The A Series of high voltage regulated DC-DC converters from Ultravolt address the needs of the miniature PCB-mount regulated high voltage power supply user. These units feature surface mount technology and encapsulation techniques providing high reliability and low cost. Eight models from 0-62 V through 0-6 kV; 4, 20 or 30 W of output power are offered.
The A converters utilise a dual-ended forward converter topology with a nominal switch frequency of <100kHz. A precision reference is provided so the remote control can program the power supply for a specific voltage. Once input voltage stabilises, under-voltage lockout is released. As soon as enable is raised above a TTL 1, the converter begins to switch. The soft-start circuit brings the converter to full power over a 1ms period, reducing surges on the source supply. A constant frequency PWM regulation system controls the MOSFET push-pull power stage which drives the high voltage transformer. The power stage is protected from output current overloads or short circuits via a secondary current limit circuit. High voltage is developed by a multistage multiplier while feedback voltage is developed and sent to the CTRL circuit to maintain regulation. Internal filters are provided to reduce input current ripple and output voltage ripple.
Wide input and output ranges
The 'A' Series is designed for full power operation at up to 90% efficiencies. A wide input range of +11 to +16 Vd.c. or +23 to +30 V d.c. will maintain full power output without derating. The derated input range is +9 to +32 V d.c. The unit is a nonisolated, unipolar converter. This means positive or negative output must be specified. Output voltage is adjustable from 0 to 62, 125, 250, 500, 1 kV, 2 kV, 4 kV, or 6 kV. As the output voltage is reduced towards 0, the maximum current capability remains unchanged. Current output from the high voltage multiplier can be monitored by reading the voltage appearing between Output Monitor and Signal Ground Return pins.
Remote control of the output voltage is possible with 0 to +5 V d.c. control voltage from either DAC, variable or fixed resistor. The A converters also have an enable function to put the converter in a standby mode. Input current is reduced to less than 30 mA. All functions other than the internal reference are shut down.
The A Series are built in PCB-mountable plastic cases requiring a footprint of 35,3 cm2 and only 70,5 cm3 of volume. Mounting plates and brackets are available for chassis mounting. This series is also available in an RF-tight metal PCB/chassis mount package. It provides full power operation at case temperatures from -40 to +65°C.
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