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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Figure 8—Converter connections

+In

Gate In (PC)

Gate Out (PR)

–In

+In

Gate In (PC)

Gate Out (PR)

–In

N

ST

L

+V

BOK

EN

–V

Vicor DC-DC

Converter

VI-ARM

R1

R2

C1

C2

V1

V2

D2

D1

C3

C5

C4

C6

F1

F2

Vicor DC-DC

Converter

To additional modules

C7*

C8*

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

03040

26108

Sizing PCB traces:

All traces shown in bold carry significant

current and should be sized accordingly.

VI-ARM- _12

N/ST/L

+/– In

10A rms at 90Vac and 500W

4A DC at 190Vdc and 750W

Required if C1 & C2 are located more than

6 inches from output of VI-ARM.

*

Z1

*

Filter

Holdup Box (HUB)

820µF HUB820-S,

2200µF HUB2200-S

1200µF HUB1200-S, 2700µF HUB2700-S

1800µF HUB1800-S, 3300µF HUB3300-S

20A rms at 90Vac and 1000W

8A DC at 190Vdc and 1500W

VI-ARM- _22

N/ST/L

+/– In

R3

C10

D3

C11

D4

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 150k

Ω 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.