PRM48BF480T400B00 Datasheet, PDF (18/22 Pages) Vicor Corporation – High Efficiency Remote Sense PRM Converter

9.2.4 Midband
(R1,R3):
Gain
Design
With reference to Figure 27: curve ABC is the:
 minimum output voltage in the application
 maximum input voltage expected in the
application
 maximum load
PRM open loop response, and is where the maximum
crossover frequency occurs. In order for the maximum
crossover frequency to occur at the design choice F_CMAX,
the compensation gain must be equal and opposite of
the powertrain gain at this frequency. For stability
purposes, the compensation should be in the Mid-band
(J-K) at the crossover. Using Equation [1], the mid-band
gain can be selected appropriately.
PRM48BF480T400B00
9.2.5 Compensation Zero Design (C1):
With reference to Figure 27: curve EFG is the:
 maximum output voltage in the application
 minimum input voltage expected in the
application
 minimum load in the application
PRM open loop response, and is where the minimum
crossover frequency F_CMIN occurs. Based on stability
criteria, the compensation must be in the mid-band at
the minimum crossover frequency, therefore F_CMIN will
occur where EFG is equal and opposite of G_MB. C1 can
be selected using Equation [2] so that F_Z1 occurs prior to
F_CMIN.
C2
C1
R3
-
+
Vref
F1
C_{IN_EXT}
VS
+IN
P
R
+OUT
C_{IN_INT}
PRM^TM
Regulator
C_{OUT_INT}
-IN _{IF RE SG}
-OUT
COUT_EXT
R2
R1
RS
Vref
Vref IC
I sense
IC
PRM® Regulator
Figure 26 – Control circuit example
Rev 1.1
800 927.9474