LTC3561A
6
3561afa
For more information www.linear.com/LTC3561A
TYPICAL PERFORMANCE CHARACTERISTICS
SHDN/R
T
(Pin 1): Combination Shutdown and Timing
Resistor Pin. The oscillator frequency is programmed by
connecting a resistor from this pin to ground. Forcing
this pin to SV
IN
causes the device to be shut down. In
shutdown all functions are disabled.
SGND (Pin 2): Signal Ground. All SGND and PGND pins
must be connected together through a thick copper trace
or ground plane.
SW (Pin 3): The Switch Node Connection to the Inductor.
This pin swings from PV
IN
to PGND.
PGND (Pin 4/Exposed Pad Pin 9): Power Ground Pins.
Connect to the (–) terminal of C
OUT
and (–) terminal of C
IN
.
The exposed pad must be soldered to electrical ground
of the PCB. All SGND and PGND pins must be connected
together through a thick copper trace or ground plane.
Load Step
V
OUT
Short to Ground
PIN FUNCTIONS
PV
IN
(Pin 5): Main Supply Pin. Must be closely decoupled
to PGND.
SV
IN
(Pin 6): The Signal Power Pin. All active circuitry
is powered from this pin. Must be closely decoupled to
SGND. SV
IN
must be greater than or equal to PV
IN
.
V
FB
(Pin 7): Receives the feedback voltage from the ex-
ternal resistive divider across the output. Nominal voltage
for this pin is 0.8V.
I
TH
(Pin 8): Error Amplifier Compensation Point. The
current comparator threshold increases with this control
voltage. Nominal voltage range for this pin is 0.4V to 1.4V.
NOMINAL (V) ABSOLUTE MAX (V)
PIN NAME DESCRIPTION MIN TYP MAX MIN MAX
1 SHDN/R
T
Shutdown/Timing Resistor –0.3 0.8 SV
IN
–0.3 SV
IN
+ 0.3
2 SGND Signal Ground 0
3 SW Switch Node 0 PV
IN
–0.3 PV
IN
+ 0.3
4 PGND Main Power Ground 0
5 PV
IN
Main Power Supply –0.3 5.5 –0.3 SV
IN
+ 0.3
6 SV
IN
Signal Power Supply 2.5 5.5 –0.3 6
7 V
FB
Output Feedback Pin 0 0.8 1.0 –0.3 SV
IN
+ 0.3
8 I
TH
Error Amplifier Compensation and Run Pin 0.4 1.4 –0.3 SV
IN
+ 0.3
T
A
= 25°C, V
IN
= 3.6V, f
O
= 1MHz, unless otherwise noted.
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 0A
V
OUT
1V/DIV
I
L
2A/DIV
3561A G26
40µs/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 200mA to 1A
V
OUT
100mV/DIV
AC COUPLED
I
L
1A/DIV
I
LOAD
1A/DIV
3561A G25
40µs/DIV
