LTC4556EUF Linear Technology, LTC4556EUF Datasheet - Page 8

• 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
LTC4556
Serial Port
The microcontroller compatible serial port provides all of
the command and control inputs for the LTC4556 as well
as the status of the smart card. Data on the D
loaded on the rising edge of SCLK. D7 is loaded first and
D0 last. At the same time the command bits are being
shifted into the D
out of the D
D
clocked into the shift register, the command data is loaded
into the command latch by bringing LD low. At this time
the command latch is updated and the LTC4556 will begin
to act on the new command set. When LD is low, the shift
register is transparent to the status data of the smart card
channel. The status data is latched into the shift register on
the rising edge of LD. SCLK should be held in the high state
when idle and should only be clocked when LD is high.
Likewise LD should only be brought high when SCLK is
high. Figure 2 shows the operation of the serial port.
Multiple LTC4556s may be daisy chained together by
connecting the D
another. Figure 7 shows an example of an LTC4556 daisy
chained together with LTC1955s.
The maximum clock rate for the serial port is 10MHz.
The serial port controls the following parameters of the
smart card socket:
• Selection/deselection of the smart card
• V
8
OUT
CC
on the rising edge of SCLK. Once all bits have been
voltage level of the card (5V/3V/1.8V/0V)
OUT
output. The status bits are presented to
OUT
IN
U
input, the status bits are being shifted
pin of one LTC4556 to the D
SCLK
D
OUT
D
LD
IN
t
LC
X
D7
t
DS
D7
t
DH
D6
Figure 2. Serial Port Timing Diagram
D6
IN
t
DD
D5
IN
input is
pin of
D2
• Clock mode of the card (synchronous, asynchronous
• Operating mode of asynchronous cards (clock stop
• Selection of the I/O, C4 or C8 pins
The serial port provides the following status data:
• It indicates the presence or absence of the smart card.
• It indicates the readiness of the smart card V
• It indicates fault status. In the event of an electrical or
Table 1 illustrates the command inputs and status outputs
associated with each bit of the serial data word.
Three voltage options are available from the LTC4556: 5V,
3V and 1.8V. Bits D0, D1 determine which voltage is
selected. Setting both control bits to 0 deactivates the card
and sets the smart card supply voltage to 0V. Table 2
shows the operation of the supply control bits.
The CLK pin to the smart card can be programmed for
various modes. Both synchronous and asynchronous
cards are supported. There are several options available
with asynchronous cards. Table 3 shows how all clock
options are obtained using bits D5–D7.
t
H
or bidirectional)
high, low, 1, 2, 4 or 8)
Communication with the smart card is disabled until its
power supply voltage has reached the final value.
ATR fault, the fault is reported. For electrical faults, the
LTC4556 will automatically deactivate the smart card.
D1
D1
D0
t
L
D0
D7 FROM
INPUT
t
CL
X
t
LW
4556 F02
D7
CC
supply.
4556f