LTC3443 Linear Technology, LTC3443 Datasheet - Page 10

• Manufacturer Part Number: LTC3443
• Description: High Current Micropower 600kHz Synchronous Buck-Boost DC/DC Converter
• Manufacturer: Linear Technology

OPERATIO
LTC3443
SOFT-START
The soft-start function is combined with shutdown. When
the SHDN/SS pin is brought above typically 1V, the IC is
enabled but the EA duty cycle is clamped from the V
10
A
B
PV
9
Figure 3. Inductor Charge Cycle During Burst Mode Operation
IN
SW1
4
+
dI
dt
COMPARATORS
GND
≈
L
6
V
L
IN
TO PWM
–
U
SW2
5
D
C
V
OUT
8
V
CI
800mA
SOFT-START
0mA
CLAMP
V
IN
T1
ENABLE
Figure 5. Soft-Start Circuitry
CHIP
C
14µA
pin.
3443 F03
A detailed diagram of this function is shown in Figure 5.
The components R
voltage on the SHDN/SS pin to provide a soft-start
function.
Figure 4. Inductor Discharge Cycle During Burst Mode Operation
A
B
PV
9
IN
SW1
+
–
+
–
ERROR AMP
4
–
dI
dt
1.22V
1V
≈ –
GND
L
6
V
OUT
SHDN/SS
L
+
V
FB
12
11
1
C
SW2
5
SS
C
P1
D
C
V
OUT
8
and C
C
V
SS
OUT
800mA
R
SS
R1
R2
SS
0mA
provide a slow ramping
www.DataSheet4U.com
ENABLE SIGNAL
3443 F05
T2
sn3443 3443fs
3443 F04