unr-3.3/3-d12 C&D Technologies., unr-3.3/3-d12 Datasheet - Page 4

• Manufacturer Part Number: unr-3.3/3-d12
• Description: Single Output, Non-isolated, 1.8/2.5/3.3vo U T 3.6-10w Dc/dc Converters
• Manufacturer: C&D Technologies.

Return Current Paths
The Input Return, Output Return and Logic Ground are all connected to each
other internal to each device. To the extent possible, all load current should
be returned through the Output Return (via low-impedance runs) and all input
current returned through the Input Return. Any control signals applied to the
On/Off Control pin should be referenced to Logic Ground. The internal trace
leading to Logic Ground is not designed to carry high current. Devices should
never be installed in a manner that results in high current flow through Logic
Ground (i.e., the Input/Output Returns should never be left open or attached
via high-impedance connections).
I/O Filtering and Noise Reduction
All D5 models of UNR 3.6-10W Series DC/DC converters achieve their
rated ripple and noise specifications without the use of external input/output
capacitors. The UNR-3.3/3-D12 and D12SM models are tested and specified
with a single, external 22µF input capacitor (minimally rated for 1.5Arms
ripple current and 120mΩ ESR).
In critical applications, input/output ripple/noise may be further reduced by
installing additional external I/O caps. Input capacitors, which function pri-
marily as energy-storage elements, should be selected for bulk capacitance,
low ESR and high rms-ripple-current ratings. Output capacitors, which func-
tion more as true filter elements, should be selected for bulk capacitance, low
ESR, and appropriate frequency response. All caps should have appropriate
voltage ratings and be mounted as close to the converters as possible.
Temperature variations for all parameters should obviously 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 will be happy to recommend
potential solutions and can discuss the possibility of our modifying a given
device’s internal filtering to meet your specific requirements. Contact our
Applications Engineering Group for additional details.
T E C H N I C A L
T E M P E R A T U R E D E R A T I N G
10
9
8
7
6
5
4
3
2
1
0
–40
UNR-3.3/3-D5
UNR-3.3/3-D5SM
UNR-3.3/3-D12
UNR-3.3/3-D12SM
0
40
45
UNR-1.8/2-D5
UNR-1.8/2-D5SM
UNR-2.5/2-D5
UNR-2.5/2-D5SM
N O T E S
50
Ambient Temperature (˚C)
55
60
65
70
www.murata-ps.com
75
80
85
Single Output, Non-Isolated, 1.8/2.5/3.3V
90
95
100
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 UNR Series 3.6-10 Watt DC/DC Converters, you
should use slow-blow type fuses with values no greater than the following.
Start-Up Threshold and Undervoltage Shutdown
(UNR-3.3/3-D12 and D12SM only)
Under normal start-up conditions, UNR-3.3/3-D12 and D12SM devices will
not begin to regulate until the ramping input voltage exceeds the Start-Up
Threshold Voltage (typically 10.2V). Once operating, devices will not turn off
until the input voltage drops below the Undervoltage Shutdown/Lockout limit
(typically 9.6V). Subsequent re-start will not occur until the input is brought
back up to the Start-Up Threshold. This built-in hysteresis obviously avoids
any indeterminate on/off conditions at a single voltage.
Start-Up Time
For the three D5 models (that do not have an input turn-on threshold), the V
to V
to the device and the fully loaded output voltage enters and remains within
its specified accuracy band.
For the UNR-3.3/3-D12 and D12SM, V
between the time at which a rapidly ramping input voltage crosses the turn-on
threshold point 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 to the converter.
The On/Off to V
the On/Off Control with the nominal input voltage already applied to the
converter. The specification defines the interval between the time at which the
converter is turned on and the fully loaded output voltage enters and remains
within its specified accuracy band.
Internal circuit design of the 3.3V
greater than 1.0V be present on the output pins at power-up. 1.8V
2.5V
output pins at power-up. Failure to comply may result in start-up problems.
OUT
OUT
Start-Up Time is the interval between the time a step input is applied
models can not have voltages greater than 1.2V present on their
UNR-3.3/3-D12/-D12SM
UNR-1.8/2-D5/-D5SM
UNR-2.5/2-D5/-D5SM
UNR-3.3/3-D5/-D5SM
Model Number
OUT
Start-Up Time assumes the converter is turned off via
Technical enquiries email: [e-mail], tel:
OUT
out
models mandates that no voltages
IN
Fuse Value
to V
3.6-10W DC/DC Converters
1.5 Amps
1.5 Amps
2 Amps
3 Amps
OUT
Start-Up Time is the interval
UNR Series
MDC_UNR 3.6-10W_B01
[phone]
OUT
and
Page 4 of 7
IN