L5963 datasheet(31/45 Pages) STMICROELECTRONICS

Part #	L5963

Description	Dual monolithic switching regulator with LDO and HSD

PDF	45 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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31 / 45 page

DocID028553 Rev 1

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L5963

Application information

Equation 12

The figure below shows the asymptotic Bode gain plot for the TYPE III compensated system

and the gain and phase equations for the compensated system

Figure 14. TYPE III compensated network diagram

Here an example of calculating the external components network step by step.

Suppose the requirements for a dc-dc regulator are the following:

Input voltage minimum Vin(min)

8 V

Input voltage maximum Vin(max)

26 V

Input voltage typical Vin(typ)

14 V

Output voltage buck regulator 1- VBUCK 1

Min = 4.75 V, Max = 5.25 V

Converter switching frequency, fsw

250 kHz

Maximum output current on buck regulator 1-VBUCK 1

3 A

Maximum ripple current IRipple

0.3* Iout

Load transition requirement

500 mA ↔ 1.5 A in Δt = TBD

Assume TYPE III Compensation network.

STEP 1 - Calculate the inductor value

Using Equation 13, to find the inductor value, assume inductor ripple current of 0.9 A.

Equation 13

L5963 Datasheet(PDF) 31 Page - STMicroelectronics