Rainbow-electronics MAX5099 Bedienungsanleitung PDF herunterladen (Seite 22)

MAX5099

Dual, 2.2MHz, Automotive Synchronous Buck

Converter with 80V Load-Dump Protection

22 ______________________________________________________________________________________

Procedure 2 (See Figure 4)

If the output capacitor used is a low-ESR ceramic type,

the ESR frequency is usually far away from the targeted

unity crossover frequency (f

). In this case, Type III

compensation is recommended. Type III compensation

provides two-pole zero pairs. The locations of the zero

and poles should be such that the phase margin peaks

around f

. It is also important to place the two zeros at

or below the double pole to avoid the conditional stabil-

ity issue.

1) Select a crossover frequency:

2) Calculate the LC double-pole frequency, f

3) Place a zero

where

and R

≥ 10kΩ.

4) Calculate C

for a target unity crossover frequency, f

5) Place a pole

6) Place a second zero, f

, at 0.2 x f

or at f

whichever is lower.

7) Place a second pole at 1/2 the switching frequency.

Boost Converter Compensation

The boost converter compensation gets complicated

due to the presence of a right-half-plane zero

ZERO,RHP

. The right-half-plane zero causes a drop in

phase while adding positive (+1) slope to the gain

curve. It is important to drop the gain significantly below

unity before the RHP frequency. Use the following pro-

cedure to calculate the compensation components:

1) Calculate the LC double-pole frequency, f

, and

the right-half-plane-zero frequency.

where

Target the unity-gain crossover frequency for:

ZERO RHP

≤

OUT

MIN

OUT

OUT MAX

−

()

ZERO RHP

MIN

OUT

()

−

()

OUT OUT

××

−1

2π

fRC

SW F F

×× ××

()

−205 1π .

××

−

ZERO ESR I

××

2π

at f

ZERO ESR1

××π

fL C V

C OUT OUT OSC

IN F

×× × ×

2π

LC F

×××

2075π .

at f

LC1

075=

××

OUT OUT

××

2π

≤

COMP_

OUT

REF

FB_

Figure 4. Type III Compensation Network

1 2 ... 17 18 19 20 21 22 23 24 25 26 27

Kommentare zu diesen Handbüchern

Keine Kommentare

Rainbow-electronics MAX5099 Bedienungsanleitung Seite 22

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für Sensoren Rainbow-electronics MAX5099