UL/IEC/EN60950-1
„
EMC compliant
high efficiency (95% for 5VOUT models), low noise
(20mVp-p typ.), tight line/load regulation (±0.25%
max.), quick step response (70μsec), stable noload operation, and no output reverse conduction.
The fully functional LQN's feature input over/
undervoltage lockout, output overvoltage and
overcurrent detection, continuous short-circuit
protection, overtemperature protection, an
output-voltage trim function, a remote on/off
control pin, and sense pin. High efficiency enables
the LQN D12s 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, MPS's nonisolated LQN D12 brick's will save you money.
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Typical topology is shown.
Figure 1. Simplified Schematic
➀ Only one phase of three shown.
For full details go to
www.murata-ps.com/rohs
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2009.09.14
MDC_LQN D12 Models.B04 Page 1 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Performance Specifications and Ordering Guide➀
Output
Models
LQN-0.8/50-D12-C
LQN-1/50-D12-C
LQN-1.2/50-D12-C
LQN-1.5/50-D12-C
LQN-1.8/50-D12-C
LQN-2/50-D12-C
LQN-2.5/45-D12-C
LQN-3.3/45-D12-C
LQN-5/45-D12-C
VOUT
(Volts)
IOUT
(Amps)
0.8
1
1.2
1.5
1.8
2
2.5
3.3
5
50
50
50
50
50
50
45
45
45
R/N (mVp-p) ➁
Input
Regulation (Max.) ➂
Typ.
Max.
Line
Load
VIN Nom.
(Volts)
30
30
20
20
20
20
20
30
20
50
50
50
50
50
50
50
50
40
±0.25%
±0.25%
±0.25%
±0.25%
±0.05%
±0.25%
±0.25%
±0.25%
±0.05%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.05%
12
12
12
12
12
12
12
12
12
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 noload conditions. Regulation specifications describe the output-voltage deviation as
the line voltage or load is varied from its nominal/midpoint value to either extreme.
Efficiency
Range
(Volts)
IIN ➃
(mA/A)
Min.
Typ.
Package
(Case, Pinout)
10.2–3.8
10.2–3.8
10.2–3.8
10.2–3.8
10.2–3.8
10.2–3.8
10.2–3.8
10.2–3.8
10.2–3.8
240/3.92
240/4.84
240/5.59
240/6.87
240/8.24
240/9.16
240/10.14
240/13.38
240/20.05
82%
80%
87%
88.5%
88.5%
88.5%
90%
90%
94%
85%
86%
89.5%
91%
91%
91%
92.5%
92.5%
95%
C41, C42, P62
C41, C42, P62
C41, C42, P62
C41, C42, P62
C41, C42, P62
C41, C42, P62
C41, C42, P62
C41, C42, P62
C41, C42, P62
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.
➅ Please see part number structure for full part numbers and additional options.
PART NUMBER STRUCTURE
Model options
L QN - 1.8 / 50 - D12 M B - C
Output
Configuration:
L = Unipolar
Low Voltage
Non-Isolated Quarter Brick
Nominal Output Voltage:
0.8, 1, 1.2, 1.5, 1.8,
2, 2.5, 3.3 or 5 Volts
Maximum Rated Output
Current in Amps
RoHS-6 hazardous substance compliant*
(Does not claim UE RoHS
exemption 7b – lead in
solder.)
Heat Transfer:
Blank = No heatsink
or baseplate, standard
B = Baseplate installed,
optional
H = Heatsink installed,
optional
Mounting Method:
Blank = Through-hole package,
standard
M = Surface-mount package,
optional
* Contact Murata Power Solutions for availability.
Note:
Some model number combinations may not be
available. Contact Murata Power Solutions
(Datel).
Input Voltage Range:
D12 = 10.2 to 13.8 Volts
(12V nominal)
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email: [email protected]
2009.09.14
MDC_LQN D12 Models.B04 Page 2 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
MECHANICAL SPECIFICATIONS
2.22 (56.4)
0.122
(3.1)
2.22 (56.4)
PINS 2-4, 10:
0.040 ±0.001
(1.016 ±0.025)
PINS 1, 5-9:
0.062 ±0.001
(1.575 ±0.025)
PLASTIC STANDOFFS
ARE RELIEVED 0.030 (0.8)
IN SOLDER JOINT AREA
2.00 (50.8)
COPPER SMT LEADS
COPLANAR TO 0.004
0.025
(0.6)
2.30 (58.4)
A
0.125 TYP.
(3.2)
B
B
A
A
6
1
6
7
2
7
3
8
3
8
4
9
5
10
BOTTOM VIEW
1.35 (34.3)
1
2
0.110 TYP.
(2.8)
10
0.600 (15.24)
4 EQ. SP. @ 0.150 (3.81)
*0.50 (11.2) WITH THE ADDITION
OF OPTIONAL HEATSINK OR BASEPLATE.
0.79 (20.1) WITH HEAT SHIELD.
*0.50 (12.7) WITH THE ADDITION
OF OPTIONAL HEATSINK OR BASEPLATE
C41 Through-Hole Package
C42 Surface-Mount Package
Dimensions are in inches (mm) shown for ref. only.
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
9
5
BOTTOM VIEW
0.600 (15.24)
4 EQ. SP. @ 0.150 (3.81)
Third Angle Projection
4
1.35 (34.3)
B
0.180 MIN.
(4.6)
0.44*
(11.2)
A
B
0.44*
(11.2)
Pin
1
2
3
4
5
I/O Connections
Function P62
Pin
Input Common
6
7
VOUT Trim
N.C.*
8
Off/On Control
9
+Input
10
Function P62
Output Common
+Output
Output Common
+Output
+Sense In
*A "Power Good" output
is available on pin 3 under
special order.
Contact Murata Power
Solutions.
See page 4 for LQN Series baseplate, heat sink,
and heat shield mechanical specifications.
Components are shown for reference only.
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email: [email protected]
2009.09.14
MDC_LQN D12 Models.B04 Page 3 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
MECHANICAL SPECIFICATIONS
2.22 (56.4)
B
A
1.030 (26.2)
1.720 (43.7)
B
A
1.35 (34.3)
#2-56 THREAD
X 0.20 DEEP
(4 PLACES)
A
2.22 (56.4)
A
1.110 (28.2)
1.860 (47.2)
0.31
(7.9)
B
#M3 THREAD
X 0.15 DEEP
(4 PLACES)
DIMENSIONS ARE IN INCHES (MM)
LQN Series Heat Sink
A
2.30 (58.4)
B
1.720 (43.7)
B
0.31
(7.9)
0.79
(20.1)
1.35 (34.3)
1.110 (28.2)
#2-56 THREAD
X 0.13 DEEP
(4 PLACES)
0.057
(1.5)
DIMENSIONS ARE IN INCHES (MM)
LQN Series Baseplate
Dimensions are in inches (mm) shown for ref. only.
1.52
(38.6)
Third Angle Projection
DIMENSIONS ARE IN INCHES (MM)
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
LQN Series Heat Shield for Surface-Mount Packages
Components are shown for reference only.
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email: [email protected]
2009.09.14
MDC_LQN D12 Models.B04 Page 4 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Performance/Functional Specifications
Line/Load Regulation [10]
See Ordering Guide
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]
Efficiency
See Ordering Guide
Maximum Capacitive Loading
10,000μF (low ESR ≤0.004Ω)
VOUT Trim Range
±10% of VNOMINAL
82A (cold start), 60A (warmed up)
85A (cold start), 70A (warmed up)
Input
Input Voltage Range
10.2-13.8 Volts (12V nominal) [13]
Start-Up Threshold
9.4-10.8 Volts
Overvoltage Shutdown
14.3 Volts typical
Current Limit Inception (98% of VOUT):
1 & 1.8V models
2.5 & 3.3V models
Undervoltage Shutdown
9.5 Volts typical
Short Circuit Detection
See Note 6
Short Circuit Protection Method
Hiccup with autorecovery
See Technical Notes
Short Circuit Current
22 Amps typical, 25 Amps maximum
Short Circuit Duration
Continuous, output shorted to ground
Overvoltage Protection
120% of VOUT
Method: comparator feedback
Input Current:
Normal Operating Conditions
Standby Mode (Off, Under Voltage)
Inrush transient
Output Short-Circuit Condition
Low Line Voltage (VIN = VMIN):
LQN-0.8/50-D12
LQN-1/50-D12
LQN-1.2/50-D12
LQN-1.5/50-D12
LQN-1.8/50-D12
LQN-2/50-D12
LQN-2.5/45-D12
LQN-3.3/45-D12
LQN-5/45-D12
Input Reflected Ripple Current [2]
See Ordering Guide
TBD mA
TBD A2sec
350mA
4.56 Amps
5.63 Amps
6.54 Amps
8.04 Amps
9.64 Amps
10.71 Amps
11.86 Amps
15.57 Amps
23.34 Amps
40mAp-p
Dynamic Characteristics
Dynamic Load Response (50% - 75% - 50% load step to ±2% of VOUT final value)
All models
70μsec
Start-Up Time
(On/Off or VIN on to VOUT regulated)
10msec for VOUT = nominal
Switching Frequency
690kHz ±30kHz
Maximum Output Capacitive Load
10,000μF, low ESR, 0.004Ω
Environmental
Input Filter Type
Capacitive, 88μF
Overvoltage Protection
None
Calculated MTBF [4]
Reverse-Polarity Protection
See external fuse information
Operating Temperature Range: (Ambient) [9]
See Derating Curves
–40 to +85°C, with derating
No-load Input Current
240mA
Remote On/Off Control [5]
Off = +2.8V to +VIN max.
On = open pin to +2V max.
Remote Control On/Off Current
Remote Sense Input Range
1mA pulldown
Storage Temperature Range
Total Output Power (VOUT x IOUT must not exceed maximum power) [3]
40 Watts
50 Watts
60 Watts
75 Watts
90 Watts
100 Watts
112.5 Watts
148.5 Watts
225 Watts
Voltage Output Accuracy:
Initial
Temperature Coefficient
Extreme [12]
±1% of VNOMINAL
±0.02% of VOUT per °C
±3% of VNOMINAL
Minimum Loading [1]
No minimum load
Ripple/Noise (20 MHz bandwidth) [8]
See Ordering Guide
–40 to +125°C
Thermal Protection/Shutdown
+115°C (PC board)
Relative Humidity
To +85%/+85°C, non-condensing
+10% of VOUT nominal
Output
LQN-0.8/50-D12
LQN-1/50-D12
LQN-1.2/50-D12
LQN-1.5/50-D12
LQN-1.8/50-D12
LQN-2/50-D12
LQN-2.5/45-D12
LQN-3.3/45-D12
LQN-5/45-D12
TBC Hours
Physical
Outline Dimensions
See Mechanical Specifications
Pin Material [11]
Weight (no heatsink)
Through-hole: Gold-plated copper alloy
Surface mount: Pure tin over nickel-plated
copper alloy
1.1 ounces (31 grams)
Flammability Rating
UL94V-0
Electromagnetic Interference
(conducted or radiated)
Safety
Designed to meet FCC Part 15,
EN55022, Class A
Designed to meet UL/cUL 60950-1,
CSA-C22.2 No.234, IEC/EN 60950-1
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email: [email protected]
2009.09.14
MDC_LQN D12 Models.B04 Page 5 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
NOTES
ABSOLUTE MAXIMUM RATINGS
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
filtering 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
appropriate 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.
[14] Output Capacitive Loading
Exceeding the maximum output capacitive load specification (at the indicated
ESR) may interfere with the Soft Start mode and possibly cause overcurrent shutdown at startup while attempting to charge output caps. This risk increases with
combinations of high output capacitance and low Equivalent Series Resistance
(ESR) inside the capacitors, especially newer ceramic caps. Use just enough
output capacitance to achieve your noise suppression or energy storage needs
and no more. Thoroughly test your application with all components installed.
Be cautious when using the On/Off control in conjunction with high output capacitance. If the output capacitors are not allowed to bleed down their voltage sufficiently after shutdown, certain converters may be damaged by lingering output
voltage applied as reverse current into the outputs. Most converters include a
warning to strictly limit the amount of current sourced back into the converter.
[15] Always connect the sense pins. If they are not connected to a remote load, wire
each sense pin to its respective voltage output at the converter pins.
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.)
+280°C. Refer to solder profile.
Absolute maximums are stress ratings. Exposure of devices to greater than 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.
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2009.09.14
MDC_LQN D12 Models.B04 Page 6 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
TECHNICAL NOTES
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 MPS LQN series DC/DC converters, we recommend the
use of a fast blow 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
All relevant national and international safety standards and regulations must
be observed by the installer. For system safety agency approvals, the converters must be installed in compliance with the requirements of the end-use
safety standard, i.e. IEC/EN/UL60950-1.
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 capacitance, 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.
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 inductance 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/circuits and
layout as shown in the following two figures. External input capacitors (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.
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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 capacitance.
The difference in start up time from VIN to VOUT and from On/Off Control to VOUT
is therefore insignificant.
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,"53§(
Figure 2. Measuring Input Ripple Current
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.
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2009.09.14
MDC_LQN D12 Models.B04 Page 7 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
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 conditions.
Operation under no-load conditions however might slightly increase the output
ripple and noise.
/54054
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42)-
Thermal Shutdown
The LQN converters are equipped with thermal-shutdown circuitry. If environmental 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.
,/!$
#/--/.
#/--/.
Figure 3. Trim Connections Using a Trimpot
/54054
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 sensing 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.
Note:
4RIM $OWN
).054
42)-
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 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.
trim-up resistor
or a fixed trim-down
4RIM 5P
#/--/.
resistor depending upon
desired output voltage.
#/--/.
Figure 4. Trim Connections Using Fixed Resistors
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.
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.
Install either a fixed
,/!$
Trim Equations
LQN-1.2/50-D12
RT DOWN (k7) =
1.24(VO – 0.8)
VO NOM – VO
– 2.05
RT UP (k7) =
1.0
VO – VO NOM
– 2.05
LQN-1.5/50-D12
RT DOWN (k7) =
RT DOWN (k7) =
1.62(VO – 0.8)
VO NOM – VO
0.5(VO – 0.8)
VO NOM – VO
– 4.02
RT UP (k7) =
–X
RT UP (k7) =
LQN-1/50-D12:
LQN-1.8/50-D12:
LQN-2/50-D12:
LQN-3.3/45-D12:
RT DOWN (k7) =
7.5(VO – 0.8)
VO NOM – VO
–X
1.3
VO – VO NOM
0.4
VO – VO NOM
– 4.02
–X
X = 0.392
X = 1.82
X = 1.3
X = 1.0
RT UP (k7) =
6
VO – VO NOM
–X
LQN-2.5/45-D12: X = 15.8
LQN-5/45-D12
RT DOWN (k7) =
0.49(VO – 0.8)
5 – VO
– 0.576 RT UP (k7) =
0.399
VO – 5
– 0.576
Note: LQN-0.8/50-D12 is not trimmable.
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.
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MDC_LQN D12 Models.B04 Page 8 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
The trim equations above 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.
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).
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.
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 resistor. 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.
).054
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/separation
requirements, in compliance with relevant safety-agency specifications (usually
UL/IEC/EN60950-1).
6
K7
/./&&
#/.42/,
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).
).054
6
/./&&
#/.42/,
n
K7
#/--/.
External Input Open: On/Off pin High = DC/DC converter Off
External Input Low: On/Off pin Low = DC/DC converter On
Figure 6. Driving The Power-Up With An External Pull-up Resistor
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 regulation, 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.
n
K7
#/--/.
To prevent high frequency voltage differences between VOUT and Sense, we
recommend installation of a 1000pF capacitor close to the converter.
ON/OFF pin open: Logic Low = DC/DC converter On
ON/OFF pin >2.8V: Logic High = DC/DC converter Off
Figure 5. Driving the On/Off Control Pin
Dynamic control of the on/off function is best accomplished with a
mechanical 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.
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
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MDC_LQN D12 Models.B04 Page 9 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
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 10.5: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 voltage at the converter's output pins.
The Trim pin (pin 2) is a relatively high impedance node that can be susceptible to noise pickup when connected to long conductors in noisy environments.
In such cases, a 0.22μF capacitor to ground can be added to reduce this long
lead effect.
Typical Performance Curves
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
.OBASEPLATE6).6./-TRANSVERSEAIRFLOW
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL
#ONVECTION
LFM
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
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2009.09.14
MDC_LQN D12 Models.B04 Page 10 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Typical Performance Curves
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
.OBASEPLATE6).6./-
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL
#ONVECTION
LFM
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
)NTERNAL0OWER$ISSIPATIONVS,OAD#URRENT
6).6
6).6
%FFICIENCY
0OWER$ISSIPATION7ATTS
6).6
6).6
6).6
6).6
,OAD#URRENT!MPS
,OAD#URRENT!MPS
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2009.09.14
MDC_LQN D12 Models.B04 Page 11 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Typical Performance Curves
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
7ITHBASEPLATE
6).6./-
.ATURAL
#ONVECTION
%FFICIENCY
/UTPUT#URRENT!MPS
LFM
LFM
LFM
n
6).6
6).6
6).6
!MBIENT4EMPERATUREo#
)NSTALLEDBASEPLATEISNOTATTACHEDTOANEXTERNALSURFACE
,OAD#URRENT!MPS
,1.$
)NTERNAL0OWER$ISSIPATIONVS,OAD#URRENT
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
7ITHBASEPLATE
AIRFLOWFROMINPUTTOOUTPUTPINS6).6./-
6).6
/UTPUT#URRENT!MPS
0OWER$ISSIPATION7ATTS
6).6
6).6
.ATURAL
#ONVECTION
LFM
LFM
LFM
n
!MBIENT4EMPERATUREo#
)NSTALLEDBASEPLATEISNOTATTACHEDTOANEXTERNALSURFACE
,OAD#URRENT!MPS
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2009.09.14
MDC_LQN D12 Models.B04 Page 12 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Typical Performance Curves
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
.OBASEPLATE6).6./-
.ATURAL
#ONVECTION
%FFICIENCY
/UTPUT#URRENT!MPS
LFM
LFM
LFM
6).6
6).6
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
,1.$
)NTERNAL0OWER$ISSIPATIONVS,OAD#URRENT
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
7ITHBASEPLATE
6).6./-
6).6
/UTPUT#URRENT!MPS
0OWER$ISSIPATION7ATTS
6).6
6).6
.ATURAL
#ONVECTION
LFM
LFM
LFM
n
!MBIENT4EMPERATUREo#
)NSTALLEDBASEPLATEISNOTATTACHEDTOANEXTERNALSURFACE
,OAD#URRENT!MPS
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2009.09.14
MDC_LQN D12 Models.B04 Page 13 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Typical Performance Curves
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
)NTERNAL0OWER$ISSIPATIONVS,OAD#URRENT
6).6
6).6
%FFICIENCY
0OWER$ISSIPATION7ATTS
6).6
6).6
6).6
6).6
,OAD#URRENT!MPS
,OAD#URRENT!MPS
,1.$
)NTERNAL0OWER$ISSIPATIONVS,OAD#URRENT
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
7ITHBASEPLATE
6).6./-
6).6
/UTPUT#URRENT!MPS
0OWER$ISSIPATION7ATTS
6).6
6).6
.ATURAL
#ONVECTION
LFM
LFM
LFM
n
!MBIENT4EMPERATUREo#
)NSTALLEDBASEPLATEISNOTATTACHEDTOANEXTERNALSURFACE
,OAD #URRENT !MPS
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2009.09.14
MDC_LQN D12 Models.B04 Page 14 of 15
LQN D12 Models
Non-Isolated, Single Output, 12VIN, 0.8-5VOUT
45-50 Amp, ¼-Brick, DC/DC Converters
Typical Performance Curves
,1.$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,1.$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
7ITHBASEPLATE
AIRFLOWFROMINPUTTOOUTPUTPINS6).6./-
.ATURAL
#ONVECTION
%FFICIENCY
/UTPUT#URRENT!MPS
LFM
LFM
LFM
n
6).6
6).6
6).6
!MBIENT4EMPERATUREo#
)NSTALLEDBASEPLATEISNOTATTACHEDTOANEXTERNALSURFACE
,OAD#URRENT!MPS
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
Murata Power Solutions, Inc. 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.
© 2009 Murata Power Solutions, Inc.
www.murata-ps.com/locations
email: [email protected]
2009.09.14
MDC_LQN D12 Models.B04 Page 15 of 15