W83637HF Datasheet, PDF (102/149 Pages) Winbond – LPC I/O

W83637HF
7.14 Power Down State
Transition from active state to power down state is accomplished by setting SCPWD to "1". Clock is
stopped for most internal core circuits except detection circuit for SCPSNT toggle (card
insertion/extraction). SCPWD could be reset by SCPSNT toggle and through this feature Smart Card
interface in power down state can be waken up by card insertion/extraction. User may also directly
write a "0" to SCPWD to wake up Smart Card interface.
Smart Card interface spends a little bit more power to maintain SCPSNT toggle detection circuit in
power down state than in disabled state while spares even more power than in active state by stopping
clock to core circuit.
Users must make sure that all on-going transactions are concluded before putting Smart Card interface
into power down state to prevent potential miss-operation of internal state machine.
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Publication Release Date: June 25, 2003
Revision 1.3