GENERAL INFORMATION:
The “EFL” 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 “EFL” 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 “EFL” 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 4 separate LV floating
outputs. 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 “EFL” Series works directly with any UltraVolt “A” or “C” Series DC-to-DC
HVPS from 0 to 62V through 0 to 40kV @ 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 “15EFL12-12W” provides floating
+12VDC @ 1 Amp, ±15VDC @ 50 mA, and
+5.1VDC @ 500mA from a single ground side
+12VDC input. The “15EFL12-24W” provides
floating +24VDC @ 1 Amp, ±15VDC @
50 mA, and +5.1VDC @ 500 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
±15VDC provides bias to floated
Op-Amps, DACs & ADCs.
The +5.1VDC can run floating micro-controllers
or watchdog reset circuits.
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ISOLATED
CONTROLS: DIGITAL CHANNELS
The “-I/O” option provides one isolated digital I/O channel
from the grounded system side to the floating hot deck and one from the hot
deck to the ground deck. The TTL bit is inverted. The output, a schmitt trigger
TTL buffer, sources up to 0.8mA and sinks up to 3 mA. This bit is typically
used to enable/disable a floated UV HVPS.
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.
This signal is typically used to remote program
a floated UV HVPS or
a floating filament regulator with precision
characteristics.
STANDBY MODE:
All “EFL” 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 < 150 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
+5VDC the converter operates normally.
MECHANICAL:
“EFL” 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 “EFL” 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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