PRM48DH480B03 Datasheet, PDF (18/22 Pages) Vicor Corporation – DC to DC Regulator

PRM48DH480T250B03
8.2.4 Midband Gain Design (R1,R3):
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.
8.2.5 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
+IN ^VS
PR
+OUT
R2
R1
R_S
C_{IN_EXT}
PRM
C_{IN_INT}
C_{OUT_INT}
-IN _{IF RE SG}
-OUT
C_{OUT_EXT}
Vref
Vref IC
I sense
IC
PRM^® Regulator
Page 18 of 23
Figure 26 – Control circuit example
Rev 1.2
7/2015
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