LTC3676/LTC3676-1
12
3676fe
For more information www.linear.com/LTC3676
PIN FUNCTIONS
used to activate the WAKE output by driving high. Drive
low to shut down WAKE.
FB_B3 (Pin 22/Pin 27): Feedback Input for Step-Down
Switching Regulator 3. Set full-scale output voltage using
resistor divider connected from the output of step-down
switching regulator 3 to this pin to ground.
FB_B4 (Pin 23/Pin 28): Feedback Input for Step-Down
Switching Regulator 4. Set full-scale output voltage using
resistor divider connected from the output of step-down
switching regulator 4 to this pin to ground.
FB_B1 (Pin 24/Pin 29): Feedback Input for Step-Down
Switching Regulator 1. Set full-scale output voltage using
resistor divider connected from the output of step-down
switching regulator 1 to this pin to ground.
FB_B2 (Pin 25/Pin 30): Feedback Input for Step-Down
Switching Regulator 2. Set full-scale output voltage using
resistor divider connected from the output of step-down
switching regulator 2 to this pin to ground.
FB_L1 (Pin 26/Pin 31): Feedback Input for LDO1. Set
output voltage using a resistor divider connected from
LDO1 to this pin to ground.
V
IN
(Pin 27/Pin 32): Supply Voltage Input. This pin should
be bypassed to ground with a 1μF or greater ceramic
capacitor. All switching regulator PV
IN
supplies should
be tied to V
IN
.
LDO1 (Pin 28/Pin 33): Always On LDO1 Output. This pin
provides an always-on supply voltage useful for light loads
such as a watchdog microprocessor or a real time clock.
Connect a 1μF capacitor from LDO1 to ground.
ON (Pin 29/Pin 34): Pushbutton Input. A weak internal
pull-up forces ON high when left floating. A normally open
pushbutton is connected from ON to ground forcing a low
state when pushed.
EN_L2 (Pin 30/Pin 35): Enable LDO2 Input. Active high
enables LDO2. A weak pull-down pulls EN_L2 low when
left floating.
SW2 (Pin 31/Pin 38): Switch Pin for Step-Down Switch
-
ing Regulator 2.
Connect one side of step-down switching
regulator2 inductor to this pin.
IRQ (Pin 32/Pin 39): Interrupt Request Output. Open-drain
driver is pulled low for power good, undervoltage, and
overtemperature warning and fault conditions. Clear IRQ
by writing to the I
2
C CLIRQ command register.
WAKE (Pin 33/Pin 40): System Wake Up. Open-drain
driver output releases high when signaled by pushbutton
activation or PWR_ON input. It may be used to initiate
a pin-strapped power-up sequence by connecting to a
regulator enable pin.
EN_B2 (
Pin 34/Pin 41): Enable Step-Down Switching
Regulator 2. Active high input enables step-down switching
regulator2. A weak pull-down pulls EN_B2 low when left floating.
PV
IN2
(Pin 35/Pin 42): Power Input for Step-Down Switch-
ing Regulator 2.
Tie this pin to V
IN
supply. This pin should
be bypassed to ground with a 10μF or greater ceramic
capacitor.
PV
IN1
(Pin 36/Pin 43): Power Input for Step-Down Switching
Regulator 1. Tie this pin to V
IN
supply. This pin should be bypassed
to ground with a 10μF or greater ceramic capacitor.
EN_B1 (Pin 37/Pin 44): Enable Step-Down Switching
Regulator 1. Active high enables step-down switching
regulator 1. The LTC3676-1 EN_B1 pin enables both VTTR
output and switching regulator 1. A week pull-down pulls
EN_B1 low when left floating.
RSTO (Pin 38/Pin 45): Reset Output. Open-drain output
pulls low when the always-on regulator LDO1 is below
regulation or during a hard reset initiated by a pushbutton
input or command registers.
PGOOD (Pin 39/Pin 46): Power Good Output. Open-drain
output pulls low when any enabled regulator falls below
power good threshold or during dynamic voltage slew
unless disabled in command register. Pulls low when all
regulators are
disabled.
SW1 (Pin 40/Pin 47): Switch Pin for Step-Down Switch-
ing Regulator
1.
Connect one side of step-down switching
regulator1 inductor to this pin.
GND (Exposed Pad Pin 41/Pin 49):
Ground. The exposed
pad must be connected to a continuous ground plane of
the printed circuit board by multiple interconnect vias
directly under the LTC3676 to maximize electrical and
thermal conduction.
