PI3420-00-LGIZ Datasheet, PDF (25/30 Pages) Vicor Corporation – 8 V to 18 Vin, 15 A Cool-Power ZVS Buck Regulator

PI34xx-00
Master V_OUT
PI34xx
R1
TRK
Slave
R2
SGND
Figure 40 — Voltage divider connections for direct tracking
All tracking regulators should have their Enable (EN) pins
connected together to work properly.
Inductor Pairing
The PI34xx-00 utilizes an external inductor from the Eaton
Inductor line at Cooper Industries. This inductor has been
optimized for maximum efficiency performance. Table 4
details the specific inductor value and part number utilized
for each PI34xx-00 device. Datasheets are available at
www.cooperindustries.com.
Device
Inductor
[nH}
Inductor
Part Number
PI3420-00
PI3421-00
PI3422-00
PI3423-00
PI3424-00
85
FPV1006-85-R
125
FPV1006-125-R
125
FPV1006-125-R
150
FPV1006-150-R
150
FPV1006-150-R
Table 4 — PI34xx-00 Inductor pairing
Manufacturer
Eaton
Eaton
Eaton
Eaton
Eaton
Thermal Derating
Thermal de-rating curves are provided that are based on
component temperature changes versus load current, input
voltage and air flow. It is recommended to use these curves
as a guideline for proper thermal de-rating. These curves
represent the entire system and are inclusive to both the
Picor regulator and the external inductor. Maximum thermal
operation is limited by either the MOSFETs or inductor
depending upon line and load conditions.
Thermal measurements were made using a standard PI34xx-
00 Evaluation board which is 3 x 4 inches in area and uses 4-
layer, 2oz copper. Thermal measurements were made on the
three main power devices, the two internal MOSFETs and the
external inductor.
Filter Considerations
The PI34xx-00 requires input bulk storage capacitance as
well as low impedance ceramic X5R input capacitors to
ensure proper start up and high frequency decoupling for the
power stage. The PI34xx-00 will draw nearly all of the high
frequency current from the low impedance ceramic
capacitors when the main high side MOSFET is conducting.
During the time the high side MOSFET is off, they are
replenished from the bulk capacitor. If the input impedance
is high at the switching frequency of the regulator, the bulk
capacitor must supply all of the average current into the
regulator, including replenishing the ceramic capacitors. This
value has been chosen to be 100μF so that the PI34xx-00 can
start up into a full resistive load and supply the output
capacitive load with the default minimum soft start capacitor
when the input source impedance is 50 Ohms at 1MHz. The
ESR for this capacitor should be approximately 20mΩ. The
RMS ripple current in this capacitor is small, so it should not
be a concern if the input recommended ceramic capacitors
are used. Table 5 shows the recommended input and output
capacitors to be used for the various models as well as
expected transient response, RMS ripple currents per
capacitor, and input and output ripple voltages. Table 6
includes the recommended input and output
ceramic capacitors.
Device
V_IN
I_LOAD
(V)
(A)
C_INPUT
Bulk
Elec.
C_INPUT
Ceramic
X5R
15
PI3420
12
7.5
100 µF
50 V
6 x 22 µF
15
PI3421
12
7.5
100 µF
50 V
6 x 22 µF
15
PI3422
12
7.5
100 µF
50 V
6 x 22 µF
15
PI3423
12
7.5
100 µF
50 V
6 x 22 µF
15
PI3424
12
7.5
100 µF
50 V
6 x 22 µF
Table 5 — Recommended input and output capacitance
C_OUTPUT
Ceramic
X5R
8 X 100 µF
2 X 1 µF
1 X 0.1 µF
8 X 100 µF
2 X 1 µF
1 X 0.1 µF
8 X 100 µF
2 X 1 µF
1 X 0.1 µF
8 X 100 µF
2 X 1 µF
1 X 0.1 µF
8 X 47 µF
2 X 1 µF
1 X 0.1 µF
C_INPUT
Ripple
Current
(I_RMS)
C_OUTPUT
Ripple
Current
(I_RMS)
0.85
1.24
1.0
1.18
1.12
1.16
1.20
1.15
1.29
1.13
Input
Ripple
(mVpp)
98
43
139
45
145
74
179
97
209
98
Output
Ripple
(mVpp)
36
27
32
20.4
28
14
26
17
34
24.8
Output
Ripple
(mVpk)
Recovery ^Load
Time
Step
(µs)
(A)
(Slew/µs)
-/+41
42
7.5
(5 A/µs)
-/+50
50
7.5
(5 A/µs)
-/+46
60
7.5
(5 A/µs)
-/+73
70
7.5
(5 A/µs)
-/+98
60
7.5
(5 A/µs)
Cool-Power^®
Page 25 of 30
Rev 1.3
12/2015
vicorpower.com
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