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•New series 22% smaller than standard "A" Series

•8 models from 0 to 62V through 0 to 6kV

•4, 20 or 30 watts of output power

•Maximum Iout capability down to 0 Volts

•Wide input voltage range

•Indefinite output short-circuit protection

•Output current & voltage monitors

•Fixed-frequency, low-stored-energy design

•>1,250,000 hour MTBF @65°C

•UL, CUL, IEC-60950-1, and Demko Recognized

The "AA" Series of high-voltage regulated DC-DC converters addresses the needs of the miniature PCB-mount regulated high voltage power supply user. Designed and built utilizing state-of-the-art power-conversion topology, these units feature surface-mount technology and encapsulation techniques that provide high reliability and low cost.

DESIGN METHODOLOGY:

The "AA" converters utilize 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 stabilizes, 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 RANGE:

The "AA" Series is designed for full power operation at up to 90% efficiency. A wide input range of +11 to +16VDC or +23 to +30VDC will maintain full power output without derating. The derated input range is +9 to +32VDC. See Application Note 16 for protection information.

WIDE OUTPUT RANGE:

The "AA" Series is a non-isolated, unipolar converter. Positive or negative output must be specified. Output voltage is adjustable from 0 to 62, 125, 250, 500, 1kV, 2kV, 4kV, or 6kV. As the output voltage is reduced towards 0, the maximum current capability remains unchanged.

OUTPUT VOLTAGE MONITOR:

The "AA" Series features a voltage monitor on pin 9 referenced to Signal Ground pin 5. The scale factor is 100:1 on models from 1kV to 6kV, and 10:1 on models below 1kV. The monitor output impedance is calibrated for use with a 10- Megohm input impedance meter. Overall accuracy is ±2.0% with a temperature coefficient of ±100 ppm per °C.

For applications requiring a different scale factor, such as an ADC-compatible design, an external resistor may be added in parallel with the output.

The "AA" Series features an output current monitor. Current from the high-voltage multiplier can be monitored by reading the voltage appearing between Output Monitor pin 3 and Signal Ground Return pin 5. Internal voltage dividers create a small, compensable, linear-offset voltage. See

Application Note 13.

REMOTE CONTROL:

The "AA" Series is remotely programmed with 0 to +5 VDC to produce an output voltage. Input may be from a control voltage, DAC, variable or fixed resistor. On a negative output converter, the programming logic of the remote adjust would be inverted, i.e.: +5 to 0VDC. Connections are on the converter for the internal reference, analog remote adjust, and the signal ground. The reference is +5.0VDC, temperature-compensated with a 464 ohm output impedance. See Figure's E & F or Application Note 1 for more information.

STANDBY MODE:

The "AA" converters also have an enable function. When the enable is TTL 0 (<+0.7V Isink=1mA), the converter is in a standby mode and input current is reduced to <30 mA. All functions other than the internal reference are shut down. If the enable pin is left unconnected, TTL 1, or at greater voltages up to +32VDC the converter operates normally. The open-circuit output voltage from the Enable pin is <+5VDC. In the inhibit/disable mode, 1 mA will have to be sunk for proper shutdown.

MECHANICAL:

"AA" Series converters are in PCB-mountable plastic cases requiring a footprint of 4.46 In² and only 3.35 In³ of volume. Mounting plates and brackets are available for chassis mounting. See Application Note 6 for thermal considerations and mounting configurations. All models are available with optional six-sided wrap-around Mu-Metal Shielding.

ENVIRONMENTAL:

The "AA" Series provides full power operation at case temperatures from -40 to +65°C. All units receive a 24-hour burn-in prior to final testing. Extended temperature range is available along with other enhanced capabilities. Please contact the factory.