Figure 1. Simplified Schematic
Features
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
regulation 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
operate from wide-range input voltages from 4.6 to 72V.
INNOVATION and EX C ELL E N C E
Single Output
UNR Series
Non-Isolated, 3.3V
8-40 Watt, DC/DC Converters
Low cost
5V or 12V inputs
3.3V1% (33mV) outputs
0.25% (8mV) max. line regulation
0.5% (17mV) max. load regulation
Guaranteed efficiencies to 86%
Power densities to 29W/in
3
High output current ... small packages:
3A (1" x 1" package)
8A (2" x 1" package)
No heat sinks required
40 to +100
o
C operating temperatures
On/off/sync control
UL, CSA, IEC safety approvals
+V
IN
+V
OUT
PWM
CONTROLLER
REFERENCE &
ERROR AMP
INPUT
RETURN
LOGIC
GROUND
ON/OFF
CONTROL
OUTPUT
RETURN
DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048 (U.S.A.)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 Email: datellit@mcimail.com
UNR-3.3/3000-D5
3.3
3000
140
0.25%
0.5%
5
4.75-5.5
25/2390
85%
C7, P9
UNR-3.3/2500-D12
3.3
2500
100
0.2%
0.5%
12
10.8-13.2
35/856
82%
C7, P10
UNR-3.3/8000-D5
3.3
8000
75
0.25%
0.5%
5
4.75-5.5
25/6330
86%
C5, P9
UNR-3.3/12000-D5
3.3
12000
125
0.25%
0.75%
5
4.75-5.5
50/9700
84%
C6, P9
UNR Series
N O N - I S O L A T E D , 3 . 3 V , 8 - 4 0 W D C / D C C O N V E R T E R S
Performance Specifications and Ordering Guide
V
OUT
(Volts)
Output
Package
(Case,
Pinout)
Efficiency
(Min.)
Regulation (Max.)
Line
V
IN
Nom.
(Volts)
Range
(Volts)
Model
Input
Input Voltage Range:
D5 = 4.75-5.5 Volts (5V nominal)
D12 = 10.8-13.2 Volts (12V nominal)
Output Configuration:
U = Unipolar
2
Non-Isolated
Nominal Output Voltage:
3.3 Volts
Maximum Output Current
in mA
Mechanical Specifications
Part Number Structure
Mechanical Specifications
I
OUT
(mA, Max.)
I
IN
(mA, Max.)
Function P9
Logic Gnd.
On/Off Control
+Output
Output Rtn.
Input Rtn.
+Input
I/O Connections
Function P10
Do Not Connect
No Connect
+Output
Output Rtn.
Input Rtn.
+Input
Pin
1
2
3
4
5
6
Ripple/Noise
(mVp-p, Max.)
Case C7
Typical at T
A
= +25C 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.
Model UNR-3.3/12000-D5 is no longer available. Use DATEL model UNR-3.3/12-D5 for replacement.
Case C5
Case C6
METAL CASE
INSULATED BASE
0.040 0.002 DIA
(1.016 0.051)
2.00
(50.80)
0.45
(11.43)
0.20 MIN
(5.08)
0.10
(2.54)
0.800
(20.320)
0.300
(7.620)
1.800
(45.720)
0.200
(5.080)
1.00
(25.40)
BOTTOM VIEW
1
2
3
4
6
0.10
(2.54)
5
0.400
(10.160)
METAL CASE
INSULATED BASE
0.040 0.002 DIA
(1.016 0.051)
1.00
(25.40)
0.45
(11.43)
0.20 MIN.
(5.08)
0.200
(5.080)
0.10
(2.54)
BOTTOM VIEW
3
1.00
(25.40)
0.800
(20.320)
0.100
(2.540)
1
2
4
6
0.800
(20.320)
0.200
(5.080)
0.400
(10.160)
5
0.10
(2.54)
Load
METAL CASE
INSULATED BASE
2.00
(50.80)
0.45
(11.43)
0.20 MIN
(5.08)
PIN DIAMETER:
PINS 1-2
0.040 0.002 (1.016 0.051)
PINS 3-6
0.060 0.002 (1.524 0.051)
0.10
(2.54)
0.400
(10.160)
1
2
3
1.800
(45.720)
0.300
(7.620)
BOTTOM VIEW
4
6
0.60
(15.24)
2.00
(50.80)
0.200
(5.080)
5
0.800
(20.320)
U NR
-
3.3
/
8000
-
D5
Performance/Functional Specifications
UNR Series
N O N - I S O L A T E D , 3 . 3 V , 8 - 4 0 W D C / D C C O N V E R T E R S
3
Typical @ T
A
= +25C under nominal line voltage and full load conditions unless noted.
Input
Input Voltage Range:
"D5" Models
4.75-5.5 Volts (5V nominal)
"D12" Models
10.8-13.2 Volts (12V nominal)
Input Current
See Ordering Guide
Input Filter Type
None
Overvoltage Shutdown
None
Reverse-Polarity Protection
Yes (Instantaneous, 10A maximum)
On/Off (Sync.) Control (Pin 2)
TTL high = off, low (or open) = on
Output
V
OUT
Accuracy (50% load)
1%
Temperature Coefficient
0.02% per C
Ripple/Noise (20MHz BW)
See Ordering Guide
Line/Load Regulation
See Ordering Guide
Efficiency
See Ordering Guide
Current Limiting
Auto-recovery
Dynamic Characteristics
Transient Response (25% load step)
100sec to 1.5% of final value
Switching Frequency:
"D5" Models
75kHz (5kHz)
"D12" Models
90kHz (5kHz)
Environmental
Operating Temperature (ambient):
Without Derating:
3A an 8A "D5" Models
40 to +50C
12A "D5" and 2.5A "D12" Models
40 to +45C
With Derating
to +100C (See Derating Curves)
Storage Temperature
55 to +105C
Physical
Dimensions:
3A "D5" and 2.5A "D12" Models
1" x 1" x 0.45" (25 x 25 x 11.4mm)
8A "D5" Model
2" x 1" x 0.45" (51 x 25 x 11.4mm)
Shielding
5-sided
Case Connection
Pin 4 (Output Return)
Case Material
Corrosion resistant steel with
epoxy-based enamel finish
Pin Material
Brass, solder coated
Weight:
3A "D5" and 2.5A "D12" Models
1 ounce (28.4 grams)
8A "D5" Model
1.5 ounces (42.5 grams)
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.
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.
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.
Cases can be provided with 6-sided shielding. Contact DATEL for details.
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.
Input Voltage:
"D5" Models
7 Volts
"D12" Models
15 Volts
Input Reverse-Polarity Protection
Current must be <10A. Brief
duration. Fusing recommended.
Output Overvoltage Protection
None
Output Current
Current limited. Max. current and
short-circuit duration model
dependent.
Storage Temperature
55 to +105C
Lead Temperature (soldering, 10sec.)
+300C
Temperature Derating
O
u
tp
u
t
C
u
rre
n
t
(A
m
p
s
)
Ambient Temperature (C)
40 0 40 45 50 55 60 65 70 75 80 85 90 95 100
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
A
B
UNR-3.3/12000-D5
A
UNR-3.3/8000-D5
B
UNR-3.3/3000-D5
C
UNR-3.3/2500-D12
D
C
D
4
UNR Series
N O N - I S O L A T E D , 3 . 3 V , 8 - 4 0 W D C / D C C O N V E R T E R S
1000
100
10
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
0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0
2
1.75
1.50
1.25
1
0.75
0.50
0.25
0
I
npu
t
C
a
paci
t
a
n
c
e
(
F
)
C
IN
R
M
S
R
ip
p
l
e
C
u
rre
n
t
(
A
m
p
s
)
Output Load Current (Amps)
Input Voltage (Volts)
C
IN
RMS Ripple Current vs. I
LOAD
Minimum Input Capacitor Value vs. V
IN
@
Full Load
UNR-3.3/8000-D5
UNR-3.3/3000-D5
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 capabilities 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 addresses all possible load conditions, we have
chosen to leave the capacitor 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.
Technical Notes
4.75 4.80 4.85 4.90 4.95 5.00 5.05 5.10
1 2 3 4 5 6 7 8
10000
1000
100
5.15 5.20 5.25 5.30 5.35 5.40 5.45 5.50
4
3.5
3
2.5
2
1.5
1
0.5
0
Input Ca
pacitance
(
F)
C
IN
RMS R
i
pple Curren
t
(A
mps)
Output Load Current (Amps)
Input Voltage (Volts)
C
IN
RMS Ripple Current vs. I
LOAD
Minimum Input Capacitor Value vs. V
IN
@
Full Load
UNR Series
N O N - I S O L A T E D , 3 . 3 V , 8 - 4 0 W D C / D C C O N V E R T E R S
5
Synchronization
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 1sec "high" duration and an amplitude between
+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 output
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
demanding 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.
Reducing Output Ripple/Noise
In addition to their internal output capacitors, UNR Series DC/DC converters
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
Output Capacitor
UNR-3.3/3000-D5
470F, 6V, Low ESR
UNR-3.3/2500-D12
100F, 6V, Low ESR
UNR-3.3/8000-D5
1000F, 6V, Low ESR
Remote On/Off Control and the Logic Ground Pin
The On/Off Control pin (pin 2 on "D5" units) may be used for digitally controlled
on/off operation. A TTL logic high (+2 to +5 Volts, 250A max.) applied to pin 2
disables the converter. A TTL logic low (0 to +0.8 Volts, 70A 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 damage 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 possible, 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 connections).
"D12" models do not have On/Off Control functions. Their pin 2 (No Connect)
is not electrically connected to any internal circuiitry 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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