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PDF LTC1472CS Data sheet ( Hoja de datos )
| Número de pieza | LTC1472CS | |
| Descripción | Protected PCMCIA VCC and VPP Switching Matrix | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC1472
Protected PCMCIA VCC and
VPP Switching Matrix
FEATURES
s Both VCC and VPP Switching in a Single Package
s Built-In Current Limit and Thermal Shutdown
s 16-Pin (Narrow) SOIC Package
s Inrush Current Limited (Drives 150µF Loads)
s Continuous 12V Power Not Required
s Extremely Low RDS(ON) NMOS Switches
s Guaranteed 1A VCC Current and 120mA VPP Current
s 1µA Quiescent Current in Standby
s No External Components Required
s Compatible with Industry Standard Controllers
s Break-Before-Make Switching
s Controlled Rise and Fall Times
U
APPLICATIONS
s Notebook Computers
s Palmtop Computers
s Pen-Based Computers
s Handi-Terminals
s Bar-Code Readers
DESCRIPTION
The LTC®1472 switching matrix routes power to both the
VCC and VPP power supply pins of the PCMCIA compatible
card socket. The VCC output of the LTC1472 is switched
between three operating states: OFF, 3.3V, and 5V. The
VPP output is switched between four operating states: 0V,
VCC, 12V, and Hi-Z. The output voltages are selected by
two sets of digital inputs which are compatible with
industry standard PC Card controllers (see Truth Tables).
The VCC output of the LTC1472 can supply up to 1A of
current and the VPP output up to 120mA. Both switches
have built-in SafeSlotTM current limiting and thermal shut-
down to protect the card, socket and power supply against
accidental short-circuit conditions.
The LTC1472 is designed to conserve power by automati-
cally dropping to 1µA standby current when the two
outputs are switched OFF. A shutdown pin is provided
which holds the external 12V regulator in standby mode
except when required for VPP power.
The LTC1472 is available in 16-pin SO.
, LTC and LT are registered trademarks of Linear Technology Corporation.
SafeSlot is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
Protected PCMCIA VCC and VPP Card Driver
3.3V
0.1µF
5V
0.1µF
PCMCIA
CARD SLOT
CONTROLLER
3VIN
5VIN
VPPIN
SHDN
VPPOUT
LTC1472
VDD
VPP EN0
VPP EN1 VCC(IN)
VCC EN0 VCC(OUT)
VCC EN1
GND
12V
0.1µF
TO 12V REGULATOR
OV, VCC, 12V, Hi-Z
0.1µF
VPP1
VPP2
PCMCIA
CARD SLOT
OFF, 3.3V, 5V
VCC
VCC
+
10k
1µF
LTC1472-TA01
Linear Technology PCMCIA Product Family
DEVICE DESCRIPTION
LT®1312 Single PCMCIA VPP Driver/Regulator
LT1313 Dual PCMCIA VPP Driver/Regulator
LTC1314 Single PCMCIA Switch Matrix
LTC1315 Dual PCMCIA Switch Matrix
LTC1470 Protected VCC 5V/3.3V Switch Matrix
LTC1471 Dual Protected VCC 5V/3.3V Switch Matrix
LTC1472 Protected VCC and VPP Switch Matrix
*Narrow Body
PACKAGE
8-Pin SO
16-Pin SO*
14-Pin SO
24-Pin SSOP
8-Pin SO
16-Pin SO*
16-Pin SO*
1
1 page  
LTC1472
TYPICAL PERFORMANCE CHARACTERISTICS (VPP Section) VCC EN0 = VCC EN1 = 0V
VCC(IN) Supply Current (No Load)
100
TA = 25°C
80
60
VPPOUT PROGRAMMED
40 TO VPPIN OR VCC(IN)
20
0
–20
0
VPPOUT PROGRAMMED
TO 0V OR Hi-Z
12
34
5
VCC(IN) SUPPLY VOLTAGE (V)
6
LTC1472 TPC10
VDD Supply Current (OFF)
5
TA = 25°C
4
VPPOUT PROGRAMMED
TO 0V OR Hi-Z
3
2
1
0
–1
0
12
34
5
VDD SUPPLY VOLTAGE (V)
6
LTC1472 TPC13
VPPIN Supply Current (OFF)
5
TA = 25°C
4
VPPOUT PROGRAMMED
TO 0V OR Hi-Z
3
2
1
0
–1
0
2 4 6 8 10 12 14
VPPIN SUPPLY VOLTAGE
LTC1472 TPC11
VDD Supply Current (No Load)
120
TA = 25°C
100
VPPOUT PROGRAMMED
TO VPPIN, NO LOAD
80
60
40
20
0
012
34
56
VDD SUPPLY VOLTAGE (V)
LTC1472 TPC14
Switch Resistances
10
VPPIN Supply Current (No Load)
120
TA = 25°C
100
VPPIN = 12V
NO LOAD
80
60 VPPOUT PROGRAMMED
TO VPPIN
40
20
VPPOUT PROGRAMMED
TO VCC(IN)
0
02
4 6 8 10 12 14
VPPIN SUPPLY VOLTAGE
LTC1472 TPC12
VDD Supply Current (ON)
120
TA = 25°C
100
VPPOUT PROGRAMMED
TO VPPIN, NO LOAD
80
60 VPPIN = 0V
40
VPPIN = 12V
20
0
012
34
56
VDD SUPPLY VOLTAGE (V)
LTC1472 TPC15
VCCIN TO VPPOUT
1
VPPIN TO VPPOUT
0.1
0
20 40 60 80
TEMPERATURE (°C)
100
LTC1472 TPC16
5
5 Page 
LTC1472
APPLICATIONS INFORMATION
Output Capacitors
The VCC(OUT) 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
5VIN or 3VIN supply pins (see graphs in Typical Perfor-
mance Characteristics). The VCC(OUT) pin should have a
0.1µF to 1µF capacitor for noise reduction and smoothing.
The VPPOUT pin should have a 0.01µF to 0.1µF capacitor
for noise reduction. The VPPIN capacitors should be at
least equal to the VPPOUT capacitors to ensure smooth
transitions between output voltages without creating spikes
on the system power supply lines.
Supply Sequencing
Because the 5V supply is the source of power for both the
VCC and VPP switch control logic, it is best to sequence the
power supplies such that the 5V supply is powered before
or simultaneous to the application of 3.3V or 12V power.
It is interesting to note however, that all of the switches in
the LTC1472 are NMOS transistors which require charge
pumps to generate gate voltages higher than the supply
rails for full enhancement. Because the gate voltages start
a 0V when the supplies are first activated, the switches
always start in the off state and do not produce glitches at
the output when powered.
Some PCMCIA switch matrix products employ PMOS
switches for 12V VPP control and great care must be taken
to ensure that the 5V control logic is powered before the
12V supply is turned on. If this sequence is not followed,
the PMOS VPP switch gate may start at ground potential
and the VPP output may be inadvertently forced to 12V.
Although, not advisable, it is possible to power the 12V
VPPIN supply pin of the LTC1472 prior to application of 5V
power. Only about 50µA flows to the VPPOUT pin under
these conditions.
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 all NMOS
switch gates are fully discharged to 0V.
Whenever possible however, it is best to leave the 5VIN and
VDD pins continuously powered. The LTC1472 quiescent
current drops to < 1µA with all the switches turned off and
therefore no 5V power is consumed in the standby mode.
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC1472CS.PDF ] | |
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