LTC3417 datasheet(6/20 Pages) LINER

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LTC3417

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PI FU CTIO S (DFN/TSSOP)

RUN1 (Pin 1/Pin 2): Enable for 1.4A Regulator. When at

Logic 1, 1.4A regulator is running. When at 0V, 1.4A

regulator is off. When both RUN1 and RUN2 are at 0V, the

part is in shutdown.

VIN1 (Pin 2/Pin 3): Supply Pin for P-Channel Switch of

1.4A Regulator.

ITH1 (Pin 3/Pin 4): Error Amplifier Compensation Point for

1.4A Regulator. The current comparator threshold in-

creases with this control voltage. Nominal voltage range

for this pin is 0V to 1.5V.

VFB1 (Pin 4/Pin 5): Receives the feedback voltage from

external resistive divider across the 1.4A regulator output.

Nominal voltage for this pin is 0.8V.

VFB2 (Pin 5/Pin 6): Receives the feedback voltage from

external resistive divider across the 800mA regulator

output. Nominal voltage for this pin is 0.8V.

ITH2 (Pin 6/Pin 7): Error Amplifier Compensation Point for

800mA regulator. The current comparator threshold in-

creases with this control voltage. Nominal voltage range

for this pin is 0V to 1.5V.

RUN2 (Pin 7/Pin 8): Enable for 800mA Regulator. When

at Logic 1, 800mA regulator is running. When at 0V,

800mA regulator is off. When both RUN1 and RUN2 are at

0V, the part is in shutdown.

VIN2 (Pin 8/Pin 9): Supply Pin for P-Channel Switch of

800mA Regulator and Supply for Analog Circuitry.

MODE (Pin 9/Pin 12): Mode Selection Pin. This pin

controls the operation of the device. When the voltage on

the MODE pin is >(VIN – 0.5V), Burst Mode operation is

selected. When the voltage on the MODE pin is <0.5V,

pulse skipping mode is selected. When the MODE pin is

held at VIN/2, forced continuous mode is selected.

SW2 (Pin 10/Pin 13): Switch Node Connection to the

Inductor for the 800mA Regulator. This pin swings from

VIN2 to PGND2.

PGOOD (Pin 11/Pin 14): Power Good Pin. This common

drain-logic output is pulled to GND when the output

voltage of either regulator is – 6% of regulation. If either

RUN1 or RUN2 is low (the respective regulator is in sleep

mode and therefore the output voltage is low), then

PGOOD reflects the regulation of the running regulator.

FREQ (Pin 12/Pin 15): Frequency Set Pin. When FREQ is

at VIN, internal oscillator runs at 1.5MHz. When a resistor

is connected from this pin to ground, the internal oscillator

frequency can be varied from 0.6MHz to 4MHz.

GNDA (Pin 13/Pin 16): Analog Ground Pin for Internal

Analog Circuitry.

PHASE (Pin 14/Pin 17): Selects 800mA regulator switch-

ing phase with respect to 1.4A regulator switching. Set to

VIN, the 1.4A regulator and the 800mA regulator are in

phase. When PHASE is at 0V, the 1.4A regulator and the

800mA regulator are switching 180 degrees out-of-phase.

SW1 (Pin 15/Pin 18): Switch Node Connection to the

Inductor for the 1.4A Regulator. This pin swings from VIN1

to PGND1.

PGND1 (Pin 16/Pin 19): Ground for SW1 N-Channel

Driver.

PGND2, GNDD (Pins 1,10,11,20): TSSOP Package Only.

Ground for SW2 N-channel driver and digital ground for

circuit.

Exposed Pad (Pin 17/Pin 21): PGND2, GNDD. Ground for

SW2 N-channel driver and digital ground for circuit. The

Exposed Pad must be soldered to PCB ground.

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