LTC1754-5 データシートの表示（PDF） - Linear Technology
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LTC1754-5 Datasheet PDF : 8 Pages
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LTC1986
PIN FUNCTIONS
VOUT (Pin 1): Charge Pump Output. The VOUT voltage will
depend on the MODE pin input voltage. VOUT = 0V in
shutdown mode, VOUT = VIN in 3V mode and VOUT = 5V in
5V mode. The LTC1986 provides a 2.9V regulated output
when the part is in 3V mode and the VIN voltage is below
2.85V. This feature allows the input voltage to be below the
minimum voltage specification for 3V SIM cards without
violating the SIM VCC specification. Bypass the VOUT pin
with a ≥ 2.2µF low ESR capacitor to ground.
GND (Pin 2): Ground. Connect to a ground plane for best
performance.
MODE (Pin 3): MODE Input Pin. The voltage on this pin
determines the operating mode of the LTC1986. It oper-
ates in either shutdown mode, 3V mode or 5V mode
depending on the MODE pin voltage with respect to VIN.
The three different modes can be realized by using two
external resistors as shown in the typical application
circuit. If VMODE < VIN/2 – 0.1V, the part is in shutdown
mode.If VIN/2 + 0.1V < VMODE < VIN – 1V, the part is in 5V
mode. If VIN – 0.25V < VMODE, the part is in 3V mode. To
achieve the lowest possible shutdown current, the MODE
pin should be pulled to 0V, i.e., both the SHDN and 3/5
signals from the controller should be pulled low.
C1– (Pin 4): Charge Pump Flying Capacitor Negative
Terminal.
C1+ (Pin 5): Charge Pump Flying Capacitor Positive
Terminal.
VIN (Pin 6): Input Supply Voltage. Bypass VIN with a
≥ 0.1µF low ESR capacitor to ground.
SI PLIFIED BLOCK DIAGRA
C1–
C1+
4
5
50Ω
LTC1986
2.5Ω
VIN 6
SOFT START
–
1.25V +
5V MODE
CHARGE
PUMP
2.9V BOOST
900kHz
OSC
3V MODE
1 VOUT
VIN – 0.6V
+
–
MODE 3
+
–
VIN/2
LOGIC
3V
UVLO/
THERMAL
5V
SHDN
SHDN
1.25V
REF
SHDN
GND
2
1986 BD
4
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