additional external load capacitance the rise time of the input voltage will determine the maximum external
capacitance value for guaranteed start up. The slower the rise time of the input voltage the greater the maximum value of the
additional external capacitance for reliable start up.
INPUT CHARACTERISTICS
Parameter
Voltage range
Ripple current (I
RIPPLE
)
Zero load input current
(I
CCZL
)
Conditions
NMT0572SC
NMT1272SC
NMT0572SC
NMT1272SC
NMT0572SC, 0% output load
NMT1272SC, 0% output load
Min.
4.5
10.8
Typ.
5.0
12
85
66
50
27.5
Max.
5.5
13.2
Units
V
mA
80
50
mA
OUTPUT CHARACTERISTICS
Parameter
Total Rated Power (P
OUT
)
Single Channel Voltage Set
Point Accuracy
Output Voltage - V
OUT
1
Output Voltage - V
OUT
2
Output Voltage - V
OUT
3
Line regulation
Load regulation
Ripple & Noise
Conditions
Total of all outputs or any single output
P
OUT
= 100mW
P
OUT
= 3W
P
OUT
= 100mW
P
OUT
= 3W
P
OUT
= 100mW
P
OUT
= 3W
P
OUT
= 100mW
P
OUT
= 3W
V
IN
= 90% to 110% of nominal
P
OUT
= 100mW to 3W
DC to 20MHz single channel (24V)
Min.
0.1
0
-7.5
24
22.2
48
44.4
72
66.6
Typ.
Max.
3.0
10
2.5
26.4
24.6
52.8
49.2
79.2
73.8
1.2
15
400
Units
W
%
DESCRIPTION
The NMT series is a range of DC/DC convert-
ers offering three output voltages of -24V, -48V
and -72V from a single isolated 5V or 12V input
voltage. The product is designed for use with
telecommunications circuits requiring an on board
supply for the -72V RING-TIP connection service
generated from a nominal 5V or 12V DC input
supply rail. The device also offers battery level
voltages of -24V and -48V for access control and
data pump IC’s. The product is packaged in an
8 pin SIP case for minimum PCB footprint. The
rated power may be shared or drawn from any
one output providing the total output load does not
exceed 3W.
V
1.01
8
220
%
mV
ISOLATION CHARACTERISTICS
Parameter
Isolation test voltage
Isolation Capacitance
Insulation Resistance
Conditions
Flash tested for 1 second
NMT0572SC, 1MHz, 1V
NMT1272SC, 1MHz, 1V
1000VDC
Min.
1000
Typ.
65
130
10
Max.
Units
VDC
pF
GΩ
1
ABSOLUTE MAXIMUM RATINGS
Short-circuit protection
4
Lead temperature 1.5mm from case for 10 seconds
Input Voltage V
IN
, NMT0572SC
Input voltage V
IN
, NMT1272SC
1 second
300°C
7V
15V
For full details go to
www.murata-ps.com/rohs
1. Assuming all 3 channels are equally loaded.
2. Assuming only 1 channel is loaded.
3. Calculated using MIL-HDBK-217F with nominal input voltage at full load.
4. Supply voltage must be disconnected at the end of the short circuit duration.
All specifications typical at T
A
=25°C, nominal input voltage and rated output current unless otherwise specified.
www.murata-ps.com/support
KDC_NMT.E04
Page 1 of 4
NMT Series
Triple Output 3W DC/DC Converters
GENERAL CHARACTERISTICS
Parameter
Efficiency
Switching frequency
Conditions
All channels or any single channel
Min.
75
Typ.
85
85
Max.
Units
%
kHz
TEMPERATURE CHARACTERISTICS
Parameter
Operating temperature
Storage
Case temperature rise above
ambient
Conditions
Min.
-40
-50
Typ.
Max.
85
125
Units
°C
1 litre static air chamber
27
OUTPUT VOLTAGE CONFIGURATION
Although the output is described for negative rails, the input and output circuits are iternally isolated hence positive rails can also be generated, or a mixture of positive
and negative. The output +V
OUT
rail reference can be taken from any of the output terminals to give the range of outputs as described in the Output Voltage Configura-
tions table below.
Channel Name
Standard Ref
Option 1
Option 2
Option 3
OV
+24V
+48V
+72V
+V
OUT
-V
OUT1
-V
OUT2
-V
OUT3
-24V
-48V
-72V
OV
-24V
-48V
+24V
OV
-24V
+48V
+24V
OV
POWER SHARING
The 3W total power delivery can be taken from either a single channel, or from any combination of all three channels. This allows an enormous amount of flexibility,
especially when combined with the selectable output OV reference. For example, using the option 2 output configuration; -24V at 0.5W, +24V at 1W and +48V at 1.5W
power supplies are available from a single NMT device.
PERFORMANCE CHARACTERISTICS
NMT0572SC - Channel -V
OUT1
(24V NOM)
NMT1272SC - Channel -V
OUT1
(24V NOM)
NMT0572SC - Channel -V
OUT2
(48V NOM)
NMT1272SC - Channel -V
OUT2
(48V NOM)
NMT0572SC - Channel -V
OUT3
(72V NOM)
NMT1272SC - Channel -V
OUT3
(72V NOM)
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KDC_NMT.E04
Page 2 of 4
NMT Series
Triple Output 3W DC/DC Converters
APPLICATION NOTES
RIPPLE SPECIFICATION
The output ripple for the NMT series is higher than standard for a Murata Power Solutions DC/DC converter.
This is due to using low value ceramic capacitors internally for longer life perfomance of the component and
the superimposition of ripples between each output channel. Consequently with a maximum 400mV ripple per
output channel, at -72V the ripple is potentially three times this value (1.2V). The ripple will always be additively
superimposed since the output windings are synchronized.
To reduce ripple, external capacitors are recommended with a value of 1μF per channel (see figure 1). This
typically reduces the ripple to 50mV per channel. Further ripple reduction can be achieved by use of series
inductors on each output channel plus additional external capacitors to form a pi-filter with the internal capaci-
tors of the device.
SLIC CIRCUITS
T
he primary application for the NMT series is in subscriber line interface circuits (SLIC’s), particularly for the
Integrated Services Digital Network (ISDN). The NMT can also be used in standard telecommunications circuits
where a local power source is preferred to the telephone system power due to either the power quality of the
telecommunications system power supply or to avoid potential power line disturbances, such as lightening
strikes and access switching, which will effect the target circuit function.
Another application area is in fibre-in-the-loop (FITL) or radio-in-the-loop (RITL) interfacing via a standard tele-
communication SLIC, where the usual telecommunication battery voltage is not available due to the transmis-
sion media in use (fibre or radio). In particular, FITL/RITL interfaces directly on PC cards, in local monitor and
boost circuits and at exchanges between the fibre/radio and wire media.
The supply rails can be used for ringing generators as well as SLIC circuits or where both are combined, such as
in the AMD AM79R79 Ringing SLIC device (see figure 2). The -72V rail is used primarily for the generation of the
ringing signal (V
BAT
1), the -48V rail is used to supply in line access circuitry (V
BAT
2) and the -24V supply for the
on-chip regulator for the logic interface (V
NEG
). Alternative devices from other manufacturers could use the -24V
output for their internal circuit supply and -72V for ringing.
Figure 1. V
OUT3
Output Ripple
Top: No external capacitors
Bottom: 1μF per channel external capacitors
Figure 2. Supply for Ringing SLIC Device
TECHNICAL NOTES
ISOLATION VOLTAGE
‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Voltage’, ‘Proof Voltage’, ‘Dielectric Withstand Voltage’ & ‘Isolation Test Voltage’ are all terms that relate to the same thing, a test voltage,
applied for a specified time, across a component designed to provide electrical isolation, to verify the integrity of that isolation.
Murata Power Solutions NMT series of DC/DC converters are all 100% production tested at their stated isolation voltage. This is 1kVDC for 1 second.
A question commonly asked is, “What is the continuous voltage that can be applied across the part in normal operation?”
For a part holding no specific agency approvals, such as the NMT series, both input and output should normally be maintained within SELV limits i.e. less than 42.4V peak, or
60VDC. The isolation test voltage represents a measure of immunity to transient voltages and the part should never be used as an element of a safety isolation system. The part
could be expected to function correctly with several hundred volts offset applied continuously across the isolation barrier; but then the circuitry on both sides of the barrier must
be regarded as operating at an unsafe voltage and further isolation/insulation systems must form a barrier between these circuits and any user-accessible circuitry according to
safety standard requirements.
REPEATED HIGH-VOLTAGE ISOLATION TESTING
It is well known that repeated high-voltage isolation testing of a barrier component can actually degrade isolation capability, to a lesser or greater degree depending on materials,
construction and environment. The NMT series has toroidal isolation transformers, with no additional insulation between primary and secondary windings of enameled wire. While
parts can be expected to withstand several times the stated test voltage, the isolation capability does depend on the wire insulation. Any material, including this enamel (typically
polyurethane) is susceptible to eventual chemical degradation when subject to very high applied voltages thus implying that the number of tests should be strictly limited. We
therefore strongly advise against repeated high voltage isolation testing, but if it is absolutely required, that the voltage be reduced by 20% from specified test voltage.
This consideration equally applies to agency recognized parts rated for better than functional isolation where the wire enamel insulation is always supplemented by a further
insulation system of physical spacing or barriers.
www.murata-ps.com/support
KDC_NMT.E04
Page 3 of 4
NMT Series
Triple Output 3W DC/DC Converters
PACKAGE SPECIFICATIONS
MECHANICAL DIMENSIONS
0.858
(21.80)
0.295
(7.50)
PIN CONNECTIONS - 8 PIN SIP
Pin
1
2
5
6
7
8
Function
+V
IN
-V
IN
+V
OUT
-V
OUT1
-V
OUT2
-V
OUT3
0.437
(11.10)
NMT0572SC
XYYWW
0.022 (0.55)
0.018 (0.45)
TUBE OUTLINE DIMENSIONS
1 2
0.181 (4.60)
0.142 (3.60)
5 6 7 8
0.022 (0.55)
0.018 (0.45)
0.046
(1.17)
0.083 (2.10)
0.0118 (0.30)
0.0078 (0.20)
All dimensions in inches ±0.01 (mm ±0.25mm). All pins on a 0.1 (2.54) pitch and within
±0.01 (0.25) of true position.
Weight: 3.85g
Unless otherwise stated all dimensions in inches ±0.02 (mm ±0.5mm).
Tube length : 20.47±0.079 (520mm±2mm).
Tube Quantity : 23
RECOMMENDED FOOTPRINT DETAILS`
RoHS COMPLIANT INFORMATION
This series is compatible with RoHS soldering
systems with a peak wave solder temperature
of 300ºC for 10 seconds. The pin termination
finish on this product series is Tin Plate, Hot
Dipped over Matte Tin with Nickel Preplate.
The series is backward compatible with Sn/Pb
soldering systems.
For further information, please visit www.murata-ps.com/rohs
Unless otherwise stated all dimensions in inches ±0.02 (mm ±0.5mm).
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following
operating requirements
and the
Life and Safety Critical Application Sales Policy:
Refer to:
http://www.murata-ps.com/requirements/
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
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