SC4612STRT datasheet(13/24 Pages) SEMTECH

Part #	SC4612STRT

Description	Wide Input Range High Performance Synchronous Buck Switching Controller

PDF	24 Pages

Scroll/Zoom	100%

Manufacturer	SEMTECH [Semtech Corporation]

Direct Link	http://www.semtech.com

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13 / 24 page

 2007 Semtech Corp.

www.semtech.com

SC4612

POWER MANAGEMENT

The design guidelines are as following:

1. Set the loop gain crossover frequency w

C for given

switching frequency.

2. Place an integrator at the origin to increase DC and low

frequency gains.

3. Select w

Z1 and wZ2 such that they are placed near wO to

dampen peaking; the loop gain should cross 0dB at a rate

of -20dB/dec.

4. Cancel w

ESR with compensation pole wP1 (wP1 = wESR ).

5. Place a high frequency compensation pole w

P2 at half

the switching frequency to get the maximum attenuation

of the switching ripple and the high frequency noise with

adequate phase lag at w

Application Information (Cont.)

0dB

ωZ1

ESR

ω o

Loop gain T(s)

Figure 2. Simplified asymptotic diagram of buck power

stage and its compensated loop gain.

Table 1

100

200

300

400

500

600

700

800

900

1000

1100

1200

100

200

300

400

500

600

700

800

900

1000 1100 1200

Frequency, (kHz)

Switching Frequency, F

SW vs. COSC.

SC4612STRT Datasheet(PDF) 13 Page - Semtech Corporation

SC4612STRT Datasheet(HTML) 13 Page - Semtech Corporation

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