PRELIMINARY
Application Note (continued)
V•I Chip Bus Converter Module
The thermal resistance of the PCB to the surrounding environment in
proximity to V•I Chips may be reduced by low profile heat sinks surface
mounted to the PCB.The PCB may also be coupled to a cold plate by low
thermal resistance standoff elements as a means of achieving effective
cooling for an array of V•I Chips, without a direct interface to their case.
CASE 3—Combined direct convection to the air and conduction to the PCB.
Parallel use of the V•I Chip internal thermal resistances (including Junction-
to-Case and Junction-to-BGA) in series with external thermal resistances
provides an efficient thermal management strategy as it reduces total
thermal resistance. This may be readily estimated as the parallel network of
two pairs of series configured resistors.
V•I Chip Bus Converter Level 1 DC Behavioral Model for 48 V to 3 V, 210 W
ROUT
IOUT
1.8 mΩ
+
+
1/16 • Iout
1/16 • Vin
•
V I
+
–
+
–
VOUT
VIN
Q
I
69 mA
K
–
–
©
Figure 25—This model characterizes the DC operation of the V•I Chip bus converter, including the converter transfer function and its losses. The model enables
estimates or simulations of output voltage as a function of input voltage and output load, as well as total converter power dissipation or heat generation.
V•I Chip Bus Converter Level 2 Transient Behavioral Model for 48 V to 3 V, 210 W
0.12 nH
Lout = 1.1 nH
ROUT
IOUT
IN
L
= 20 nH
1.8 mΩ
+
+
R
COUT
R
0.6 mΩ
1/16 • Vin
CIN
•
V I
0.085 mΩ
1.3 mΩ
1/16 • Iout
+
–
4µF
254 µF
+
–
CIN
COUT
VOUT
VIN
IQ
69 mA
K
–
–
©
Figure 26—This model characterizes the AC operation of the V•I Chip bus converter including response to output load or input voltage transients or steady state
modulations. The model enables estimates or simulations of input and output voltages under transient conditions, including response to a stepped load with or
without external filtering elements.
vicorpower.com
800-735-6200
V•I Chip Bus Converter Module
B048K030T21
Rev. 1.0
Page 12 of 15
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