LTM4677 datasheet(17/116 Pages) AD

17 / 116 page

LTC3883/LTC3883-1

Rev. F

For more information www.analog.com

OPERATION

OVERVIEW

TheLTC3883isaconstantfrequency,analogcurrentmode

controller for DC/DC step-down applications with a digital

interface. The LTC3883 digital interface is compatible with

PMBus which supports bus speeds of up to 400kHz. A

typical application circuit is shown on the first page of this

data sheet. Major features include:

Programmable Output Voltage

Programmable Input Voltage Comparator

Programmable Current Limit

Programmable Switching Frequency

Programmable OV and UV Comparators

Programmable On and Off Delay Times

Programmable Output Rise/Fall Times

Phase-LockedLoopforSynchronous,PolyphaseOpera-

tion (2, 3, 4 or 6 Phases)

Input and Output Voltage/Current, Temperature and

Duty Cycle Telemetry

Fully Differential Load Sense

Integrated Gate Drivers

Non-Volatile Configuration Memory with ECC

Optional External Configuration Resistors for Key

Operating Parameters

Optional Time-Base Interconnect for Synchronization

Between Multiple Controllers

Fault Logging

WP Pin to Protect Internal Configuration

StandaloneOperationAfterUserFactoryConfiguration

PMBus, 400kHz Compliant Interface

The PMBus interface provides access to important power

management data during system operation including:

Internal Controller Temperature

External System Temperature via Optional Diode Sense

Elements

Average Output Current

Average PWM Duty Cycle

Average Output Voltage

Average Input Voltage

Average Input Current

Configurable, Latched and Unlatched Individual Fault

and Warning Status

Fault reporting and shutdown behavior are fully configu-

rable using the GPIO output (GPIO). A dedicated pin for

ALERT is provided. The shutdown operation also allows

all faults to be individually masked and can be operated

in either unlatched (hiccup) or latched modes.

Individual status commands enable fault reporting over

the serial bus to identify the specific fault event. Fault or

warning detection includes the following:

Output Undervoltage/Overvoltage

Input Undervoltage/Overvoltage

Input and Output Overcurrent

Internal Overtemperature

External Overtemperature

Communication, Memory or Logic (CML) Fault

MAIN CONTROL LOOP

The LTC3883 is a constant frequency, current mode step-

down controller that operates at a user-defined relative

phasing. During normal operation the top MOSFET is

turnedonwhentheclockforthatchannelsetstheRSlatch,

and turned off when the main current comparator, ICMP,

resets the RS latch. The peak inductor current at which

ICMPresetstheRSlatchiscontrolledbythevoltageonthe

ITH pin which is the output of the error amplifier, EA. The

EAnegativeterminalisequaltotheVSENSEvoltagedivided

by5.5(2.75ifrange=1).ThepositiveterminaloftheEAis

connectedtotheoutputofa12-bitDACwithvaluesranging

from 0V to 1.024V. The output voltage, through feedback

of the EA, will be regulated to 5.5 times the DAC output

(2.75 times if range = 1). The DAC value is calculated by

the part to synthesize the users desired output voltage.

The output voltage is programmed by the user either

LTM4677 Datasheet(PDF) 17 Page - Analog Devices

LTM4677 Datasheet(HTML) 17 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL