LTC7813 datasheet(9/28 Pages) AD

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LTC7878

Rev. 0

For more information www.analog.com

PIN FUNCTIONS

PHASMD (Pin 18): Phase Mode Program Pin. This pin

sets the phase relationship between the internal oscillator

clock and the output clock on the CLKOUT pin. Tie this

pin to SGND sets 180-degree phase-shift, float this pin

sets 120-degree phase-shift and tie this pin to INTVCC

sets 90-degree phase-shift. See Applications Information

section for details.

FREQ (Pin 19): Frequency Set Pin. A resistor between

this pin and SGND sets the switching frequency. This pin

sources 10µA current.

CLKOUT (Pin 20): Clock Output Pin. Use this pin to syn-

chronize the switching frequency of multiple LTC7878

ICs for parallel operations. Signal swings is from INTVCC

to ground.

SYNC (Pin 21): Switching Frequency Synchronization Pin.

Applying an external clock between 100kHz to 600kHz

will cause the switching frequency to synchronize to the

external clock. If SYNC is low, a resistor from the FREQ

pin to SGND sets the default switching frequency. This

pin has a 500k internal resistor to ground.

SETCUR (Pin 22): Average Current Regulation Pin. A

resistor from this pin to SGND sets the maximum aver-

age input or output current sensed by the CSP and CSN

pins. This pin sources 15μA current.

CSP, CSN (Pins 23, 24): Average Current Sensing Pins.

The positive/negative inputs of the internal rail-to-rail

average current sense amplifier.

VOUT (Pin 25): Floating Driver Bias Pin in Boost Mode.

Supply the bias current for the BOOST1 to SW1 driver

circuitry when VOUT is much higher than VIN.

NC (Pin 26): No Connect Pin.

ISNSN (Pin 27): Negative Current Sense Comparator

Inputs. The negative input of the current comparator is

normally connected to the DCR sensing network.

ISNSP (Pin 28): Positive Current Sense Comparator

Inputs. This pin must be Kelvin connected to the inductor

on the switching node SW1.

ISNSD (Pin 29): DC Current Sense Comparator Inputs.

These inputs amplify the DC portion of the sensed current

signal to the IC’s current comparator. If no use in large

DCR applications, short ISNSD pin to ISNSP pin locally.

See Applications Information section for details.

SGND (Exposed Pad Pin 33): Signal Ground Pin. Must be

soldered to PCB ground for rated thermal performance.

All small signal components e.g., INTVCC, SS, ITH, VFB,

FREQ, etc. should be connected here.

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