LTC3400BES6 データシートの表示（PDF） - Linear Technology
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LTC3400BES6 Datasheet PDF : 12 Pages
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LTC3400/LTC3400B
PI FU CTIO S
SW (Pin 1): Switch Pin. Connect inductor between SW
and VIN. Optional Schottky diode is connected between
SW and VOUT. Keep these PCB trace lengths as short and
wide as possible to reduce EMI and voltage overshoot. If
the inductor current falls to zero, or SHDN is low, an
internal 100Ω antiringing switch is connected from SW to
VIN to minimize EMI.
GND (Pin 2): Signal and Power Ground. Provide a short
direct PCB path between GND and the (–) side of the output
capacitor(s).
FB (Pin 3): Feedback Input to the gm Error Amplifier.
Connect resistor divider tap to this pin. The output voltage
can be adjusted from 2.5V to 5V by:
VOUT = 1.23V • [1 + (R1/R2)]
SHDN (Pin 4): Logic Controlled Shutdown Input.
SHDN = High: Normal free running operation, 1.2MHz
typical operating frequency.
SHDN = Low: Shutdown, quiescent current < 1µA.
100Ω connected between SW and VIN.
Typically, SHDN should be connected to VIN through a 1M
pull-up resistor.
VOUT (Pin 5): Output Voltage Sense Input and Drain of the
Internal Synchronous Rectifier MOSFET. Bias is derived
from VOUT. PCB trace length from VOUT to the output filter
capacitor(s) should be as short and wide as possible. VOUT
is held at VIN – 0.6V in shutdown due to the body diode of
the internal PMOS.
VIN (Pin 6): Battery Input Voltage. The device gets its
start-up bias from VIN. Once VOUT exceeds VIN, bias
comes from VOUT. Thus, once started, operation is com-
pletely independent from VIN. Operation is only limited by
the output power level and the battery’s internal series
resistance.
BLOCK DIAGRA
+ SINGLE
CELL
INPUT
6 VIN
START-UP
OSC
CIN
1µF
A A/B
MUX
B
L1
4.7µH
1 SW
VOUT
GOOD
2.3V
0.45Ω
OPTIONAL
SCHOTTKY
VOUT
5
3.3V
OUTPUT
RAMP
GEN
1.2MHz
PWM
CONTROL
PWM
COMPARATOR
SLOPE
COMP
SLEEP
Burst Mode
OPERATION
CONTROL
SYNC
DRIVE
CONTROL
Σ
0.35Ω
CURRENT
SENSE
RC
80k
CC
150pF
CP2
2.5pF
gm
ERROR
AMP
R1
1.02M
1%
(EXTERNAL)
FB
3
1.23V
REF
COUT
4.7µF
R2
604k
1%
(EXTERNAL)
4
SHDN
4
SHUTDOWN
CONTROL
SHUTDOWN
2 GND
3400 BD
3400f
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