LTC1555L-1.8
1
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
The LTC
1555L-1.8 provides power conversion and level
shifting needed for low voltage GSM and WCDMA cellular
telephones to interface with either 1.8V, 3V or 5V sub-
scriber 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 1.8V, 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 1.8V, 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 32
A operating current, and
1
A shutdown current. Board area is minimized by the
miniature 16-pin narrow SSOP packages and the need for
only three small external capacitors.
s
SIM Interface in GSM Cellular Telephones
s
WCDMA SIM Interface
s
Smart Card Readers
, LTC and LT are registered trademarks of Linear Technology Corporation.
SIM Power Supply and
Level Translator
s
Buck/Boost Charge Pump Generates 1.8V, 3V or 5V
s
Input Voltage Range: 2.6V to 6V
s
Controller V
CC
Range: 1.425V to 4.4V
s
>10kV ESD on All SIM Contact Pins
s
Short-Circuit and Overtemperature Protected
s
Meets all ETSI and IMT-2000 SIM Interface
Requirements
s
1.8V to 5V Signal Level Translators
s
Very Low Operating Current: 32
A
s
Very Low Shutdown Current: <1
A
s
Soft-Start Limits Inrush Current at Turn-On
s
1MHz Switching Frequency
s
Available in 16-Pin Narrow SSOP Package
GSM Cellular Telephone SIM Interface
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CIN
RIN
DATA
DDRV
DV
CC
M2
M1
M0
CLK
RST
I/O
V
CC
= 1.8V,3V,5V
I
VCC
=
10mA
GND
CLK
RST
I/O
V
CC
V
IN
C1
+
C1
GND
0.1
F
1
F
LTC1555L-1.8
GSM
CONTROLLER
SIM
V
IN
2.6V TO 6V
1.425V TO 4.4V
2.2
F
1555L TA01
V
CC
*U.S. Patent No.: 5,973,944
LTC1555L-1.8
2
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
T
JMAX
= 125
C,
JA
= 150
C/W
LTC1555LEGN-1.8
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
ELECTRICAL CHARACTERISTICS
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 = 0.1
F, C
OUT
= 2.2
F unless otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Operating Voltage
q
2.6
6
V
DV
CC
Operating Voltage
q
1.425
4.4
V
DV
CC
Undervoltage Lockout
1.2
V
V
IN
Operating Current
V
CC
= 3V, I
VCC
= 0V
q
27
65
A
V
IN
Shutdown Current
M0, M1 = 0V
q
1
A
DV
CC
Operating Current
M0, M1, DATA = DV
CC
, C
IN
= 1MHz
q
5
30
A
DV
CC
Shutdown Current
M0, M1 = 0V, DATA, C
IN
= DV
CC
q
1
A
V
CC
Output Voltage
0 < I
VCC
< 10mA
M0, M1 = DV
CC
, 2.6V < V
IN
< 6V
q
4.55
5
5.25
V
M0, M1 = DV
CC
, 2.7V < V
IN
< 6V
q
4.75
5
5.25
V
M0 = DV
CC
, M1 = 0
q
2.8
3
3.2
V
M0 = 0, M1 = DV
CC
q
V
IN
0.2
V
IN
V
M0 = DV
CC
, M1 = 0, M2 = DV
CC
, 0
I
VCC
6mA
q
1.71
1.8
1.89
V
M0 = DV
CC
, M1 = 0, M2 = DV
CC
, V
IN
3V, I
VCC
10mA
q
1.71
1.8
1.89
V
V
CC
Short-Circuit Current
V
CC
Shorted to GND
q
50
150
mA
Charge Pump f
OSC
1
MHz
TOP VIEW
GN PACKAGE
16-LEAD PLASTIC SSOP
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CIN
RIN
DATA
DDRV
DV
CC
M2
M1
M0
CLK
RST
I/0
V
CC
V
IN
C1
+
C1
GND
GN PART MARKING
555L18
Consult factory for parts specified with wider operating temperature ranges.
LTC1555L-1.8
3
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Controller Inputs/Outputs (DV
CC
= 1.8V)
Input Current (I
IH
/I
IL
)
M0, M1, M2, RIN, CIN
q
100
100
nA
Input Current (I
IH
/I
IL
)
DDRV
q
5
5
A
High Level Input Current (I
IH
)
DATA
q
20
20
A
Low Level Input Current (I
IL
)
DATA
q
1
mA
High Input Voltage Threshold (V
IH
)
M0, M1, M2, RIN, CIN, DDRV
q
0.7
DV
CC
V
DATA
q
DV
CC
0.6
V
Low Input Voltage Threshold (V
IL
)
M0, M1, M2, RIN, CIN, DDRV
q
0.2
DV
CC
V
DATA
q
0.4
V
High Level Output Voltage (V
OH
)
DATA Source Current = 20
A I/O = V
CC
q
0.7
DV
CC
V
Low Level Output Voltage (V
OL
)
DATA Sink Current = 200
A I/O = 0V (Note 3)
q
0.4
V
DATA Pull-Up Resistance
Between DATA and DV
CC
q
13
20
30
k
DATA Output Rise/Fall Time
DATA Loaded with 30pF
q
1.3
2
s
SIM Inputs/Outputs (V
CC
= 3V or 5V)
I/O High Input Voltage Threshold (V
IH
)
I
IH(MAX)
=
20
A
q
0.7
V
CC
V
I/O Low Input Voltage Threshold (V
IL
)
I
IL(MAX)
= 1mA
q
0.4
V
High Level Output Voltage (V
OH
)
I/O, Source Current = 20
A DATA or DDRV = DV
CC
q
0.8
V
CC
V
Low Level Output Voltage (V
OL
)
I/O, Sink Current = 1mA DATA or DDRV = 0V (Note 3)
q
0.4
V
High Level Output Voltage (V
OH
)
RST, CLK Source Current = 20
A
q
0.9
V
CC
V
Low Level Output Voltage (V
OL
)
RST, CLK Sink Current = 200
A
q
0.4
V
I/O Pull-Up Resistance
Between I/O and V
CC
q
6.5
10
14
k
SIM Inputs/Outputs (V
CC
= 1.8V)
I/O High Input Voltage Threshold (V
IH
)
I
IH(MAX)
=
20
A
q
0.7
V
CC
V
I/O Low Input Voltage Threshold (V
IL
)
I
IL(MAX)
= 1mA
q
0.2
V
CC
V
High Level Output Voltage (V
OH
)
I/O, Source Current = 20
A DATA or DDRV = DV
CC
q
0.8
V
CC
V
Low Level Output Voltage (V
OL
)
I/O, Sink Current = 200
A DATA or DDRV = 0V (Note 3)
q
0.4
V
High Level Output Voltage (V
OH
)
RST, CLK Source Current = 20
A
q
0.9
V
CC
V
Low Level Output Voltage (V
OL
)
RST, CLK Sink Current = 200
A
q
0.2
V
CC
V
SIM Timing Parameters (DV
CC
= 1.8V, V
CC
= 5V)
CLK Rise/Fall Time
CLK Loaded with 30pF, V
CC
= 3V or 5V
q
18
ns
V
CC
= 1.8V
q
50
ns
RST, I/O Rise/Fall Time
RST, I/O Loaded with 30pF
q
1
s
CLK Frequency
CLK Loaded with 30pF
q
5
MHz
V
CC
Turn-On Time
C
OUT
= 2.2
F, I
VCC
= 0
0.5
ms
V
CC
Discharge Time to 1V
I
VCC
= 0, V
CC
= 5V, C
OUT
= 2.2
F
0.5
ms
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC1555LEGN-1.8 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.
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 = 0.1
F, C
OUT
= 2.2
F unless otherwise noted)
ELECTRICAL CHARACTERISTICS
LTC1555L-1.8
4
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
V
IN
(V)
2
I
VIN
(
A)
30
40
6
1555L G01
20
10
3
4
5
50
V
CC
= 5V
V
CC
= 3V
V
CC
= 1.8V
I
VCC
= 0mA
T
A
= 25
C
TEMPERATURE (
C)
40
I
VIN
(
A)
30
40
120
1555L G02
20
10
0
40
80
50
V
CC
= 5V
V
CC
= 3V
V
CC
= 1.8V
V
IN
= 3.6V
I
VCC
= 0mA
V
DVCC
(V)
1
I
DVCC
(
A)
10
15
5
1555L G03
5
0
2
3
4
20
F
CLK
= 1MHz
T
A
= 40
C
T
A
= 85
C
T
A
= 25
C
V
IN
(V)
2
V
CC
(V)
5.0
5.5
6
1555L G04
4.5
4.0
3
4
5
6.0
V
CC
= 5V
I
VCC
= 10mA
T
A
= 40
C
T
A
= 85
C
T
A
= 25
C
V
IN
(V)
2
V
CC
(V)
3.0
3.3
6
1555L G05
2.7
2.4
3
4
5
3.6
T
A
= 40
C
T
A
= 85
C
V
CC
= 3V
I
VCC
= 10mA
T
A
= 25
C
V
IN
(V)
2
V
CC
(V)
1.8
2.0
6
1555L G06
1.6
1.4
3
4
5
2.2
T
A
= 40
C
V
CC
= 1.8V
I
VCC
= 10mA
T
A
= 85
C
T
A
= 25
C
I
VIN
vs V
IN
V
CC
vs V
IN
I
VIN
vs Temperature
I
DVCC
vs V
DVCC
V
CC
vs V
IN
V
CC
vs V
IN
PI
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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 1
A
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-1.8 goes into shutdown mode regardless
of the signals on the M0-M2 pins.
LTC1555L-1.8
5
V
IN
(Pin 12): Charge Pump Input Pin. May be between 2.6V
and 6V. There is no power-up sequencing requirement 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-M2 pins (see Table 1). V
CC
is discharged
to GND during shutdown (M0, M1 = 0V). A 2.2
F 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 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 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.
M0
M1
M2
OPERATING MODE
0V
0V
0V or DV
CC
Shutdown (V
CC
= 0V)
0V
DV
CC
0V or DV
CC
V
CC
= V
IN
DV
CC
0V
0V
V
CC
= 3V
DV
CC
0V
DV
CC
V
CC
= 1.8V
DV
CC
DV
CC
0V or DV
CC
V
CC
= 5V
Table 1. Truth Table
PI
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M2 (Pin 6): Mode Control Bit 2 (see Table 1). (Pin 6 was
previously used for soft-start control on the LTC1555.)
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 10kV ESD specifications.
C1
(Pin 10): Charge Pump Flying Capacitor Negative Input.
C1
+
(Pin 11): Charge Pump Flying Capacitor Positive Input.
BLOCK DIAGRA
W
DDRV
OPTIONAL
1
A
I/O
DATA
20k
10k
CLK
CIN
RST
DV
CC
M2
1.8V
RIN
GND
M1
M0
V
IN
V
BATT
C
IN
1
F
V
CC
I/O
CLK
RST
GND
V
CC
C1
+
0.1
F
C1
STEP-UP/
STEP-DOWN
CHARGE PUMP
DC/DC
CONVERTER
SIM
CONTROLLER
V
CC
C
OUT
2.2
F
UVLO
LTC1555L-1.8
1555L BD
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