WM8321 datasheet(246/253 Pages) WOLFSON

246 / 253 page

WM8321

Production Data

PD, February 2012, Rev 4.0

246

As a minimum requirement, the DC current rating should be equal to the maximum load current plus

one half of the inductor current ripple:

To be suitable for the application, the chosen inductor must have a saturation current that is higher

than the peak inductor current given by the above equation. To maximise the converter efficiency, the

inductor should also have a low DC Resistance (DCR), resulting in minimum conduction losses. Care

should also be taken to ensure that the component’s inductance is valid at the applicable operating

temperature.

The WM8321 incorporates a current-limit protection feature for all DC-DC Converter outputs. In order

to achieve the benefit of this feature, the output inductor saturation current limit must be greater than

or equal to the P-channel Current Limit for the applicable converter (see Section 7).

Wolfson recommends the following external components for use with DC-DC Converters 1 and 2.

The output inductor must be consistent with the DCm_FREQ register settings. The supported

configurations are listed in Table 84. Note that for output voltages greater than 1.4V, the 2MHz mode

must be used.

DCm_FREQ

SWITCHING

FREQUENCY

OUTPUT

INDUCTOR

COMMENTS

n/a

2MHz

2.2

H

Best efficiency

4MHz

1.0

H

Good transient performance and efficiency

4MHz

0.5

H

Best transient performance

Table 84 Output Inductor Selection - DC-DC1, DC-DC2

The output capacitor must be consistent with the DCm_CAP register settings. For best performance,

the 47

F component is recommended. For typical applications, the 22F is suitable. The alternative

values may be used for size or cost reasons if preferred.

COMPONENT

VALUE

PART NUMBER

SIZE

0.5

H

Coilcraft XPL2010-501ML_

1.9 x 2 x 1mm

1.0

H

Coilcraft XFL3012-102ME_

3 x 3 x 1.2mm

2.2

H

Coilcraft LPS3015-222ML_

3 x 3 x 1.5mm

COUT

F

MuRata GRM21BR60G476MEA1

0805

F

MuRata GRM21BR60J226ME39

0805

F

MuRata GRM188R60J106ME84

0603

4.7

F

MuRata GRM188R60J475ME84

0603

CIN

F

MuRata GRM188R60J106ME84

0603

Table 85 Recommended External Components - DC-DC1, DC-DC2

WM8321 датащи(PDF) 246 Page - Wolfson Microelectronics plc

WM8321 датащи(HTML) 246 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL