New low-voltage microprocessor and memory chips are driving the migration
from centralized to distributed power processing in modern telecommunication
and computer systems. Powering these new chips requires local, on-board power
converters that rapidly source large amounts of current while maintaining accurate
voltages with minimal ripple and noise. The distribution losses, unpredictable regula-
tion and poor transient response of traditional centralized power systems are no
longer acceptable. Power processing at the "point-of-use" is frequently the only way
to achieve desired performance.
DATEL’s new UNR Series of non-isolated, 3.3V output, 5V or 12V input, switching
DC/DC converters were specifically designed for on-board usage in today’s mixed-
logic 5V/3.3V systems. They also support those systems that are already drawing
maximum current from their 5V buses and must resort to their 12V buses.
These low-cost, extremely efficient (typically 90%) power converters are capable
of delivering full rated output currents (2.5-12 Amps) while maintaining low case
temperatures without the need for heat sinks or any auxiliary cooling. UNR Series
devices combine proven circuit architectures, contemporary SMT-on-ceramic and
SMT-on-pcb assembly techniques, and a new thermally-conductive potting com-
pound to achieve high output power in the smallest packages possible.
DATEL is currently developing UNR Series devices that incorporate active load
sharing with output current/voltage-sensing capabilities. We can also quickly modify
existing devices for application-specific output voltages from 1.8 to 5 Volts. Please
contact us with your unique requirements ... we may already have the product you
need.
DATEL also makes a complete line of isolated 3.3V DC/DC converters that oper-
ate from wide-range input voltages from 4.6 to 72V.
+V
IN
+V
OUT
INPUT
RETURN
LOGIC
GROUND
OUTPUT
RETURN
ON/OFF
CONTROL
PWM
CONTROLLER
REFERENCE &
ERROR AMP
For full details go to
www.murata-ps.com/rohs
Figure 1. Simplified Schematic
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MDC_UNR8-40W.C01
Page 1 of 6
UNR Series
Performance Specifications and Ordering Guide
Output
Model
UNR-3.3/3000-D5
UNR-3.3/2500-D12
UNR-3.3/8000-D5
UNR-3.3/12000-D5
➀
➁
➂
➃
➀
Single Output, Non-Isolated, 3.3V
8-40 Watt, DC/DC Converters
Input
I
IN
➃
(mA, Max.)
25/2390
35/856
25/6330
50/9700
V
OUT
(Volts)
3.3
3.3
3.3
3.3
I
OUT
(mA, Max.)
3000
2500
8000
12000
Ripple/Noise
➁
(mVp-p, Max.)
140
100
75
125
Regulation (Max.)
Load
➂
Line
±0.25%
±0.2%
±0.25%
±0.25%
±0.5%
±0.5%
±0.5%
±0.75%
V
IN
Nom.
(Volts)
5
12
5
5
Range
(Volts)
4.75-5.5
10.8-13.2
4.75-5.5
4.75-5.5
Efficiency
(Min.)
85%
82%
86%
84%
Package
(Case,
Pinout)
C7, P9
C7, P10
C5, P9
C6, P9
Typical at T
A
= +25°C under nominal line voltage and full load conditions unless otherwise noted. These devices require external input and output capacitors for normal operation.
20MHz bandwidth. Specified with external I/O capacitors. See Technical Notes.
10% to 100% load.
Nominal line voltage, no load/full load conditions.
Part Number Structure
Case C5
U NR
-
3.3
/
8000
-
D5
Output Configuration:
U
= Unipolar
Non-Isolated
Nominal Output Voltage:
3.3 Volts
Maximum Output Current
in mA
Input Voltage Range:
D5
= 4.75-5.5 Volts (5V nominal)
D12
= 10.8-13.2 Volts (12V nominal)
Mechanical Specifications
Case C7
Case C6
Pin
1
2
3
4
5
6
I/O Connections
Function P9
Function P10
Logic Gnd.
Do Not Connect
On/Off Control
No Connect
+Output
+Output
Output Rtn.
Output Rtn.
Input Rtn.
Input Rtn.
+Input
+Input
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MDC_UNR8-40W.C01
Page 2 of 6
UNR Series
Typical @ T
A
= +25°C under nominal line voltage and full load conditions unless noted.
➀ ➁
Performance/Functional Specifications
Input
Input Voltage Range:
"D5" Models
"D12" Models
Input Current
Input Filter Type
➁
Overvoltage Shutdown
Reverse-Polarity Protection
On/Off (Sync.) Control
(Pin 2)
➂
Single Output, Non-Isolated, 3.3V
8-40 Watt, DC/DC Converters
Absolute Maximum Ratings
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. Storage temperatures have been verified for 168 hours.
4.75-5.5 Volts (5V nominal)
10.8-13.2 Volts (12V nominal)
See Ordering Guide
None
None
Yes (Instantaneous, 10A maximum)
TTL high = off, low (or open) = on
Output
Input Voltage:
"D5" Models
"D12" Models
Input Reverse-Polarity Protection
7 Volts
15 Volts
Current must be <10A. Brief
duration. Fusing recommended.
None
Current limited. Max. current and
short-circuit duration model
dependent.
–55 to +105°C
+300°C
V
OUT
Accuracy
(50% load)
Temperature Coefficient
Ripple/Noise
(20MHz BW)
➁
Line/Load Regulation
Efficiency
Current Limiting
±1%
±0.02% per °C
See Ordering Guide
See Ordering Guide
See Ordering Guide
Auto-recovery
Dynamic Characteristics
Output Overvoltage Protection
Output Current
Storage Temperature
Lead Temperature
(soldering, 10sec.)
Transient Response
(25% load step)
Switching Frequency:
"D5"
Models
"D12" Models
100µsec to ±1.5% of final value
Temperature Derating
75kHz (±5kHz)
90kHz (±5kHz)
20
19
18
17
16
15
UNR-3.3/12000-D5
UNR-3.3/8000-D5
UNR-3.3/3000-D5
UNR-3.3/2500-D12
A
B
C
D
Environmental
Operating Temperature
(ambient):
Without Derating:
3A an 8A "D5" Models
12A "D5" and 2.5A "D12" Models
With Derating
Storage Temperature
Output Current (Amps)
–40 to +50°C
–40 to +45°C
to +100°C (See Derating Curves)
–55 to +105°C
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
40
0
40
45
50
55
60
65
70
D
C
B
A
Physical
Dimensions:
3A "D5" and 2.5A "D12" Models
8A "D5" Model
12A "D5" Model
Shielding
Case Connection
Case Material
Pin Material
Weight:
3A "D5" and 2.5A "D12" Models
8A "D5" Model
12A "D5" Model
1" x 1" x 0.45" (25 x 25 x 11.4mm)
2" x 1" x 0.45" (51 x 25 x 11.4mm)
2" x 2" x 0.45" (51 x 51 x 11.4mm)
5-sided
➃
Pin 4 (Output Return)
Corrosion resistant steel with
epoxy-based enamel finish
Brass, solder coated
1 ounce (28.4 grams)
1.5 ounces (42.5 grams)
2 ounces (56.7 grams)
75
80
85
90
95
100
Ambient Temperature (°C)
➀
These power converters require a minimum 10% loading to maintain specified regulation.
Operation under no-load conditions will not damage these devices, however, they may
not meet all listed specifications.
➁
These power converters do not have internal input filters and do require external input
and output capacitors to achieve rated specifications. Application-specific internal input/
output filtering can be added upon request. Contact DATEL for details.
➂
On/Off Control pins are included on "D5" models only. See Technical Notes for details.
Applying a voltage to the Control pin when no input power is applied to the converter can
cause permanent damage to the converter.
➃
Cases can be provided with 6-sided shielding. Contact DATEL for details.
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MDC_UNR8-40W.C01
Page 3 of 6
UNR Series
Single Output, Non-Isolated, 3.3V
8-40 Watt, DC/DC Converters
Technical Notes
Input Capacitors
As shown in the simplified schematic, UNR Series power converters do not
have internal input capacitors. Users must install external input capacitors for
the devices to achieve specified operation. The input capacitor functions as a
true energy-storage element. Its required capacitance varies as a function of
applied line voltage. Additionally, as the power converter’s input FET switch
cycles on and off, the input capacitor must have the ability to rapidly supply
pulses of relatively high current. Therefore, required rms-ripple-current capa-
bilities of the input capacitor will vary as a function of the power converter’s
load current. Rather than install a large, expensive, internal capacitor that
UNR-3.3/12000-D5
Minimum Input Capacitor Value vs. V
IN
@ Full Load
10000
8
addresses all possible load conditions, we have chosen to leave the capaci-
tor out so that you may select a cost-effective component appropriate to your
particular application.
Use the charts below to determine how much input capacitance is required
as a function of input voltage and also to determine the required rms-ripple-
current capabilities of the needed capacitor as a function of output load
current. Note that "low-line" conditions will require proportionally more input
capacitance in order to maintain the required energy levels and that higher
output currents will obviously require higher input currents. Contact DATEL’s
Applications Engineering Group if you have any questions.
C
IN
RMS Ripple Current vs. I
LOAD
C
IN
RMS Ripple Current (Amps)
4.80
4.85
4.90
4.95
5.00
5.05
5.10
5.15
5.20
5.25
5.30
5.35
5.40
5.45
5.50
7
6
5
4
3
2
1
0
1
2
3
4
5
6
7
8
9
10
11
12
Input Capacitance (μF)
1000
100
4.75
Input Voltage (Volts)
Output Load Current (Amps)
UNR-3.3/8000-D5
10000
Minimum Input Capacitor Value vs. V
IN
@ Full Load
4
3.5
3
2.5
2
1.5
1
0.5
0
C
IN
RMS Ripple Current vs. I
LOAD
1000
100
4.75
4.80
4.85
4.90
4.95
5.00
5.05
5.10
5.15
5.20
5.25
5.30
5.35
5.40
5.45
5.50
C
IN
RMS Ripple Current (Amps)
Input Capacitance (μF)
1
2
3
4
5
6
7
8
Input Voltage (Volts)
Output Load Current (Amps)
UNR-3.3/3000-D5
1000
Minimum Input Capacitor Value vs. V
IN
@ Full Load
2
1.75
C
IN
RMS Ripple Current vs. I
LOAD
C
IN
RMS Ripple Current (Amps)
4.80
4.85
4.90
4.95
5.00
5.05
5.10
5.15
5.20
5.25
5.30
5.35
5.40
5.45
5.50
Input Capacitance (μF)
1.50
1.25
1
0.75
0.50
0.25
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3.0
100
10
4.75
Input Voltage (Volts)
Output Load Current (Amps)
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MDC_UNR8-40W.C01
Page 4 of 6
UNR Series
Single Output, Non-Isolated, 3.3V
8-40 Watt, DC/DC Converters
Reducing Output Ripple/Noise
In addition to their internal output capacitors, UNR Series DC/DC convert-
ers require the installation of external output capacitors to achieve their
published ripple/noise specifications. The selected caps should be low-ESR,
tantalum or electrolytic types, and they should be located as close to the
converters as possible. Recommended values are listed in the table below.
Part Number
UNR-3.3/3000-D5
UNR-3.3/2500-D12
UNR-3.3/8000-D5
UNR-3.3/12000-D5
Output Capacitor
470µF, 6V, Low ESR
100µF, 6V, Low ESR
1000µF, 6V, Low ESR
1000µF, 6V, Low ESR
If desired, a synchronizing clock can be applied to pin 2 on "D5" models to
control the converter’s internal clock oscillator. The applied clock should be
a square wave with a maximum 1µsec "high" duration and an amplitude be-
tween +2V and +5V (see On/Off Control) referenced to pin 1 (Logic Ground).
The frequency of the synchronizing clock must be higher than that of the
standalone converter. Therefore, it should be 85kHz ±5kHz.
Synchronization Issues
Because of the comparatively small differential between their input and out-
put voltages, 5V-to-3.3V DC/DC converters capable of sourcing high output
current also demand high input current. Most of these high-current DC/DC’s
use switching architectures employing fixed-frequency clock oscillators, and
their input currents include both dc (average) and ac (ripple) components.
If you have multiple DC/DC’s connected to a single main power bus, you may
need to consider that all the converters will not be switching at exactly the
same frequency (due to normal component and manufacturing tolerances).
Consequently, the converters may randomly "self-synchronize" in their de-
manding of peak current from the main power bus. Peak currents all drawn
simultaneously can be significantly greater than the sum of average input
currents. This phenomenon can result in unwanted harmonic interactions
from converter to converter along the power bus.
One solution to this potential problem is to use the converters' On/Off Control
function to effectively "de-synchronize" their clocks. Forcing the multiple
clocks to be out of phase with each other relaxes the required performance
characteristics of the main power bus so the bus now has to carry the sum of
the average currents of all the converters plus only one peak current.
Remote On/Off Control and the Logic Ground Pin
The On/Off Control pin (pin 2 on "D5" units) may be used for digitally con-
trolled on/off operation. A TTL logic high (+2 to +5 Volts, 250µA max.) ap-
plied to pin 2 disables the converter. A TTL logic low (0 to +0.8 Volts, 70µA
max.), or no connection, enables the converter. Control voltages should be
referenced to pin 1 (Logic Ground). Applying a voltage to the Control pin
when no input power is applied to the converter can cause permanent dam-
age to the converter.
The Input Return (pin 5), Output Return (pin 4) and Logic Ground (pin 1 on
"D5" models) are all tied together internal to the device. To the extent pos-
sible, load current should be returned to pin 4. Pin 5 should be connected
back to the input supply with as low an impedance as possible so that input
return current flows through pin 5. The internal trace leading to the Logic
Ground pin is not designed to carry high currents. Devices should not be
installed in a manner that results in high current flow through pin 2 (i.e., pins
4 and 5 should never be left open or attached via high-impedance connec-
tions).
"D12" models do not have On/Off Control functions. Their pin 2 (No Con-
nect) is not electrically connected to any internal circuitry and may be tied
to any convenient external run. Their pin 1 (Do Not Connect) is a test point.
Pin 1 may be soldered to an island for mechanical mounting purposes, but it
should not have an electrical connection to external circuitry.
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