GENERAL INFORMATION:
The “FL” Series of floating-hot-deck,
low-voltage power supplies offers an integrated
solution for systems requiring LV power & controls
with high-voltage isolation. Combining a highly
isolated, DC-to-DC, multi-output low-voltage
power supply (LVPS) with an advanced isolated
digital & analog I/O topology, the “FL” sub-system
provides both power and controls to floating-hot-deck
circuitry. This solution, when combined with
one or more UV HVPS or other circuitry, can
provide high-performance solutions for applications
such as:
| Floating/Stacked Ion- or E-Beam Biases |
Floating Filament Bias |
| Floating Pulsers & Gated Grids |
Floating Capacitance Meters |
| Floating High Side Current Monitors |
Floating Leakage Testers |
Please
contact UltraVolt's customer service department
for an analysis of your requirements.
DESIGN METHODOLOGY:
The “FL” Series utilizes a dual-ended forward converter
topology with a nominal switching frequency of <100 kHz. Once
input voltage stabilizes, under-voltage lockout is released.
When the LVPS 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 with optically
isolated feedback controls the MOSFET push-pull power stage,
driving a highly isolated transformer. This isolated power ultimately
provides 3 separate LV floating outputs at >80% efficiency. The power
stage is protected from intermittent output-current overloads or short
circuits via a primary current limit circuit. The isolated digital
I/O channel(s) are optically transmitted directly to the floating
hot deck with a schmitt trigger buffer providing glitch-free
output on the floating hot deck. The isolated analog I/O channel(s)
are converted to digital data and optically transmitted directly
to the floating hot deck for conversion back to analog.
COMPATIBILITY:
The “FL” Series works directly with any UltraVolt “A”
or “C” Series DC-to-DC HVPS from
0 to 62V through 0 to 35kV @ 0 to 4 watts through
0 to 20 watts. By providing isolated power,
TTL enable/disable, and voltage programming,
UV HVPS can be floated or stacked on one another.
ISOLATED POWER OUTPUTS:
The “15FL12-12W” provides floating
+12VDC @ 1 Amp, -12VDC @ 10 mA, and +5VDC
@ 10 mA from a single ground side +12VDC
input. The “15FL24-24W” provides
floating +24VDC @ 1 Amp, -12VDC @ 10 mA,
and +5VDC @ 10 mA from a single ground side
+24VDC input. The main output is typically
used to drive a floating HVPS, or filament
switching regulator, etc. The -12VDC is for
use with the +DC in providing bias to floated
Op-Amps, DACs & ADCs. The +5 VDC can
run floating micro-controllers or watchdog
reset circuits.
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ISOLATED
CONTROLS: DIGITAL CHANNELS
The “-I/O” option provides isolated digital I/O channel(s) from
the grounded system side to the floating hot deck. The TTL bit is inverted.
The output, a schmitt trigger TTL buffer, sources up to 0.8mA and sinks up
to 13 mA. This bit is typically used to enable/disable a floated UV HVPS. It
can also be used at up to 300kHz to drive a pulser, gate, sample-and-hold multiplexer
or to communicate with a floated micro controller. The “-R/B” option
provides one additional down channel.
ISOLATED CONTROLS:
ANALOG CHANNELS
The “-I/O” option provides isolated
analog I/O channel(s) from the grounded system
side to the floating hot deck. The analog
signal is converted to digital and translated
back to analog at the floating hot deck.
The output is buffered with a source impedance
of 1.5KΩ. This signal is typically
used to remote program a floated UV HVPS.
It can be used at up to 30 Hz to drive an
amplifier, sample-and-hold, or to program
other devices such as a floating filament
regulator. The “-R/B” option
provides one additional down channel.
STANDBY MODE:
All “FL” models feature an LVPS enable/disable function. When the
enable is TTL 0 (<+0.7 VDC +/-0.2 Isink=1mA), the floating LVPS is in standby
mode. All isolated outputs go to 0VDC; input current drops to < 90 mA; and
all functions are shut down except the +5 Volt reference, which is always operational.
If the LVPS enable pin is left unconnected, TTL 1 or at greater voltages up to
+32VDC the converter operates normally.
MECHANICAL:
“FL” Series units are in PCB-mountable plastic cases requiring a
footprint of 8.5 in² and only 10 in³ of volume. Mounting plates and
brackets are available for chassis mounting. See Application
Note 6 for thermal considerations
and for mounting configurations.
ENVIRONMENTAL:
The “FL” Series provides full
power operation at case temperatures from
-20 to +55°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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