LTC4556EUF Linear Technology, LTC4556EUF Datasheet - Page 9

• Manufacturer Part Number: LTC4556EUF
• Description: IC SMART CARD SAM CARD 24QFN
• Manufacturer: Linear Technology

Specifications of LTC4556EUF

• Function: Power Management, Signal Level Translation
• Rf Type: Cellular
• Secondary Attributes: SIM & Smart Card Interface
• Package / Case: 24-WFQFN Exposed Pad
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

OPERATIO
Table 1. Serial Port Commands
STATUS OUTPUT
0
0
0
0
Card Electrical Fault
Card ATR Fault
Card V
Card Present
Table 2. V
D1
0
0
1
1
Table 3. Clock Options
D7
0
0
0
0
1
1
1
1
To receive status data from the serial port, a read/write
operation must be performed. When polling for the pres-
ence of a smart card, the input word may be set to $00
since this is the shutdown command for the LTC4556.
Data Channel
The data channel is level shifted to the appropriate V
voltages at the I/O pin.
An NMOS pass transistor performs the level shifting. The
gate of the NMOS transistor is biased such that the
transistor is completely off when both sides have relin-
quished the channel. If one side of the channel asserts an
L, then the transistor will convey the L to the other side.
CC
D0
0
1
0
1
Ready
D6
0
0
1
1
0
0
1
1
CC
STATUS
V
V
V
V
and Shutdown Options
CC
CC
CC
CC
= 0V (Shutdown)
= 1.8V
= 3V
= 5V
D5
0
1
0
1
0
1
0
1
U
BIT
CLOCK MODE
Synchronous Mode
Bidirectional Mode
Asynchronous Stop Low
Asynchronous Stop High
Asynchronous 1
Asynchronous 2
Asynchronous 4
Asynchronous 8
D0
D1
D2
D3
D4
D5
D6
D7
COMMAND INPUT
V
(See Table 2)
Card Select/Deselect
Card Communications
Options (See Table 4)
Card Clock Options
(See Table 3)
CC
Options
CC
Note that current passes from the receiving side of the
channel to the transmitting side. The low output voltage of
the receiving side will be dependent upon the voltage at the
transmitting side plus the IR drop of the pass transistor.
When a card socket is selected, it becomes a candidate to
drive data on the DATA pin and likewise receive data from
the DATA pin. When a card socket is deselected, the
voltage on its I/O pin will return to the idle state (H) and the
DATA side of that channel will become high impedance.
The LTC4556 includes provision for unidirectional com-
munication with the C4 and C8 pins of the smart card. The
C4, C8 and I/O pins are individually multiplexed to the
DATA pin using bits D3 and D4 as shown in Table 4.
Table 4. Communications Options
D4
0
0
1
1
Dynamic Pull-Up Current Sources
The current sources on the bidirectional pins (DATA, I/O)
are dynamically activated to achieve a fast rise time with a
relatively small static current. Once a bidirectional pin is
relinquished, a small start up current begins to charge the
node. An edge rate detector determines if the pin is
released by comparing its slew rate with an internal
reference value. If a valid transition is detected, a large
pull-up current enhances the edge rate on the node. The
higher slew rate corroborates the decision to charge the
node thereby affecting a dynamic form of hysteresis.
D3
0
1
0
1
BIDIRECTIONAL
Figure 3. Dynamic Pull-Up Current Sources
COMMUNICATION MODE
Nothing Selected
C4 Connected to DATA Pin
C8 Connected to DATA Pin
I/O Connected to DATA Pin
SUPPLY
LOCAL
I
START
PIN
dv
dt
+
–
LTC4556
V
4556 F03
REF
9
4556f