ETC NPH25S4812EI

NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
features
p
p
High Efficiency to 89%
p
p
p
p
p
p
p
1.5kV Input to Output Isolation
p
p
p
p
p
Operation to Zero Load
Power Density up to 1.78W/cm3
(28W/in3)
Industry Standard Pinout
UL 1950 Recognised
Non Latching Current Limit
Constant 350kHz Frequency
Versatile Control Options
Continuous Rating to 30W at 60°C
Without Heatsink
Protected Against All Load Faults
pin connections
Single Output Type (top view)
Internal Over Temperature Protection
Uses No Electrolytic Capacitors
UL 94V-0 Package Materials
0V
description
The NPH25S series of DC-DC Converters
combines ease of application with versatility. The
pin pattern is based on the popular industry
standard, but two additional pins may optionally
be fitted to provide a variety of features not
commonly found on units of this type. High
efficiency enables full rating to be achieved in a
small package without heatsinking, and a high
surge capability will provide for start-up and
transient loads, whilst being thermally protected
against sustained overload. Overload protection
of the “constant current” type ensures start-up
into complex load conditions. The copper case
achieves efficient heat transfer and screening.
The product range has been recognised by
Underwriters Laboratory (UL) to UL 1950 for
operational insulation, file number E179522
applies.
Newport Components
ADJ*
–VIN
+VIN
SS*
+VOUT
*Optional
UL 1950 RECOGNISED
File Number E179522.
PRELIMINARY
Notice : This is not a final specification.
Some parametric limits may be subject to change.
NPH25S SERIES
1
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
absolute maximum ratings
Input voltage, 24V input types · · · · · · · · · · · · · · · · · · · · · · · · · · · –0.5V to 40V
Input voltage, 48V input types · · · · · · · · · · · · · · · · · · · · · · · · · · · –0.5V to 80V
Output Voltage · · · · · · · · · · · · · · · · · · · · · · · · · · · · –0.3V to regulated voltage
Output trim control · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · –1V to +30V
Synchronisation/shutdown control · · · · · · · · · · · · · · · · · · ±15V relative to input return
electrical specifications
Specifications typical at TA=25°C, nominal input voltage rated output current unless otherwise specified.
Order
Code1
1
2
Nominal Input
Voltage
Output
Voltage
Output
Current
Efficiency
(V)
(V)
(A)
(%)
NPH25S2403i
24
3.4
7.3
81
NPH25S2405i
24
5.1
5.0
84
NPH25S2412i
24
12.1
2.1
86
NPH25S2415i
24
15.1
1.7
87
NPH25S4803i
48
3.4
7.3
83
NPH25S4805i
48
5.1
5.0
85
NPH25S4812i
48
12.1
2.1
88
NPH25S4815i
48
15.1
1.7
89
If optional pins ADJ and SS are required (as indicated in the pin connections diagram) prefix the ending “i” with an E when
ordering, e.g. NPH25S4803Ei.
Newport Components
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
family characteristics - input
Specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
Parameter
Voltage Range
Conditions
MIN
NOM
MAX
Continuous operation, 24V input types
18
24
36
Continuous operation, 48V input types
36
48
75
Units
V
family characteristics - output
Specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
Parameter
Conditions
Voltage Set Point Error
Overall Voltage Error
MIN
TYP
MAX
Units
50% load
0.5
%
Case temperature –40 to 110°C
Load 0% - 100%
Input specified range
2.5
%
250
ppm°C
1
%
Temperature Coefficient of
Output Voltage (slope)
Deviation of Output Voltage
Temperature MIN-MAX
0.5
Line Regulation
Operating voltage range, 50% load
0.1
%
Load Regulation
0% - 100% rated load 1
0.5
%
Ripple
rms
70
mV
family characteristics - isolation
Specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
1
Parameter
Conditions
MIN
Isolation Voltage
Flash tested for 1 second
1500
Resistance
Viso=500VDC
1
TYP
MAX
Units
VDC
4000
GΩ
A minimum load of 10% of rating is recommended for typical applications ; see application notes.
Newport Components
NPH25S SERIES
3
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
family characteristics - control
Specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
Parameter
Conditions
MIN
Voltage Trimming Range
At rated load,
Trim control at either output
±10
Remote Switch Input1
Not operating
–15
0
1.5
(voltage relative to input negative)
Operating, open circuit voltage
9
10
11
25
50
ms
440
kHz
395
kHz
MAX
Units
Start Delay
Time from application of valid input
voltage to output being in specification
Synchronisation1
Specified drive signal
Switching Frequency
TYP
Units
%
320
330
MAX
350
V
family characteristics - general
Specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
Parameter
Conditions
MIN
Package Weight
Thermal Protection
Current Limit
TYP
45
Operates at case temperature
g
110
°C
Continuous short circuit causes no damage
family characteristics - environment
1
4
Parameter
Conditions
MIN
Case Temperature
Full load
Storage
Absolute MAX internal temperature
Relative Humidity
Non-condensing 85°C
TYP
MAX
Units
–40
110
°C
–40
125
°C
85
%
Optional - Where fitted.
Newport Components
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
typical characteristics
thermal performance
35
30
Output Power (W)
2403
15
4812
25
2405
20
4815
30
2412
25
Output Power (W)
35
2415
10
5
4805
20
4803
15
10
5
0
0
-40
-20
0
20
40
60
80
100 120
-40
-20
0
Temperature (°C)
20
40
60
80
100 120
Temperature (°C)
UL 1950 recognition - MAX permissible loads for a given ambient
temperature for any NPH25S model
Temperature (°C)
Power (W)
Temperature (°C)
Power (W)
40
25.0
80
13.9
50
22.2
85
12.5
60
19.4
90
11.1
70
16.6
MAX power rating with case temperature maintained by external means
(eg forced air cooling)
Case Temperature
Part Number
Units
100°C
105°C
110°C
NPH25S2403
24
20
15
NPH25S2405
25
22
18
NPH25S2412
30
24
21
NPH25S2415
30
27
22
NPH25S4803
25
20
16
NPH25S4805
25
24
20
NPH25S4812
30
29
24
NPH25S4815
30
30
26
Newport Components
W
W
NPH25S SERIES
5
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
application notes
set voltage
In a typical application, the NPH series of dc-dc
converters require nothing more than a dc supply
of correct polarity and voltage to generate its
specified output. These notes are intended to
offer help in the use of other facilities offered by
these converters, and to provide assistance in
achieving their full potential.
The output voltage of all units is set to 100mV
above nominal, to offset resistive losses and thus
assist with worst case error calculations. For the
Ei versions, this allowance can be altered with a
single fixed resistor, connected from the
trimming pin to one of the output pins.
The product range includes optional control pins
on each side of the isolation barrier. These can
be programmed with external circuits to
perform a variety of functions.
voltage trimming
The trimming (adjust) input on the secondary
side allows output voltage adjustment within the
capability of the power circuit.
When open circuit, the trimming pin ADJ
operates at near half the output voltage. A basic
trimming
arrangement
consists
of
a
potentiometer of 10kΩ to 100kΩ connected
across the output, with its wiper connected to
the ADJ pin (see figure 1). Dependent on
model, the output will be reduced by about
15% when the wiper is at the positive output, or
increased by about 24% when at the negative
rail. Regulation will be maintained to at least
10% adjustment either way.
If finer adjustment is required, a resistor may be
included between the wiper and the pin. For
example, 62kΩ will restrict a 3.3V model to ±5%
adjustment range. The corresponding values for
the other voltages are 5V:56kΩ, 12V:100kΩ and
15V:150kΩ.
+VIN
–VIN
DC
DC
+VOUT
ADJ
0V
100KΩ
other trimming functions
The voltage applied to the trim pin need not be
from a potentiometer. The trim facility may be
driven electronically to provide “margining”,
remote sense, active load sharing, current
control or remote programming (There is a
minimum output voltage below which control is
not possible).
shutdown
When the shutdown pin is shorted to the negative
input, the converter will stop. Its current
consumption will then be less than 1mA at
nominal supply voltage. The low voltage must be
less than 1.5V to ensure that the unit stops, and
must sink the above small input current.
The unit will restart if the control pin is left open
circuit or raised to a value close to its normal
open circuit voltage. This is typically 10V. Note
however, that the unit will not meet specification
while a significant current drain remains.
If the shutdown pin is to be connected to a long
wire, it is recommended that a capacitor decouples
the pin to the supply common in order to avoid
the risk of injecting noise into the converter
circuit. A series resistor may also be helpful.
Values of 10nF and 1kΩ may be used.
Many NPH series converters may be switched
together simply by linking the primary control
pins. The primary common pins must also be
linked.
Figure 1 : Voltage trimming
6
Newport Components
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
frequency control
If the primary side dc control voltage is pulled
away from its open circuit voltage, the converter
frequency will be changed, approximately in
proportion to the voltage. With a 8.5VDC
voltage to SS pin, the typical switching frequency
will be 300kHz. If this is raised to 15VDC, the
switching frequency will typically be 510kHz. The
frequency may thus be moved away from a
sensitive value or into a safe area. Deviation of at
least –10% to 30% is achievable, though the
efficiency will decline with significant changes.
Also note that if the frequency is lowered, the
switching frequency component of output ripple
will increase. Since the design uses no large
electrolytic capacitors, any use of a lower
frequency must allow for the effects of increased
ripple. Additional external filtering may be
required.
synchronisation
The converter frequency may be synchronised to
an external frequency by connecting a negative
going pulse the sync/shutdown pin. The drive
signal is typically 8V to 12V amplitude and 100ns
to 200ns duration. A suitable circuit consists of a
CMOS timer (7555 series or TLC555) connected
as an oscillator or as a pulse shaper. Its logic
output (not the discharge output) should be
connected via a 4.7nF capacitor to the converter
pin. The synchronised frequency is above the free
running value. However, the free running
frequency can be lowered, so that sychronisation
may include frequencies near or below the
natural value. An example of a practical circuit is
shown in figure 2, which uses a zener diode to
lower the natural frequency. If the zener diode
does not have a sufficiently sharp characteristic,
it may be necessary to add a bias resistor.
Several converters of this family may be
synchronised from the same reference provided
the waveform can be maintained by the use of an
adequate driver circuit. If the rise time is more
than 20ns, for example, synchronisation may not
be achieved over the specified frequency range.
For best efficiency, set the frequency within the
specified range of its natural state.
filtering
The module includes a basic level of filtering,
sufficient for many applications. Where lower
noise levels are desired, filters can easily be
added to achieve any required noise
performance.
A dc-dc converter generates noise in two
principle forms: that which is radiated from its
body and that conducted on its external
connections. There are three separate modes of
conducted noise: input differential, output
differential and input-output.
+10V
Set Frequency
7
R2
(5k6)
VR1
(8k2)
IC1 (TLC555C)
8
R1
(470R)
6
C1
(100pF, 16V)
C3 (4n7F, 25V)
3
2
C4
(470nF, 16V)
0V
4
C2
(10nF, 16V)
SS
D1 (1N4148)
5
1
ZD1 (BZX55C8V2)
0V
Figure 2 : Synchronisation
Newport Components
NPH25S SERIES
7
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
10µH
100µH
2.2µF
2.2µF
1mH
DC
10µF
DC
100µH
10nF, 250Vac Y Rated
10nF, 250Vac Y Rated
Figure 3 : Recommended Configuration to Reduce Noise
This last appears as common mode at the input
and the output, and cannot therefore be removed
by filtering at the input or output alone. The first
level of filtering is to connect a capacitor between
input and output returns, to reduce this form of
noise. It typically contains high harmonics of the
switching frequency, which tend to appear as
spikes on surrounding circuits. The voltage rating
of this capacitor must match the required
isolation voltage. (Due to the great variety in
isolation
voltage
and
required
noise
performance, this capacitor has not been
included within the converter.)
Input ripple is a voltage developed across the
internal input decoupling capacitor. It is therefore
measured with a defined supply source
impedance. Although simple series inductance
will provide filtering, on its own it can degrade
the stability. A shunt capacitor is therefore
recommended across the converter input
terminals, so that it is fed from a low impedance.
If no filtering is required, the inductance of long
supply wiring could also cause a problem,
requiring an input decoupling capacitor for
stability. An electrolytic will perform well in these
situations.
See figure 3 for a recommended configuration to
reduce all three conducted modes.
The component values and ratings will depend
on the converter rating and voltage, and the
required noise performance, but the values
quoted in figure 3 suit a 48V to 5V 25W
8
converter. The input-output filtering is performed
by the common-mode choke on the primary.
This could be placed on the output, but would
then degrade the regulation and produce less
benefit for a given size, cost, and power loss.
Radiated noise is present in magnetic and
electrostatic forms. The latter is suppressed by
the metal case, which is connected to the output
return, typically a zero-volt point. Thanks to the
small size of these units, neither form of noise will
be radiated “efficiently”, so will not normally
cause a problem. Any question of this kind
usually better repays attention to conducted
signals.
mounting considerations
The copper case is connected to the output (0V)
pin. Care is needed in the design of the circuit
board on which the converter is mounted. Top
side tracks must not contact the edge of the case
or the ferrite core, visible on the underside of the
unit.
protection
The “absolute maximum” ratings in the specification
define conditions which may degrade life but will
not result in immediate damage. This section of
the application notes deals with those
unavoidable or accidental occasions when the
ratings are exceeded.
Newport Components
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
The unit will protect itself against a wide range of
abnormal conditions. In others, where failure is
inevitable, the consequent hazards have been
minimised.
If the supply polarity is reversed, the unit is
unable to protect itself. The simple preventative
measure of a series diode would add
unacceptable power loss for the basic product,
but it may be appropriate in some applications
to fit this diode externally.
With no polarity protection, tracks and
components will safely fail to high impedance,
disconnecting the power. A large fault current
will occur in this process.
Newport Components
NPH25S SERIES
9
NPH25S SERIES
Isolated 25W Single Output DC-DC Converters
outline dimensions1
50.00
NPH25S4803Ei
35.00
XYYWW
4.50
3.70
10.00
1.04
Ø 0.90
*
5.08
20.32
*
14.96
14.84
20.32
recommended footprint details
2.54
Ø 1.75
1.60
x6 HOLES
0.1
*
*
1
All dimensions in mm ±0.25mm.
All pins on a 2.54mm pitch and within ±0.25mm of true position.
*
Optional pins (refer to pin connections diagram on page 1).
10
2.54
Newport Components
INFORMATION
The following Newport Components publications are also available :
p The Power Components Handbook (also in CD ROM format)
p EMC Design Guidelines
Please contact Newport Components or your local supplier for a copy of these
data books.
Newport Components Limited reserve the right to alter or improve the specification, internal design or manufacturing process at any
time, without notice. Please check with your supplier or visit our web site to ensure that you have the current and complete specification for
your product before use.
For information and instructions on use, please consult the current Power Handbook.
 Newport Components Limited 1999
No part of this publication may be copied, transmitted or stored in a retrieval system or reproduced in any way including, but not limited
to, photography, photocopy, magnetic or other recording means, without prior written permission from Newport Components Limited.
Newport Components Limited
Newport Components Inc.
1 Tanners Drive, Blakelands North
Milton Keynes MK14 5BU, England
8917 Glenwood Avenue, Raleigh
NC 27612, USA
Tel: +44 (0)1908 615232
Fax: +44 (0)1908 617545
email: [email protected]
www: http://www.newport-comps.com
Tel: +1 (919) 571-9405
Fax: +1 (919) 571-9262
email: [email protected]
MEMBERS OF NEWPORT TECHNOLOGY GROUP
9000SANPH25S Issue 4 06/99 DCR 2308