LTC1555C 概述
SIM Power Supply and Level Translator SIM电源和电平转换器
LTC1555C 数据手册
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PDF下载LTC1555/LTC1556
SIM Power Supply
and Level Translator
U
DESCRIPTION
FEATURES
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
programmedto3V,5VordirectconnectiontotheVIN pin.
■
Step-Up/Step-Down Charge Pump Generates 5V
■
Input Voltage Range: 2.7V to 10V
Output Current: 10mA (VIN ≥ 2.7V)
■
20mA (VIN ≥ 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
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.
■
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
U
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.
APPLICATIONS
■
SIM Interface in GSM Cellular Telephones
Smart Card Readers
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATION
GSM Cellular Telephone SIM Interface
3V GSM
CONTROLLER
V
IN
2.7V TO 10V
3V
LTC1555
SIM
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CIN
CLK
RST
I/O
CLK
RST
I/O
RIN
DATA
DDRV
V
V
CC
CC
5V ±5%
≤ 10mA
V
DV
CC
V
CC
IN
+
I
VCC
10µF
+
SS
M1
M0
C1
C1
0.1µF
10µF
–
GND
GND
1555/56 TA01
1
LTC1555/LTC1556
W W U W
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN, DVCC to GND ..................................... –0.3V to 12V
VCC to GND ............................................... –0.3V to 12V
Digital Inputs to GND................................ –0.3V to 12V
LDO, CLK, RST, I/O to GND ........ –0.3V to (VCC + 0.3V)
VCC, LDO Short-Circuit Duration..................... Indefinite
Storage Temperature Range ................. –65°C to 150°C
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
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PACKAGE/ORDER INFORMATION
TOP VIEW
ORDER PART
ORDER PART
NUMBER
NUMBER
TOP VIEW
CIN
RIN
1
2
3
4
5
6
7
8
9
20 CLK
19 RST
18 I/O
1
2
3
4
5
6
7
8
CLK
RST
I/O
16
15
14
13
12
11
10
9
CIN
RIN
LTC1556CGN
LTC1556IGN
LTC1555CGN
LTC1555IGN
DATA
DDRV
EN
17 LDO
DATA
DDRV
16
15
V
V
V
CC
CC
FB
V
IN
IN
+
DV
CC
+
DV
CC
14 C1
13 C1
C1
SS
M1
M0
–
–
SS
C1
M1
12 GND
11 GND
GND
M0 10
GN PACKAGE
16-LEAD PLASTIC SSOP
GN PACKAGE
20-LEAD PLASTIC SSOP
TJMAX = 150°C, θJA = 135°C/ W
TJMAX = 150°C, θJA = 95°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
VIN = 2.7V to 10V, DVCC = 1.8V to 5.5V, controller digital pins tied to DVCC, SIM digital pins floating, EN, FB pins tied to GND
(LTC1556), C1 = 0.1µF, COUT = 10µF unless otherwise specified.
PARAMETER
Operating Voltage
CONDITIONS
MIN
2.7
TYP
MAX
10
UNITS
V
●
●
V
V
IN
DV Operating Voltage
1.8
5.5
CC
V
Operating Current
2.7V ≤ V ≤ 5V, V = 5V, I
= 0
VCC
= 0
VCC
●
●
60
75
100
135
µA
µA
IN
IN
CC
5V < V ≤ 10V, V = 5V, I
IN
CC
V
Shutdown Current
M0, M1 = 0V, 2.7V ≤ V ≤ 5V
1
2
25
µA
µA
µA
IN
IN
M0, M1 = 0V, 2.7V ≤ V ≤ 5V
●
IN
M0, M1 = 0V, 5V < V ≤ 10V
IN
DV Operating Current
M0, M1 = DV , C = 1MHz
●
●
6
20
1
µA
µA
CC
CC IN
DV Shutdown Current
M0, M1 = 0V
CC
V
Output Voltage
0 ≤ I
0 ≤ I
≤ 10mA, 2.7V ≤ V ≤ 10V
IN
CC
VCC
VCC
≤ 20mA, 3V ≤ V ≤ 10V
IN
M0, M1 = DV
●
●
●
4.75
2.80
5.00
3.00
5.25
3.20
V
V
V
CC
M0 = DV , M1 = 0
CC
M0 = 0, M1 = DV
V
– 0.3
V
CC
IN
IN
V
Output Ripple
V
= 3.6V, I
= 10mA, V = 5V
75
mV
P-P
CC
IN
VCC
CC
2
LTC1555/LTC1556
ELECTRICAL CHARACTERISTICS
VIN = 2.7V to 10V, DVCC = 1.8V to 5.5V, controller digital pins tied to DVCC, SIM digital pins floating, EN, FB pins tied to GND
(LTC1556), C1 = 0.1µF, COUT = 10µF unless otherwise specified.
PARAMETER
Short-Circuit Current
CONDITIONS
Shorted to GND
MIN
TYP
12.5
4.3
MAX
40
UNITS
mA
V
V
V
●
●
●
CC
CC
Auxiliary LDO V
(V
)
EN = High, V = 5V, FB = LDO, I = 5mA (LTC1556)
LDO
4.00
4.55
30
OUT LDO
CC
Auxiliary Switch Resistance
FB Input Resistance
EN = High, V = 5V, FB = GND (LTC1556)
18
Ω
CC
(LTC1556)
200
650
kΩ
kHz
Charge Pump f
●
500
800
OSC
Controller Inputs/Outputs, DV = 3V
CC
Input Current (I , I )
M0, M1, SS, RIN, CIN
DDRV, EN
●
●
–1
–5
1
5
µA
µA
IH IL
High Level Input Current (I )
DATA
DATA
●
●
–20
20
1
µA
IH
Low Level Input Current (I )
mA
IL
High Input Voltage Threshold (V )
M0, M1, RIN, CIN, DDRV, EN
DATA
●
●
0.7 × DV
V
V
IH
CC
DV – 0.6
CC
Low Input Voltage Threshold (V )
M0, M1, RIN, CIN, DDRV, EN
DATA
●
●
0.2 × DV
V
V
IL
CC
CC
0.4
High Level Output Voltage (V
)
OH
DATA Source Current = 20µA, I/O = V
●
●
●
●
0.7 × DV
V
V
CC
Low Level Output Voltage (V
DATA Pull-up Resistance
DATA Output Rise/Fall Time
)
OL
DATA Sink Current = –200µA, I/O = 0V (Note 3)
Between DATA and DV
0.4
28
2
13
20
kΩ
µs
CC
DATA Loaded with 30pF
1.3
SIM Inputs/Outputs, DV = 3V, V = 3V or 5V
CC
CC
I/O High Input Voltage Threshold (V )
I
I
= ±20µA
●
●
0.5 × V
0.7 × V
CC
V
V
IH
IH(MAX)
IL(MAX)
CC
I/O Low Input Voltage Threshold (V )
= 1mA
0.4
IL
High Level Output Voltage (V
)
OH
I/O, Source Current = 20µA, DATA or DDRV = DV
RST, CLK, Source Current = 20µA
●
●
0.8 × V
0.9 × V
V
V
CC
CC
CC
Low Level Output Voltage (V
)
OL
I/O, Sink Current = –1mA, DATA or DDRV = 0V (Note 3)
RST, CLK, Sink Current = –200µA
●
●
0.4
0.4
V
V
I/O Pull-Up Resistance
Between I/O and V
●
6.5
10
14
kΩ
CC
SIM Timing Parameters, DV = 3V, V = 5V
CC
CC
CLK Rise/Fall Time
RST, I/O Rise/Fall Time
CLK Frequency
CLK Loaded with 30pF
RST, I/O Loaded with 30pF
CLK Loaded with 30pF
●
●
●
18
1
ns
µs
5
MHz
V
Turn-On Time
SS = DV , C
= 10µF, I = 0
VCC
1
6
ms
ms
CC
CC OUT
SS = 0V, C
= 10µF, I
= 0
OUT
VCC
V
Discharge Time to 1V
I
= 0, V = 5V, C = 10µF
OUT
3
ms
CC
VCC
CC
The
range.
●
denotes specifications which apply over the specified temperature
over the –40°C to 85°C temperature range by design or correlation, but
are not production tested.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 3: The DATA and I/O pull-down drivers must also sink current
sourced by the internal pull-up resistors.
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
3
LTC1555/LTC1556
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TYPICAL PERFORMANCE CHARACTERISTICS
Operating Current
vs Input Voltage
Shutdown Current
vs Input Voltage
VCC Output Voltage
vs Input Voltage (5V Mode)
120
100
80
5.2
5.1
5.0
4.9
4.8
20
15
10
5
I
= 10mA
NO EXTERNAL LOAD
VCC
M0 = DV
M1 = DV
CC
CC
C
T
= 10µF
OUT
= 25°C
A
85°C
25°C
85°C
25°C
–40°C
60
–40°C
40
0
6
8
2
10
6
6
4
2
8
10
2
8
10
4
4
V
INPUT VOLTAGE (V)
V
INPUT VOLTAGE (V)
V
INPUT VOLTAGE (V)
IN
IN
IN
1555/56 G01
1555/56 G02
1555/56 G03
VCC Output Voltage Turn-On Time,
SS Disabled
VCC Output Voltage Turn-On Time,
SS Enabled
V
CC Output Voltage
vs Input Voltage (3V Mode)
3.2
3.1
3.0
2.9
2.8
I
= 10mA
VCC
M0 = DV
M1 = 0V
CC
C
T
= 10µF
OUT
= 25°C
A
1555/56 G05
1555/56 G06
VIN = 3V
SS = 0V
1ms/DIV
1ms/DIV
V
IN = 3V
SS = DVCC
6
8
2
10
4
V
IN
INPUT VOLTAGE (V)
1555/56 G04
3V VCC Efficiency vs Input Voltage
5V VCC Efficiency vs Input Voltage
100
80
100
80
V
I
= 5V
V
I
= 3V
CC
CC
= 10mA
= 10mA
VCC
VCC
T
= 25°C
T
= 25°C
A
A
60
60
40
40
20
20
2
4
6
8
10
12
0
2
4
6
8
10
V
INPUT VOLTAGE (V)
V
INPUT VOLTAGE (V)
IN
IN
1555/56 G08
1555/56 G07
4
LTC1555/LTC1556
U
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PIN FUNCTIONS
LTC1555/LTC1556
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 VIN/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.
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).
C1+ (Pins11/13):ChargePumpFlyingCapacitorPositive
Input.
VIN (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 VIN pin.
VCC (Pins 13/15): SIM Card VCC Output. This pin should
be connected to the SIM VCC contact. The VCC output
voltage is determined by the M0 and M1 pins (see Truth
Table). VCC is discharged to GND during shutdown
(M0, M1 = 0V). A 10µF low ESR output capacitor should
connect close to the VCC pin.
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 DVCC (an internal 1µA current
source will pull the DDRV pin up to DVCC if left floating).
DVCC (Pins5/7):SupplyVoltageforControllerSideDigital
I/O Pins. May be between 1.8V and 5.5V (typically 3V)
.
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
shouldbeconnectedtotheSIMI/Ocontact.TheSIMcard
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.
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
VCC 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).
RST(Pins15/19):LevelShiftedResetOutputPin.Should
be connected to the SIM RST contact.
This table defines the various operating modes that may
be obtained via the M0 and M1 mode control pins.
CLK(Pins16/20):LevelShiftedClockOutputPin.Should
be connected to the SIM CLK contact. Careful trace
routing is recommended due to fast rise and fall edge
speeds.
Truth Table
M0
0V
0V
M1
MODE
Shutdown (V = 0V)
0V
CC
DV
V
CC
V
CC
V
CC
= V
IN
CC
DV
0V
DV
= 3V
= 5V
CC
CC
DV
CC
5
LTC1555/LTC1556
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PIN FUNCTIONS
LTC1556 Only
ground,theregulatoractsasa≤30ΩswitchbetweenVCC
and LDO.
EN (Pin 5): Auxiliary LDO/Power Switch Enable Pin. A
logic high on this pin from the controller will enable the
auxiliary LDO output. When the LDO is disabled, the LDO
LDO (Pin 17): LDO Output Pin. This pin should be tied to
the FB pin for 4.3V LDO operation. The 4.3V LDO output
output will float or be pulled to ground by the load. If left is usable only when VCC is 5V (or greater). It is not
floating, the EN pin will be pulled down to GND by an
available when VCC = 3V. The LDO output may also be
used as a ≤30Ω power switch if the FB pin is grounded
or left floating. When used as a regulator, LDO must be
bypassed to GND with a ≥3.3µF capacitor. The LDO
output current will subtract from available VCC current.
internal 1µA current source.
FB (Pin 6): Auxiliary LDO Feedback Pin. When FB is
connected to the LDO pin (Pin 17), the LDO output is
regulated to 4.3V (typ). If the FB pin is left open or tied to
W
BLOCK DIAGRAM
V
BATT
0.1µF
+
C
IN
10µF
+
–
C1
C1
V
IN
V
CC
V
CC
C
OUT
10µF
M1
M0
SS
STEP-UP/
STEP-DOWN
CHARGE PUMP
DC/DC
CONVERTER
3V
DV
CC
V
CC
RIN
RST
CLK
RST
CLK
CONTROLLER
SIM
CIN
20k
10k
DATA
I/O
I/O
1µA
OPTIONAL
DDRV
EN
GND
GND
1µA
–
+
GND
LDO
1.23V
153k
FREQUENCY
SYNTHESIZER
POWER
4.3V
FB
+
C
LDO
10µF
61k
LTC1555/LTC1556
LTC1556 ONLY
1555/56 BD
6
LTC1555/LTC1556
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APPLICATIONS INFORMATION
The LTC1555/LTC1556 perform the two primary func-
tions necessary for 3V controllers (e.g., GSM cellular
telephone controllers, smart card readers, etc.) to com-
municate with 5V SIMs or smart cards. They produce a
regulated 5V VCC supply for the SIM and provide level
translators for communication between the SIM and the
controller.
Capacitor Selection
For best performance, it is recommended that low ESR
(<0.5Ω)capacitorsbeusedforbothCINandCOUTtoreduce
noise and ripple. The CIN and COUT capacitors should be
either ceramic or tantalum and should be 10µF or greater
(ceramiccapacitorswillproducethesmallestoutputripple).
Iftheinputsourceimpedanceisverylow(<0.5Ω),CIN may
notbeneeded.IncreasingthesizeofCOUTto22µForgreater
willreduceoutputvoltageripple—particularlywithhighVIN
voltages (8V or greater). A ceramic capacitor is recom-
mended for the flying capacitor C1 with a value of 0.1µF or
0.22µF.
VCC Voltage Regulator
The regulator section of the LTC1555/LTC1556 (refer to
theBlockDiagram)consistsofastep-up/step-downcharge
pump DC/DC converter. The charge pump can operate
over a wide input voltage range (2.7V to 10V) while
maintaining a regulated VCC output. The wide VIN range
enables the parts to be powered directly from a battery (if
desired) rather than from a 3V DC/DC converter output.
When VIN is less than the desired VCC the parts operate as
switched capacitor voltage doublers. When VIN is greater
than VCC the parts operate as gated switch step-down
converters. In either case, voltage conversion requires
only one small flying capacitor and output capacitor.
Output Ripple
Normal LTC1555/LTC1556 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 < 8V) under maximum load is
75mV peak-to-peak with a low ESR, 10µF output capaci-
tor. For applications requiring VIN to exceed 8V, a 22µF or
larger COUT capacitor is recommended to maintain maxi-
mum ripple in the 75mV range.
The VCC output can be programmed to either 5V or 3V via
the M0 and M1 mode pins. This feature is useful in
applicationswhereeithera5Vor3VSIMmaybeused. The
chargepumpVCC outputmayalsobeconnecteddirectlyto
VIN ifdesired. Whenthechargepumpisputintoshutdown
(M0, M1 = 0), VCC is pulled to GND via an internal switch
to aid in proper system supply sequencing.
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
instep-upmodeforthesamereason.Largeoutputcurrent
load and/or a small output capacitor (< 10µF) 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.
The soft start feature limits inrush currents upon start-up
or coming out of shutdown mode. When the SS pin is tied
to GND, the soft start feature is enabled. This limits the ef-
fective inrush current out of VIN to approximately 25mA
(COUT = 10µF). Inrush current limiting is especially useful
when powering the LTC1555/LTC1556 from a 3V DC/DC
output since the unlimited inrush current may approach
200mAandcausevoltagetransientsonthe3Vsupply.How-
ever, in cases where fast turn-on time is desired, the soft
startfeaturemaybeoverriddenbytyingtheSSpintoDVCC.
A 10µF ceramic capacitor on the VCC pin should produce
acceptable levels of output voltage ripple in nearly all
applications. However, there are several ways to further
7
LTC1555/LTC1556
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APPLICATIONS INFORMATION
reducetheripple.AlargerCOUT capacitor(22µForgreater)
will reduce both the low and high frequency ripple due to
the lower COUT charging and discharging dV/dt and the
lower ESR typically found with higher value (larger case
size) capacitors. A low ESR ceramic output capacitor will
minimize the high frequency ripple, but will not reduce the
low frequency ripple unless a high capacitance value is
chosen (10µF or greater). A reasonable compromise is to
usea10µFto22µFtantalumcapacitorinparallelwitha1µF
to 3.3µF ceramic capacitor on VOUT to reduce both the low
and high frequency ripple. An RC filter may also be used
to reduce high frequency voltage spikes (see Figure 1).
hundredmillisecondstocompletelyshutdown. Toensure
prompt and proper VCC shutdown, always force the M0
and M1 pins to a logic low state before shutting down the
DVCC supply (see Figure 2). Similarly, bring the DVCC
supply to a valid level before allowing the M0 and M1 pins
to go high when coming out of shutdown. This can be
achieved with pull-down resistors from M0 and M1 to
GND if necessary. (Note: shutting down the DVCC supply
with VIN active is not recommended with early date code
material. Consult factory for valid date code starting point
for shutting down the DVCC supply.)
Level Translators
All SIMs and smart cards contain a clock input, reset input
and a bidirectional data input/output. The LTC1555/
LTC1556 provide level translators to allow controllers to
communicate with the SIM (see Figures 3a and 3b). 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 configu-
ration is only allowed if the controller data output pin is
open drain (all SIM I/O pins are open drain). Internal pull-
up resistors are provided for both the DATA pin and the
SIM
CC
V
CC
V
+
1µF
15µF
CERAMIC
TANTALUM
LTC1555/
LTC1556
2Ω
SIM
V
CC
V
CC
10µF
10µF
LT1555/56 F01
Figure 1. VCC Output Ripple Reduction Techniques
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 brought to 0V, weak internal currents will force the
LTC1555/LTC1556 into shutdown mode regardless of the
voltages present on the M0 and M1 pins. However, if the
M0 and M1 pins are floating or left connected to DVCC as
the supply is shut down, the parts may take several
LTC1555/LTC1556
CLK TO SIM
RST TO SIM
CIN
CLK
RST
I/O
RIN
DATA TO/FROM SIM
DATA
DDRV
V
CC
CONTROLLER
SIDE
DV
CC
SIM SIDE
1555/56 F3a
DV
CC
Figure 3a. Level Translator Connections for
Bidirectional Controller DATA Pin
M0
M1
0V
DV
CC
LTC1555/LTC1556
0V
CLK TO SIM
RST TO SIM
CIN
CLK
RST
I/O
DV
CC
RIN
DV
CC
DATA FROM SIM
DATA TO SIM
DATA
DDRV
0V
V
CC
V
CC
CONTROLLER
SIDE
DV
CC
V
CC
SIM SIDE
0V
1555/56 F3b
1555/56 F02
Figure 3b. Level Translator Connections for
One-Directional Controller Side DATA Flow
Figure 2. Recommended DVCC Shutdown and Start-Up Timing
8
LTC1555/LTC1556
U
W U U
APPLICATIONS INFORMATION
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
receivedatafromtheSIM.WhentheDDRVpinisnotused,
it should either be left floating or tied to DVCC.
requiredtoensureoutputstability. A10µFlowESRcapaci-
tor is recommended, however, to minimize LDO output
noise. The LDO output may also be used as an auxiliary
switch to VCC. If the FB pin is left floating or is tied to GND,
the LDO pin will be internally connected to the VCC output
through the P-channel pass device. The LDO may be dis-
abledatanytimebyswitchingtheENpinfromDVCC toGND.
The 4.3V LDO output is usable only when VCC is 5V (or
greater). It is not available when VCC = 3V.
Level Translation with DVCC > VCC
It is assumed that most applications for these parts will
use controller supply voltages (DVCC) less than or equal
to VCC. In cases where DVCC is greater than VCC by more
than0.6Vorso, theparts’operationwillbeaffectedinthe
following ways: 1) A small DC current (up to 100µA) will
flowfromDVCC toVCC throughtheDATApull-upresistor,
N-channel pass device and the I/O pull-up resistor
(except when the part is in shutdown at which time DVCC
is disconnected from VCC by turning off the pass device).
If the VCC load current is less than the DVCC current, the
VCC outputmaybepulledoutofregulationuntilsufficient
load current pulls VCC back into regulation. 2) When the
SIM is sending data back to the controller, a logic high on
the I/O pin will result in the DATA pin being pulled up to
[VCC + 1/3(DVCC – VCC)], not all the way up to DVCC. For
example, if DVCC is 5V and VCC is 3V, the DATA pin will
only swing from ≈0.1V to 3.67V when receiving data
from the SIM side.
EN
OFF ON
1µA
V
CC
= 5V
LDO
–
+
V
REF
FB
I
153k
61k
4.3V
LDO
0mA to
10mA
+
10µF
TANT
1555/56 F04
Figure 4. Auxiliary LDO Connections (LTC1556 Only)
10kV ESD Protection
All pins that connect to the SIM (CLK, RST, I/O, VCC, GND)
withstandover10kVofhumanbodymodel(100pF/1.5kΩ)
ESD. In order to ensure proper ESD protection, careful
board layout is required. The GND pins 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.
Optional LDO Output
The LTC1556 also contains an internal LDO regulator for
providingalownoiseboostedsupplyvoltageforlowpower
external circuitry (e.g., frequency synthesizers, etc.) Tying
the FB pin to the LDO pin provides a regulated 4.3V at the
LDOoutput(seeFigure4). A3.3µF(minimum)capacitoris
9
LTC1555/LTC1556
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
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
2
3
4
5
6
7
8
0.015 ± 0.004
(0.38 ± 0.10)
× 45°
0.053 – 0.068
(1.351 – 1.727)
0.004 – 0.0098
(0.102 – 0.249)
0.007 – 0.0098
(0.178 – 0.249)
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.008 – 0.012
(0.203 – 0.305)
0.025
(0.635)
BSC
*
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
GN16 (SSOP) 1197
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
10
LTC1555/LTC1556
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
GN Package
20-Lead Plastic SSOP (Narrow 0.150)
(LTC DWG # 05-08-1641)
0.337 – 0.344*
(8.560 – 8.737)
20 19 18 17 16 15 14 13 12 11
0.229 – 0.244
(5.817 – 6.198)
0.150 – 0.157**
(3.810 – 3.988)
1
2
3
4
5
6
7
8
9 10
0.015 ± 0.004
(0.38 ± 0.10)
0.053 – 0.068
(1.351 – 1.727)
0.004 – 0.0098
(0.102 – 0.249)
× 45°
0.007 – 0.0098
(0.178 – 0.249)
0° – 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.008 – 0.012
(0.203 – 0.305)
0.025
(0.635)
BSC
*
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
GN20 (SSOP) 1197
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LTC1555/LTC1556
U
TYPICAL APPLICATION
SIM Interface with Auxilary Power
4.3V
50mA
AUXILIARY LDO/POWER SWITCH
(FREQUENCY SYNTHESIZER)
+
10µF
3V GSM
CONTROLLER
V
IN
2.7V TO 10V
3V
LTC1556
SIM
1
2
20
19
18
17
16
15
14
13
12
11
CIN
CLK
RST
I/O
CLK
RST
I/O
RIN
DATA
DDRV
EN
3
4
LDO
5
V
V
CC
CC
6
5V ±5%
≤ 10mA
FB
V
IN
+
I
VCC
7
V
DV
CC
C1
C1
CC
10µF
0.1µF
8
–
SS
M1
M0
+
9
10µF
GND
GND
10
GND
1555/56 TA02
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1514-3.3/LTC1514-5 Regulated Step-Up/Step-Down Charge Pumps with Low Bat Comparator 3.3V and 5V Output Versions
LTC1515 Series
LTC1516
Regulated Step-Up/Step-Down Charge Pumps with Reset Output
Micropower, Regulated 5V Charge Pump DC/DC Converter
Micropower, Regulated 5V Charge Pump DC/DC Converter
Adjustable, 3V/5V, 3.3V/5V Versions
= 20mA (V ≥ 2V), I = 50mA (V ≥ 3V)
I
OUT
IN
OUT
IN
LTC1517-5
LTC1522 Without Shutdown and
Packaged in SOT-23
LTC1522
Micropower, Regulated 5V Charge Pump DC/DC Converter
Low Noise, Charge Pump Voltage Inverter
I
= 20mA (V ≥ 3V), I = 6µA
OUT IN Q
LTC1550-4.1
LTC660
1mV Ripple at 900kHz
P-P
100mA Charge Pump DC/DC Converter
5V to –5V at 100mA
15556f LT/TP 0398 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1997
Linear Technology Corporation
●
1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900
12
●
●
FAX: (408) 434-0507 TELEX: 499-3977 www.linear-tech.com
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