LTC2952
10
2952fb
PIN FUNCTIONS
EN (Pin 14/Pin 11): DC/DC Enable Output. This pin is a
high voltage open-drain pull-down used to control system
power. EN pin goes high impedance after an initial turn-on
command (via either the digital on or a valid pushbutton
on—refer to the Applications Information section). EN pin
pulls low at the end of a valid power-down sequence, or
when KILL pin is driven low anytime after a valid power-up
sequence.This pin can connect directly to a DC/DC converter
shutdown pin that provides an internal pull-up. Otherwise
a pull-up resistor to an external supply is required. The
voltage can not exceed the absolute maximum voltage of
both the pin and the circuit it is driving.
Exposed Pad (Pin 21, QFN Package): The exposed pad
may be left open or connected to device ground.
G1 (Pin 19/Pin 16): Primary P-Channel MOSFET Gate Drive
Output. When the primary ideal diode function is enabled
and in regulation, the ideal diode controller drives this pin
to maintain a forward voltage (V
FR
) of 20mV between the
V1 and VS pins. When another power source is driving
the VS pin, causing the voltage level at the VS pin to be
greater than the voltage level at the V1 pin or when the
primary ideal diode driver is disabled via the mode select
input pins, this pin pulls up to the MAX (V1, VS) voltage,
turning off the primary P-channel power switch. Leave this
pin open when primary ideal diode function is not used.
G1STAT (Pin 20/Pin 17): Open-Drain Primary Ideal Diode
Status Output. When the primary P-channel power switch
is off, the G1STAT pin will go from an open state to a strong
pull-down. This pin can be used to signal the state of the
primary ideal diode PowerPath to a microcontroller. Leave
this pin open or tied to GND when unused.
G2 (Pin 15/Pin 12): Secondary P-Channel MOSFET Gate
Drive Output. When the secondary ideal diode function
is enabled and in regulation, the ideal diode controller
drives this pin to maintain a forward voltage (V
FR
) of 20mV
between the V2 and VS pins. When another power source
is driving the VS pin, causing the voltage level at the VS
pin to be greater than the voltage level at the V2 pin or
when the secondary ideal diode driver is disabled via the
mode select input pins, this pin pulls up to the MAX (V2,
VS) voltage, turning off the secondary P-channel power
switch. Leave this pin open when secondary ideal diode
function is not used.
GND (Pin 12/Pin 9): Device Ground.
INT (Pin 13/Pin 10): Interrupt Output. This pin is an
open-drain pull-down pin used to signal the system that
a power shutdown is imminent. The INT pin asserts low
26ms after the initial falling edge of the pushbutton off
event and during the power-down sequence. Leave this
pin open or tied to GND if interrupt signal is unused.
KILL (Pin 3/Pin 20): System Power Shutdown Input. Set-
ting this pin low asserts the EN pin low. In modes where
M1 is above threshold, setting this pin low also shuts
off the ideal diodes. During system turn-on, input to this
pin is ignored until 400ms (t
KILL,ON
BLANK
) after the EN
pin first becomes high impedance. This pin has an accu-
rate 0.5V falling threshold and can be used as a voltage
monitor input.
M1 (Pin 2/Pin 19): Mode Select Input 1. Input to an ac-
curate comparator with 0.5V falling threshold and 15mV
hysteresis. Has a 3μA internal pull-up to an internal supply
(4V). Together with M2 determines the ideal PowerPath and
on/off control behavior of the part. Refer to the Operation
and Applications Information sections for configurations
based on the voltage levels at M1 and M2.
M2 (Pin 1/Pin 18): Mode Select Input 2. High imped-
ance input to an accurate comparator with 0.5V falling
threshold and 15mV hysteresis. When M1 is low, M2
controls whether the primary (G1) ideal diode function
is enabled. When M1 is high, M2 acts as a digital on/off
control input: A rising edge on this pin is interpreted as
a turn-on command and a falling edge is interpreted as
a turn-off command. Refer to the Operation and Applica-
tions Information sections for configurations based on
the voltage levels at M1 and M2.
OFFT (Pin 11/Pin 8): Off Timing Input. Attach 110pF
of external capacitance (C
OFFT
) to GND for each
additional millisecond of turn-off debounce time
beyond the internally set 26ms. Leave open if additional
debounce time is not needed.
ONT (Pin 10/Pin 7): On Timing Input. Attach 110pF of
external capacitance (C
ONT
) to GND for each additional
millisecond of turn-on debounce time beyond the inter-
nally set 26ms. Leave open if additional debounce time
is not needed.
(TSSOP/QFN)
