DC-DC High Voltage Power Supplies

Form, Fit and Function Design:

Spellman’s UM Series of printed circuit board mountable, high voltage modules offer a form, fit and function replacement for presently available commercially made units, while providing additional features and benefits at competitive pricing. Utilizing proprietary power conversion technology and Spellman's six decades of high voltage experience, these SMT based high voltage modules provide improved performance/reliability and easier system integration at a lower cost when compared to the competition.

Advanced Power Conversion Topology:

UM converters use a proprietary zero voltage switching power conversion topology providing exceptional efficiency and inherent low noise and ripple. Radiated emissions are reduced compared to conventional switching topologies, minimizing or even eliminating the need to shield the unit from adjacent circuitry.

The high voltage output is generated using a ferrite core high voltage step up transformer which feeds the output circuitry. Units at 1kV or higher utilize an arrangement of half wave Cockcroft-Walton voltage multiplier stages to obtain the specified high voltage output, while lower voltage units use a robust rectification and filter circuit.

Due to the fixed, high frequency conversion rate the output capacitance is small resulting in minimal stored energy. Through the use of generously rated surge limiting resistors and a fast acting current loop, all units are fully arc and short circuit protected.

Control and Regulation:

The actual output voltage generated is sampled via a high impedance divider to create a voltage feedback signal. A current feedback signal is created via a current sense resistor in the low end return of the high voltage output circuitry. These two accurate ground referenced feedback signals are used to precisely regulate and control the units in addition to external monitoring purposes.

Due to the UM’s unique converter topology it can provide full current into low impedance loads or even a short circuit. Standard units limit at 103% of maximum rated output current.

Standard Interface:

The Spellman UM Series interface provides current program­ming capability and positive polarity, buffered, low output imped­ance voltage and current monitor signals (zero to +4.64Vdc equals zero to full scale rated). A voltage programming input is provided where 0 to +4.64Vdc equals 0 to 100% of rated voltage. Current programmability allows the user to set where the unit will current limit, anywhere from 0 to 100% of maximum rated current. This feature is beneficial where less than full output current is desired, like in the case of protecting a sensitive load.

The buffered low impedance voltage and current monitor signals can drive external circuitry directly, while minimizing loading and pickup effects. These features save the user the expense and implementation of external interface buffering circuitry while improving overall signal integrity. This standard interface is made available via a row of 13 pins with 0.1. pin spacing. A legacy interface (7 pins on a 0.2. spacing) that is compatible with presently available commercially made units can be provided by ordering the “L” option.

Mechanical and Environmental Considerations:

The UM Series are solid encapsulated, printed circuit board mountable, plastic cased converters measuring only 2.97. X 1.5. X 0.83. (75.4mm X 38.1mm X 21.1mm). All units are encapsulated using a silicon based potting material which is considerably lighter in weight than epoxy. Two isolated, non grounded 2-56 machine screws thread into the module to securely mount it to the printed circuit board, relieving any stress on the interface pins. Mounting plates, brackets and flanged mounting options are also available.

Regulatory Approvals:

Compliant to 2004/108/EC, the EMC Directive and Compliant to EEC EMC Directive. Compliant to EEC Low Voltage Directive. UL/CUL recognized, File E227588. RoHS Compliant.

Specifications

^{(Ref. 128068-001 REV. R)}

Input Voltage:

12Vdc for 4W, 24Vdc for 20W and 30W

Nominal Voltage Range:

11Vdc to 30Vdc for 4W, 23Vdc to 30Vdc for 20W and 30W

Input Current: (typical)

Disabled: 30mA

No load: 90mA

Full load:

4 watt units: 0.5A

20 watt units: 1.0A

30 watt units: 1.5A

Efficiency:

80-85%, typical

Voltage Regulation:

Line: <0.01%

Load: <0.01%

Current Regulation:

Line: <0.01%

Load: <0.01%

Stability:

0.01% per 8 hours, 0.02% per day after 30 min. warmup

Accuracy:

2% on all programming and monitoring, except I Sense 10%

Temperature Coefficient: (typical)

Standard: 100ppm/°C Optional: 25ppm/°C (T Option)

Environmental:

Temperature Range:

Operating: 0°C to 65°C case temperature

Storage: -55°C to 85°C, non operational

Humidity:

10% to 90%, non-condensing.

Cooling:

Convection cooled, typical. 30 watt units operating at full power might require additional cooling to maintain case temperature below 65°C. Methods may include: forced air cooling, use of heat sink or metal case, etc. It is the user’s responsibility to maintain the case temperature below 65°C. Damage to the power supply due to inadequate cooling is considered misuse and repairs will not be covered under warranty.

Dimensions:

2.97" L X 1.49" W X 0.81" H (75.2mm X 37.9mm X 20.6mm)

Weight:

4 oz. (113g), typical

UM 4W SELECTION TABLE

UM 20W SELECTION TABLE

UM 30W SELECTION TABLE

Note: Total ripple is the sum of the low frequency and high frequency ripple. Grayed text indicates Legacy interface signals.

STANDARD INTERFACE

Grayed out signals are provided for backward legacy compatibility and their use is not required

Power Ground Return, Signal Ground and HV Ground Return are connected internally. For best performance they should not be connected externally.

LEGACY INTERFACE (L OPTION)

Power Ground Return, Signal Ground and HV Ground Return are connected internally. For best performance they should not be connected externally.

Tables & Diagrams

Standard Interface Connections
Seventeen (17) gold plated 0.025˝ (0.64mm) square pins suitable for direct PCB mounting. See mechanical drawing for location and spacing details.

Programming and Monitor Signals
Voltage and current programming is done via positive polarity, high input impedance, 0 to 4.64Vdc signals.
Voltage and current monitors are positive polarity, buffered low output impedance 0 to 4.64Vdc signals.

I Mon
The I Mon signal is a true output current monitoring signal. All internal offsets due to feedback divider
currents have been compensated for.

Signature Resistor
A unique identifying signature resistor for each type of unit is connected from Pin 1A to ground. Details if desired are available upon request.

Legacy Interface Connections
Eleven (11) gold plated 0.025˝ (0.64mm) square pins suitable for direct PCB mounting. See mechanical drawing for location and spacing details.

I Sense Signal
The I Sense signal polarity is opposite of the output polarity of the module. This signal is protected via a transorb and provided via a series connected 47k isolation resistor. Internal HV dividers create a small, linear offset voltage on the I sense signal that can be compensated for.

Adhesive Backed Heat Sink
UM modules are provided with an uninstalled top mounted adhesive backed heat sink. Label removal is not required if the customer elects to install and use the provided heat sink.
The UM's internal power dissipation causes a case temperature rise. If the case exceeds 65°C, the unit needs external cooling (fan or heat sink). Even if the case is below 65°C, it is prudent to keep it much lower. Like a semiconductor device; the hotter it is, the shorter the life. For every 10°C reduction of temperature the lifetime will be increased by a factor of ≈2.35. The thermal resistance from internal circuitry to ambient is 8°C/watt without a heat sink (still air). This reduces to 6°C/watt with the heat sink.

Example:
Assuming ≈80% efficiency for a 20 watt UM module, the
5 watts of internal power dissipation would create a 40°C rise. Using the heat sink there would be only a 30°C rise. Ultimately it is up to the user to determine what cooling method is applicable for their application, but the general recommendation is to keep the module as cool as possible.

UM OPTIONS

T Option
Low Temperature Coefficient-
The T Option offers the UM with an improved temperature coefficient. The standard voltage
feedback divider is replaced with one having a superior temperature coefficient, resulting in
a unit with 25ppm/C° (typical) temperature coefficient.

PHYSICAL INTERFACING

A Option

Adapter Board-
Spellman’s UM module can be fitted with an adapter board that will allow a drop in replacement for other commercially available modules of a physically larger size, while providing
identical functionality with superior performance.

B Option
Terminal Block-
The B Option provides terminal block connections for both the customer interface and high voltage output/return. This feature can be helpful in situations where frequent wiring changes are anticipated, as in a testing or prototype environment.

SHIELDING

M Option
Mu Metal Shield-
UM modules can be fitted with an adhesive backed Mu Metal foil shield to help protect sensitive adjacent circuitry.

Same as standard unit.

S Option
RF Tight Shielded Can-
The S Option mounts the UM module inside of a flanged RF tight aluminum can.

CHASSIS MOUNTING

E Option
Eared Mounting Plate-
An eared mounting plate is affixed to the top surface of the UM module allowing simple chassis mounting of unit.

E2 Option
Eared Mounting Plate-
An eared mounting plate is affixed to the top surface of the UM module allowing simple chassis mounting of units ordered with the Adapter Board (A Option).

DIMENSIONS: in.[mm]

17 PIN - Standard Interface

11 PIN - Standard Interface

Note: There may be some restrictions on multiple option combinations. Please contact our sales department for more details.

ORDERING INFORMATION

STANDARD UNIT ORDERING EXAMPLE

OPTION ORDERING INFORMATION

OPTION ORDERING EXAMPLE

Frequently Asked Questions

What Is a Safe Level of High Voltage?
Where Can I Obtain Information on High Voltage Safety Practices?
How Should I Ground Your Supply?
Why Is Arcing an Issue for a High Voltage Power Supply?