GENERAL INFORMATION:
The “C” Series of high-voltage
regulated DC-DC converters are designed for
fast rise-time/charging applications utilizing
state-of-the-art power conversion topology.
Surface-mount technology and encapsulation
techniques provide high reliability and low
cost. See
Application Note 10 for
more charging information.
DESIGN METHODOLOGY:
The “C” converters utilize a dual-ended forward converter topology
with a nominal switching frequency of <100kHz. A precision reference
is provided so the remote control can program the power supply for a specific
voltage. A 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 and high-voltage transformer. The power
stage is protected from output current overloads or short circuits via a secondary
current limit circuit. This current limit is optimized for low-impedance capacitor
charging. The high voltage developed in the multistage multiplier generates feedback
voltage, which is sent to the CTRL circuit to maintain regulation. The AC feedback
networks are configured for maximum speed of rise with little or no overshoot
into capacitive loads.
WIDE INPUT VOLTAGE
RANGE:
The “C” Series is designed for full DC power operation at
up to 92% efficiency. A wide input range of +23 to +30VDC maintains
full output power. The derated input range is +9 to +32VDC.
See Application Note 16 for
protection information.
WIDE OUTPUT RANGE:
The “C” Series is a non-isolated,
unipolar converter. Positive or negative output
must be specified. Output voltage is adjustable
from 0 to 62V, 125V, 250V, 500V, 1kV, 2kV,
4kV or 6kV. As the output voltage is reduced
towards 0, the maximum current capability remains
unchanged.
OUTPUT VOLTAGE & CURRENT
MONITORS:
The “C” Series features a 100:1
voltage monitor. Units 2kV or higher have
a 100 MegΩ/1.1 MegΩ divider;
units below 2kV use a 10 MegΩ/102k
divider. The monitor output impedance is
calibrated for use with a 10 MegΩ input
impedance meter. Overall accuracy is ±2.0%
with a temperature coefficient of ±200
ppm per °C. The voltage monitor is output
on pin 9 and referenced to Signal Ground
pin 5.
Current from the high-voltage multiplier can be monitored by reading the voltage
appearing between Output Monitor pin 3 and Signal Ground pin 5. See Application
Note 13.
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REMOTE CONTROL:
The “C” Series is remotely programmed with 0 to +5VDC to produce
an output voltage. Input may be from a control voltage, a DAC, or from a 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 464Ω output
impedance. See Figure E and Application Note 1 for more information.
ENABLE/DISABLE:
The “C” 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 <30mA. 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
will initiate soft-start before beginning
to operate normally. The open-circuit output
voltage from the enable pin is <+5VDC.
In the inhibit mode 1mA will have to be sunk
for proper shutdown.
MECHANICAL:
“C” Series converters are in PCB-mountable plastic cases requiring
a footprint of 5.5 in² and only 4.3 in³ 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. 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 “C” 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.
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