WM8976CGEFLSLASHV datasheet(19/114 Pages) WOLFSON

19 / 114 page

Production Data

WM8976

PD, Rev 4.5, November 2011

Figure 9 Typical Power up Sequence where DVDD is Powered before AVDD

Figure 9 shows a typical power-up sequence where DVDD comes up first. First it is assumed that

DVDD is already up to specified operating voltage. When AVDD goes above the minimum threshold,

Vpora, there is enough voltage for the circuit to guarantee PORB is asserted low and the chip is held in

reset. In this condition, all writes to the control interface are ignored. When AVDD rises to Vpora_on,

PORB is released high and all registers are in their default state and writes to the control interface

may take place.

On power down, where DVDD falls first, PORB is asserted low whenever DVDD drops below the

minimum threshold Vpord_off.

SYMBOL

MIN

TYP

MAX

UNIT

Vpora

0.4

0.6

0.8

Vpora_on

0.9

1.2

1.6

Vpora_off

0.4

0.6

0.8

Vpord_on

0.5

0.7

0.9

Vpord_off

0.4

0.6

0.8

Table 3 Typical POR Operation (typical values, not tested)

Notes:

If AVDD and DVDD suffer a brown-out (i.e. drop below the minimum recommended operating level but do not go below Vpora_off

or Vpord_off) then the chip will not reset and will resume normal operation when the voltage is back to the recommended level

again.

The chip will enter reset at power down when AVDD or DVDD falls below Vpora_off or Vpord_off. This may be important if the supply

is turned on and off frequently by a power management system.

The minimum tpor period is maintained even if DVDD and AVDD have zero rise time. This specification is guaranteed by design

rather than test.

WM8976CGEFL/V датащи(PDF) 19 Page - Wolfson Microelectronics plc

WM8976CGEFL/V датащи(HTML) 19 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