®
®
A SUBSIDIARY OF C&D TECHNOLOGIES
Single Output
LEN D12 Models
Non Isolated, 12VIN, 0.8-5VOUT
28 Amp DC/DC Converters
Features
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The LEN D12 Series of non-isolated eighth 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. LEN 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, or 3.3 Volt output
fully rated at 28 Amps, or 5 Volt output at 25 Amps.
LEN D12's are ideal POLPP's (point-of-use/load power processors) and they
typically require no external components. They occupy the standard eighth-brick
board space (0.9" x 2.3") and come in either through-hole packages or surfacemount packages with a profile of only 0.46" (0.5" including optional heat sink).
The LEN's best-in-class power density is achieved with a fully synchronous,
fixed-frequency, 2-phase buck topology that delivers extremely high efficiency (95%
for 5VOUT models), low noise (25mVp-p typ.), tight line/load regulation (±0.25%
max.), quick step response (150µsec), stable no-load operation, and no output
reverse conduction.
The fully functional LEN'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 a
sense pin. High efficiency enables the LEN D12's to deliver rated output currents of
25 Amps at ambient temperatures to +65°C with 200 lfm air flow without heat sink.
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 ¼ and 1/8 brick's will save you money.
Eighth brick, through hole or SMT
2-phase buck regulators for new
distributed 12V power architectures
12V input (10.2-13.8V range)
0.8-2.5VOUT, 3.3VOUT @ 28A, 5VOUT @ 25A
Non-isolated, fixed-frequency,
synchronous-rectifier topology
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Efficiencies to 95% @ 25 Amps
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Noise as low as 25mVp-p
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Stable no-load operation
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On/Off control, trim & sense functions
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Output Overvoltage Protection
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Input Over/Undervoltage lockout
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Thermal shutdown
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Designed to meet UL/EN/IEC60950
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EMC compliant
+OUTPUT
(7,9)
+INPUT
(5)
➀
+SENSE
(10)
COMMON
(6, 8)
COMMON
(1)
CURRENT
SENSE
VCC
ON/OFF
CONTROL
(4)
➀
2-PHASE
PWM
CONTROLLER
REFERENCE &
ERROR AMP
VOUT
TRIM
(2)
Only one phase of two shown.
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
LEN D12 Models
N O N - I S O L AT E D , 2 8 A E I G H T H B R I C K , D C / D C C O N V E R T E R S
Performance/Functional Specifications
Absolute Maximum Ratings
Typical @ TA = +25°C under nominal line voltage and full-load conditions unless noted. ➀
Input Voltage:
Continuous or transient
Input Voltage Range
10.2-13.8 Volts (12V nominal) ➅
Input Current:
Normal Operating Conditions
Inrush Transient
Standby/Off Mode
Output Short-Circuit Condition ➁
See Ordering Guide
TBD
3.5mA
130mA
Input Reflected Ripple Current ➁
+VIN
20mAp-p
Input Filter Type
15.5 Volts
On/Off Control (Pin 11)
Input
None
Output Overvoltage Protection
VOUT +20%
Output Current
Current limited. Devices can
withstand sustained output short
circuits without damage.
Capacitive (66µF)
Storage Temperature
–55� to +125°C
14.3 Volts
Overvoltage Protection
Input Reverse-Polarity Protection
Lead Temperature (soldering, 10 sec.)
+300°C
Reverse-Polarity Protection
None
Undervoltage Shutdown
9.4 Volts
On/Off Control ➂
On = open or 0 to +0.4V
Off = +2.8V to +VIN (<3mA)
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
VOUT Accuracy (50% load)
±1.5% maximum
Minimum Loading ➀
No load
Maximum Capacitive Load
10,000µF (low ESR, OSCON)
VOUT Trim Range ➁
±10% for VOUT = ≥1.8V
+10%/–3% for VOUT 1.5V and lower
(no trim for 0.8V models)
Ripple/Noise (20MHz BW) ➀ ➁ ➃
The LEN 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).
3% over line/load temperature
Efficiency ➁
See Ordering Guide
Overcurrent Detection and Short-Circuit Protection: ➁
Current-Limiting Detection Point
35 Amps
Short-Circuit Detection Point
98% of VOUT set
SC Protection Technique
Hiccup with auto recovery
Short-Circuit Current
TBD
I/O Filtering and Noise Reduction
Dynamic Characteristics
Transient Response (25% load step)
All models in the LEN D12 Series are tested and specified with external
33µF 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 LEN 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.
100µsec to ±2% of final value
Start-Up Time: ➁
VIN to VOUT and On/Off to VOUT
20ms
Switching Frequency
320kHz ±40kHz
Environmental
Calculated MTBF ➄
TBD million hours
Operating Temperature: (Ambient) ➁
Without Derating (With 200 lfm)
With Derating
–40 to +65°C (model dependent)
See Derating Curves
Thermal Shutdown
+125°C
In particular, the LEN 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
33µF tantalum output caps has minimal effect on output noise.
Physical
Dimensions
See Mechanical Dimensions
Pin Material
Copper, solder coated over nickel underplate
Weight
0.6 ounces (17g)
Flamability Rating
N O T E S
Return Current Paths
See Ordering Guide
Total Accuracy
T E C H N I C A L
UL94V-0
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 and the frequencies of interest. Highly inductive
source impedances can greatly affect system stability. Your specific system
configuration may necessitate additional considerations.
➀ All models are tested and specified with external 33µF 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 Input Ripple Current is tested/specified over a 5-20MHz bandwidth with an external 33µF
input capacitor and a simulated source impedance of 220µF and 12µH. See I/O Filtering,
Input Ripple Current and Output Noise for details.
➂ The On/Off Control (pin 4) is designed to be driven with open-collector logic or the application of appropriate voltages (referenced to Common, pins 1, 6 and 8).
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, TA = +25°C, full
power, natural convection, TBD pcb temperature.
➅ See Performance Specifications, note 6.
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
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