vi-armb-c123 Vicor Corporation, vi-armb-c123 Datasheet - Page 5

• Manufacturer Part Number: vi-armb-c123
• Description: Autoranging Rectifier Modules Up To 1500 Watts
• Manufacturer: Vicor Corporation

Figure 8 — Functional block diagram
The VI-ARM Autoranging Rectifier Module (ARM) provides
an effective solution for the AC front end of a power supply
designed with Vicor DC-DC converters. This high performance
power system building block satisfies a broad spectrum of
requirements and agency standards.
The ARM contains all of the power switching and control
circuitry necessary for autoranging rectification, inrush current
limiting, and overvoltage protection. This module also provides
converter enable and status functions for orderly power
up/down control or sequencing. To complete the AC front-end
configuration, the user needs only to add holdup capacitors and
a suitable input filter with transient protection.
limiting PTC (positive temperature coefficient) thermistor is
open when power is applied, as is the switch that engages the
strap for voltage doubling. (See Fig. 8). In addition, the
downstream DC-DC modules are disabled via the Enable (EN)
line, and Bus-OK (B OK) is high.
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Upon application of input power, the output bus capacitors
begin to charge. The thermistor limits the charge current,
and the exponential time constant is determined by the
holdup capacitor value and the thermistor cold resistance.
The slope (dv/dt) of the capacitor voltage approaches zero
as the capacitors become charged to the peak of the AC
line voltage.
Thermistor
PTC
The switch that bypasses the inrush
(See Fig. 9).:
Microcontroller
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Strap
+OUT
Strap
EN
BOK
–OUT
ARM, Autoranging Rectifier Module
turned off or fails, the following sequence occurs as the bus
voltage decays:
Figure 9 — Timing diagram: power up/down sequence
Thermistor
Converter
90–132 V
AC Line
Bus OK
Bypass
Enable
Output
(Vdc)
Strap
PTC
If the bus voltage is less than 200 V as the slope nears
zero, the voltage doubler is activated, and the bus voltage
climbs exponentially to twice the peak line voltage.
If the bus voltage is greater than 200 V, the doubler is
not activated.
If the bus voltage is greater than 235 V as the slope
approaches zero, the inrush limiting thermistor is
bypassed. Below 235 V, the thermistor is not bypassed.
The converters are enabled ~150 milliseconds after the
thermistor bypass switch is closed.
Bus-OK is asserted after an additional ~150 millisecond
delay to allow the converter outputs to settle within
specification.
Bus-OK is deasserted when the bus voltage falls below
205 Vdc (Typ.).
The converters are disabled when the bus voltage falls
below 200 Vdc. If power is reapplied after the converters
are disabled, the entire power-up sequence is repeated. If
a momentary power interruption occurs and power is
reestablished before the bus reaches the disable threshold,
the power-up sequence is not repeated.
Bus
400
300
200
100
Power
~150 ms
0
Up
~150 ms
1.1
2.1
3.1
(See Fig. 9). When input power is
4.1
5.1
Power
Rev. 3.8
Down
1.2
2.2
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