MC33997 Datasheet, PDF(15/20 Page) Motorola, Inc – Switching Power Supply with Linear Regulators

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MC33997 Datasheet, PDF (15/20 Pages) Motorola, Inc – Switching Power Supply with Linear Regulators

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Freescale Semiconductor, Inc.

APPLICATIONS

Cf1

10 uF

Lf1

10uH

Cf 2 C1

1.0uF 100uF

VPW R

1.0uF

Dp1

Dp2

KA _V PWR

VR EF1

Cs1 21

33 nF

VR EF2

C s2

33nF

3 399 7

D ri ve

I-lim

Soft

St art

Enb

O sc

Logic

Latc h

Ramp

Vb g

R e tr y

VREF 1

Re g.

Ba ndgap

Vol ta g e

Vb g

Sn senb Referen ce

R etr y

VREF 2

Re g.

Snse nb

Sns enb

Enable

Control En b

Enb

3. 3V

Linear

Regulat or

D r iv er

P OR

E nb

V bg

3.3V

Standby

Reg.

Ch arge

P um p

P wrO K

VkamO K

VS W

FBKB

VSUM

VD DH

15uH

VDDH = 5.0V

@ 1400mA total

2 .2 R 68uF

390 pF

O pt io nal

Snubber

100nF

Cc1 Rc1

2. 2nF 3.6k

DR VL

FB L

1 00n F

VKA M

4 .7 uF

PW ROK

VKAMOK

VDDL = 3. 3V

@ 40 0mA

68uF

VKAM = 3.3V

@ 10mA

R1 R2

10k 10k

CRES 3

22nF

SNSEN 22 EN 23

5-8 G ND

17-20

Note The VDDH total output current is 1.4 A. This includes the current used by the linear regulator VDDL and buffered outputs VREF1 and VREF2.

Figure 8. 33997 Application Circuit Schematic Diagram

Table 1. Recommended Components

Designator

Cf1

Cf2, C2

C3 (Note 15)

C4, C5

C8 (Optional)

Value / Rating

10 ÂµF/50 V

1.0 ÂµF/50 V

100 ÂµF/50 V

68 ÂµF/10 V

4.7 ÂµF/10 V

100 nF/16 V

390 pF/50 V

22 nF/25 V

Description/Part No.

Aluminum Electrolytic/UUB1H100MNR

Ceramic X7R/C1812C105K5RACTR

Aluminum Electrolytic/UUH1V101MNR

Tantalum / T494D686M010AS

Tantalum / T494A475M010AS

Ceramic X7R

Manufacturer (Note 16)

Nichicon

Kemet

Nichicon

Kemet

Any Manufacturer

Notes

15. It is possible to use ceramic capacitors in the switcher output, e.g. C3 = 2 x 22 ÂµF/6.3 V X7R ceramic. In this case the compensation resistor

has to be changed to Rc1 = 200 â¦ to stabilize the switching regulator operation.

16. Motorola does not assume liability, endorse, or warrant components from external manufacturers that are referenced in circuit drawings or

tables. While Motorola offers component recommendations in this configuration, it is the customerâs responsibility to validate their application.

MOTOROLA ANALOG INTEGRATED CIRFCoUIrTMDEoVrICeEIDnAfoTArmation On This Product,

Go to: www.freescale.com

33997

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