LTC1555/LTC1556
SIM Power Supply
and Level Translator
FEATURES
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DESCRIPTION
The LTC
®
1555/LTC1556 provide power conversion and
level shifting needed for 3V GSM cellular telephones to
interface with either 3V or 5V Subscriber Identity Mod-
ules (SIMs). These parts contain a charge pump DC/DC
converter that delivers a regulated 5V to the SIM card.
Input voltage may range from 2.7V to 10V, allowing
direct connection to the battery. Output voltage may be
programmed to 3V, 5V or direct connection to the V
IN
pin.
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.
The LTC1556 also includes an auxiliary LDO regulator/
power switch that may be used to power the frequency
synthesizer or other low power circuitry.
Battery life is maximized by 60µA operating current and
1µA shutdown current. Board area is minimized by minia-
ture 16- and 20-pin narrow SSOP packages and the need
for only three small external capacitors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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Step-Up/Step-Down Charge Pump Generates 5V
Input Voltage Range: 2.7V to 10V
Output Current: 10mA (V
IN
≥
2.7V)
20mA (V
IN
≥
3V)
3V to 5V Signal Level Translators
> 10kV ESD on All SIM Contact Pins
Short-Circuit and Overtemperature Protected
Very Low Operating Current: 60µA
Very Low Shutdown Current: < 1µA
Soft Start Limits Inrush Current at Turn-On
Programmable 3V or 5V Output Voltage
650kHz Switching Frequency
Auxiliary 4.3V LDO/Power Switch (LTC1556 Only)
Available in a 16- and 20-Pin Narrow SSOP
APPLICATIONS
s
s
SIM Interface in GSM Cellular Telephones
Smart Card Readers
TYPICAL APPLICATION
GSM Cellular Telephone SIM Interface
3V GSM
CONTROLLER
3V
1
2
3
4
LTC1555
CIN
RIN
DATA
DDRV
DV
CC
SS
M1
M0
CLK
RST
I/O
V
CC
V
IN
C1
+
C1
–
GND
16
15
14
13
12
11
10
9
V
IN
2.7V TO 10V
CLK
RST
I/O
V
CC
5
6
7
8
+
0.1µF
10µF
U
U
U
SIM
10µF
V
CC
5V
±
5%
I
VCC
≤
10mA
GND
1555/56 TA01
1
LTC1555/LTC1556
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
V
IN
, DV
CC
to GND ..................................... – 0.3V to 12V
V
CC
to GND ............................................... – 0.3V to 12V
Digital Inputs to GND ................................ – 0.3V to 12V
LDO, CLK, RST, I/O to GND ........ – 0.3V to (V
CC
+ 0.3V)
V
CC
, LDO Short-Circuit Duration ..................... Indefinite
Storage Temperature Range ................. – 65°C to 150°C
PACKAGE/ORDER INFORMATION
TOP VIEW
CIN
RIN
DATA
DDRV
DV
CC
SS
M1
M0
1
2
3
4
5
6
7
8
16 CLK
15 RST
14 I/O
13 V
CC
12 V
IN
11 C1
+
10 C1
–
9
GND
ORDER PART
NUMBER
LTC1555CGN
LTC1555IGN
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 135°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
V
IN
= 2.7V to 10V, DV
CC
= 1.8V to 5.5V, controller digital pins tied to DV
CC
, SIM digital pins floating, EN, FB pins tied to GND
(LTC1556), C1 = 0.1µF, C
OUT
= 10µF unless otherwise specified.
PARAMETER
V
IN
Operating Voltage
DV
CC
Operating Voltage
V
IN
Operating Current
V
IN
Shutdown Current
2.7V
≤
V
IN
≤
5V, V
CC
= 5V, I
VCC
= 0
5V < V
IN
≤
10V, V
CC
= 5V, I
VCC
= 0
M0, M1 = 0V, 2.7V
≤
V
IN
≤
5V
M0, M1 = 0V, 2.7V
≤
V
IN
≤
5V
M0, M1 = 0V, 5V < V
IN
≤
10V
M0, M1 = DV
CC
, C
IN
= 1MHz
M0, M1 = 0V
0
≤
I
VCC
≤
10mA, 2.7V
≤
V
IN
≤
10V
0
≤
I
VCC
≤
20mA, 3V
≤
V
IN
≤
10V
M0, M1 = DV
CC
M0 = DV
CC
, M1 = 0
M0 = 0, M1 = DV
CC
V
IN
= 3.6V, I
VCC
= 10mA, V
CC
= 5V
CONDITIONS
q
q
q
q
q
q
q
DV
CC
Operating Current
DV
CC
Shutdown Current
V
CC
Output Voltage
V
CC
Output Ripple
2
U
U
W
W W
U
W
Temperature Range
LTC1555C/LTC1556C .............................. 0°C to 70°C
LTC1555I/LTC1556I ........................... – 40°C to 85°C
Extended Commercial Operating Temperature Range
(Note 2) ............................................. – 40°C to 85°C
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
CIN
RIN
DATA
DDRV
EN
FB
DV
CC
SS
M1
1
2
3
4
5
6
7
8
9
20 CLK
19 RST
18 I/O
17 LDO
16 V
CC
15 V
IN
14 C1
+
13 C1
–
12 GND
11 GND
ORDER PART
NUMBER
LTC1556CGN
LTC1556IGN
M0 10
GN PACKAGE
20-LEAD PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 95°C/ W
MIN
2.7
1.8
TYP
MAX
10
5.5
UNITS
V
V
µA
µA
µA
µA
µA
µA
µA
60
75
100
135
1
2
25
6
20
1
q
q
q
4.75
2.80
V
IN
– 0.3
5.00
3.00
75
5.25
3.20
V
IN
V
V
V
mV
P-P
LTC1555/LTC1556
ELECTRICAL CHARACTERISTICS
V
IN
= 2.7V to 10V, DV
CC
= 1.8V to 5.5V, controller digital pins tied to DV
CC
, SIM digital pins floating, EN, FB pins tied to GND
(LTC1556), C1 = 0.1µF, C
OUT
= 10µF unless otherwise specified.
PARAMETER
V
CC
Short-Circuit Current
Auxiliary LDO V
OUT
(V
LDO
)
Auxiliary Switch Resistance
FB Input Resistance
Charge Pump f
OSC
Controller Inputs/Outputs, DV
CC
= 3V
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
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
)
I/O Pull-Up Resistance
CLK Rise/Fall Time
RST, I/O Rise/Fall Time
CLK Frequency
V
CC
Turn-On Time
V
CC
Discharge Time to 1V
M0, M1, SS, RIN, CIN
DDRV, EN
DATA
DATA
M0, M1, RIN, CIN, DDRV, EN
DATA
M0, M1, RIN, CIN, DDRV, EN
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
RST, CLK, Source Current = 20µA
I/O, Sink Current = – 1mA, DATA or DDRV = 0V (Note 3)
RST, CLK, Sink Current = – 200µA
Between I/O and V
CC
CLK Loaded with 30pF
RST, I/O Loaded with 30pF
CLK Loaded with 30pF
SS = DV
CC
, C
OUT
= 10µF, I
VCC
= 0
SS = 0V, C
OUT
= 10µF, I
VCC
= 0
I
VCC
= 0, V
CC
= 5V, C
OUT
= 10µF
q
q
q
q
q
q
q
q
q
q
q
q
CONDITIONS
V
CC
Shorted to GND
EN = High, V
CC
= 5V, FB = LDO, I
LDO
= 5mA (LTC1556)
EN = High, V
CC
= 5V, FB = GND (LTC1556)
(LTC1556)
q
q
q
q
MIN
4.00
TYP
12.5
4.3
18
200
MAX
40
4.55
30
800
1
5
20
1
0.7
×
DV
CC
DV
CC
– 0.6
UNITS
mA
V
Ω
kΩ
kHz
µA
µA
µA
mA
V
V
V
V
V
500
–1
–5
– 20
650
0.2
×
DV
CC
0.4
0.7
×
DV
CC
0.4
13
20
1.3
0.5
×
V
CC
0.4
0.8
×
V
CC
0.9
×
V
CC
0.4
0.4
6.5
10
14
18
1
5
1
6
3
28
2
0.7
×
V
CC
V
kΩ
µs
V
V
V
V
V
V
kΩ
ns
µs
MHz
ms
ms
ms
SIM Inputs/Outputs, DV
CC
= 3V, V
CC
= 3V or 5V
q
q
q
q
q
q
q
SIM Timing Parameters, DV
CC
= 3V, V
CC
= 5V
q
q
q
The
q
denotes specifications which apply over the specified temperature
range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
C grade device specifications are guaranteed over the 0°C to 70°C
temperature range. In addition, C grade device specifications are assured
over the – 40°C to 85°C temperature range by design or correlation, but
are not production tested.
Note 3:
The DATA and I/O pull-down drivers must also sink current
sourced by the internal pull-up resistors.
3
LTC1555/LTC1556
TYPICAL PERFORMANCE CHARACTERISTICS
Operating Current
vs Input Voltage
120
NO EXTERNAL LOAD
OPERATING CURRENT (µA)
SHUTDOWN CURRENT (µA)
100
85°C
80
25°C
V
CC
OUTPUT VOLTAGE (V)
60
40
2
6
8
4
V
IN
INPUT VOLTAGE (V)
V
CC
Output Voltage
vs Input Voltage (3V Mode)
3.2
I
VCC
= 10mA
M0 = DV
CC
M1 = 0V
C
OUT
= 10µF
T
A
= 25°C
V
CC
OUTPUT VOLTAGE (V)
3.1
1V/DIV
3.0
2.9
V
IN
= 3V
SS = 0V
2.8
2
6
8
4
V
IN
INPUT VOLTAGE (V)
10
1555/56 G04
1ms/DIV
1555/56 G05
1V/DIV
3V V
CC
Efficiency vs Input Voltage
100
V
CC
= 3V
I
VCC
= 10mA
T
A
= 25°C
80
80
EFFICIENCY (%)
EFFICIENCY (%)
60
40
20
0
2
4
U W
– 40°C
10
1555/56 G01
Shutdown Current
vs Input Voltage
20
V
CC
Output Voltage
vs Input Voltage (5V Mode)
5.2
I
VCC
= 10mA
M0 = DV
CC
M1 = DV
CC
C
OUT
= 10µF
T
A
= 25°C
15
5.1
10
85°C
5
25°C
5.0
4.9
– 40°C
0
2
6
8
4
V
IN
INPUT VOLTAGE (V)
4.8
10
1555/56 G02
2
6
8
4
V
IN
INPUT VOLTAGE (V)
10
1555/56 G03
V
CC
Output Voltage Turn-On Time,
SS Enabled
V
CC
Output Voltage Turn-On Time,
SS Disabled
V
IN
= 3V
SS = DV
CC
1ms/DIV
1555/56 G06
5V V
CC
Efficiency vs Input Voltage
100
V
CC
= 5V
I
VCC
= 10mA
T
A
= 25°C
60
40
20
6
8
4
V
IN
INPUT VOLTAGE (V)
10
1555/56 G07
2
4
8
10
6
V
IN
INPUT VOLTAGE (V)
12
1555/56 G08
LTC1555/LTC1556
PIN FUNCTIONS
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
0V
0V
DV
CC
DV
CC
M1
0V
DV
CC
0V
DV
CC
MODE
Shutdown (V
CC
= 0V)
V
CC
= V
IN
V
CC
= 3V
V
CC
= 5V
U
U
U
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.
5
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