LTC1470/LTC1471
Single and Dual
PCMCIA Protected
3.3V/5V VCC Switches
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FEATURES
DESCRIPTIO
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The LTC®1470 switches the VCC pins of a Personal Computer Memory Card International Association (PCMCIA)
card slot between three operating states: OFF, 3.3V and
5V. Two low RDS(ON) N-channel power MOSFETs are
driven by a built-in charge pump which generates a
voltage higher than the supply voltage to fully enhance
each switch when selected by the input control logic.
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Single 3.3V/5V Switch in 8-Pin SO Package
Dual 3.3V/5V Switch in 16-Pin SO Package
Built-In Current Limit and Thermal Shutdown
Built-In Charge Pumps (No 12V Required)
Extremely Low RDS(ON) MOSFET Switches
Output Current Capability: 1A
Inrush Current Limited (Drives 150µF Loads)
Quiescent Current in Standby: 1µA
No Parasitic Body Diodes
Built-In XOR Function Eliminates “Glue” Logic
Break-Before-Make Switching
Controlled Rise and Fall Times
Available in 8-Pin and 16-Pin SO Packages
The LTC1470 inputs are compatible with industry standard PCMCIA controllers. A built-in XOR ensures that both
switches are never on at the same time. This function also
makes the LTC1470 compatible with both active-low and
active-high controllers (see Applications Information section). The switch rise times are controlled to eliminate
power supply glitching.
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APPLICATIO S
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The LTC1470 features built-in SafeSlotTM current limit and
thermal shutdown. The output is limited to 1A during short
circuit to ground but 2A of peak operating current is
allowed.
Set Top Box/Open Cable
Notebook Computers
Palmtop Computers
Pen-Based Computers
Handi-Terminals
3.3V/5V Power Supply Switch
The LTC1471 is a dual version of the LTC1470 and is
available in a 16-pin SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
SafeSlot is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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TYPICAL APPLICATIO
Dual Slot PCMCIA 3.3V/5V VCC Switch
5V
Linear Technology PCMCIA Product Family
3.3V
0.1µF
0.1µF
VCC
5VIN
3VIN
AOUT
(Hi-Z/3.3V/5V)
VCC
+
1µF
LTC1471
10k
AEN1
PCMCIA
CARD SLOT
CONTROLLER
VCC
AEN0
BEN1
PCMCIA
CARD SLOT
(Hi-Z/3.3V/5V)
BOUT
BEN0
GND
VCC
PCMCIA
CARD SLOT
+
1µF
10k
DEVICE
DESCRIPTION
PACKAGE
LT ®1312
Single PCMCIA VPP Driver/Regulator
8-Pin SO
LT1313
Dual PCMCIA VPP Driver/Regulator
16-Pin SO*
LTC1314
Single PCMCIA Switch Matrix
14-Pin SO
LTC1315
Dual PCMCIA Switch Matrix
24-Pin SSOP
LTC1470
Single Protected VCC 3.3V/5V Switch Matrix
8-Pin SO
LTC1471
Dual Protected VCC 3.3V/5V Switch Matrix
16-Pin SO*
LTC1472
Protected VCC and VPP Switch Matrix
16-Pin SO*
*Narrow Body
1470/71 TA01
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LTC1470/LTC1471
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ABSOLUTE MAXIMUM RATINGS
(Note 1)
3.3V Supply Voltage (3VIN) (Note 2) ........................ 7V
5V Supply Voltage (5VIN) (Note 2) ............................ 7V
Enable Input Voltage ..................... 5VIN to (GND – 0.3V)
Output Voltage (OFF) (Note 2) ......... 7V to (GND – 0.3V)
Output Short-Circuit Duration .......................... Indefinite
Operating Temperature
LTC1470C .............................................. 0°C to 70°C
LTC1470E (Note 7) ............................. –40°C to 85°C
Junction Temperature .......................................... 100°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
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PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
TOP VIEW
LTC1470CS8
LTC1470ES8
AOUT 1
16 AOUT
A5VIN 2
15 A3VIN
AEN1 3
14 A3VIN
AEN0 4
13 GND
OUT 1
8
OUT
5VIN 2
7
3VIN
EN1 3
6
3VIN
GND 5
12 BEN0
EN0 4
5
GND
B3VIN 6
11 BEN1
B3VIN 7
10 B5VIN
BOUT 8
9
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 150°C/W
S8 PART MARKING
1470
1470E
ORDER PART
NUMBER
TOP VIEW
LTC1471CS
BOUT
S PACKAGE
16-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 100°C/W
Consult LTC Marketing 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. 3VIN = 3.3V, 5VIN = 5V (Note 3), unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
3VIN
3.3V Supply Voltage Range
5VIN
5V Supply Voltage Range
5.25
V
I3VIN
3.3V Supply Current
Program to Hi-Z (Note 4)
Program to 3.3V, No Load (Note 4)
Program to 5V, No Load (Note 4)
●
●
●
0.01
40
0.01
10
80
10
µA
µA
µA
I5VIN
5V Supply Current
Program to Hi-Z (Note 4)
Program to 3.3V (Note 4)
Program to 5V (Note 4)
●
●
●
0.01
100
140
10
160
200
µA
µA
µA
RON
3.3V Switch ON Resistance
5V Switch ON Resistance
Program to 3.3V, IOUT = 500mA
Program to 5V, IOUT = 500mA
0.12
0.14
0.16
0.18
Ω
Ω
ILKG
Output Leakage Current OFF
Program to Hi-Z, 0V ≤ VOUT ≤ 5V (Note 4)
±10
µA
ILIM3V
3.3V Current Limit
Program to 3.3V, VOUT = 0V (Note 5)
1
A
ILIM5V
5V Current Limit
Program to 5V, VOUT = 0V (Note 5)
1
A
VENH
Enable Input High Voltage
VENL
Enable Input Low Voltage
IEN
Enable Input Current
2.70
4.75
●
●
●
0V ≤ VEN ≤ 5V
MAX
UNITS
3.60
V
2.0
V
0.8
V
±1
µA
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LTC1470/LTC1471
ELECTRICAL CHARACTERISTICS
3VIN = 3.3V, 5VIN = 5V (Note 3), TA = 25°C, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
t0 to t3
Delay and Rise Time (Note 6)
Transition from 0V to 3.3V, ROUT = 100Ω, COUT = 1µF
0.2
0.32
1.0
ms
t3 to t5
Delay and Rise Time (Note 6)
Transition from 3.3V to 5V, ROUT = 100Ω, COUT = 1µF
0.2
0.52
1.0
ms
t0 to t5
Delay and Rise Time (Note 6)
Transition from 0V to 5V, ROUT = 100Ω, COUT = 1µF
0.2
0.38
1.0
ms
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: For the LTC1470, the two output pins (1, 8) must be connected
together and the two 3.3V supply input pins (6 , 7) must be connected
together. For the LTC1471, the two AOUT pins (1, 16) must be connected
together, the two BOUT pins (8, 9) must be connected together, the two
A3VIN supply input pins (14, 15) must be connected together, the two
B3VIN supply pins (6, 7) must be connected together and the two GND
pins (5, 13) must be connected together.
Note 3: Power for the input logic and charge pump circuitry is derived
from the 5VIN supply pin(s) which must be continuously powered.
Note 4: Measured current is per channel with the other channel
programmed off for the LTC1471.
Note 5: The output is protected with foldback current limit which reduces
the short-circuit (0V) currents below peak permissible current levels at
higher output voltages.
Note 6: To 90% of final value.
Note 7: The LTC1470 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.
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TYPICAL PERFORMANCE CHARACTERISTICS
3VIN Supply Current (OFF)
3VIN Supply Current (3.3V ON)
3
2
1
TA = 25°C
PROGRAMMED TO
3.3V, NO LOAD
100
80
60
40
20
3
1
2
3VIN SUPPLY VOLTAGE (V)
0
3
1
2
3VIN SUPPLY VOLTAGE (V)
0
4
5VIN Supply Current (3.3V ON)
1
150
100
50
1470/71 G03
1
5
2
3
4
5VIN SUPPLY VOLTAGE (V)
3.3V Switch Resistance
TA = 25°C
PROGRAMMED
TO 5V, NO LOAD
250
200
150
100
0
6
0.30
50
6
0
1470/71 G01
3.3V SWITCH RESISTANCE (Ω)
5VIN SUPPLY CURRENT (µA)
200
5
2
3
4
5VIN SUPPLY VOLTAGE (V)
2
5VIN Supply Current (5V ON)
TA = 25°C
PROGRAMMED
TO 3.3V, NO LOAD
1
3
–1
4
300
300
0
4
1470/71 G05
1470/71 G04
250
TA = 25°C
PROGRAMMED TO OFF
0
0
–1
5VIN SUPPLY CURRENT (µA)
4
3VIN SUPPLY CURRENT (µA)
3VIN SUPPLY CURRENT (µA)
TA = 25°C
PROGRAMMED TO OFF
0
5VIN SUPPLY CURRENT (µA)
5VIN Supply Current (OFF)
5
120
5
0
(LTC1470 or 1/2 LTC1471)
PROGRAMMED
TO 3.3V
0.25
0.20
0.15
0.10
0.05
0
0
1
5
2
3
4
5VIN SUPPLY VOLTAGE (V)
6
1470/71 G02
0
25
50
75
100
JUNCTION TEMPERATURE (°C)
125
1470/71 G07
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LTC1470/LTC1471
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TYPICAL PERFORMANCE CHARACTERISTICS
Inrush Current (3.3V Switch)
5V Switch Resistance
PROGRAMMED
TO 5V
0.20
0.15
0.10
0.05
0
0
25
50
75
100
JUNCTION TEMPERATURE (°C)
125
Inrush Current (5V Switch)
3
2
TJ = 25°C
OUTPUT VOLTAGE (V) INRUSH CURRENT (A)
OUTPUT VOLTAGE (V) INRUSH CURRENT (A)
5V SWITCH RESISTANCE (Ω)
0.30
0.25
(LTC1470 or 1/2 LTC1471)
COUT = 150µF
ROUT = 6.6Ω
1
0
COUT = 15µF
ROUT = 6.6Ω
6
4
COUT = 150µF
ROUT = 6.6Ω
2
0
– 0.2
0
0.2
0.4 0.6 0.8
TIME (ms)
1470/71 G06
1.0
1.2
1.4
3
2
TJ = 25°C
CURRENT
LIMITED
1
0
COUT = 150µF
ROUT = 10Ω
COUT = 15µF
ROUT = 10Ω
6
4
2
0
– 0.2
0
0.2
1470/71 G09
0.4 0.6 0.8
TIME (ms)
1.0
1.2 1.4
1470/71 G08
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PIN FUNCTIONS
LTC1470
OUT (Pins 1, 8): Output Pins. The outputs of the LTC1470
are switched between three operating states: OFF, 3.3V
and 5V. These pins are protected against accidental short
circuits to ground by SafeSlot current limit circuitry which
protects the socket, the card, and the system power
supplies against damage. A second level of protection is
provided by thermal shutdown circuitry which protects
both switches against over-temperature conditions.
5VIN (Pin 2): 5V Input Supply Pin. The 5VIN supply pin
serves two purposes. The first purpose is as the power
supply input for the 5V NMOS switch. The second purpose
is to provide power for the input, gate drive, and protection
circuitry for both the 3.3V and 5V VCC switches. This pin
must therefore be continuously powered.
EN1, EN0 (Pins 3, 4): Enable Inputs. The two VCC Enable
inputs are designed to interface directly with industry
standard PCMCIA controllers and are high impedance
CMOS gates with ESD protection diodes to ground, and
should not be forced above 5VIN or below ground. Both
inputs have about 100mV of built-in hysteresis to ensure
clean switching between operating modes. The LTC1470
is designed to operate without 12V power. The gates of the
VCC NMOS switches are powered by charge pumps from
the 5VIN supply pins (see Applications Information section
for more detail). The Enable inputs should be turned off
(both asserted high or both asserted low) at least 100µs
before the 5VIN power is removed to ensure that both VCC
NMOS switch gates are fully discharged and both switches
are in the high impedance mode.
GND (Pin 5): Ground Connection.
3VIN (Pins 6, 7): 3V Input Supply Pins. The 3VIN supply
pins serve as the power supply input for the 3.3V switches.
These pins do not provide any power to the internal control
circuitry and therefore do not consume any power when
unloaded or turned off.
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LTC1470/LTC1471
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PIN FUNCTIONS
LTC1471
AOUT, BOUT(Pins 1, 16, 8, 9): Output Pins. The outputs
of the LTC1471 are switched between three operating
states: OFF, 3.3V and 5V. These pins are protected against
accidental short circuits to ground by SafeSlot current
limit circuitry which protects the socket, the card, and the
system power supplies against damage. A second level of
protection is provided by thermal shutdown circuitry.
5VIN (Pins 2, 10): 5V Input Supply Pins. The 5VIN supply
pins serve two purposes. The first purpose is as the power
supply input for the 5V NMOS switches. The second
purpose is to provide power for the input, gate drive, and
protection circuitry. These pins must therefore be continuously powered.
EN1, EN0 (Pins 3, 4, 11, 12): Enable Inputs. The enable
inputs are designed to interface directly with industry
standard PCMCIA controllers and are high impedance
CMOS gates with ESD protection diodes to ground, and
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BLOCK DIAGRAM
should not be forced above 5VIN or below ground. All four
inputs have about 100mV of built-in hysteresis to ensure
clean switching between operating modes. The LTC1471
is designed to operate without 12V power. The gates of the
VCC NMOS switches are powered by charge pumps from
the 5VIN supply pins (see Applications Information section
for more detail). The enable inputs should be turned off at
least 100µs before the 5VIN power is removed to ensure
that all NMOS switch gates are fully discharged and are in
the high impedance mode.
GND (Pins 5, 13): Ground Connections.
3VIN (Pins 6, 7, 14, 15): 3V Input Supply Pins. The 3VIN
supply pins serve as the power supply input for the 3.3V
switches. These pins do not not provide any power to the
internal control circuitry, and therefore, do not consume
any power when unloaded or turned off.
(LTC1470 or 1/2 LTC1471)
5VIN
GATE CHARGE
AND
DISCHARGE
CONTROL LOGIC
EN0
EN1
TTL-TO-CMOS
CONVERTER
TTL-TO-CMOS
CONVERTER
BREAK-BEFOREMAKE SWITCH
AND CONTROL
OSCILLATOR
AND BIAS
CHARGE
PUMP
GATE CHARGE
AND
DISCHARGE
CONTROL LOGIC
0.14Ω
CURRENT LIMIT
AND THERMAL
SHUTDOWN
OUTPUT
0.12Ω
3VIN
LTC1470-BD01
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LTC1470/LTC1471
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OPERATION
The LTC1470 (or 1/2 of the LTC1471) consists of the
following functional blocks:
on slowly (400µs typical rise time) but turns them off
much more quickly (typically 10µs).
Input TTL/CMOS Converters
Bias, Oscillator and Gate Charge Pump
The enable inputs are designed to accommodate a wide
range of 3V and 5V logic families. The input threshold
voltage is approximately 1.4V with approximately 100mV
of hysteresis. The inputs enable the bias generator, the
gate charge pumps and the protection circuity which are
powered from the 5V supply. Therefore, when the inputs
are turned off, the entire circuit is powered down and the
5V supply current drops below 1µA.
When either the 3.3V or 5V switch is enabled, a bias
current generator and high frequency oscillator are turned
on. The on-chip capacitive charge pump generates approximately 12V of gate drive for the internal low RDS(ON)
NMOS VCC switches from the 5VIN power supply. Therefore, an external 12V supply is not required to switch the
VCC output. The 5VIN supply current drops below 1µA
when both switches are turned off.
XOR Input Circuitry
Gate Charge and Discharge Control
By employing an XOR function, which locks out the 3.3V
switch when the 5V switch is turned on and locks out the
5V switch when the 3.3V switch is turned on, there is no
danger of both switches being on at the same time. This
XOR function also makes it possible to work with either
active -low or active-high PCMCIA VCC switch control logic
(see Applications Information section for further details).
All switches are designed to ramp on slowly (400µs typical
rise time). Turn-off time is much quicker (typically 10µs).
To ensure that both VCC NMOS switch gates are fully
discharged, program the switch to the high impedance
mode at least 100µs before turning off the 5V power
supply.
Switch Protection
Break-Before-Make Switch Control
Built-in delays are provided to ensure that the 3.3V and 5V
switches are non-overlapping. Further, the gate charge
pump includes circuitry which ramps the NMOS switches
Both switches are protected against accidental short circuits with SafeSlot foldback current limit circuits which
limit the output current to typically 1A when the output is
shorted to ground. Both switches also have thermal shutdown which limits the power dissipation to safe levels.
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APPLICATIONS INFORMATION
The LTC1470/LTC1471 are designed to interface directly
with industry standard PCMCIA card controllers.
3.3V
0.1µF
3VIN
Interfacing with the CL-PD6710
5V
3VIN
5VIN
0.1µF
Figure 1 is a schematic diagram showing the LTC1470
interfaced with a standard PCMCIA slot controller. The
LTC1470 accepts logic control directly from the CL-PD6710.
The XOR input function allows the LTC1470 to interface
directly to the active-low VCC control outputs of the CLPD6710 for 3.3V/5V voltage selection (see the following
Switch Truth Table). Therefore, no “glue” logic is required
to interface to this PCMCIA compatible card controller.
CL-PD6710
LTC1470
VCC _3
EN0
OUT
VCC _5
EN1
OUT
GND
(OFF/3.3V/5V)
+
1µF
TANT
TO CARD
VCC PINS
10k
1470/71 F01
Figure 1. Direct Interface to CL-PD6710 PCMCIA Controller
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LTC1470/LTC1471
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APPLICATIONS INFORMATION
Truth Table for CL-PD6710 Controller
A_VCC _3
A_VCC _5
EN0
EN1
OUT
0
0
Hi-Z
0
1
3.3V
1
0
5V
1
1
Hi-Z
Supply Bypassing
For best results bypass the supply input pins with 1µF
capacitors as close as possible to the LTC1470. Sometimes much larger capacitors are already available at the
outputs of the 3.3V and 5V power supply. In this case it is
still good practice to use 0.1µF capacitors as close as
possible to the device, especially if the power supply
output capacitors are more than 2" away on the printed
circuit board.
Interfacing with “365” Type Controllers
The LTC1470 also interfaces directly with “365” type
controllers as shown in Figure 2. Note that the VCC Enable
inputs are connected differently than to the CL-PD6710
controller because the “365” type controllers use activehigh logic control of the VCC switches (see the following
Switch Truth Table). No “glue” logic is required to interface to this type of PCMCIA compatible controller.
3.3V
5V
3VIN
5VIN
0.1µF
“365” TYPE
CONTROLLER
The output pin is designed to ramp on slowly, typically
400µs rise time. Therefore, capacitors as large as 150µF
can be driven without producing voltage spikes on the
3VIN or 5VIN supply pins (see graphs in Typical Performance Characteristics section). The output pin should
have a 0.1µF to 1µF capacitor for noise reduction and
smoothing.
A 10k pull-down resistor is recommended at the output to
ensure that the output capacitor is fully discharged when the
output is switched OFF. This resistor also ensures that the
output is discharged between the 3.3V and 5V transition.
0.1µF
3VIN
Output Capacitors and Pull-Down Resistor
LTC1470
A_VCC _EN0
A_VCC _EN1
Supply Sequencing
OUT
EN0
OUT
EN1
GND
(OFF/3.3V/5V)
+
1µF
TANT
TO CARD
VCC PINS
10k
1470/71 F02
Figure 2. Direct Interface with “365” Type PCMCIA Controller
Truth Table for “365” Type Controller
A_VCC _EN0
A_VCC _EN1
EN0
EN1
OUT
0
0
Hi-Z
0
1
3.3V
1
0
5V
1
1
Hi-Z
Because the 5V supply is the source of power for both of the
switch control circuits, it is best to sequence the power
supplies such that the 5V supply is powered before, or
simultaneous to, the application of 3.3V.
It is interesting to note, however, that the switches are NMOS
transistors which require charge pumps to generate gate
voltages higher than the supply rails for full enhancement.
Because the gate voltages start at 0V when the supplies are
first activated, the switches always start in the off state and
do not produce glitches at the outputs when powered.
If the 5V supply must be turned off, it is important to program
all switches to the Hi-Z or 0V state at least 100µs before the
5V power is removed to ensure that the NMOS switch gates
are fully discharged to 0V. Whenever possible, however, it is
best to leave the 5VIN pin(s) continuously powered. The
LTC1470/LTC1471 quiescent current drops to
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