LTC3443
5
3443fa
TYPICAL PERFOR A CE CHARACTERISTICS
UW
PMOS R
DS(ON)
Minimum Start Voltage
TEMPERATURE (°C)
–50
0.05
PMOS R
DS(ON)
(Ω)
0.07
0.09
0.11
–25
5
35 65
3443 G16
95
0.13
0.15
125
V
IN
= V
OUT
= 3.6V
SWITCHES A AND D
TEMPERATURE (°C)
–55
2.10
MINIMUM START VOLTAGE (V)
2.15
2.20
2.25
2.30
–25 5 35 65
3443 G17
UU
U
PI FU CTIO S
SHDN/SS (Pin 1): Combined Soft-Start and Shutdown.
Applied voltage < 0.4V shuts down the IC. Tie to >1.4V to
enable the IC and >2.4V to ensure the error amp is not
clamped from soft-start. An RC from the shutdown com-
mand signal to this pin will provide a soft-start function by
limiting the rise time of the V
C
pin.
GND (Pin 2): Signal Ground for the IC.
PGND (Pins 3, 6, 13 Exposed Pad): Power Ground for the
Internal NMOS Power Switches. The exposed pad must be
soldered to PCB ground for optimal thermal performance.
SW1 (Pin 4): Switch pin where the internal switches A and
B are connected. Connect inductor from SW1 to SW2. An
optional Schottky diode can be connected from this SW1
to ground. Minimize trace length to keep EMI down.
SW2 (Pin 5): Switch pin where the internal switches C
and D are connected. An optional Schottky diode can be
connected from SW2 to V
OUT
(it is required where
V
OUT
> 4.3V). Minimize trace length to keep EMI down.
MODE/SYNC (Pin 7): Burst Mode Select and Oscillator
Synchronization.
MODE/SYNC = High: Enable Burst Mode Operation.
During the period where the IC is supplying energy to
the output, the inductor peak inductor current will reach
0.8A and return to zero current on each cycle. In Burst
Mode operation the operation is variable frequency,
which provides a significant efficiency improvement at
light loads. The Burst Mode operation will continue until
the pin is driven low.
NMOS R
DS(ON)
TEMPERATURE (°C)
–55
0.05
NMOS R
DS(ON)
(Ω)
0.07
0.09
0.11
0.13
0.15
–25
53565
3443 G15
95 125
V
IN
= V
OUT
= 3.6V
SWITCHES B AND C
(T
A
= 25°C unless otherwise specified)
Error Amp Sink Current
TEMPERATURE (°C)
–55
200
EA SINK CURRENT (μA)
250
300
350
400
–25 5 35 65
3443 G12
95 125
V
IN
= V
OUT
= 3.6V
Output Frequency Current Limit
TEMPERATURE (°C)
–55
0.50
FREQUENCY (MHz)
0.55
0.60
0.65
0.70
–25 5 35 65
3443 G13
95 125
V
IN
= V
OUT
= 3.6V
TEMPERATURE (°C)
–55
2.8
CURRENT LIMIT (A)
3.0
3.2
3.4
–25 5 35 65
3443 G14
95
125
V
IN
= V
OUT
= 3.6V
