LTC3539 LINER [Linear Technology], LTC3539 Datasheet - Page 6

• Manufacturer Part Number: LTC3539
• Description: 2A, 1MHz/2MHz Synchronous Step-Up DC/DC Converters
• Manufacturer: LINER [Linear Technology]

PIN FUNCTIONS
LTC3539/LTC3539-2
SW (Pin 1): Switch Pin. Connect inductor between SW
and V
sible to reduce EMI. If the inductor current falls to zero,
or SHDN is low, an internal anti-ring resistor is connected
from SW to V
PGND (Pin 2), GND (Pin 3): Signal and Power Ground.
Provide a short direct PCB path between PGND, GND and
the (–) side of the input and output capacitors.
V
of 2.2μF ceramic decoupling capacitor from this pin to
ground.
SHDN (Pin 5): Logic Controlled Shutdown Input. There
is an internal 4MΩ pull-down on this pin.
BLOCK DIAGRAM
6
IN
SHDN = High: Normal operation.
SHDN = Low: Shutdown, quiescent current <1μA.
(Pin 4): Battery Input Voltage. Connect a minimum
IN
PWM
. Keep PCB trace lengths as short and wide as pos-
OFF
BURST
ON
IN
5
7
to minimize EMI.
SHDN
MODE
SHUTDOWN
V
OUT
V
BEST
UVLO
V
REF
SHUTDOWN
1MHz/2MHz
9
THERMAL
START-UP
V
V
SHUTDOWN
OSC
EXPOSED PAD
REF
B
UVLO
CLK
TSD
2
GATE DRIVERS
CONDUCTION
BURST MODE
ANTI-CROSS
LOGIC AND
CONTROL
PGND
AND
V
SEL
I
I
BURST
WAKE
PK
ZERO
1
3
SW
GND
COMPARATOR
FB (Pin 6): Feedback Input to the g
nect resistor divider tap to this pin. The output voltage
can be adjusted from 1.5V to 5.25V by: V
[1 + (R2/R1)]
MODE (Pin 7): Burst Mode Pin. A logic controlled input
to select either automatic Burst Mode operation or forced
fi xed frequency operation.
V
Internal Synchronous Rectifi er. PCB trace length from
V
wide as possible.
Exposed Pad (Pin 9): The exposed pad must be soldered
to the PCB ground plane. It serves as another ground
connection, and as a means of conducting heat away
from the die.
I
PK
OUT
OUT
–
+
MODE = High: Burst Mode operation at light loads
MODE = Low: Fixed frequency PWM Mode
to the output fi lter capacitor should be as short and
(Pin 8): Output Voltage Sense and Drain of the
COMPARATOR
CLAMP
SLOPE
SOFT-START
SWITCH
WELL
V
4
IN
V
IN
COMPARATOR
I
ZERO
AMPLIFIER/SLEEP
COMPARATOR
ERROR
+
–
V
FB
REF
m
Error Amplifi er. Con-
V
3539 BD
OUT
FB
8
6
OUT
R2
R1
= 1.20V •
V
OUT
3539f