LTC3371 datasheet(13/26 Pages) LINER

13 / 26 page

LTC3371

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For more information www.linear.com/LTC3371

PIN FUNCTIONS (QFN/TSSOP)

VINE (Pin 22/Pin 26): Power Stage E Input Supply. Bypass

to GND with a 10µF or larger ceramic capacitor.

SWE(Pin23/Pin27):PowerStageESwitchNode.External

inductor connects to this pin.

SWF(Pin24/Pin28):PowerStageFSwitchNode.External

inductor connects to this pin.

VINF (Pin 25/Pin 29): Power Stage F Input Supply. Bypass

to GND with a 10µF or larger ceramic capacitor.

VING(Pin26/Pin30):PowerStageGInputSupply.Bypass

to GND with a 10µF or larger ceramic capacitor.

SWG(Pin27/Pin31):PowerStageGSwitchNode.External

inductor connects to this pin.

SWH(Pin28/Pin32):PowerStageHSwitchNode.External

inductor connects to this pin.

VINH(Pin29/Pin33/):PowerStageHInputSupply.Bypass

to GND with a 10µF or larger ceramic capacitor.

FB4 (Pin 30/Pin 34): Buck Regulator 4 Feedback Pin.

Receives feedback by a resistor divider connected across

the output.

EN4 (Pin 31/Pin 35): Buck Regulator 4 Enable Input.

Active high. Do not float.

RST4 (Pin 32/Pin 36): Buck Regulator 4 Reset Pin

(Active Low). Open-drain output. When Buck 4 is disabled

or its regulated output voltage is more than 5% below its

programmed level, this pin is driven low. Assertion delay

is scaled by the CT capacitor.

RT (Pin 33/Pin 37): Oscillator Frequency Pin. This pin

provides two modes of setting the switching frequency.

ConnectingaresistorfromRTtogroundsetstheswitching

frequency based on the resistor value. If RT is tied to VCC

the internal 2MHz oscillator is used. Do not float.

PLL/MODE (Pin 34/Pin 38): Oscillator Synchronization

and Buck Mode Select Pin. Driving PLL/MODE with an

external clock signal synchronizes all switches to the

applied frequency, and the buck converters operate in

forced continuous mode. The slope compensation is au-

tomatically adapted to the external clock frequency. The

absence of an external clock signal enables the frequency

programmed by the RT pin. When not synchronizing to

an external clock this input determines how the LTC3371

operates at light loads. Pulling this pin to ground selects

Burst Mode operation. Tying this pin to VCC invokes forced

continuous mode operation. Do not float.

VCC (Pin 35/Pin 1): Internal Bias Supply. Bypass to GND

with a 10µF or larger ceramic capacitor.

TEMP (Pin 36/Pin 2): Temperature Indication Pin. TEMP

outputs a voltage of 220mV (typical) at 25°C. The TEMP

voltage increases by 7mV/°C (typical) at higher tempera-

tures giving an external indication of the LTC3371 internal

die temperature.

RST1 (Pin 37/Pin 3): Buck Regulator 1 Reset Pin (Active

Low). Open-drain output. When Buck 1 is disabled or

its regulated output voltage is more than 2% below its

programmed level, this pin is driven low. Assertion delay

is scaled by the CT capacitor.

EN1 (Pin 38/Pin 4): Buck Regulator 1 Enable Input. Active

high. Do not float.

GND (Exposed Pad Pin 39): Ground. The exposed pad

must be connected to a continuous printed circuit board

ground plane directly under the LTC3371.

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