Vicor Micro Family of DC-DC Converter - Manual (Page 34)

Design Guide & Applications Manual
For Maxi, Mini, Micro Family DC-DC Converters and Configurable Power Supplies
Maxi, Mini, Micro Design Guide Rev 4.9 vicorpower.com
Page 33 of 88
Apps. Eng. 800 927.9474 800 735.6200
7. Autoranging Rectifier Module (ARM)
Bus OK (BOK) Pin. (Figure 7–5) The Bus OK pin is
intended to provide early-warning power fail information
and is also referenced to the negative output pin.
CAUTION: There is no input-to-output isolation in
the ARM. It is necessary to monitor Bus OK via an
optocoupler if it is to be used on the secondary
(output) side of the converters. A line-isolation
transformer should be used when performing scope
measurements. Scope probes should never be applied
simultaneously to the input and output as this will
damage the module.
Filter. Two input filter recommendations are shown for
low-power VI-ARM-x1 and high-power VI-ARMB-x2.
(Figures 7–6a and 7–6b)
Both filter configurations provide sufficient common-mode
and differential-mode insertion loss in the frequency range
between 100 kHz and 30 MHz to comply with the Class B
conducted emissions limit.
Hold-up Capacitors. Hold-up capacitor values should be
determined according to output bus voltage ripple, power
fail hold-up time, and ride-through time. (Figure 7–7)
Many applications require the power supply to maintain
output regulation during a momentary power failure of
specified duration, i.e., the converters must hold up or
ride through such an event while maintaining undisturbed
output voltage regulation. Similarly, many of these same
systems require notification of an impending power failure
to allow time to perform an orderly shutdown.
The energy stored on a capacitor, which has been charged
to voltage V, is:
ε
= 1/2(CV 2 ) (1)
where:
ε
= stored energy
C = capacitance
V = voltage across the capacitor
Energy is given up by the capacitors as they are discharged
by the converters. The energy expended (the power-time
product) is:
ε
= P
∆t = C(V
12
– V
22
) / 2 (2)
where: P = operating power
∆t = discharge interval
V
1 = capacitor voltage at the beginning of
∆t
V
2
= capacitor voltage at the end of
∆t
Figure 7–6a — Recommended filter design; Low power filter
connection for VI-ARM-x1 Figure 7–6b — Recommended filter design; High power filter
connection for VI-ARMB-x2
N
ST
L
C2
R4
C4
L2/N
L1
GND
L1
R3
L2
R1
R2
L3
C1
C3 F1
Z1
Part Description Vicor Part Number
C1 1.0 µF 02573
C2, C3 4700pF (Y2 type) 03285
C4 0.15µF 03269
F1 10 A Max 05147
L1, L2 27 µH 32012
L3 2.2 mH 32006
R1, R2 10 Ω
R3 150 kΩ, 0.5 W
R4 2.2 Ω
Z1 MOV 30076
CM
C2
C4
R1
C3
C5
L4
L2
L1
L3
R2
C1
L1
L2/N
GND
F1
N
ST
L
Z1
Part Description Vicor Part Number
L1,L4 1,000 µH 12 A / 6.5 M Ω 31743
L2, L3 22 µH 33206
C1 0.68 µF (X type) 02573
C2,C3,C4,C5 4700pF (Y2 type) 03285
C6 0.22 µF (X type) 04068
R1 390 k Ω 1/2 W
R2 10 Ω 1/2 W
F1 15 A Max
Z1 MOV 30076
C6 CM CM
Figure 7–4 — Enable (EN) function
+IN
PC (GATE IN)
PR
–IN
N
ST
L
+V
BOK
EN
–V
Vicor
DC-DC
Converter
Micro-
controller
15 Vdc
To additional modules
Not used with VI-260/VI-J60 +IN
PC
PR
–IN
N
ST
L
+V
BOK
EN
–V
Vicor
DC-DC
Converter
Micro-
controller
15 Vdc
+5 Vdc
Secondary
referenced
To additional modules
Figure 7–5 — Bus OK (BOK) isolated power status indicator