DS8313 Datasheet, PDF (15/18 Pages) Maxim Integrated Products – Smart Card Interface

Smart Card Interface
Smart Card Power Select
The DS8313/DS8314 support three smart card V_CC
voltages: 1.8V, 3V, and 5V. The power select is con-
trolled by the 1_8V and 5V/3V signals as shown in
Table 3. The 1_8V signal has priority over 5V/3V. When
1_8V is asserted high, 1.8V is applied to V_CC when the
smart card is active. When 1_8V is deasserted, 5V/3V
dictates V_CC power range. V_CC is 5V if 5V/3V is assert-
ed to a logic-high state, and V_CC is 3V if 5V/3V is pulled
to a logic-low state. Care must be exercised when
switching from one V_CC power selection to the other. If
both 1_8V and 5V/3V are high with CMDVCC high at
the same time, the DS8313/DS8314 enter stop mode.
To avoid accidental entry into stop mode, the state of
1_8V and 5V/3V must not be changed simultaneously.
A minimum delay of 100ns should be observed
between changing the states of 1_8V and 5V/3V. See
Figure 9 for the recommended sequence of changing
the V_CC range.
Table 3. V_CC Select and Operation Mode
1_8V
5V/3V
CMDVCC
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
V_CC SELECT (V)
3
3
5
5
1.8
1.8
1.8
1.8
CARD INTERFACE STATUS
Activated
Inactivated
Activated
Inactivated
Activated
Inactivated
Reserved (Activated)
Not Applicable—Stop Mode
V_CC SELECT
1.8V
CMDVCC
1_8V
5V/3V
3V
5V
3V
1.8V
STOP MODE
Figure 9. Smart Card Power Select
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