LT1312 查看數據表（PDF） - Linear Technology
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LT1312 Datasheet PDF : 12 Pages
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LT1312
PIN FUNCTIONS
Supply Pin: Power is supplied to the device through the
supply pin. The supply pin should be bypassed to ground
if the device is more than 6 inches away from the main
supply capacitor. A bypass capacitor in the range of 0.1µF
to 1µF is sufficient. The supply voltage to the LT1312 can
be loosely regulated between 13V and 20V. See Applica-
tions Information section for more detail.
VPPOUT Pin: This regulated output supplies power to the
PCMCIA card VPP pins which are typically tied together
at the card socket. The VPPOUT output is current limited
to approximately 330mA. Thermal shutdown provides a
second level of protection. A 1µF to 10µF tantalum output
capacitor is recommended. See Applications Informa-
tion section for more detail on output capacitor consid-
erations.
Input Enable Pins: The two digital input pins are high
impedance inputs with approximately 20µA input current
at 2.4V. The input thresholds are compatible with CMOS
controllers and can be driven from either 5V or 3.3V
CMOS logic. ESD protection diodes limit input excursions
to 0.6V below ground.
VALID Output Pin: This pin is an open-collector NPN
output which is driven low when the VPPOUT pin is in
regulation, i.e., when it is above 11V. An external 51k pull-
up resistor is connected between this output and the same
5V or 3.3V logic supply powering the PCMCIA compatible
control logic.
VCC Sense Pin: A built-in comparator and 4V reference
automatically switches the VPPOUT from 5V to 3.3V de-
pending upon the voltage sensed at the PCMCIA card
socket VCC pin. The input current for this pin is approxi-
mately 30µA. For 5V only operation, connect the Sense pin
directly to ground. An ESD protection diode limits the
input voltage to 0.6V below ground.
BLOCK DIAGRAM
VS
VCC SENSE
+
–
4V
EN0
EN1
LOW DROPOUT
LINEAR
REGULATOR
VOLTAGE
LOGIC CONTROL
+
–
11V
VPPOUT
VALID
LT1312 BD
5
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