PRM48JH480T250A00 Datasheet, PDF (37/44 Pages) Vicor Corporation – High Efficiency Converter

Midband Gain Design: R1, R3 (Remote Sense Operation)
With reference to Figure 37: curve ABC is the:
n minimum output voltage in the application
n maximum input voltage expected in the application
n 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 (8), the mid-band gain can be
selected appropriately.
Compensation Zero Design :C1 (Remote Sense Operation)
With reference to Figure 37: curve EFG is the:
n maximum output voltage in the application
n minimum input voltage expected in the application
n 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 (9) so that F_Z1 occurs prior to F_CMIN.
High Frequency Pole Design: C2 (Remote Sense Operation):
Using Equation (10), 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.
PRM48JH480x250A00
PRM^TM Regulator
Page 37 of 44
Rev 1.2
11/2015
vicorpower.com
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