lm27241 National Semiconductor Corporation, lm27241 Datasheet - Page 19

• Manufacturer Part Number: lm27241
• Description: Synchronous Buck Regulator Controller For Mobile Systems
• Manufacturer: National Semiconductor Corporation

Application Information
COMPENSATION
Modulator Gain
The LM27241 input voltage feed forward mechanism
changes the Error Amp ramp slope, and peak to peak volt-
age. The DC gain of the Modulator is dependent on the peak
to peak voltage of the oscillator’s ramp. The oscillator peak
to peak voltage can be determined by referring back to the
Oscillator section in the Electrical Characteristics table.
This ratio for the above equation is usually between 9.5 for
lower input voltages and as low as 8 higher input voltages.
The DC Gain of the power stage for a Buck-Converter is
equal to V
term in the numerator in the above equation is obtained.
OUT
/D, which is equal to V
IN
, and this is where the
(Continued)
19
Output Filter Gain
Exact Filter Gain
Reduces to proper form with the understanding that:
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