FEATURES
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LTC1955
Dual Smart Card Interface
with Serial Control
DESCRIPTIO
The LTC
®
1955 provides all necessary supervisory and
power control functions for two smart cards, two S.A.M.
cards or a combination of S.A.M. and smart cards. It
provides a charge pump for battery powered applications
as well as all necessary level shifting circuitry.
The card voltages can be independently set to 1.8V, 3V or
5V. Both card interfaces include a card detection channel
with automatic debounce circuitry. To reduce wiring costs,
the LTC1955 interfaces to a microcontroller via a simple
4-wire serial interface. Multiple devices may be connected
in daisy-chain fashion so that the number of wires to the
card socket board is independent of the number of sock-
ets. Status data is returned over the same interface.
Extensive security features ensure proper deactivation
sequencing in the event of a supply fault or a smart card
electrical fault. The smart card pins can withstand greater
than 10kV ESD in-situ with no additional components.
The LTC1955 is available in a small 5mm
×
5mm QFN
package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
*U.S. Patent No. 6,411,531
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Compatible with ISO7816-3 and EMV Electrical
Specifications
Power Management and Control for Two Smart
Cards
Control/Status Serial Port May be Daisy-Chained
for Multicard Applications
Automatic Shutdown on Electrical Faults
Buck/Boost Charge Pump Generates 5V, 3V or 1.8V
Outputs (Smart Card Classes A, B and C)*
Independent 5V/3V/1.8V Level Control for Both Cards
Automatic Level Translation
Supervisory Functions Prevent Smart Card Faults
Low Operating Current: 250µA Typical
Ultralow Shutdown Current
>10kV ESD on Smart Card Pins
Small 32-Pin 5mm
×
5mm QFN Package
APPLICATIO S
s
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Handheld Payment Terminals
Pay Telephones
ATM Machines
POS Terminals
Computer Keyboards
Multiple S.A.M. Sockets
TYPICAL APPLICATIO
Deactivation Sequence
RST A
5V/DIV
240k
23
1
12,13
INPUT
POWER
0.1µF
4.7µF
9, 10
24
27
DV
CC
V
BATT
LTC1955
GND
FAULT
D
IN
D
OUT
SCLK
LD
180k
UNDERV
2
PRES A
C8A
C4A
I/O A
RST A
CLK A
V
CCA
PRES B
CLK A
5V/DIV
4-WIRE
COMMAND
INTERFACE
28
26
25
I/O A
5V/DIV
29
V
CCA
5V/DIV
10µs/DIV
1955 G11.eps
4-WIRE
CARD
INTERFACE
30
32
31
22
DATA
R
IN
SYNC
ASYNC
NC/NO
C
+
14
C
–
11
I/O B
RST B
CLK B
V
CCB
CPO
15
4.7µF
1µF
U
3
4
5
6
7
8
21
20
19
18
17
U
U
CARD
DETECT
SMART CARD
1µF
VENDOR CARD
1µF
1955 TA01
sn1955 1955fs
1
LTC1955
ABSOLUTE
AXI U RATI GS
V
BATT
, DV
CC
, CPO, FAULT,
UNDERV to GND ....................................... –0.3V to 6.0V
PRES A/PRES B, DATA, R
IN
, SYNC, ASYNC,
LD, D
IN
, SCLK to GND ............... –0.3V to (DV
CC
+ 0.3V)
I/O A .......................................... –0.3V to (V
CCA
+ 0.3V)
I/O B .......................................... –0.3V to (V
CCB
+ 0.3V)
PACKAGE/ORDER I FOR ATIO
ASYNC
SYNC
DATA
SCLK
D
OUT
R
IN
D
IN
DV
CC
1
PRES A 2
C8A 3
C4A 4
I/O A 5
RST A 6
CLK A 7
V
CCA
8
32 31 30 29 28 27 26 25
PIN 1
24 FAULT
TOP VIEW
23 UNDERV
22 NC/NO
21 PRES B
20 I/O B
19 RST B
18 CLK B
17 V
CCB
9 10 11 12 13 14 15 16
SGND
PGND
–
LD
C
+
CPO
SV
BATT
UH PACKAGE
32-LEAD PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 34°C/W
EXPOSED PAD IS SGND
Consult LTC Marketing 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
PVBATT
= V
SVBATT
= 3.3V, DV
CC
= 3.3V unless otherwise noted.
PARAMETER
Input Power Supply
V
BATT
Operating Voltage
I
PVBATT
+ I
SVBATT
Operating Current
I
PVBATT
+ I
SVBATT
Shutdown Current
DV
CC
Operating Voltage
I
DVCC
Operating Current
I
DVCC
Shutdown Current
Charge Pump
R
OLCP
5V Mode Open-Loop
Output Resistance
CPO Turn On Time
V
BATT
= 3.075V, I
CPO
= I
CCA
+ I
CCB
= 120mA, (Note 3)
q
I
CCA/B
= 0mA, 10% to 90%
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
PV
BATT
NC
C
V
CCA
= 5V, V
CCB
= 0V, I
CCA
= 0µA
V
CCA
= V
CCB
= 5V, I
CCA
= I
CCB
= 0µA
No Cards Present, V
CPO
= 0V
2
U
U
W
W W
U
W
(Note 1)
I
VCCA
/I
VCCB ...........................................................................
80mA
V
CCA
/V
CCB
Short-Circuit Duration .................... Indefinite
Operating Ambient Temperature Range
(Note 4) .............................................. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 125°C
ORDER PART
NUMBER
LTC1955EUH
UH PART MARKING
1955
MIN
2.7
TYP
MAX
5.5
UNITS
V
µA
µA
µA
V
µA
µA
Ω
ms
sn1955 1955fs
q
q
q
q
q
q
250
350
0.75
1.7
10
0.5
5.7
0.6
400
500
1.75
5.5
25
1.5
8.5
1.5
LTC1955
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
PVBATT
= V
SVBATT
= 3.3V, DV
CC
= 3.3V unless otherwise noted.
SYMBOL
Smart Card Supplies V
CCA
, V
CCB
V
CCA/B
Output Voltage
5V Mode, 0 < I
CCA/B
< 60mA
3V Mode, 0 < I
CCA/B
< 50mA
1.8V Mode, 0 < I
CCA/B
< 30mA
I
CCA/B
= 0mA, 10% to 90%
Relative to Nominal Output
5V Mode
D15/D7) V
NC/NO
= 0V
V
PRESA/B
= 0
I
CCA/B
= 0mA, C
VCCA/B
= 1µF
Sink Current = – 200µA
Source Current = 200µA
Loaded with 50pF, 10% to 90%
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
4.65
2.75
1.65
–9
65
20
TYP
5.0
3.0
1.8
0.8
–5
100
35
1.25
20
MAX
5.35
3.25
1.95
1.5
– 2.5
135
60
2.5
250
0.2
UNITS
V
V
V
ms
%
mA
ms
µA
µs
V
V
ns
MHz
V
CCA/B
Turn On-Time
Undervoltage Detection
Overcurrent Detection
Smart Card Detection
Debounce Time (
Deactivation Time (
CLK A, CLK B
Low Level Output Voltage (V
OL
), (Note 2)
High Level Output Voltage (V
OH
), (Note 2)
Rise/Fall Time, (Note 2)
CLK A, CLK B Frequency, (Note 2)
RST A, RST B, C4A, C8A
Low Level Output Voltage (V
OL
), (Note 2)
High Level Output Voltage (V
OH
), (Note 2)
Rise/Fall Time, (Note 2)
I/O A, I/O B
Low Level Output Voltage (V
OL
), (Note 2)
High Level Output Voltage (V
OH
), (Note 2)
Rise/Fall Time, (Note 2)
Short Circuit Current, (Note 2)
DATA
Low Level Output Voltage (V
OL
)
High Level Output Voltage (V
OH
)
Rise/Fall Time
R
IN
, D
IN
, SCLK, LD, SYNC, ASYNC, NC/NO
Low Input Threshold (V
IL
)
High Input Threshold (V
IH
)
Input Current (I
IH
/I
IL
)
D
OUT
Low Level Output Voltage (V
OL
)
High Level Output Voltage (V
OH
)
UNDERV
Threshold
Leakage Current
PRES A/B to
q
q
q
PRES A, PRES B Pull-Up Current
RST to V
CC
= 0.4V)
q
q
q
q
V
CCA/B
– 0.2
16
10
0.2
V
CCA/B
– 0.2
100
0.3
500
5
10
0.3
0.8 • DV
CC
500
0.15 • DV
CC
0.85 • DV
CC
–1
1
0.3
DV
CC
– 0.3
1.17
1.23
1.29
50
Sink Current = – 200µA
Source Current = 200µA
Loaded with 50pF, 10% to 90%
Sink Current = –1mA (V
DATA
= 0V)
Source Current = 20µA (V
DATA
= V
DVCC
)
Loaded with 50pF, 10% to 90%
V
DATA
= 0V
Sink Current = – 500µA (V
I/OA/B
= 0V)
Source Current = 20µA (V
I/OA/B
= V
CCA/B
)
Loaded with 50pF, 10% to 90%
q
q
q
V
V
ns
V
V
ns
mA
V
V
ns
V
V
µA
V
V
V
nA
q
q
0.85 • V
CCA/B
q
q
q
q
q
q
q
q
Sink Current = – 200µA
Source Current = 200µA
q
q
q
V
UNDERV
= 3.3V
q
sn1955 1955fs
3
LTC1955
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
PVBATT
= V
SVBATT
= 3.3V, DV
CC
= 3.3V unless otherwise noted.
PARAMETER
FAULT
Low Level Output Voltage (V
OL
)
Leakage Current
SYMBOL PARAMETER
Serial Port Timing
t
DS
t
DH
t
DD
t
L
t
H
t
LW
t
CL
t
LC
D
IN
Valid to SCLK Setup
D
IN
Valid to SCLK Hold
D
OUT
Output Delay
SCLK Low Time
SCLK High Time
LD Pulse Width
SCLK to LD
LD to SCLK
C
LOAD
= 15pF
q
q
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
q
q
TYP
0.005
MAX
0.3
1
UNITS
V
µA
UNITS
ns
ns
Sink Current = – 200µA
V
FAULT
= 5.5V
CONDITIONS
MIN
8
8
15
50
50
50
50
0
TYP
MAX
60
ns
ns
ns
ns
ns
ns
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
This specification applies to all three smart card voltage classes:
1.8V, 3V and 5V.
Note 3:
R
OLCP
≡
(2V
BATT
– V
CPO
)/I
CPO
; V
CPO
will depend upon total load
(I
CCA
+ I
CCB
) and minimum supply voltage V
BATT
. See Figure 6.
Note 4:
The LTC1955E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the – 40°C to 85°C operating
ambient temperature range are assured by design, characterization and
correlation with statistical process controls.
TYPICAL PERFOR A CE CHARACTERISTICS
No Load Supply Current vs V
BATT
600
SHORT-CIRCUIT CURRENT (mA)
500
SUPPLY CURRENT (µA)
400
300
200
100
0
2.7
3.1
3.5 3.9 4.3 4.7
SUPPLY VOLTAGE (V)
5.1
5.5
V
CCA
= 1.8V, V
CCB
= 0V
T
A
= 25°C
I
CCA
= I
CCB
= 0µA
V
CCA
= V
CCB
= 5V
6.0
DV
CC
= V
BATT
= 5.5V
V
CCX
= 5V
OUTPUT RESISTANCE (Ω)
4
U W
1955 G01
I/O X Short-Circuit Current vs
Temperature
7.0
Charge Pump Open-Loop Output
Resistance vs Temperature
(2V
IN
– V
CPO
) / I
LOAD(MAX)
V
IN
= 2.7V
V
CPO
= 4.9V
5.5
6.5
5.0
6.0
4.5
5.5
4.0
5.0
3.5
–40
–15
10
35
TEMPERATURE (°C)
60
85
1955 G02
4.5
–40
–15
10
35
TEMPERATURE (°C)
60
85
1955 G03
sn1955 1955fs
LTC1955
TYPICAL PERFOR A CE CHARACTERISTICS
V
CCX
Overcurrent Shutdown
Threshold vs Temperature
180
V
BATT
= 3.3V
V
CPO
= 5.75V
DEBOUNCE TIME (ms)
V
CCX
= 1.8V
140
V
CCX
= 3V
60
I/O A, I/O B LOW OUTPUT VOLTAGE (V)
160
LOAD CURRENT (mA)
120
100
V
CCX
= 5V
80
–40
–15
10
35
TEMPERATURE (°C)
60
85
1955 G04
V
BATT
Quiescent Current
[I
BATT
– 2 (I
CCA
+ I
CCB
)]
vs Load Current
10
9
V
BATT
QUIESCENT CURRENT (mA)
V
BATT
= 3.1V
T
A
= 25°C
8
SUPPLY CURRENT (µA)
7
6
5
4
3
2
1
0
10µ
100µ
1m
10m
LOAD CURRENT (A)
100m
1955 G07
2.0
T
A
= 25°C
1.5
1.0
T
A
= –40°C
SUPPLY CURRENT (µA)
Charge Pump and LDO Activation
RST A
5V/DIV
V
CPO
5V/DIV
V
CCA
5V/DIV
I/O A
5V/DIV
1ms/DIV
1955 G10
U W
Card Detection Debounce Time vs
V
BATT
Supply Voltage
0.16
55
50
45
40
35
30
25
2.7
T
A
= –40°C
T
A
= 85°C
T
A
= 25°C
Bidirectional Channel (I/O A, I/O B)
Low Output Level vs Temperature
V
DATA
= 0V
I
OL
= –1mA
V
BATT
= 2.7V
V
CCX
= 1.8V
0.14
0.12
V
CCX
= 3V
0.10
V
CCX
= 5V
0.08
3.1
3.9 4.3 4.7 5.1
V
BATT
SUPPLY VOLTAGE (V)
3.5
5.5
0.06
–40
–15
10
35
TEMPERATURE (°C)
60
85
1955 G06
1955 G05
V
BATT
Shutdown Current vs
Supply Voltage
3.0
V
DVCC
= V
BATT
2.5
0.8
1.0
DV
CC
Shutdown Current vs Supply
Voltage
V
DVCC
= V
BATT
T
A
= –40°C
0.6
0.4
T
A
= 25°C, 85°C
0.2
T
A
= 85°C
0.5
0
2.7
3.1
3.9 4.3 4.7 5.1
V
BATT
SUPPLY VOLTAGE (V)
3.5
5.5
0
2.7
3.1
3.5 3.9 4.3 4.7 5.1
V
DVCC
SUPPLY VOLTAGE (V)
5.5
1955 G08
1955 G09
Deactivation Sequence
Data – I/O Channel, C
L
= 50pF
CLK A
5V/DIV
I/O A
5V/DIV
V
CCA
5V/DIV
I/O A
2V/DIV
DATA
2V/DIV
10µs/DIV
1955 G11.eps
100ns/DIV
1955 G12
sn1955 1955fs
5
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