5
LTC1555/LTC1556
LTC1555/LTC1556
CIN (Pin 1): Clock Input Pin from Controller.
RIN (Pin 2): Reset Input Pin from Controller.
DATA (Pin 3): Controller Side Data Input/Output Pin. Can
be used for single pin bidirectional data transfer between
the controller and the SIM card as long as the controller
data pin is open drain. The controller output must be able
to sink 1mA max when driving the DATA pin low due to
the internal pull-up resistors on the DATA and I/O pins. If
the controller data output is not open drain, then the
DDRV pin should be used for sending data to the SIM
card and the DATA pin used for receiving data from the
SIM card (see Figure 1).
DDRV (Pin 4): Optional Data Input Pin for Sending Data
to the SIM card. When not needed, the DDRV pin should
be left floating or tied to DV
CC
(an internal 1µA current
source will pull the DDRV pin up to DV
CC
if left floating).
DV
CC
(Pins 5/7): Supply Voltage for Controller Side Digital
I/O Pins. May be between 1.8V and 5.5V (typically 3V)
.
SS (Pins 6/8): Soft Start Enable Pin. A logic low will
enable the charge pump inrush current limiting feature.
A logic high will disable the soft start feature and allow
V
CC
to be ramped as quickly as possible upon start-up
and coming out of shutdown.
M1 (Pins 7/9): Mode Control Bit 1 (see Truth Table).
M0 (Pins 8/10): Mode Control Bit 0 (see Truth Table).
This table defines the various operating modes that may
be obtained via the M0 and M1 mode control pins.
Truth Table
M0 M1 MODE
0V 0V Shutdown (V
CC
= 0V)
0V DV
CC
V
CC
= V
IN
DV
CC
0V V
CC
= 3V
DV
CC
DV
CC
V
CC
= 5V
GND (Pins 9/11, 12): Ground for Both the SIM and the
Controller. Should be connected to the SIM GND contact
as well as to the V
IN
/Controller GND. Proper grounding
and supply bypassing is required to meet 10kV ESD
specifications.
C1
–
(Pins 10/12): Charge Pump Flying Capacitor Nega-
tive Input.
C1
+
(Pins 11/13): Charge Pump Flying Capacitor Positive
Input.
V
IN
(Pins 12/14): Charge Pump Input Voltage Pin. Input
voltage range is 2.7V to 10V. Connect a 10µF low ESR
input bypass capacitor close to the V
IN
pin.
V
CC
(Pins 13/15): SIM Card V
CC
Output. This pin should
be connected to the SIM V
CC
contact. The V
CC
output
voltage is determined by the M0 and M1 pins (see Truth
Table). V
CC
is discharged to GND during shutdown
(M0, M1 = 0V). A 10µF low ESR output capacitor should
connect close to the V
CC
pin.
I/O (Pins 14/18): SIM Side I/O Pin. The pin is an open
drain output with a nominal pull-up resistance of 10k and
should be connected to the SIM I/O contact. The SIM card
must sink up to 1mA max when driving the I/O pin low
due to the internal pull-up resistors on the I/O and DATA
pins. The I/O pin is held active low when the part is in
shutdown.
RST (Pins 15/19): Level Shifted Reset Output Pin. Should
be connected to the SIM RST contact.
CLK (Pins 16/20): Level Shifted Clock Output Pin. Should
be connected to the SIM CLK contact. Careful trace
routing is recommended due to fast rise and fall edge
speeds.
PIN FUNCTIONS
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