DS8113_10 Datasheet, PDF (15/17 Pages) Maxim Integrated Products – Smart Card Interface

Smart Card Interface
Smart Card Power Select
The DS8113 supports three smart card V_CC voltages:
1.8V, 3V, and 5V. The power select is controlled 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 VCC 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 asserted 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 DS8113 enters stop mode. To avoid acciden-
tal 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 recom-
mended 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
______________________________________________________________________________________ 15