Datasheet

LTC3561A
7
3561af
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): Power Ground. Connect to the (–) terminal
of C
OUT
, and (–) terminal of C
IN
. All SGND and PGND pins
must be connected together through a thick copper trace
or ground plane.
PV
IN
(Pin 5): Main Supply Pin. Must be closely decoupled
to PGND.
PIN FUNCTIONS
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 Amplifi er Compensation Point. The current
comparator threshold increases with this control voltage.
Nominal voltage range for this pin is 0.4V to 1.4V.
Exposed Pad (Pin 9): Signal Ground. All small-signal
components and compensation components should be
connected to this ground (see Board Layout Consider-
ations). Must be soldered to electrical ground on PCB.
All SGND and PGND pins must be connected together
through a thick copper trace or ground plane.
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
5PV
IN
Main Power Supply –0.3 5.5 –0.3 SV
IN
+ 0.3
6SV
IN
Signal Power Supply 2.5 5.5 –0.3 6
7V
FB
Output Feedback Pin 0 0.8 1.0 –0.3 SV
IN
+ 0.3
8I
TH
Error Amplifi er Compensation and Run Pin 0.4 1.4 –0.3 SV
IN
+ 0.3