Application Note, continued
Off-Line Power Supply Configuration
The ARM maintains the DC output bus voltage between 200
and 375Vdc over the entire universal input range, which is
compatible with Vicor VI-260 series and VI-J60 series DC-DC
converters, as well as next-generation 300V input Vicor
converters. The ARM automatically switches to the proper
rectification mode (doubled or undoubled) depending on the
input voltage, eliminating the possibility of damage due to
improper line connection. The ARM–1 is rated at 500W in the
low range (90-132Vac input), and 750W in the high range
(180-264Vac input). The ARM–2 is rated for 1000W and
1500W for the low and high input ranges respectively. Either
of these modules can serve as the AC front end for any number
and combination of compatible converters as long as the
maximum power rating is not exceeded.
Strap (ST) Pin.
In addition to input and output power pin
connections, it is necessary to connect the Strap pin to the
junction of the series holdup capacitors (C1,
C2, Fig. 8)
for proper (autoranging) operation. Gas tubes across the
capacitors provide input transient protection. The bleeder
resistors (R1,
R2, Fig. 8)
discharge the holdup capacitors when
power is switched off.
Enable (EN) Pin.
(See
Fig. 9).
The Enable pin must be
connected to the Gate-In or PC pin of all converter modules to
disable the converters during power-up. Otherwise, the
converters would attempt to start while the holdup capacitors
were being charged through an unbypassed thermistor,
preventing the bus voltage from reaching the thermistor
bypass threshold thus disabling the power supply. The Enable
output (the drain of an N channel MOSFET) is internally
pulled up to 15V through a 150kΩ resistor.
A signal diode should be placed close to and in series with the
Gate-In pin of each converter to eliminate the possibility of
control interference between converters. The Enable pin
switches to the high state (15V) with respect to the negative
output power pin to turn on the converters after the power-up
inrush is over. The Enable function also provides input
overvoltage protection for the converters by turning off the
converters if the DC bus voltage exceeds 400Vdc. The
thermistor bypass switch opens if this condition occurs,
placing the thermistor in series with the input voltage, which
reduces the bus voltage to a safe level while limiting input
current in case the gas tubes fire. The thermistor bypass switch
also opens if a fault or overload reduces the bus voltage to less
than 180Vdc.
Holdup Box (HUB)
820µF HUB820-S,
2200µF HUB2200-S
C3
F1
+In
C10
Gate In (PC)
Vicor DC-DC
Converter
Gate Out (PR)
–In
R2
C2
1200µF HUB1200-S, 2700µF HUB2700-S
1800µF HUB1800-S, 3300µF HUB3300-S
R1
V1
C1
N
Z1
+V
VI-ARM
BOK
EN
–V
C7*
C8*
Filter
ST
L
V2
D3
Part
C1,2
C3–6
R1,2
V1,2
F1,2
D1,2
C7,8
*
Z1
D3,D4
C10,C11
R3
Description
Holdup capacitors
4700pF
150kΩ, 0.5W
220V MOV
3A, PC Tron
Diode
Film Cap., 0.8µf
MOV
1N5817
0.001µF
500Ω
Vicor
Part Number
see text
01000
00127-1503
13755
02178
00670
R3
C4
D1
F2
C5
+In
C11
D2
D4
Gate Out (PR)
–In
Gate In (PC)
Vicor DC-DC
Converter
03040
26108
Sizing PCB traces:
All traces shown in bold carry significant
current and should be sized accordingly.
VI-ARM- _12
N/ST/L 10A rms at 90Vac and 500W
4A DC at 190Vdc and 750W
+/– In
*
VI-ARM- _22
N/ST/L 20A rms at 90Vac and 1000W
+/– In
8A DC at 190Vdc and 1500W
Required if C1 & C2 are located more than
6 inches from output of VI-ARM.
C6
To additional modules
Figure 8—Converter
connections
Vicor Corp.
Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
ARM, Autoranging Rectifier Module
Rev. 2.4
Page 6 of 12
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