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| L7986TR Datasheet, PDF (22/43 Pages) STMicroelectronics – 3 A step-down switching regulator | |||
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Application information
L7986
Equation 27
R3 = -4---------fï----L--B----C--R----W----1-------â-----1- ï¬
C3 = -2---ï°-----ï---R-----3--1--ï---4-----ï---B----W----
The suggested maximum system bandwidth is equal to the switching frequency divided by
3.5 (FSW / 3.5), anyway, lower than 100 kHz if the FSW is set higher than 500 kHz.
For example, with VOUT = 5 V, VIN = 24 V, IO = 3 A, L = 18 ïH, COUT = 22 ïF, ESR < 1 mï,
the type III compensation network is:
R1 = 4.99kïï¬ R2 = 680ïï¬ R3 = 200ïï¬ R4 = 2kïï¬ C3 = 3.3nFï¬ C4 = 22nFï¬ C5 = 220pF
In Figure 12 the module and phase of the open-loop gain is shown. The bandwidth is about
58 kHz and the phase margin is 50°.
22/43
DocID022450 Rev 6
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