w83637hg Winbond Electronics Corp America, w83637hg Datasheet - Page 101

• Manufacturer Part Number: w83637hg
• Description: Winbond Lpc I/o Lpc I/o
• Manufacturer: Winbond Electronics Corp America

W83637HF/HG
7.10 Power States
W83637HF/HG employs a sophisticated algorithm to partition Smart Card interface's internal circuits to
achieve optimal power utilization. However, users must pay extra care in the design of application
circuits following guidelines stated below to prevent potential signal conflict and unnecessary power
consumption.
There're four power states: disabled state, active state, idle state and power down state. Disabled
state is the default state when power is first applied to the IC. Active state is entered by setting a "1" to
enable bits at bit 0 of CR30 in logical device 0 (refer to Configuration Register section for details). Idle
state means that I/O pins of deselected socket output a predetermined voltage level to disable power
to socket and to prevent leakage from floating connections while Smart Card interface core circuits
might still be servicing other selected socket. SCPWD (Smart Card Power Down, bit 7 of CR22 global
control register) controls whether in active state (SCPWD = 0) or in power down state (SCPWD = 1).
7.11 Disabled State
Smart Card interface is in disabled state initially. Clock is stopped in this state and therefore it is the
least power-consuming state. To prevent current leakage from floating connections, it is designed to
output a predetermined voltage level on all the I/O pins of Smart Card interface as follows:
SCPWR# outputs high to disable power supply to socket;
SCRST#, SCCLK, SCIO, SCC4, SCC8 and SCLED output low;
SCPSNT is tri-stated.
These I/O conditions also apply to both socket A and socket B in power down state (SCPWD = 1) or
deselected socket in idle state. Designers of application circuits must take extra care so that no
contention occurs when Smart Card interface is in those power-saving states.
Please refer to
Winbond's recommended application circuit for example.
7.12 Active State
Active state is when Smart Card interface is actually performing all its functions: configuration of control
and interrupt registers, detection of card insertion/extraction, reception of ATR (Answer to Reset)
packet and communication of information between host and card. Refer to section 2.3 for detailed
function description.
Smart Card interface enters active state by setting a "1" to bit 0 of CR30 in logical device 0. This is the
most power-consuming state and actual power consumption is dependent on traffic of interface.
7.13 Idle State
W83637HF/HG supports up to two Smart Card sockets. Only one socket could be active at a time and
the other deselected socket is considered to be in idle state. Selection of active socket is controlled
through socket selection bits which are bits 0 at base address + 3. I/O pins of deselected socket also
output a predetermined voltage level as described in section 2.4.1. Power consumption in this state is
similar to active state because one of the two sockets is selected and core circuit is still functioning.
There is no idle state for W83637HF/HG because only one Smart Card socket is supported and it is
always selected.
Publication Release Date: March, 2006
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Revision 1.6