LTC3889 datasheet(20/118 Pages) AD

20 / 118 page

LTC3888/LTC3888-1/

LTC3888-2

Rev. B

For more information www.analog.com

OPERATION

OVERVIEW

The LTC3888/3888-1/3888-2 is a constant frequency

analog current mode controller for DC/DC step-down

switch-mode applications. It provides up to two inde-

pendent voltage loops (masters) and also contains six

additional slave modulators, affording a wide range of

predetermined PolyPhase configurations.

The device is designed to be used with external power

stages that provide an output current monitor, either as a

voltage or current. This includes higher level integrations

such as non-isolated power blocks. The LTC3888/3888-1/

3888-2 provides a direct interface to the shared tempera-

ture and fault indication bus commonly found on such

power stages, as well as an optional DrMOS gate drive

supply voltage supervisor.

The chip operates from a VIN power supply between 4.5V

and 28.5V. Without any other programming the LTC3888-1

output voltage may be set to any value between 0.4V and

3.45V using an external resistor divider and the factory

EEPROM settings. The LTC3888/3888-2 output voltage can

be set either with resistor configuration pins (see Table 10)

or EEPROM.

The LTC3888/3888-1/3888-2 also features a PMBus

compliant digital interface for monitoring and setting of

important power system parameters, including direct out-

put control using the external resistor divider, if desired.

About This Document

PMBus command pages 0 and 1 control the two volt-

age regulation loops associated with PWM0 and PWM1,

respectively. In this document, these may also be referred

to as masters or master channels. There are often unique IC

pins associated with each of these master channels, such as

ITH0 and ITH1. In cases where discussion applies to both or

either of the master channels, these pin names may appear

without index. Statements herein related to the LTC3888

also apply to the LTC3888-1 and LTC3888-2 unless specifi-

cally noted.

PWM2 to PWM7 are not directly controlled by PMBus oper-

ation, but instead are managed by the master channel that

is assigned to control them. In this document, the modula-

tors associated with PWM2 to PWM7 will be referred to as

slaves or slave channels. Occasionally the term PWM or

channel may apply to any of the eight PWM modulators.

Rail will designate a master channel and the group of slaves

it controls to produce a single output voltage, including

multiple master channels with wire-OR ITH control.

The phrase operating memory or simply RAM refers to

volatile onboard RAM holding PMBus commands during

operation.

PMBus commands in this document are given in all

capital letters with no white space, although hyphens or

underscores may be included. For brevity, the indentify-

ing phrase PMBus command is most often omitted when

this typeface appears. All PMBus commands from 0x00

through 0xFF not listed in Table 7 are implicitly not

supported by the LTC3888. Writing to any command

not listed in this table may result in a CML fault and/or

undesired operation of the part.

MAJOR PRODUCT FEATURES

• Analog and/or Digitally Programmable Output Voltage

with UV/OV Supervisors

• Digitally Programmable Output Current Limit

• Digitally Programmable Input Voltage Supervisor

• Digitally Programmable Switching Frequency

• Digitally Programmable On and Off Delay Times

• Digitally Programmable Soft-Start/Stop

• Digitally Programmable Load Step Emulation

• Operating Condition Telemetry

• Phase-LockedLoopforSynchronousPolyPhaseOperation

• Non-Volatile Configuration Memory

• Optional External Configuration Resistors for Key

Operating Parameters

• Optional Time-Base Interconnect for Synchronization

Between Multiple Controllers

• Fault Event Data Logging

• Capable of Standalone Operation via EEPROM

Configuration

LTC3889 Datasheet(PDF) 20 Page - Analog Devices

LTC3889 Datasheet(HTML) 20 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