Vox Power NEVO+600 Series User manual

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
_____________________________________________________________________________________________________
Page 1of 31
DOC-MN-005-03, NEVO+600 User Manual
Vox Power Limited | Unit 2, Red Cow Interchange Estate, Ballymount, Dublin 22, D22 Y8H2, Ireland | T [phone] | www.vox-power.com
600 Watt in the palm of your hand
5”x3”x1.61”
SMALL
600W
POWERFUL
600g
LIGHT
The NEVO+600 series user manual has been prepared by the Vox Power design team to assist qualified
engineers in correctly implementing the product and to achieve the best reliability and performance
possible.
All specifications are believed to be correct at time of publishing. Vox Power Ltd reserves the right to make changes to any of its products and to change or improve any part of
the specification, electrical or mechanical design or manufacturing process without notice. Vox Power Ltd does not assume any liability arising out of the use or application of
any of its products and of any information to the maximum extent permitted by law. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is
granted by this document or by any products of Vox Power Ltd. VOX POWER LTD DISCLAIMS ALL WARRANTIES AND REPRESENTATIONS OF ANY KIND WHETHER EXPRESS
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF SUITABILITY, FITNESS FOR PURPOSE, MERCHANTABILITY AND NONINFRINGEMENT.
Please consult your local distributor or Vox Power directly to ensure that you have the latest revision before using the product and refer to the latest relevant user manual for
further information relating to the use of the product. Vox Power Ltd products are not intended for use in connection with life support systems, human implantations, nuclear
facilities or systems, aircraft, spacecraft, military or naval missile, ground support or control equipment used for the purpose of guidance navigation or direction of any aircraft,
spacecraft or military or naval missile or any other application where product failure could lead to loss of life or catastrophic property damage. The user will hold Vox Power Ltd
harmless from any loss, cost or damage resulting from its breach of these provisions.
NEVO600+ series overview
The NEVO+600 switch mode power supply series offers truly unrivalled power density, providing 600 W at 25 W/in3in a 5” x 3”x 1U package. It is the
ultimate power solution for system designers as they address the pressing demands for more power within less space. Providing multiple isolated outputs,
the series carry full UL60601 (NEVO+600M only) and UL60950 (NEVO+600S only) safety approvals.
The basic system consists of an input module together with up to four fully isolated output modules. Single output modules have advanced remote
voltage and current programming functionality as standard. While dual output modules allow for up to eight fully isolated outputs.
The input module delivers up to 600 W of output power and has 4 slots, each capable of separately delivering up to 150 W. A 5 V, 200 mA medically
isolated bias supply together with an AC_OK signal and a global inhibit signal that can disable all outputs simultaneously, comes as standard on all
models.
Output modules are available in a range of output voltages to suit all applications.
Single output modules with voltage ranges from 1.5V to 60V, currents up to 25A and paralleling and series capability can result in a voltage range up to
240V and a maximum current of up to 100 Amps from a single Nevo+600 configuration.
Dual output modules have a voltage ranges from 1.5V to 15V and currents up to 5A with series capability.
By selecting the correct output modules, a custom power solution can be configured in a few minutes. This instantly available custom solution offers
industry leading power density, total system efficiencies of up to 89% and suits all types of applications including industrial, medical, aerospace, military
and telecoms.

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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DOC-MN-005-03, NEVO+600 User Manual
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Contents
NEVO600+ series overview ....................................................................................... 1
Part numbers and ordering information ......................................................................... 3
Installation Notes................................................................................................... 4
Theory of operation................................................................................................ 5
Input module operation ........................................................................................... 5
Signalling............................................................................................................ 9
Single Output module operation ................................................................................11
Advanced Single Output module features......................................................................13
Series Connected outputs ........................................................................................17
Paralleled outputs .................................................................................................18
Dual Output module operation..................................................................................22
Audible noise ......................................................................................................25
Mechanical dimensions and mounting..........................................................................26
Connectors.........................................................................................................27
Configuring your power supply..................................................................................28
Safety...............................................................................................................30
EMC compliance ..................................................................................................31
Reliability ...........................................................................................................31

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Part numbers and ordering information
INPUT MODULES
Model
Details
NEVO+600S
600 Watt input stage with standard leakage current.
NEVO+600M
600 Watt input stage with medical leakage current and isolation requirements.
OUTPUT MODULES
Model
Nominal voltage
Rated current
Rated Power
Adjustment range
Load regulation
Line regulation
OVP
0
Unused slots
1
5V
25A
125W
1.5V-7.5V
±50mV
±0.1%Vnom
9V
2
12V
15A
150W
3V-15V
±100mV
±0.1%Vnom
18V
3
24V
7.5A
150W
9V-30V
±150mV
±0.1%Vnom
36V
4
48V
3.75A
150W
18V-58V
±300mV
±0.1%Vnom
66V
5
12V Dual
5A
75W x 2
3.3V-15V Each Ch
±50mV
±0.1%Vnom
22V
8
24V Dual
3.125A
75W x 2
24V Each Ch
±100mV
±0.1%Vnom
30V
PART NUMBERING SYSTEM
NEVO Input
Module
NEVO+600
M
-
1
1
2
3
-
0
0
0
Factory Use
Product Type
Use ‘0’ for unused slots.
Blanking plates will be
inserted at factory
S - Standard
M - Medical
Slot A –Output #
Slot D –Output #
Slot B –Output #
Slot C –Output #
Our design team will assist with value add requirement if an application requires standard/non-standard accessories or non-nominal voltage
settings. Once approved, the factory will issue a 3 or 4 digit code for your specific configuration which can be used for all future orders of the
same configuration. When ordering an input unit with no outputs inserted, simply order NEVO+600S.

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Installation Notes
This power supply is intended for use within equipment or enclosures which restricts access to authorised personnel only. The instructions in this manual
and all warning labels on the product must be followed carefully.
Safety
All power supplies must be installed correctly in a controlled environment which restricts access to any unauthorised personnel. Equipment and system
manufacturers must protect service personnel against unintentional contact with the output terminals.
Hazards
If series and/or parallel combinations of outputs exceed safe voltage and/or energy levels, the final equipment manufacturer must provide appropriate
protection for both users and service personnel.
Health and safety
To comply with section 6 of the health and safety at work act, a label that is clearly visible to service personnel must be placed on the final equipment,
which warns that surfaces of the power supply may be hot and should not be touched when the product is operating.
Fusing
The power supply has internal single pole fusing in the L (Live) line.
Servicing
The power supply contains no user serviceable parts. Repairs must be carried out by authorised personnel only. Contact Vox Power Ltd for further
information.
Cooling
For proper cooling of the power supply, the air intake and outlet must not be impeded. Allow 50 mm clearance at both ends and position cabling
appropriately. Avoid excessive back pressure in the general system or when using ducting to navigate hot air out of the system.
Earth terminal marking
To comply with the requirements of UL60950-1, EN60950-1, IEC60950-1, CSA22.2 no. 60950-1, UL60601-1, EN60601-1, EN61010-1, IEC60601-1, IEC61010-1,
CSA22.2 no 601-1 where the incoming wiring earth is intended for connection as the main protective earthing conductor and where the terminals for such
a connection is not supplied on a component or subassembly such as a terminal block, the user shall add an appropriate label displaying a protective
earth symbol in accordance with 60417-2-IEC-5019 directly adjacent to the terminal. The label should be durable and legible and should withstand the 15s
rub test as per UL60950-1 section 1.7.15.
Mounting
The unit can be mounted using the bottom or side mounting points. Each mounting point accepts an M4 screw where the maximum penetration,
inclusive of 1.75 mm chassis thickness, should never exceed 4.00 mm. The maximum torque for the M4 screws is 0.55Nm.
Other
•To prolong the life of the unit, use in a dust free environment.
•If units are damaged during transit, contact your sales agent or Vox Power and DO NOT apply power to the unit.
•Always use adequately sized cables and ensure good crimp connections.
•Use cable supports to minimise stress on connectors.
•Avoid excessive shock or vibration.
General installation parameters
•Equipment class I
•Installation category II
•Pollution degree 2
•Material group IIIb (Indoor use only)
•Flammability rating 94V-2
•IP rating IP10
•RoHS compliance 2011/65/EU

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Theory of operation
The diagram below outlines the topology and major internal components of a fully assembled system. Four output slots are provided and can be
populated by any combination of output modules. The remaining components in the block diagram are housed in the input module.
The input module is responsible for receiving the AC mains line voltage and converting it to an appropriate DC voltage whilst providing protection from
AC line disturbances and preventing excessive EMI emissions and current harmonics. The integrated EMI filter attenuates high frequency current emissions
to levels below EN55022 class B. It also provides single pole fusing in the live conductor and protection from line disturbances as outlined in EN61000.
Inrush current is controlled by a resistive element upon initial connection to the AC line. Once the internal capacitances have been charged, the resistive
element is bypassed to reduce losses.
Active Power Factor Correction (PFC) is used to ensure an accurate input current waveform with extremely low harmonic content, exceeding the
requirements of EN61000. This stage also provides active input current limiting which prevents overloading of the input stage while maintaining high
power factor.
The output of the PFC stage charges the hold-up electrolytic capacitors which store enough energy to allow the system to continue operating during
minor line disturbances. These are the only electrolytic capacitors in the entire power supply and to further increase system reliability, long life and high
temperature capacitors are used.
A highly efficient zero voltage switching circuit is used to drive the medically isolated transformer from the hold-up capacitors. The output modules
connect to the transformer secondary and provide safe isolated power to a high performance synchronous rectifier power converter which is controlled
using the latest analog control technology to produce superior output performance in an extremely reduced size.
Input module operation
Startup & shut down
The NEVO+ input modules operate from a universal input voltage range and start automatically upon application of adequate AC mains voltage
(>84Vrms). After a short delay, the global 5V bias supply starts and the ACOK signal goes high to indicate that the mains voltage is present and input
stage is operating correctly. Once the ACOK signal is high, the output modules turn on and deliver power to the application loads. The power good
signals will indicate that the output voltages are within specification. The diagram below shows the normal start up/shut down sequence and gives typical
timings.

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Typical timing values:t1300 ms, t250 ms, t325 ms, t415 ms, t5= 5 ms (minimum), t6100 ms
When the AC mains voltage is removed, the internal hold-up capacitors will supply power to the load for typically 20 ms (t4+t5) at maximum power. The
ACOK signal will go low at least 5ms before the output voltages fall below the power good threshold level. This allows the application to prepare for the
impending loss of power. The 5V bias supply will remain on for typically 100ms, after the output modules have turned off.
Hold-up
For short line distubances (<20ms), the output voltages will not be affected*. However, the ACOK signal may still go low to warn that there is an
impending loss of output power. The ACOK signal will return to the high state once the unit has recovered from the disturbance.
*Outputs that are adjusted above the hold-up voltage as detailed in their respective datasheets, may experience a dip in voltage but never below the
hold-up voltage specified.
Idle power
The idle power of the NEVO+ PSU is extremely low when compared to similar power supplies.
With the output modules enabled the unit typically only requires 28 W with no output load. To reduce the idle power further the outputs can be disabled
using the global inhibit (GINH) pin. With the outputs disabled the unit typically requires less than 21 W.
Over temperature Protection (OTP)
The input module is protected from excessive temperatures by means of various internal sensors. If temperature thresholds are exceeded the entire unit
may latch off, with no ACOK warning. To re-enable the unit the AC mains must be disconnected for approximately 2 minutes.

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Power derating
NEVO+600 units must always be operated within its stated operating limits. Equipment manufacturers and other users must take appropriate deratings
into account at all times when specifying a unit for the intended application. If in doubt contact your sales representative or Vox Power for assistance.
There are two main deratings for NEVO+ power supplies, temperature and input line voltage. Temperature deratings apply to both input and output
modules, while line deratings apply only to the input module.
For temperature, the derating for both input and output modules is 2.5% (of maximum rated power) per degree Celsius above 50°C. While, for input line
voltage, the derating for the input module only is 0.7143% (of maximum rated power) per volt below 120Vrms. These deratings can be calculated using
the following conditional equations;
Equation for line derating:
If Vin < 120,
Pout = Prated*Line derating factor
= Prated*(1-(0.007143*(120-Vin))
Otherwise,
Pout = Prated
Equation for temp derating:
If temp > 50C,
Pout = Prated*Temp derating factor
= Prated*(1-(Temp-50)*0.025)
Otherwise,
Pout = Prated
Depending on the application conditions, one or both of the deratings may apply. Where both apply, the derating factors given above can be multiplied
together to obtain the total derating factor.
Example: What are the NEVO+600 input and output module deratings at 60°C at 100V line?
Input power rating = Prated*line derating factor*Temp derating factor
Output power rating = Prated*Temp derating factor
Line derating factor = (1-(0.007143*(120-Vin)) = (1-(0.007143*(120-100)) = 0.85714
Temperature derating factor = (1-(Temp-50)*0.025) = (1-(60-50)*0.025) = 0.75
Input power rating = 600*0.85714*0.75 = 385.7W
Output 2 power rating = 150*0.75 = 112.5W
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
-30 -10 10 30 50 70
Normalised Derating factor
Temperature
Temperature derating
250
300
350
400
450
500
550
600
650
80 100 120 140 160 180 200 220 240 260
Output Power (Watts)
Input Voltage (Vrms)
Line Derating
Derate at 4.28W per volt below 120V
Derate at 2.5% per volt above 50˚C

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AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
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Efficiency
The efficiency of the overall unit is dependent on several parameters such as input voltage, load level and on the combination of output modules. The
plots below show typical efficiencies of a NEVO+600 over the full load and line voltage range and fitted with four of each type of output module, equally
loaded.
An estimate of the efficiency for any particular system may be obtained from these graphs using the procedure outlined in the example below.
Example: Estimate the efficiency of an NEVO+600-1123, at 160Vrms input and 100W load on each output?
1. Define load efficiencies for each output module at the specified load and 220V.
2. Define change in efficiency from 220Vrms to 160Vrms for each output module.
3. Sum the values from step one and two for each output module.
4. Calculate the average efficiency for the total system.
Step
Details
Slot A
OP1
Slot B
OP1
Slot C
OP2
Slot D
OP3
1
Є220 (Load chart)
0.84
0.84
0.87
0.87
2
∆Є(220-160) (Line chart)
-0.01
-0.01
-0.01
-0.01
3
Єx= Є220 + ∆Є(220-160)
0.83
0.83
0.86
0.86
4
ЄAVE = (Є1+ Є2+ Є3+ Є4)/4
0.845
400
425
450
475
500
525
550
575
600
0.78
0.80
0.82
0.84
0.86
0.88
0.90
80 100 120 140 160 180 200 220 240 260
Efficiency
Input Voltage (Vrms)
Typical Line Efficiency (Maximum power)
OP1 OP2 OP3
OP4 Pout
400
425
450
475
500
525
550
575
600
0.78
0.80
0.82
0.84
0.86
0.88
0.90
80 100 120 140 160 180 200 220 240 260
Efficiency
Input voltage (Vrms)
Typical Line Efficiency (Derated Power)
OP1 OP2 OP3
OP4 Pout
0.66
0.68
0.70
0.72
0.74
0.76
0.78
0.80
0.82
0.84
0.86
0.88
0.90
050 100 150 200 250 300 350 400 450 500 550 600
Efficiency
Output Power (Watts)
Typical Load Efficiency (120Vrms)
OP1 OP2
OP3 OP4
0.66
0.68
0.70
0.72
0.74
0.76
0.78
0.80
0.82
0.84
0.86
0.88
0.90
050 100 150 200 250 300 350 400 450 500 550 600
Efficiency
Output Power (Watts)
Typical Load Efficiency (220Vrms)
OP1 OP2
OP3 OP4

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Signalling
To reduce cabling in the end system, all major input and output signals and the global 5V bias supply are wired to a single signals circuit that is accessed
through the connector (J2) located at the output side of the chassis as shown in the diagram below.
All of the signals are referenced to the bias supply common rail (COM) and external control and/or monitoring circuits can be easily powered and
interfaced to the PSU through this connector. The entire signals circuit is fully medically isolated and can be considered a SELV output. The table below
lists the isolation voltages.
Signals isolation voltages
Signals to Input
4000
Vac
Signals to Chassis
250
Vdc
Signals to Output
250
Vdc
5V bias supply (Power)
A 5V bias supply that can deliver up to 200mA is provided as standard on all units. This supply is available whenever the AC mains voltage is connected
and the input module is operating correctly. To ensure safety, the following abnormal conditions may cause the entire unit to latch off, which will disable
the 5V bias supply:
•Over temperature of any part of the unit
•Over voltage on the output
•Internal over current (device failure)
AC mains signal (ACOK [Output])
An ACOK signal is provided to indicate to the user that the AC mains voltage is applied and the input module is operating correctly. The output signal is
driven from an internal operational amplifier as shown in the following diagram. Under normal operating conditions this signal gives a warning of 5ms
before the output voltage falls below the power good threshold. However, to ensure safety, the following abnormal conditions may cause the entire unit
to latch off without an ACOK warning:
•Over temperature of any part of the unit
•Over voltage on the output
•Internal over current (device failure)
Pin
Name
Description
1
PG1
Power Good
Slot A
2
INH1
Inhibit
3
PG2
Power Good
Slot B
4
INH2
Inhibit
5
PG3
Power Good
Slot C
6
INH3
Inhibit
7
PG4
Power Good
Slot D
8
INH4
Inhibit
9
GINH
Global inhibit
10
ACOK
AC mains signal
11
+5V
Global 5V Bias
12
COM
Common

NEVO+600 Series
AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
User Manual
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Power Good signals (PG1-PG4 [Output])
Each output module provides a power good (PG) signal to indicate when
the output voltage is above approximately 90% of the preset voltage for
that module. Each PG signal on an output module is internally connected
through an opto-isolator to the signals circuit, which buffers the signal
through a PNP transistor with a 10k pull down resistor, as shown.
The LED on the front of each module gives a visual confirmation of the PG
status.
Note that remote adjustments of the output voltage using the Vcontrol and
Icontrol pins do not change the PG signal threshold. The PG threshold is
always approximately 90% of the voltage set with the manual
potentiometer.
Output Inhibits (INH1-INH4, GINH [Input])
The signals circuit provides four inhibit inputs to disable each output module individually and a fifth global inhibit input (GINH) to inhibit all modules
simultaneously. Each inhibit input is internally connected through an opto-isolator to the respective output modules. The basic internal electrical circuit
and timing diagrams are shown below. Typically, tOFF = 100 μs and tON = 8 ms.
To inhibit each output module individually, GINH should be connected to COM, and 5V applied to the appropriate input INH1/2/3/4. To start with all
outputs inhibited and then enable them individually, GINH should be connected to +5V, then pull down the appropriate input INH1/2/3/4. If GINH is left
unconnected, then INH1/2/3/4 will all behave as global inhibit inputs. i.e. 5V on any INH input will disable all outputs.

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AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
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Single Output module operation
Power profile
The power profile diagram below is a voltage/current plot that together with the
associated table provides details of the main features of the currently available output
modules.
Output voltage adjustment
Each output can be adjusted within the range as described in
the table above or in the datasheet. Voltage adjustment can be
achieved by two methods;
1. Manual potentiometer adjustment
Using the manual adjust potentiometer, the preset output
voltage (VSET) of each output module is adjustable over the
entire range of VMIN to VMAX as specified in the power profile table above. A clockwise rotation of the potentiometer results in an increase of the output
voltage while an anti-clockwise rotation results in a decrease of the output voltage.
2. Remote voltage programming
Using remote voltage programming, the output voltage may be adjusted beyond the VMIN and VMAX range specified in the power profile table above.
However, certain precautions must be taken to ensure correct operation. Please see the “Advanced output module features” section for more details.
Over Voltage Protection (OVP)
In the event of an output module fault, the modules are protected against excessive output voltages. This is implemented as a fixed voltage threshold
(VOVP, in the table above) and if the output voltage exceeds this threshold the entire chassis will be latched off. To resume operation of the unit,
disconnect the AC input voltage for 2 minutes, remove the faulty output module and reconnect the AC input voltage.
Note that no warning is given on the AC_OK signal for faults of this type.
Over Current & Short Circuit Protection (OCP & SCP)
For increased safety and reliability all output modules in the NEVO series have over current and short circuit protection. The over current threshold is
typically set at 110% of the rated current and has a constant current, straight line characteristic that reduces the output voltage as the load resistance
decreases. If the output voltages falls below the hiccup voltage threshold (VHICCUP) the module enters short circuit protection mode. In this mode the
output module uses a hiccup scheme to reduce system losses and potential damage. When in this mode, the output will be enabled for approximately 3%
of the time, disabled for 97% and will attempt to restart at approximately 125 ms intervals. The module remains in this state until the short circuit condition
is removed, at which point the module returns to normal operation.
Parameter
OP1
OP2
OP3
OP4
VNOM (V)
5
12
24
48
VMIN (V)
1.5
4.5
9
18
VMAX (V)
7.5
15
30
58
VOVP (V)
9.5
17
32
62
IRATED (A)
25
15
7.5
3.75
IOCP (A)
27.5
16.5
8.25
4.125
VHICCUP (V)
1
2
4
4
IHICCUP (A)
22
13.2
6.6
3.3
PRATED (W)
125
150
150
150
PPEAK (W)
187.5
225
225
217.5

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AC/DC MODULAR CONFIGURABLE POWER SUPPLIES
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Reverse Current Protection (RCP)
The standard output modules use synchronous rectification in the output stages to achieve high efficiency and as a result the outputs can both source
and sink current. The sink current is internally limited to approximately -6% of the maximum rated current. However, in applications where the output
modules are connected to external power sources such as batteries or other power supplies certain precautions must be observed to prevent damage to
the unit.
The outputs should never be directly connected to to external power sources without some form of reverse current protection such as an external diode
or controlled mosfet. If protection is not used, large reverse currents which will ultimately result in damage to the unit will occur, especially when the AC
mains is disconnected.
Output module Average and Peak power
All modules have an average and peak power rating. The average power of each unit must at all times remain below it’s specified limit. However, each
output can deliver up to 150% of it’s average power rating for a maximum of 5 seconds at 50% duty cycle, subject to the current limit not being exceeded
and subject to the overall average power drawn being less than the specified average power rating (including any input derating due to temperature or
line voltage). The available peak power is a function of the output voltage and maximum current for each module. Full peak power is only possible when
the output voltage is adjusted to VMAX and the maximum current is drawn from the module. Note that both average and peak power ratings are subject to
the same temperature derating as the input module (derate by 2.5% per °C above 50°C), but are not subject to any line derating.
Start up & Shut down
All outputs are designed to have a regulated monotonic start-up with a rise time of
approximately 3 ms as shown in the diagram right. The power good signal stays low until
the voltage exceeds the power good threshold (≈90%).
Where multiple output modules are used, the default start up scheme is ratio-metric with
all outputs starting at the same time as shown in the diagram right. External control
circuits may be used to implement tracking or sequenced start up if necessary.
The outputs are not designed to start into a pre-biased load and may discharge any
externally capacitance before beginning to ramp the output voltage up in the normal way.
At shutdown the outputs enter a high impedance state. Where no external load is present it
may take some time for the voltage to decay. When driving inductive loads, care must be
taken to limit the voltage at the output terminals so as to prevent damage to the unit.
Synchronisation
All output modules in the same chassis are synchronised. The typical operating frequency is 260kHz and paralleled/seriesed units will not produce beat
frequencies.

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Ripple and Noise
The ripple and noise figures stated in the datasheet are defined based on a standard measuring method. To obtain the same results the same test setup
must be used and care must be taken to eliminate any parasitic noise pickup. The diagram below shows details of the setup and also sources of noise
pickup.
Over Temperature Protection (OTP)
Each output module is protected against excessive temperatures. In the event of the internal temperatures exceeding safe levels the entire unit may be
latched off. To resume operation of the unit, disconnect the AC input voltage for 2 minutes, ensure external ambient temperatures are within
specifications and then reconnect the AC input voltage. Note that no warning is given on the AC_OK signal for faults of this type.
Transient response
The NEVO output modules have been especially designed to have high reliability and to achieve this all electrolytic capacitors have been eliminated from
the design. Due to this, high dynamic load transients can cause relatively high voltage deviations at the output and although the outputs have a very high
loop bandwidth with typical recovery times of less than 100μs, the voltage deviations may still be excessive for some applications.
An example application is detailed in the diagram below and shows typical responses at the terminals of the output module and at the load. Notice that
the voltage deviation due to cable inductance exceeds the module response and hence a capacitor located at the module terminals will have little effect
at the load. The optimum solution is to locate a low impedance electrolytic capacitor at the load which will eliminate the inductive cable drop and also
reduce the typical voltage deviation at the module.
Advanced Single Output module features

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Remote voltage programming (External voltage control)
The output voltage of the module can be adjusted using an external voltage source connected between the COM and Vcontrol pins on the signals
connector J5 as shown below.
In this configuration the output voltage will follow the typical equation below,
Vo = Vset((1.8-Vctrl) / 0.6), where Vset is the manual preset voltage of the module.
The output voltage can be controlled from 0% to 300% of the preset voltage using this control method. However, care must be taken to ensure the
output voltage does not exceeed the OVP level, as this is considered a safety hazzard and will latch the entire unit off. To determine the level of control
voltage that will trigger OVP, insert Vovp into the equation above.
Example: Vovp = 9.5V, Vset = 5V;
=> Vctrl = 1.8-(Vovp*0.6/Vset) = 0.66V
Hence, Vctrl should never fall below 0.66V, otherwise OVP may latch the entire unit off.
Alternatively, by manually adjusting the output voltage to less than 1/3rd of the OVP voltage ensures that OVP can never be tripped by remote voltage
control.
Also, remote adjustment of the output voltage using the Vcontrol pin does not affect the preset power good threshold. Hence, remotely adjusting the
output voltage below 0.9*Vset will cause the power good signal to go low.
Where tight voltage adjustment tolerances are required, it is recommended to use external circuitry to provide closed loop control of the Vcontrol pin.

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Remote current programming (External voltage control)
The output current limit of the module can be reduced using an external voltage source connected between the COM and Icontrol pins on the signals
connector as shown below. In practice this also means that the output can be used as a modulated or constant current source.
In the diagram above, Vi_out is an internal voltage source that is proportional to the internal inductor current and approximates the equation,
Vi_out = 0.6 + (Iout/(Irated*1.25)), where Irated is the maximum rated current for the module.
In this configuration the output current limit will approximate the following equation,
Ilimit = (Vctrl-0.6)*Irated*1.25, where Irated is the maximum rated current for the module.
It is not possible to increase the maximum current limit of the module, and control voltages (Vctrl)exceeding 1.53 V will have no effect on the current limit.
When using an output module as a modulated current source, the output voltage should be manually adjusted to the maximum that will be required by
the application and this will be the upper voltage limit. Once the load is connected, the output current can then be modulated by applying a control
voltage as described above.
Note that the power-good threshold level is fixed and defined by the manually preset voltage. Hence, while the output module is limiting or modulating
the output current the PG signal may go low.
Where tight current adjustment tolerances are required, it is recommended to use external circuitry to provide closed loop control of the Icontrol pin.
Output current measurement
The output current of the module can be measured using the Icontrol signal. If this pin is unloaded its output voltage will follow the equation,
Vi_out = 0.6 + (Iout/(Irated*1.25)), where Irated is the maximum rated current for the module.
Note that the Icontrol output voltage is representative of the internal inductor current not the actual load current. However, this will only have an influence
during dynamic events. It is recommended to add an external amplifier (as shown above left) when using the Icontrol signal to measure the output current
as loading the Icontrol signal, even with microamps can cause the current limit to be reduced. If it is required to measure the output current and adjust the
output current limit simultaneously, this can be achieved by using a clamp circuit instead of a voltage source to adjust the current limit, while continuing to

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use an amplifier to measure the output current. An example circuit is shown above right. In this case Vctrl will control the current limit while the amplified
Icontrol signal will provide a measurement of the output current.
Remote sensing
Remote sensing is available on all output modules and can be used to compensate for any voltage drop in the main power leads between the power
supply and the load. To implement remote sensing connect the positive sense pin (S+, connector J5.2) to the positive side of the remote load and the
negative sense pin (S-, connector J5.1) to the negative side of the remote load. The voltage will be regulated at the points where the sense cables are
connected.
Active protection against worn out power cables or accidental power cable removal is provided and prevents damage to the unit in each case. An internal
circuit measures the voltage between S+ to V+ and S- to V-, when this voltage exceeds the thresholds specified in the datasheet, the output voltage is
reduced to benign levels. During system design, care must be taken to ensure power cables have a sufficiently low voltage drop at maximum load current
to ensure this protection does not activate unintentionally.
In systems where remote sensing is not used, the output voltage at the power terminals will be slightly higher than that at the sense terminals. This voltage
difference is termed, open sense offset and occurs due to internal bias currents in the sensing circuit. Factory set units are set with the sense cables
connected unless otherwise specified.
Local Bias supply
A local non-isolated +5 V bias supply is provided on each output module (+5 V on J5.6, referenced to COM on J5.5). This supply is intended to power
interface circuits for monitoring and controlling the output modules, such as amplifying the current output signal as described earlier. The output can
supply up to 10mA maximum, and exceeding this can damage the unit.
Also, as COM is connected to an internal voltage that is NOT equivalent to S- or V-, particular attention must be given to grounding issues when
interfacing COM to any control circuit in the application. Connecting COM to S- or V- may result in damage to the unit.

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Series Connected outputs
NEVO output modules of the same type can be seriesed in any number to achieve higher output voltages, even across multiple chassis! The following
instructions must be followed for output modules configured in this manner.
Isolation to ground
Care must be taken not to exceed the output module isolation to chassis ground when seriesing outputs. Each output is rated for 250 volts maximum
between each output terminal and chassis ground. Exceeding this voltage may damage the unit.
Remote sensing
For seriesed modules, remote sensing is achieved by connecting the upper most positive sense terminal (S+) and the lower most negative sense terminal
(S-) from the series of modules to their respective load regulation points. All inner sense terminals in the series must be daisy chained, S+ to S- from the
first module in the series to the last module in the series. An example of two seriesed modules is shown below.
Seriesed remote voltage/current control
Remote voltage and/or current control is possible with series connected output modules using the advanced V-control and
I-control functions as described earlier. However, individual control of each module can be complex as the various control terminals are referenced to the
positive output of the preceding module and require the use of multiple isolated control voltages to attain control over the full voltage range. In practice,
individual control of each module is rarely required and a more straightforward method is to control all outputs simultaneously with a single control
voltage. With NEVO output modules this is achieved with the use of the Nevo Series Tracker Interface, the datasheet for this interface is available from the
Vox Power website i.e. www.vox-power.com. By using the series tracker interface all modules in a series can be controlled by a single control voltage that
can be referenced to the COM (J5.5) pin on any module.
SELV precautions
Where series combinations of output modules exceed 60 V, the output can no longer be considered SELV (Safety Extra Low Voltage) and hence the final
equipment manufacturer must provide suitable protection for both users and service personnel.
WARNING!
Energy and voltage hazards may arise when individual modules are seriesed.
See the Safety section for more details.
WARNING!
When modules are seriesed, their inhibit lines (J2), if used, should be paralleled.
Inhibiting seriesed modules individually may cause damage

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Paralleled outputs
NEVO single type output modules of the same type can be paralleled in any number within the same chassis to achieve higher output currents.
When paralleled, the outputs can operate in two distinct modes, Normal parallel mode or Share parallel mode.
Normal parallel mode
For normal parallel mode, the positive power cables should be connected together and the negative power cables should be connected together. No
other connections are required.
In this mode the highest adjusted output module will
supply all of the load current until it’s current limit is
reached. If the load demand exceeds this level the output voltage will drop to the level of the next highest adjusted module and that module will begin to
supply the load current while the first module continues delivering full current. This process repeats for the total number of paralleled modules. The
diagram above shows the VI curve for such a system.
For best output voltage stability, the output voltages of each paralleled module should be adjusted as close as possible.
Output modules that are not delivering current will typically sink a small amount of current from the other outputs, but this will not exceed -6% of each
modules maximum rated current.
Typically, system reliability is reduced in this mode as the higher adjusted modules will do most of the work with the lower adjusted modules only
delivering current during peak load demand.
WARNING!
Energy hazards may arise when individual modules are paralleled.
See the Safety section for more details.
WARNING!
When modules are paralleled, their inhibit lines (J2), if used, should also be paralleled.
Inhibiting paralleled modules individually may cause damage

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Share parallel mode
In Share parallel mode, the outputs are paralleled as before and the Icontrol pin for each module is connected together as shown in the diagram below.
Connecting the Icontrol pins together forces all the
outputs to deliver the same current, ensuring that
the system reliability is maximised and the work load is distributed evenly across all paralleled modules.
In this mode the lowest adjusted output module will determine the actual output voltage and all higher adjusted outputs will reduce their voltage. There
may be a small amount of circulating current between the modules, approximately 6% of the maximum rated current for each module.
The current output signal (Icontrol) can still be used to measure the output current but it must be scaled by N, where N is the number of paralleled
modules.
Paralleling across multiple chassis
Paralleling across multiple chassis is not possible without external protection (such as external diodes or controlled MOSFETs) to prevent circulating
currents between each chassis. Failure to provide such protection may result in damage to the units. Consult Vox Power for details on how best to
implement such applications.
Where units are paralleled across multiple chassis, the outputs in each chassis will not be synchronised and the peak to peak output ripple may contain
beat frequencies in the audio spectrum.
WARNING!
Care must be taken to avoid differential voltages between the negative power output terminals of the
paralleled modules as this can cause errors at the control pins. To avoid this, it is recommended that a low
impedance connection be made between the negative power terminals close to the PSU output and cables
then connected from this common point to the load.
.

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Parallel remote sensing
Remote sensing can be used as normal with paralleled modules. The sense lines (S+ and S-) from each of the output modules should be connected
together, S+ to S+, and S- to S- as shown below. This should be done close to the power supply output and a single pair of cables brought from these
sense lines to the load. Keeping cable lengths to a minimum and using twisted pairs where necessary will help reduce noise pickup in the sense lines.
N+1 configurations
When using N+1 redundant configurations, a suitably rated diode (or controlled MOSFET) must be used on each output to prevent a device failure from
causing a system failure. However, the diode introduces voltage drops between the supply and the load that significantly degrade the load regulation. To
counteract this, the remote sense lines can be used to regulate the voltage at the load as shown below.
Typically, this configuration can damage the internal sense resistors used within a power supply. However, the NEVO outputs have integrated protection
to prevent this type of damage and are completely N+1 compatible without any additional external protection circuitry. Note that only the positive sense
terminal is protected and diodes should be used in the positive connection only.