LINER LTC1555L

LTC1555L
SIM Power Supply and
Level Translator
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FEATURES
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DESCRIPTIO
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 VCC
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 VIN pin.
Buck/Boost Charge Pump Generates 3V or 5V
Input Voltage Range: 2.6V to 6V
Controller VCC 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
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.
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APPLICATIO S
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SIM Interface in GSM Cellular Telephones
Smart Card Readers
, LTC and LT are registered trademarks of Linear Technology Corporation.
*U.S. Patent No.: 5,973,944
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TYPICAL APPLICATIO
GSM Cellular Telephone SIM Interface
GSM
CONTROLLER
1.425V TO 4.4V
1
2
3
4
VCC
5
6
7
8
VIN
2.6V TO 6V
LTC1555L
CIN
RIN
CLK
RST
SIM
16
CLK
15
RST
14
DATA
I/O
DDRV
VCC
DVCC
VIN
N/C
C1 +
11
M1
C1 –
10
M0
GND
I/O
13
VCC
IVCC = 10mA
12
9
2.2µF
0.1µF
1µF
GND
OUTPUT VOLTAGE
MODES
VCC = 3V
VCC = 5V
VCC* = VIN
*ACTUAL VCC WILL
DEPEND ON OUTPUT
CURRENT IN THIS MODE
1555L TA01
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LTC1555L
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ABSOLUTE
AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
(Note 1)
VIN, DVCC to GND ..................................... –0.3V to 6.5V
VCC 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 VCC + 0.3V
VCC 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
TOP VIEW
CIN 1
16 CLK
RIN 2
15 RST
DATA 3
14 I/0
DDRV 4
13 VCC
DVCC 5
12 VIN
N/C 6
11 C1+
M1 7
10 C1–
M0 8
9
LTC1555LEGN
GN PART MARKING
GND
1555L
GN PACKAGE
16-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 150°C/W
Consult factory for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (VIN = 2.6V to 6V, DVCC = 1.425V to 4.4V, controller digital pins tied to
DVCC, SIM digital pins floating, C1 = 0.1µF, COUT = 2.2µF unless otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VIN Operating Voltage
●
2.6
6
V
DVCC Operating Voltage
●
1.425
4.4
V
DVCC Undervoltage Lockout
1.2
VIN Operating Current
VCC = 5V, IVCC = 0V
●
VIN Shutdown Current
M0, M1 = 0V
●
DVCC Operating Current
M0, M1, DATA = DVCC, CIN = 1MHz
●
DVCC Shutdown Current
M0, M1 = 0V, DATA, CIN = DVCC
●
VCC Output Voltage
0 < IVCC < 10mA
M0, M1 = DVCC, 2.6V < VIN < 6V
M0, M1 = DVCC, 2.7V < VIN < 6V
M0 = DVCC, M1 = 0
M0 = 0, M1 = DVCC
●
4.55
●
4.75
●
2.8
● VIN – 0.2
VCC Shorted to GND
●
VCC Short-Circuit Current
Charge Pump fOSC
2
35
V
65
µA
1
µA
30
µA
1
µA
5
5
3
5.25
5.25
3.2
VIN
V
V
V
V
50
150
5
1
mA
MHz
LTC1555L
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (VIN = 2.6V to 6V, DVCC = 1.425V to 4.4V, controller digital pins tied to
DVCC, SIM digital pins floating, C1 = 0.1µF, COUT = 2.2µF unless otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
100
nA
Controller Inputs/Outputs (DVCC = 3V)
Input Current (IIH /IIL)
M0, M1, M2, RIN, CIN
●
–100
Input Current (IIH /IIL)
DDRV
●
–5
5
µA
High Level Input Current (IIH)
DATA
●
–20
20
µA
Low Level Input Current (IIL)
DATA
●
1
mA
High Input Voltage Threshold (VIH)
M0, M1, M2, RIN, CIN, DDRV
DATA
●
●
0.7 × DVCC
DVCC – 0.6
Low Input Voltage Threshold (VIL)
M0, M1, M2, RIN, CIN, DDRV
DATA
●
●
0.2 × DVCC
0.4
V
V
High Level Output Voltage (VOH)
DATA Source Current = 20µA I/O = VCC
●
0.7 × DVCC
V
Low Level Output Voltage (VOL)
DATA Sink Current = –200µA I/O = 0V (Note 3)
●
DATA Pull-Up Resistance
Between DATA and DVCC
●
DATA Output Rise/Fall Time
DATA Loaded with 30pF
●
I/O High Input Voltage Threshold (VIH)
IIH(MAX) = ±20µA
●
I/O Low Input Voltage Threshold (VIL)
IIL(MAX) = 1mA
●
0.4
V
High Level Output Voltage (VOH)
I/O, Source Current = 20µA DATA or DDRV = DVCC
●
0.8 × VCC
V
Low Level Output Voltage (VOL)
I/O, Sink Current = –1mA DATA or DDRV = 0V (Note 3)
●
High Level Output Voltage (VOH)
RST, CLK Source Current = 20µA
●
Low Level Output Voltage (VOL)
RST, CLK Sink Current = –200µA
●
I/O Pull-Up Resistance
Between I/O and VCC
●
CLK Rise/Fall Time
CLK Loaded with 30pF, VCC = 3V, or 5V
RST, I/O Rise/Fall Time
CLK Frequency
VCC Turn-On Time
COUT = 2.2µF, IVCC = 0
0.5
ms
VCC Discharge Time to 1V
IVCC = 0, VCC = 5V, COUT = 2.2µF
0.5
ms
13
V
V
0.4
V
20
30
kΩ
1.3
2
µs
0.7 × VCC
V
SIM Inputs/Outputs (VCC = 3V or 5V)
0.4
V
0.9 × VCC
V
0.4
V
14
kΩ
●
18
ns
RST, I/O Loaded with 30pF
●
1
µs
CLK Loaded with 30pF
●
5
MHz
6.5
10
SIM Timing Parameters (DVCC = 3V, VCC = 5V)
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.
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LTC1555L
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TYPICAL PERFOR A CE CHARACTERISTICS
IVIN vs Temperature
IVIN vs VIN
50
50
IVCC = 0mA
TA = 25°C
IDVCC vs VDVCC
20
VIN = 3.6V
IVCC = 0mA
FCLK = 1MHz
VCC = 5V
40
15
30
IVIN (µA)
IVIN (µA)
VCC = 5V
VCC = 3V
TA = 85°C
VCC = 3V
IDVCC (µA)
40
30
10
TA = –40°C
TA = 25°C
20
20
10
2
4
3
5
5
10
–40
6
40
0
80
1555L • G02
VCC vs VIN
4
5
1555L • G03
VCC vs VIN
3.6
VCC = 5V
IVCC = 10mA
VCC = 3V
IVCC = 10mA
3.3
5.5
TA = 85°C
VCC (V)
VCC (V)
3
2
VDVCC (V)
1555L • G01
5.0
TA = 25°C
TA = –40°C
TA = 85°C
3.0
TA = 25°C
TA = –40°C
2.7
4.5
4.0
1
TEMPERATURE (°C)
VIN (V)
6.0
0
120
2
3
4
2.4
5
6
2
3
4
5
6
VIN (V)
VIN (V)
1555L • G04
1555L • G05
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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.
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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 DVCC (an internal 1µA
current source will pull the DDRV pin up to DVCC if left
floating).
DVCC (Pin 5): Supply Voltage for Controller Side Digital
Input/Output Pins (typically 3V). May be between 1.425V
and 4.4V. The DVCC supply may be powered-down in
shutdown for further reduction in battery current. When
DVCC 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.
LTC1555L
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PIN FUNCTIONS
N/C (Pin 6): No Internal Connection.
VIN (Pin 12): Charge Pump Input Pin. May be between
2.6V and 6V. There is no power-up sequencing requirement for VIN with respect to DVCC.
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 VIN/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
M1
OPERATING MODE
0V
0V
Shutdown (VCC = 0V)
0V
DVCC
VCC* = VIN
DVCC
0V
VCC = 3V
DVCC
DVCC
VCC = 5V
VCC (Pin 13): SIM Card VCC Output. Should be connected
to the SIM VCC contact. The VCC output voltage is determined by the M0-M1 pins (see Table 1). VCC is discharged
to GND during shutdown (M0, M1 = 0V). A 2.2µF low ESR
ouptut capacitor should connect close to the VCC 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.
*Actual VCC will depend on the output current in this mode.
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BLOCK DIAGRA
VBATT
0.1µF
CIN
1µF
C1+
C1–
LTC1555L
VIN
VCC
M0
M1
VCC
COUT
2.2µF
STEP-UP/
STEP-DOWN
CHARGE PUMP
DC/DC
CONVERTER
1.8V
UVLO
DVCC
VCC
CONTROLLER
RIN
RST
CIN
CLK
RST
SIM
20k
DATA
CLK
10k
I/O
I/O
1µA
OPTIONAL
DDRV
GND
GND
1555L BD
5
LTC1555L
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APPLICATIO S I FOR ATIO
The LTC1555L performs the two primary functions necessary for low voltage controllers (e.g., GSM cellular
telephone controllers, smart card readers, etc.) to communicate with 5V SIMs or smart cards. The part produces
a regulated 3V or 5V VCC supply for the SIM, and also
provides level translators for communication between the
SIM and the controller.
If the input source impedance is very low (< 0.5Ω), CIN may
not be needed. Increasing the size of COUT to 2.2µF or greater
will reduce output voltage ripple—particularly with high VIN
voltages (4V or greater). A ceramic X5R or X7R type
capacitor is recommended for the flying capacitor C1 with
a value of 0.1µF or 0.22µF.
Output Ripple
VCC Voltage Regulator
The regulator section of the LTC1555L (refer to Block
Diagram) consists of a buck/boost charge pump DC/DC
converter. The charge pump can operate over a wide input
voltage range (2.6V to 6V) while maintaining a regulated
VCC output. The wide VIN range enables the part to be
powered directly from a battery (if desired) rather than
from a DC/DC converter output. When VIN is less than the
selected VCC voltage, the part operates as a switched
capacitor voltage doubler. When VIN is greater than VCC,
the part operates as gated switch step-down converter. In
either case, voltage conversion requires only one small
flying capacitor and output capacitor.
The VCC output can be programmed via the M0-M1 pins to
either 3V, 5V or direct connection to VIN. This flexibility is
useful in applications where multiple voltage SIMs may be
used. When the charge pump is put into shutdown (M0,
M1 = 0), VCC is pulled to GND via an internal switch to aid
in proper system supply sequencing.
An internal soft-start feature helps to limit inrush currents
upon start-up or when coming out of shutdown mode.
Inrush current limiting is especially useful when powering
the LTC1555L from a DC/DC output since the unlimited
inrush current may approach 300mA and cause voltage
transients on the 3V supply. The part is fully short-circuit
and over temperature protected, and can survive an indefinite short from VCC to GND.
Capacitor Selection
For best performance, it is recommended that low ESR
(< 0.5Ω) capacitors be used for both CIN and COUT to reduce
noise and ripple. The CIN and COUT capacitors should be
either ceramic or tantalum and should be 1µF or greater
(ceramic capacitors will produce the smallest output ripple).
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Normal LTC1555L operation produces voltage ripple on
the VCC pin. Output voltage ripple is required for the parts
to regulate. Low frequency ripple exists due to the hysteresis in the sense comparator and propagation delays in the
charge pump enable/disable circuits. High frequency ripple
is also present mainly from the ESR (equivalent series
resistance) in the output capacitor. Typical output ripple
(VIN < 4V) under maximum load is 75mV peak-to-peak
with a low ESR, 2.2µF output capacitor. (VCC = 5V)
The magnitude of the ripple voltage depends on several
factors. High input voltages increase the output ripple
since more charge is delivered to COUT per charging cycle.
A large C1 flying capacitor (> 0.22µF) also increases ripple
in step-up mode for the same reason. Large output current
load and/or a small output capacitor (< 1µF) results in
higher ripple due to higher output voltage dV/dt. High ESR
capacitors (ESR > 0.5Ω) on the output pin cause high
frequency voltage spikes on VOUT with every clock cycle.
A 2.2µF ceramic capacitor on the VCC pin should produce
acceptable levels of output voltage ripple in nearly all
applications. Also, in order to keep noise down to a
minimum all capacitors should be placed close to
LTC1555L.
Level Translators
All SIMs and smart cards contain a clock input, a reset
input, and a bidirectional data input/output. The LTC1555L
provides level translators to allow controllers to
communicate with the SIM. (See Figure 1a and 1b). The
CLK and RST inputs to the SIM are level shifted from the
controller supply rails (DVCC and GND) to the SIM supply
rails (VCC and GND). The data input to the SIM may be
provided two different ways. The first method is to use the
DATA pin as a bidirectional level translator. This configuration is only allowed if the controller data output pin is
LTC1555L
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APPLICATIO S I FOR ATIO
open drain (all SIM I/O pins are open drain). Internal
pull-up resistors are provided for both the DATA pin and
the I/O pin on the SIM side. The second method is to use
the DDRV pin to send data to the SIM and use the DATA pin
to receive data from the SIM. When the DDRV pin is not
used, it should either be left floating or tied to DVCC.
Shutting Down the DVCC Supply
To conserve power, the DVCC supply may be shut down
while the VIN supply is still active. When the DVCC supply
is forced below 1.2V, an undervoltage lockout circuit
forces the LTC1555L into shutdown mode regardless of
the status of the M0-M1 pins.
10kV ESD Protection
All pins that connect to the SIM (CLK, RST, I/O, VCC, GND)
withstand over 10kV of human body model ESD. In order
to ensure proper ESD protection, careful board layout is
required. The GND pin should be tied directly to a GND
plane. The VCC capacitor should be located very close to
the VCC pin and tied immediately to the GND plane.
LTC1555L
LTC1555L
CLK TO SIM
CIN
CLK
CLK TO SIM
CIN
CLK
RST TO SIM
RIN
RST
RST TO SIM
RIN
RST
DATA
I/O
DATA FROM SIM
DATA
I/O
DDRV
VCC
DATA TO SIM
DDRV
VCC
DATA TO/FROM SIM
CONTROLLER
SIDE
DVCC
SIM SIDE
CONTROLLER
SIDE
DVCC
1555L F01a
Figure 1a. Level Translator Connections for
Bidirectional Controller DATA Pin
SIM SIDE
1555L F01b
Figure 1b. Level Translator Connections for
One-Directional Controller Side DATA Flow
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC1555L
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TYPICAL APPLICATIO
GSM Cellular Telephone SIM Interface
GSM
CONTROLLER
1.425V TO 4.4V
1
2
3
4
5
VCC
6
7
8
VIN
2.6V TO 6V
LTC1555L
CIN
CLK
RIN
RST
SIM
16
CLK
15
RST
14
DATA
I/O
DDRV
VCC
DVCC
VIN
N/C
C1 +
11
M1
C1 –
10
M0
GND
I/O
VCC = 3V, 5V
or VIN
IVCC = 10mA
13
12
2.2µF
0.1µF
1µF
GND
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1555L TA01a
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PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
GN Package
16-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.189 – 0.196*
(4.801 – 4.978)
16 15 14 13 12 11 10 9
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
1
0.015 ± 0.004
× 45°
(0.38 ± 0.10)
0.007 – 0.0098
(0.178 – 0.249)
0.009
(0.229)
REF
2 3
4
5 6
7
0.053 – 0.068
(1.351 – 1.727)
8
0.004 – 0.0098
(0.102 – 0.249)
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.008 – 0.012
(0.203 – 0.305)
0.0250
(0.635)
BSC
* DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
GN16 (SSOP) 1098
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1555L-1.8
SIM Power Supply and Level Translator
VIN = 2.6V to 6V; Interface with 1.8V, 3V and 5V SIMs
LTC1555/LTC1556
SIM Power Supply and Level Translator
VIN = 2.7V to 10V; Step-Up/Step-Down Charge Pump; 3V and 5V VOUT
LTC1755
Smart Card Interface
VIN = 2.7V to 6V; 24-Pin SSOP Package; IQ = 60µA
LTC1756
Smart Card Interface
VIN = 2.7V to 6V; 16-Pin SSOP Package; IQ = 75µA
LTC1986
3V/5V SIM Power Supply in SOT-23
VIN = 2.6V to 4.4V; IQ = 14µA
8
Linear Technology Corporation
1555lf LT/TP 0601 2K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 2000