wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 135

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

w
Pre-Production
POWER SEQUENCING
As part of the start-up sequence (initiated by setting a logic high level on NPDN), the power
sequencer outputs PSEQ1, PSEQ2, PSEQ3 and PSEQ4 are asserted according to a fixed sequence
described in Table 78 and illustrated in Figure 84.
The sequencer commences operation approximately 40ms after NPDN has been set high.
Table 78 Power Sequencing Outputs
Figure 84 Power Sequencing Timing
The power sequencer outputs are digital outputs referenced to the LINE power domain. Each of
these outputs may be connected to one or more of the DC-DC Converter or LDO Regulator hardware
enable pins (see “Enabling the Converters”) in order to implement the desired power-up sequencing.
2 ms
4 ms
8 ms
16 ms
TIME
PSEQ1 asserted
PSEQ1 + PSEQ2 asserted
PSEQ1 + PSEQ2 + PSEQ3 asserted
PSEQ1 + PSEQ2 + PSEQ3 + PSEQ4 asserted
OUTPUT
PP, April 2009, Rev 3.0
WM8400
135