LTC4260
8
4260fc
For more information
pin FuncTions
ADIN: ADC Input. A voltage between 0V and 2.56V applied
to this pin can be measured by the onboard ADC. Tie to
ground if unused.
ADR0 to ADR2: Serial Bus Address Inputs. Tying these
pins to ground, open or INTV
CC
configures one of 27 pos-
sible addresses. See Table 1 in Applications Information.
ALERT
: Fault Alert Output. Open-drain logic output that can
be pulled to ground when a fault occurs to alert the host
controller. A fault alert is enabled by the ALERT register.
This device is compatible with SMBus alert protocol. See
Applications Information. Tie to ground if unused.
BD_PRST: Board Present Input. Ground this pin to en-
able the N-channel FET to turn on after 100ms debounce
delay. When this pin is high, the FET is off. An internal
10µA current source pulls up this pin. Transitions on this
pin will be recorded in the FAULT register. A high-to-low
transition activates the logic to read the state of the ON
pin and clear Faults. See Applications Information.
Exposed Pad (Pin 33, UH Package): Exposed pad may
be left open or connected to device ground.
FB: Foldback and Power Good Input. A resistive divider
from the output voltage is tied to this pin. When the
voltage at this pin drops below 3.41V, the output power
is considered bad and the current limit is reduced. The
power bad condition can be indicated with the GPIO pin
and a power bad fault can be logged in this condition. See
Applications Information.
GATE: Gate Drive for External N-Channel FET. An internal
18µA current source charges the gate of the external
N-channel MOSFET. A resistor and capacitor network from
this pin to ground sets the turn-on rate and compensates
the active current limit. During turn-off there is a 1mA
pull-down current. During a short circuit or undervoltage
lockout (V
DD
or INTV
CC
), a 600mA pull-down current
source between GATE and SOURCE is activated.
GND: Device Ground.
GPIO: General Purpose Input/Output. Open-drain logic
output and logic input. Defaults to pull low to indicate
power is bad. Configure according to Table 3.
INTV
CC
: Internal Low Voltage Supply Decoupling Output.
Connect a 0.1µF capacitor from this pin to ground. This
pin can be used to drive the other pins to logic high and
has an undervoltage lockout threshold of 3.8V.
NC: No Connect. Unconnected pins. These pins provide
extra distance between high and low voltage pins.
ON: On Control Input. A rising edge turns on the external
N-channel FET and a falling edge turns it off. This pin is
also used to configure the state of the FET ON bit (and
hence the external FET) at power up. For example if the
ON pin is tied high, then the FET ON control bit (A3) will
go high 100ms after power-up. Likewise if the ON pin is
tied low then the part will remain off after power-up until
the FET ON control bit is set high using the I
2
C bus. A
high-to-low transition on this pin will clear faults.
OV (GN/UH Packages): Overvoltage Comparator Input.
Connect this pin to an external resistive divider from V
DD
.
If the voltage at this pin rises above 3.5V, an overvoltage
fault is detected and the switch turns off. Tie to GND if
unused.
SCL: Serial Bus Clock Input. Data at the SDA pin is shifted
in or out on rising edges of SCL. This is a high impedance
pin that is generally driven by an open-collector output
from a master controller. An external pull-up resistor or
current source is required.
SDAI: Serial Bus Data Input. A high impedance input used
for shifting in address, command or data bits. Normally
tied to SDAO to form the SDA line.
