DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 Email: sales@datel.com Internet: www.datel.com
Single Output
UNR Open-Frame Series
Features
Figure 1. Simplifi ed Schematic
INNOVATION and EX C ELL E N C E
DATEL's 30-66W UNR Series deliver an excellent solution to situations in which
users of modern DSP's and CPLD's requiring up to 20 Amps of "low-voltage"
(1.5-3.3V) current are constrained to drawing that power from a legacy 5V bus.
These are non-isolated DC/DC converters that deliver up to 20 Amps of 1.5-3.3V
current from a 5V input. Combining a modern, fully synchronous buck topology with
a unique, integrated-metal-technology (IMT) package, the automatically assembled
30-66W UNR's deliver high effi ciency (to 91%), excellent thermal performance (to
+70C with 100lfm air fl ow), and low cost.
These converters require no compromises. They are fully line (0.1%) and
load (0.5%) regulated and feature low noise (typically 75mVp-p) and quick step
response (50msec). Their feature set includes V
OUT
trim capability, an on/off control
function, output remote-sense pins, and output overcurrent detection and short-
circuit protection ("hiccup" technique with auto-recovery). Their unique package
integrates an anodized aluminum heat sink with the circuit's thermal-clad aluminum
baseplate. With minimal air fl ow (100lfm), all models deliver full output power/current
up to +65C.
All UNR 30-66W Open-Frame DC/DC Converters are UL1950/EN60950 certi-
fi ed. Safety certifi cations, EMC compliance test reports, and qualifi cation (including
HALT) test reports are available upon request.
+INPUT
(7)
+OUTPUT
(4)
10.5
10.5
+SENSE
(3)
INPUT
RETURN
(8)
ON/OFF
CONTROL
(6)
PWM
CONTROLLER
VOLTAGE
BOOST
REFERENCE &
ERROR AMP
OVERCURRENT
DETECTION
OUTPUT
RETURN
(5)
V
OUT
TRIM
(1)
SENSE
(2)
+V
CC
Non-Isolated, 15-20 Amp
5V
IN,
1.5-3.3V
OUT
DC/DC Converters
Output: Non-isolated
1.5V or 1.8V @ 20 Amps
2.5V or 3.3V @ 15 or 20 Amps
Input Voltage: 4.75-5.5V (5V nominal)
Package: 2" x 2" x 0.49" open-frame with
attached heat sink
Full synchronous-rectifi er topology
Effi ciencies as high as 91%
Noise as low as 75mVp-p
Stable no-load operation
Excellent thermal derating
Output short-circuit protection
On/off control, trim and sense functions
UL60950/EN60950 certifi ed
Qual tested, HALT tested, EMI tested
UNR Series
N O N - I S O L A T E D , 3 0 - 6 6 W , O P E N - F R A M E D C / D C C O N V E R T E R S
M E C H A N I C A L S P E C I F I C A T I O N S
Performance Specifi cations and Ordering Guide
Output
Input
P A
T NUM
E S T U C T U
E
Non-Isolated
Output Confi guration:
U = Unipolar
Nominal Output Voltage:
1.2, 1.5, 1.8, 2.5 or 3.3 Volts
Maximum Rated Output
Current in Amps
Input Voltage Range:
D5 = 4.75 to 5.5 Volts (5V nominal)
U NR
20
-
/
D5
-
3.3
2
Package
V
OUT
I
OUT
R/N (mVp-p)
Regulation (Max.)
V
IN
Nom. Range I
IN
Effi ciency (Case,
Model (Volts) (Amps) Typ.
Max. Line
Load
(Volts) (Volts) (mA/A) Min.
Typ. Pinout)
UNR-1.5/20-D5 1.5 20 80
100 0.1%
0.5% 5 4.75-5.5 150/7080 82.5%
84% C21, P26
UNR-1.8/20-D5 1.8 20 80
100 0.1%
0.5% 5 4.75-5.5 150/8500 83.5%
85% C21, P26
UNR-2.5/15-D5 2.5 15 75
120 0.1%
0.5% 5 4.75-5.5 150/8430 86%
89% C21, P26
UNR-2.5/20-D5 2.5 20 75
120 0.1%
0.5% 5 4.75-5.5 150/11360 83%
86% C21, P26
UNR-3.3/15-D5 3.3 15 75
120 0.1%
0.5% 5 4.75-5.5 150/10880 87%
91% C21, P26
UNR-3.3/20-D5 3.3 20 75
120 0.1%
0.5% 5 4.75-5.5 150/14830 86%
89% C21, P26
I/O Connections
Pin Function P26
1 Trim
2 Sense
3 +Sense
4 +Output
5 Output Return
6 On/Off Control
7 +Input
8 Input Return
Typical at T
A
= +25C under nominal line voltage and full-load conditions, unless
otherwise noted. All models are tested and specifi ed with a 22F output capacitor with a
200m
ESR and a 4000F input capacitor with 9.75Arms ripple-current rating and 20m ESR.
See I/O Filtering and Noise Reduction for more details.
Ripple/Noise (R/N) is tested/specifi ed over a 20MHz bandwidth. Output noise may be further
reduced by installing additional external output caps. See I/O Filtering and Noise Reduction.
These devices have no minimum-load requirements and will regulate under no-load conditions.
Nominal line voltage, no-load/full-load conditions.
PRELIMINAR
Y
1
2
3
4
6
7
8
5
2.00
(50.80)
0.25
(6.35)
0.600
(15.24)
3 EQ. SP. @
0.200 (5.08)
0.400
(10.16)
0.500
(12.70)
0.49
(12.45)
0.040 0.002 DIA.
(1.016 0.051)
4 PLACES
0.080 0.002 DIA.
(2.032 0.051)
4 PLACES
1.640
(41.66)
1.600
(40.64)
2.00
(50.80)
1.640
(41.66)
0.180
(4.57)
0.180
(4.57)
0.320
(8.13)
BOTTOM VIEW
#4-40 THD THRU
4 PLACES
DIMENSIONS ARE IN INCHES (MM)
Case C21
UNR Models
N O N - I S O L A T E D , 3 0 - 6 6 W , O P E N - F R A M E D C / D C C O N V E R T E R S
Input
Input Voltage Range 4.75 to 5.5 Volts (5V nominal)
Input Current:
Normal Operating Conditions See Ordering Guide
Standby/Off Mode TBD
Input Ripple Current:
UNR-1.5/20-D5, UNR-1.8/20-D5 260mAp-p
UNR-2.5/15-D5 150mAp-p
UNR-2.5/20-D5 140mAp-p
UNR-3.3/15-D5 100mAp-p
UNR-3.3/20-D5 150mAp-p
Input Filter Type Capacitive (74F)
Overvoltage Protection None
Reverse-Polarity Protection None
On/Off Control (Pin 6)
On = open or +4V to +V
IN
; I
IN
= TBD
Off = +0.4V to 1V; I
IN
= TBD
Output
V
OUT
Accuracy (50% load) 1% maximum
V
OUT
Trim Range (3.3V
OUT
models):
Trim pin tied to +Output V
OUT
= <1.53 Volts
Trim pin tied to Output Return V
OUT
= >3.6 Volts
Minimum Loading No load
Temperature Coeffi cient 0.02% per C
Ripple/Noise (20MHz BW)
See Ordering Guide
Line/Load Regulation See Ordering Guide
Effi ciency See Ordering Guide
Overcurrent Protection:
Technique "Hiccup" with auto-recovery
15 Amp Models 146 to 173% (160% typical)
20 Amp Models 115 to 130% (120% typical)
Average Output Current 1 Amp typical, 3 Amps maximum
Dynamic Characteristics
Transient Response (50 to 75% step) 50sec to 2% of fi nal value
Start-Up Time:
V
IN
to V
OUT
30msec
On/Off to V
OUT
30msec
Switching Frequency 200kHz (20kHz)
Environmental
Operating Temperature (Ambient):
Without Derating 40 to +35-65C
With Derating to +100C (See Derating Curves)
Storage Temperature 40 to +105C
Physical
Dimensions 2" x 2" x 0.49" (51 x 51 x 12.45mm)
Shielding Open-frame
Attached Heatsink Black anodized aluminum
Circuit Board Single-layer conductors on aluminum base
Pin Material Brass, solder dip alloy
Weight 1.7 ounces (48.2 grams)
Performance/Functional Specifi cations
Typical @ T
A
= +25C under nominal line voltage and full-load conditions unless noted.
All models are tested and specifi ed with a 22F output capacitor with a 200m ESR and a
4000F input capacitor with 9.75Arms ripple-current rating and 20m
ESR. See I/O Filtering
and Noise Reduction for more details. These devices have no minimum-load requirements
and will regulate under no-load conditions.
See Output Overcurrent Detection for details.
See On/Off Control for details.
See Output Voltage Trimming for details.
See Start-Up Time for details.
See Temperature Derating for details.
Input Voltage:
Continuous 5 Volts
Transient (100msec) 7 Volts
Input Reverse-Polarity Protection None
Input/Output Overvoltage Protection None
Output Current Current limited. Devices can
withstand a sustained output
short circuit without damage.
Storage Temperature 40 to +105C
Lead Temperature (Soldering, 10 sec.) +300C
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 Specifi cations Table is not implied.
Absolute Maximum Ratings
3
T E C H N I C A L N O T E S
Return Current Paths
These are non-isolated DC/DC converters. The Input Return and Output
Return pins are connected to each other internally. To the extent possible,
all input and load currents should be returned through the Input Return and
Output Return, respectively (via low-impedance runs). Any control signals
applied to the On/Off Control pin should be referenced to Input/Output
Return.
I/O Filtering and Noise Reduction
All models in the UNR 30-66W Series are tested and specifi ed with an
external 22F output capacitor (200m
ESR) and a 4000F input capacitor
with a 9.75Arms ripple-current rating. External input capacitance is required
and must be rated to handle the input ripple current as follows:
(The large value of the input capacitor is due mainly to output characteristics
of DATEL's outgoing ATE test system. Ripple current rating is an important
consideration for the end user.) In critical applications, input/output ripple/
noise may be further reduced by installing additional I/O caps.
External input capacitors serve primarily as energy-storage elements. They
should be selected for bulk capacitance (at appropriate frequencies), low
ESR, and high rms-ripple-current ratings. The switching nature of modern
DC/DC converters requires that dc input voltage sources have low ac
impedance, and highly inductive source impedances can affect system
stability. Your specifi c system confi guration may necessitate additional con-
siderations.
Output ripple/noise (also referred to as periodic and random deviations or
PARD) can be reduced below specifi ed limits using fi ltering techniques, the
simplest of which is the installation of additional external output capacitors.
Output capacitors function as true fi lter elements and should be selected for
bulk capacitance, low ESR, and appropriate 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.
I
RMS
= I
OUT
V
OUT
V
IN
V
OUT
V
IN
(
1
)
r
UNR Series
N O N - I S O L A T E D , 3 0 - 6 6 W , O P E N - F R A M E D C / D C C O N V E R T E R S
4
Output ripple/noise (also referred to as periodic and random deviations or
PARD) can be reduced below specifi ed limits using fi ltering techniques, the
simplest of which is the installation of additional external output capacitors.
Output capacitors function as true fi lter elements and should be selected for
bulk capacitance, low ESR, and appropriate 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.
All external capacitors should have appropriate voltage ratings and be
located as close to the converters as possible. Temperature variations for all
relevant parameters should be taken into consideration.
The most effective combination of external I/O capacitors will be a function
of your line voltage and source impedance, as well as your particular load
and layout conditions. Our Applications Engineers can recommend potential
solutions and discuss the possibility of our modifying a given device's internal
fi ltering to meet your specifi c requirements. Contact our Applications Engi-
neering Group for additional details.
Input Fusing
UNR 30-66W Series DC/DC converters are not internally fused. 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
exist. To allow for inrush transients, fuses should rated for approximately 2
times the maximum input rms current.
Start-Up Time
The V
IN
to V
OUT
Start-Up Time is the interval between the time at which a
ramping input voltage crosses the lower limit of the specifi ed input voltage
range (4.75 Volts) and the fully loaded output voltage enters and remains
within it specifi ed accuracy band. Actual measured times will vary with input
source impedance, external input capacitance, and the slew rate and fi nal
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 Remote On/Off Control with the nominal input voltage already applied to
the converter. The specifi cation defi nes the interval between the time at which
the converter is turned on and the fully loaded output voltage enters and
remains within its specifi ed accuracy band. See Typical Performance Curves
for details
Figure 2. Driving the On/Off Control Pin
Input Overvoltage and Reverse-Polarity Protection
UNR 30-66W Series DC/DC converters do not incorporate either input over-
voltage or input reverse-polarity protection. Input voltages in excess of the
listed absolute maximum ratings and input polarity reversals of longer than
"instantaneous" duration can cause permanent damage to these devices.
+INPUT
INPUT
RETURN
ON/OFF
CONTROL
5k
6
7
8
Output Overvoltage Protection
UNR 30-66W 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
=
V
IN
). 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.
Output Overcurrent Detection
Overloading the output of a power converter for an extended period of
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. UNR 30-66W Series DC/DC converters incorporate an output overcur-
rent detection and shutdown function that serves to protect both the power
converter and its load.
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 power (system 5V
power) is ramping up and then "released" once the input has stabilized.
The time duration between the point at which the converter is released and
its fully loaded output settles to within specifi ed accuracy can be found in
the Performance/Functional Specifi cations Table. See Start-Up Time for more
details.
On/Off Control
The On/Off Control pin may be used for remote on/off operation. UNR
30-66W Series DC/DC converters are designed so that they are enabled
when the control pin is pulled high or left open, and disabled when the control
pin is pulled low (see Performance Specifi cations for limits). As shown in
Figure 2, all models have internal 5k
pull-up resistors to +Input.
Dynamic control of the on/off function is best accomplished with a mechani-
cal relay or open-collector/open-drain drive circuit (optically isolated if appro-
priate). The drive circuit should be able to sink appropriate current when
activated and withstand appropriate voltage when deactivated.
UNR Models
N O N - I S O L A T E D , 3 0 - 6 6 W , O P E N - F R A M E D C / D C C O N V E R T E R S
5
LOAD
20k
5-10
Turns
+INPUT
INPUT
RETURN
+OUTPUT
TRIM
OUTPUT
RETURN
Trim
Down
Trim Up
LOAD
+INPUT
INPUT
RETURN
+OUTPUT
TRIM
OUTPUT
RETURN
Figure 4. Trim Connections Using Fixed Resistors
Temperature Derating
The outstanding electrical effi ciency of the UNR 30-66W Series' synchro-
nous-rectifi er design and the excellent thermal conductivity of its aluminum
base PCB/Heatsink construction combine to eliminate the need for supple-
mental forced-air cooling in the majority of routine applications. See Derat-
ing Curves.
Note: Install either a fi xed trim-up resistor or a fi xed trim-down resistor
depending upon desired output voltage.
Output Voltage Trimming
Trimming is accomplished with either a trimpot or a single fi xed resistor. The
trimpot should be connected between +Output and Output Return 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 fi xed resistor
which should 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 Output
Return to trim up the output voltage. Fixed resistors should be metal-fi lm
types with absolute TCR's less than 100ppm/
C to ensure stability.
The equations and look-up table below can be used as starting points for
selecting specifi c trim-resistor values. Recall that untrimmed devices are
guaranteed to be
1% accurate.
UNR-3.3/15-D5 & UNR-3.3/20-D5 Trim Equations
UNR-2.5/15-D5 & UNR-2.5/20-D5 Trim Equations
Figure 3. Trim Connections Using a Trimpot
When the output current of a thermally stabilized converter exceeds the
maximum rating (15A models by 20% typ., 30% max.; 20A models by 60%
typ., 73% max.), the internal overcurrent detection circuit automatically shuts
down the converter by discharging the soft-start circuit of the pulse width
modulator (PWM). In this off state, which is similar to that achieved by pulling
the On/Off Control low, the output voltage quickly drops as the output capaci-
tors discharge into the load. Since there is no longer any output current,
the overcurrent detection circuit is released, allowing the soft-start circuit
to recharge and the converter to turn on again. If the faulty load condition
persists, the overcurrent detection circuit will again discharge the soft-start
circuit and shut down the converter. This continuous on/off cycling of the
converter is referred to as "hiccup mode." Once the overload condition is
removed, the converter remains on, and the output voltage is quickly restored
to its regulated value.
The components used to sense the output current have large temperature
coeffi cients. Consequently, in a "cold-start" situation, the Overcurrent Detec-
tion Point may temporarily move to 160% to 195% for 15A models and 120%
to 145% for 20A models above the rated current specifi cation. The device
quickly heats up, particularly if an overload situation exists, and restores the
normal Overcurrent Detection Point.
The overcurrent detection circuitry helps keep internal current levels and
operating temperatures within safe operating limits. Nevertheless, sustained
operation at current levels above the rated output current but below the Over-
current Detection Point may result in permanent damage to the converter
(unless active cooling keeps internal temperatures below safe limits).
UP
V
O
3.3
R
T
(k
) =
9.495
DOWN
3.3 V
O
R
T
(k
) =
1
1
7.5(V
O
1.27)
UP
V
O
2.5
R
T
(k
) =
9.45
DOWN
2.5 V
O
R
T
(k
) =
1.62
1.62
7.5(V
O
1.26)
Note: Resistor values are in k
. Accuracy of adjustment is subject to
tolerances of resistors and factory-adjusted, initial output accuracy.
V
O
= desired output voltage.
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