PRM48BX480Y600A00 Datasheet, PDF (19/22 Pages) Vicor Corporation – High Efficiency Remote Sense PRM Converter

PRM48Bx480y600A00
80
60 I
Compensation Gain
40
E
F
PRM Open Loop Min Load
A
20
PRM Open Loop Max Load
0
Open Loop Gain vs. Frequency
10MHz GBW
B
J
F_CMIN F_CMAX
K
L
-20
C
-40
G
Frequency (Hz)
Figure 27 – reference asymptotic Bode plot for the considered system
10.2.6 High Frequency Pole Design (C2):
Using Equation [3], C2 should be selected so that F_P2 is
at least one decade above F_CMAX and prior to the gain
bandwidth product of the operational amplifier (10MHz
for this example). For applications with a higher desired
crossover frequency the use of a high gain bandwidth
product amplifier may be necessary to ensure that the
real pole can be set at least one decade above the
maximum crossover frequency.
10.2.7 Verifying Stability:
The preferred method for verifying stability is to use a
network analyzer, measuring the closed loop response
across various lines and load conditions.
In the absence of a network analyzer, a load step
transient response can be used in order to estimate
stability.
Figure 28 illustrates an example of a load step response.
Equation [4] can be used to predict the phase margin
based on the ratio of the “kick” to “droop” (as defined in
Fig. 28).
Figure 28 – load step response example and “droop”
vs. “kick” definition
PRM® Regulator
Page 19 of 22
Rev 1.2
07/2015
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