LTM4677 datasheet(35/110 Pages) AD

35 / 110 page

LTC3888-1

Rev. 0

For more information www.analog.com

OPERATION

SERIAL INTERFACE

The LTC3888-1 has a PMBus compliant serial interface

that can operate at any frequency between 10kHz and

400kHz. The LTC3888-1 is a bus slave device that commu-

nicates bidirectionally with a host (master) using standard

PMBus protocols. The Timing Diagram found earlier in

this document, along with related Electrical Characteristics

table entries, define the timing relationships of the SDA

and SCL bus signals. SDA and SCL must be high when

the bus is not in use. External pull-up resistors or current

sources are required on these lines.

PMBus, an incremental extension of the SMBus standard,

offers more robust operation than a 2-wire I2C interface.

In addition to adding a protocol layer to improve interop-

erability and facilitate reuse, PMBus supports bus time-

out recovery for system reliability, optional packet error

checking (PEC) to ensure data integrity, and peripheral

hardware alerts for system fault management. In general,

a programmable device capable of functioning as an I2C

bus master can be configured for PMBus management

with little or no change to hardware. However, not all

I2C controllers support repeat start (restart) required for

PMBus reads.

For a description of the minor extensions and exceptions

PMBus makes to the SMBus standard, refer to PMBus

Specification Part I Revision 1.2 Paragraph 5 on Transport.

For a description of the differences between SMBus

and I2C, refer to System Management Bus (SMBus)

Specification Version 2.0 Appendix B on Differences

Between SMBus and I2C.

The user is encouraged to reference Part I of the latest

PMBus Power System Management Protocol Specification

to understand how to interface the LTC3888-1 to a PMBus

system. This specification can be found at http://www.

pmbus.org/specs.html.

The LTC3888-1 uses the following standard serial

interface protocols defined in the SMBus and PMBus

specifications:

• Quick Command

• Send Byte

• Write Byte

• Write Word

• Read Byte

• Read Word

• Block Read

• Block Write – Block Read Process Call

• Alert Response Address

The LTC3888-1 does not require PEC for Quick Command

under any circumstances. The LTC3888-1 also supports

group command protocol (GCP) as required by PMBus

specification Part I, section 5.2.3. GCP is used to send

commands to more than one PMBus device in one contin-

uous transmission. It should not be used with commands

that require the receiving device to respond with data,

such as a STATUS_BYTE command. Refer to Part I of the

PMBus specification for additional details on using GCP.

All LTC3888-1 message transmission types allow

for packet error checking. The later section on Serial

Communication Errors provides more detail on packet

error checking.

Figure 5 to Figure 21 illustrate these protocols. Figure 4

provides a key to the protocol diagrams. Not all proto-

col elements will be present in every data packet. For

instance, not all packets are required to include the packet

error code. A number shown above a field in these dia-

grams indicates the number of bits in that field. All data

transfers are initiated by the present bus master regard-

less of how many times data direction flow may change

during the subsequent transmission. The LTC3888-1

never functions as a bus master.

This device includes handshaking features to ensure

robust system communication. Please refer to the PMBus

Communication and Command Processing section in

Applications Information for more details.

LTM4677 Datasheet(PDF) 35 Page - Analog Devices

LTM4677 Datasheet(HTML) 35 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