LTC3400 Linear Technology, LTC3400 Datasheet - Page 4

• Manufacturer Part Number: LTC3400
• Description: 600mA/ 1.2MHz Micropower Synchronous Boost Converter in ThinSOT
• Manufacturer: Linear Technology

BLOCK DIAGRA
LTC3400/LTC3400B
PI FU CTIO S
SW (Pin 1): Switch Pin. Connect inductor between SW
and V
SW and V
wide as possible to reduce EMI and voltage overshoot. If
the inductor current falls to zero, or SHDN is low, an
internal 100 antiringing switch is connected from SW to
V
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
Connect resistor divider tap to this pin. The output voltage
can be adjusted from 2.5V to 5V by:
SHDN (Pin 4): Logic Controlled Shutdown Input.
4
IN
V
SHDN = High: Normal free running operation, 1.2MHz
typical operating frequency.
U
to minimize EMI.
OUT
IN
. Optional Schottky diode is connected between
= 1.23V • [1 + (R1/R2)]
1.2MHz
RAMP
GEN
OUT
+
U
SINGLE
CELL
INPUT
. Keep these PCB trace lengths as short and
U
6
V
COMPARATOR
IN
SHDN
W
4
PWM
START-UP
SLEEP
OSC
+
–
–
OPERATION
SHUTDOWN
Burst Mode
CONTROL
CONTROL
CONTROL
SLOPE
g
COMP
PWM
m
Error Amplifier.
C
1 F
IN
A
B
MUX
A/B
SHUTDOWN
R
80k
C
C
150pF
C
4.7 H
CONTROL
L1
DRIVE
SYNC
GOOD
V
Typically, SHDN should be connected to V
pull-up resistor.
V
Internal Synchronous Rectifier MOSFET. Bias is derived
from V
capacitor(s) should be as short and wide as possible. V
is held at V
the internal PMOS.
V
start-up bias from V
comes from V
pletely independent from V
the output power level and the battery’s internal series
resistance.
OUT
OUT
IN
C
2.5pF
+
–
P2
SHDN = Low: Shutdown, quiescent current < 1 A.
100 connected between SW and V
(Pin 6): Battery Input Voltage. The device gets its
(Pin 5): Output Voltage Sense Input and Drain of the
2.3V
OUT
1
2
0.35
. PCB trace length from V
IN
CURRENT
SENSE
SW
GND
– 0.6V in shutdown due to the body diode of
0.45
OUT
ERROR
AMP
g
. Thus, once started, operation is com-
m
–
+
IN
SCHOTTKY
OPTIONAL
. Once V
V
OUT
5
IN
. Operation is only limited by
1.23V
REF
FB
3
OUT
OUTPUT
OUT
3.3V
R1
1.02M
1%
(EXTERNAL)
R2
604k
1%
(EXTERNAL)
exceeds V
to the output filter
IN
.
IN
3400 BD
through a 1M
C
4.7 F
OUT
IN
, bias
OUT
3400f