LT4293 datasheet(19/44 Pages) AD

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LTC9101-2/LTC9102

Rev. 0

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DEVICE CONFIGURATION

An LTC9101-2 can control between one and four LTC9102.

Each LTC9102 controls 12 power channels. Thus, each

LTC9101-2 can control up to 48 power channels.

As described later in Bus Addressing, each group of four

channels occupies a single I2C address.

Table 4. Device Configuration Options

CFG

[1:0]

NUMBER

OF PORTS

NUM

9102s

I2C

ADDRs

I2C ADDRESS OFFSET OCCUPIED

0 1 2 3 4 5 6 7 8 9 10 11

0 00

1 01

✓ ✓ ✓ ✓ ✓ ✓

2 10

✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

3 11

✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

OPERATING MODES

The LTC9101-2/LTC9102 controls up to 48 indepen-

dent channels, each of which can operate in one of three

modes: manual, semi-auto, or auto. A fourth mode, shut-

down, disables the port (see Table 5).

As described previously, groups of two channels operate

as a 4-pair port. However independent channel controls

do exist. For the remainder of this section the port refers

to both the port and its underlying channels.

Table 5. Operating Modes

MODE

AUTO

MODE

PORT

MODE

DETECT/

CLASS

POWER-UP

AUTOMATIC

THRESHOLD

ASSIGNMENT

Auto

11b

Enabled

at Reset Automatically

Yes

11b

Host

Enabled Automatically

Yes

Semi-Auto

10b

Host

Enabled

Upon

Request

Yes

Manual

01b

Once

Upon

Request

Upon

Request

Yes

Shutdown

00b

Disabled

In manual mode, the port waits for instructions from the

host system before taking any action. It runs a single

detection, or detection and classification cycle when

commanded to by the host, and reports the result in its

Port Status register. The host system can command the

port to apply or remove power at any time.

In semi-auto mode, the port repeatedly attempts to detect

and classify any PD attached to it. It reports the status of

these attempts back to the host, and waits for a command

from the host before applying power to the port. The host

must enable detection and classification.

Auto mode operates the same as semi-auto mode except

it will automatically apply power to the port if detection

and classification are successful. Auto mode will autono-

mously set the 2P Police, 4P Police and 4P ILIM values

based on the Class result. This operational mode may

be entered by tying the PWRMD0 pin to VEE through a

resistor as listed in Table 11, or by changing the oper-

ating mode register to Auto mode. See the Auto Mode

Maximum PSE Power section.

In shutdown mode the port is disabled and will not detect

or power a PD.

Regardless of which mode it is in, the LTC9101-2/

LTC9102 will remove power automatically from any port

or channel, as appropriate, that generates a fault. It will

also automatically remove power from any port/channel

that generates a disconnect event if disconnect detection

is enabled. The host controller may also command the

port to remove power at any time.

Reset and the PWRMD

The initial LTC9101-2/LTC9102 configuration depends

on the state of PWRMD0 during reset. Reset occurs at

power-up, whenever RESET is pulled low, or when the

global Reset All bit is set. Changing the state of PWRMD0

after power-up will not change the port behavior of the

LTC9101-2/LTC9102 until a reset occurs. The PWRMD1

pin is reserved for future use.

With auto mode enabled via RPWRMD, each port will

detect and classify repeatedly until a PD is discovered,

set 2P Police, 4P Police, and DC Disconnect according

to the PSE assigned Class, apply power to valid PDs, and

remove power when a PD is disconnected.

APPLICATIONS INFORMATION

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