Datasheet

LTC3676/LTC3676-1
11
3676fa
For more information www.linear.com/LTC3676
PIN FUNCTIONS
FB_B4 (Pin 23): 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): 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): 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): Feedback Input for LDO1. Set output
voltage using a resistor divider connected from LDO1 to
this pin to ground.
V
IN
(Pin 27): Supply Voltage Input. This pin should be by-
passed to ground with a 1μF or greater ceramic capacitor.
All
switching regulator PV
IN
supplies should be tied to V
IN
.
LDO1 (Pin 28): 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): Pushbutton Input. A weak internal pull-up
forces
ON high when left floating. A normally open push-
button is connected from ON
to ground forcing a low state
when pushed.
EN_L2 (Pin 30): Enable LDO2 Input. Active high enables
LDO2. A weak pull-down pulls EN_L2 low when left floating.
SW2 (Pin 31): Switch Pin for Step-Down Switching
Regulator 2. Connect one side of step-down switching
regulator2 inductor to this pin.
IRQ (Pin 32): Interrupt Request Output. Open-drain driver
is pulled low for power good, undervoltage, and overtem
-
perature warning and fault conditions. Clear IRQ by writing
to the I
2
C CLIRQ command register.
WAKE (Pin 33): 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): Enable Step-Down Switching Regulator2 .
Active high input enables step-down switching regulator2 .
A weak pull-down pulls EN_B2 low when left floating.
PV
IN2
(Pin 35): Power Input for Step-Down Switching
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): 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): Enable Step-Down Switching Regulator1 .
Active high enables step-down switching regulator 1. A
weak pull-down pulls EN_B1 low when left floating.
RSTO (Pin 38): 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): 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 regula
-
tors are disabled.
SW
1 (
Pin 40): Switch Pin for Step-Down Switching
Regulator 1. Connect one side of step-down switching
regulator1 inductor to this pin.
GND (Exposed Pad Pin 41):
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.