LTC1555L
SIM Power Supply and
Level Translator
FEATURES
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
Buck/Boost Charge Pump Generates 3V or 5V
Input Voltage Range: 2.6V to 6V
Controller V
CC
Range: 1.425V to 4.4V
>10kV ESD on All SIM Contact Pins
Short-Circuit and Overtemperature Protected
3V to 5V Signal Level Translators
Very Low Operating Current: 40µA
Very Low Shutdown Current: <1µA
Soft-Start Limits Inrush Current at Turn-On
1MHz Switching Frequency
Available in 16-Pin Narrow SSOP Package
The LTC
®
1555L provides power conversion and level
shifting needed for low voltage GSM cellular telephones to
interface with either 3V or 5V Subscriber Identity Modules
(SIMs). The part contains a patented buck/boost charge
pump DC/DC converter* that delivers a regulated V
CC
supply voltage to the SIM card. Input voltage may range
from 2.6V to 6V allowing direct connection to the battery.
The output voltage may be programmed to 3V, 5V or direct
connection to the V
IN
pin.
Internal level translators allow controllers operating with
supplies as low as 1.425V to interface with 3V and 5V
SIMs. A soft-start feature limits inrush current at turn-on,
mitigating start-up problems that may result when the
input is supplied by another low-power DC/DC converter.
Battery life is maximized by 40µA operating current, and
1µA shutdown current. Board area is minimized by the
miniature 16-pin narrow SSOP packages and the need for
only three small external capacitors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
*U.S. Patent No.: 5,973,944
APPLICATIO S
s
s
SIM Interface in GSM Cellular Telephones
Smart Card Readers
TYPICAL APPLICATIO
GSM Cellular Telephone SIM Interface
GSM
CONTROLLER
V
IN
2.6V TO 6V
16
15
14
13
12
11
0.1µF
1µF
GND
2.2µF
CLK
RST
I/O
V
CC
I
VCC
=
10mA
OUTPUT VOLTAGE
MODES
V
CC
= 3V
V
CC
= 5V
V
CC
* = V
IN
*ACTUAL V
CC
WILL
DEPEND ON OUTPUT
CURRENT IN THIS MODE
1555L TA01
1.425V TO 4.4V
1
2
3
4
LTC1555L
CIN
RIN
DATA
DDRV
DV
CC
N/C
M1
M0
CLK
RST
I/O
V
CC
V
IN
C1
+
SIM
V
CC
5
6
7
8
10
C1
–
GND
9
U
U
U
1
LTC1555L
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CIN 1
RIN 2
DATA 3
DDRV 4
DV
CC
5
N/C 6
M1 7
M0 8
16 CLK
15 RST
14 I/0
13 V
CC
12 V
IN
11 C1
+
10 C1
–
9
GND
V
IN
, DV
CC
to GND ..................................... –0.3V to 6.5V
V
CC
to GND ...............................................– 0.3V to 6.5V
Digital Inputs to GND ................................– 0.3V to 6.5V
CLK, RST, I/O to GND ..................... – 0.3V to V
CC
+ 0.3V
V
CC
Short-Circuit Duration ............................... Indefinite
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering,10 sec)................... 300°C
ORDER PART
NUMBER
LTC1555LEGN
GN PART MARKING
1555L
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 150°C/W
Consult factory for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (V
IN
= 2.6V to 6V, DV
CC
= 1.425V to 4.4V, controller digital pins tied to
DV
CC
, SIM digital pins floating, C1 = 0.1µF, C
OUT
= 2.2µF unless otherwise noted)
PARAMETER
V
IN
Operating Voltage
DV
CC
Operating Voltage
DV
CC
Undervoltage Lockout
V
IN
Operating Current
V
IN
Shutdown Current
DV
CC
Operating Current
DV
CC
Shutdown Current
V
CC
Output Voltage
V
CC
= 5V, I
VCC
= 0V
M0, M1 = 0V
M0, M1, DATA = DV
CC
, C
IN
= 1MHz
M0, M1 = 0V, DATA, C
IN
= DV
CC
0 < I
VCC
< 10mA
M0, M1 = DV
CC
, 2.6V < V
IN
< 6V
M0, M1 = DV
CC
, 2.7V < V
IN
< 6V
M0 = DV
CC
, M1 = 0
M0 = 0, M1 = DV
CC
V
CC
Shorted to GND
q
q
q
q
q
4.55
q
4.75
q
2.8
q
V
IN
– 0.2
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
q
q
TYP
MAX
6
4.4
UNITS
V
V
V
µA
µA
µA
µA
V
V
V
V
mA
MHz
2.6
1.425
1.2
35
5
65
1
30
1
5
5
3
50
1
5.25
5.25
3.2
V
IN
150
V
CC
Short-Circuit Current
Charge Pump f
OSC
2
U
W
U
U
W W
W
LTC1555L
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (V
IN
= 2.6V to 6V, DV
CC
= 1.425V to 4.4V, controller digital pins tied to
DV
CC
, SIM digital pins floating, C1 = 0.1µF, C
OUT
= 2.2µF unless otherwise noted)
PARAMETER
Controller Inputs/Outputs (DV
CC
= 3V)
Input Current (I
IH
/I
IL
)
Input Current (I
IH
/I
IL
)
High Level Input Current (I
IH
)
Low Level Input Current (I
IL
)
High Input Voltage Threshold (V
IH
)
Low Input Voltage Threshold (V
IL
)
High Level Output Voltage (V
OH
)
Low Level Output Voltage (V
OL
)
DATA Pull-Up Resistance
DATA Output Rise/Fall Time
SIM Inputs/Outputs (V
CC
= 3V or 5V)
I/O High Input Voltage Threshold (V
IH
)
I/O Low Input Voltage Threshold (V
IL
)
High Level Output Voltage (V
OH
)
Low Level Output Voltage (V
OL
)
High Level Output Voltage (V
OH
)
Low Level Output Voltage (V
OL
)
I/O Pull-Up Resistance
SIM Timing Parameters (DV
CC
= 3V, V
CC
= 5V)
CLK Rise/Fall Time
RST, I/O Rise/Fall Time
CLK Frequency
V
CC
Turn-On Time
V
CC
Discharge Time to 1V
CLK Loaded with 30pF, V
CC
= 3V, or 5V
RST, I/O Loaded with 30pF
CLK Loaded with 30pF
C
OUT
= 2.2µF, I
VCC
= 0
I
VCC
= 0, V
CC
= 5V, C
OUT
= 2.2µF
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
q
q
q
q
q
q
q
q
q
q
q
q
TYP
MAX
100
5
20
1
0.7
×
DV
CC
DV
CC
– 0.6
UNITS
nA
µA
µA
mA
V
V
V
V
V
M0, M1, M2, RIN, CIN
DDRV
DATA
DATA
M0, M1, M2, RIN, CIN, DDRV
DATA
M0, M1, M2, RIN, CIN, DDRV
DATA
DATA Source Current = 20µA I/O = V
CC
DATA Sink Current = –200µA I/O = 0V (Note 3)
Between DATA and DV
CC
DATA Loaded with 30pF
I
IH(MAX)
=
±20µA
I
IL(MAX)
= 1mA
I/O, Source Current = 20µA DATA or DDRV = DV
CC
I/O, Sink Current = –1mA DATA or DDRV = 0V (Note 3)
RST, CLK Source Current = 20µA
RST, CLK Sink Current = –200µA
Between I/O and V
CC
–100
–5
–20
0.2
×
DV
CC
0.4
0.7
×
DV
CC
0.4
13
20
1.3
30
2
0.7
×
V
CC
0.4
0.8
×
V
CC
0.4
0.9
×
V
CC
0.4
6.5
10
14
18
1
5
0.5
0.5
V
kΩ
µs
V
V
V
V
V
V
kΩ
ns
µs
MHz
ms
ms
q
q
q
q
q
q
q
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC1555LEGN is guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the – 40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3:
The DATA and I/O pull-down drivers must also sink current
sourced by the internal pull-up resistor.
3
LTC1555L
TYPICAL PERFOR A CE CHARACTERISTICS
I
VIN
vs V
IN
50
I
VCC
= 0mA
T
A
= 25°C
50
40
V
CC
= 5V
I
VIN
(µA)
30
V
CC
= 3V
30
I
DVCC
(µA)
I
VIN
(µA)
20
10
2
3
4
V
IN
(V)
5
V
CC
vs V
IN
6.0
V
CC
= 5V
I
VCC
= 10mA
3.6
5.5
V
CC
(V)
V
CC
(V)
5.0
T
A
= 25°C
4.5
T
A
= –40°C
4.0
2
3
PIN FUNCTIONS
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.
DDRV (Pin 4):
Optional Data Input Pin for Sending Data to
the SIM Card. When not needed, the DDRV pin should
either 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
(Pin 5):
Supply Voltage for Controller Side Digital
Input/Output Pins (typically 3V). May be between 1.425V
and 4.4V. The DV
CC
supply may be powered-down in
shutdown for further reduction in battery current. When
DV
CC
drops below 1.2V, the charge pump is disabled and
the LTC1555L goes into shutdown mode regardless of the
signals on the M0-M1 pins.
4
U W
6
1555L • G01
I
VIN
vs Temperature
V
IN
= 3.6V
I
VCC
= 0mA
V
CC
= 5V
40
V
CC
= 3V
I
DVCC
vs V
DVCC
20
F
CLK
= 1MHz
15
T
A
= 85°C
10
T
A
= –40°C
T
A
= 25°C
20
5
10
–40
0
40
TEMPERATURE (°C)
80
120
1555L • G02
0
1
2
3
V
DVCC
(V)
4
5
1555L • G03
V
CC
vs V
IN
V
CC
= 3V
I
VCC
= 10mA
3.3
T
A
= 85°C
3.0
T
A
= 25°C
2.7
T
A
= –40°C
T
A
= 85°C
4
V
IN
(V)
2.4
5
6
1555L • G04
2
3
4
V
IN
(V)
5
6
1555L • G05
U
U
U
LTC1555L
PIN FUNCTIONS
N/C (Pin 6):
No Internal Connection.
M1 (Pin 7):
Mode Control Bit 1 (see Table 1).
M0 (Pin 8):
Mode Control Bit 0 (see Table 1).
GND (Pin 9):
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 15kV ESD specifications.
C1
–
(Pin 10):
Charge Pump Flying Capacitor Negative Input.
C1
+
(Pin 11):
Charge Pump Flying Capacitor Positive Input.
Table 1. Truth Table
M0
0V
0V
DV
CC
DV
CC
M1
0V
DV
CC
0V
DV
CC
OPERATING MODE
Shutdown (V
CC
= 0V)
V
CC*
= V
IN
V
CC
= 3V
V
CC
= 5V
*Actual V
CC
will depend on the output current in this mode.
BLOCK DIAGRA
V
CC
CONTROLLER
W
U
U
U
V
IN
(Pin 12):
Charge Pump Input Pin. May be between
2.6V and 6V. There is no power-up sequencing require-
ment for V
IN
with respect to DV
CC
.
V
CC
(Pin 13):
SIM Card V
CC
Output. Should be connected
to the SIM V
CC
contact. The V
CC
output voltage is deter-
mined by the M0-M1 pins (see Table 1). V
CC
is discharged
to GND during shutdown (M0, M1 = 0V). A 2.2µF low ESR
ouptut capacitor should connect close to the V
CC
pin.
I/O (Pin 14):
SIM Side I/O Pin. The pin is an open drain
output with a nominal pull-up resistance of 10kΩ 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 during shutdown.
RST (Pin 15):
Level Shifted Reset Output Pin. Should be
connected to the SIM RST contact.
CLK (Pin 16):
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.
V
BATT
0.1µF
C
IN
1µF
C1
+
V
IN
M0
M1
1.8V
UVLO
DV
CC
RIN
RST
RST
SIM
CLK
CLK
STEP-UP/
STEP-DOWN
CHARGE PUMP
DC/DC
CONVERTER
C1
–
LTC1555L
V
CC
C
OUT
2.2µF
V
CC
CIN
20k
DATA
1µA
OPTIONAL
DDRV
10k
I/O
I/O
GND
GND
1555L BD
5
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