LT8697 datasheet(30/40 Pages) AD

30 / 40 page

LT8698S/LT8698S-1

Rev. A

For more information www.analog.com

APPLICATIONS INFORMATION

having been selected nor a USB connection made, select

2 cannot return a valid response. In this case, select state

2 indicates an invalid response with a 9ms oscillation on

the STATUS pin. Selecting any state other than select state

0, 1, or 2 clears the CDP connection information from the

internal register.

Refer to Figure 13 and Figure 14 for a timing diagram

of a successful CDP handshake sequence. Note, the

LT8698S will report an unsuccessful CDP session if a

portable device takes longer than 1 second to enumerate

and connect. Select 2 accuracy can depend on a portable

device's compliance to the USB specification, state, and

configuration.

SDP Modes of Operation

The LT8698S implements the USB BC 1.2 Specification

Standard Downstream Port (SDP). This is the most com-

mon USB host configuration and allows a device to draw

up to 500mA of charge current. Select state 3, 4, 5, 18,

19 and 20 activate various versions of the LT8698S SDP

modes. What is common to these states is the termination

pull-down resistors that LT8698S places from D+ and D–

to ground. The SDP modes differ by allowing the user to

open or close the dataline switches, to power VBUS, not

power VBUS or discharge VBUS. See Table 6.

For SDP modes of operation with VBUS in regulation

(select states 4 and 19), STATUS high indicates IBUS load

>120mA and STATUS low indicates IBUS load <100mA.

For SDP modes of operation with VBUS disabled (select

states 3 and 18), STATUS high indicates VBUS < 0.85V

and STATUS low indicates VBUS > 0.85V. For SDP modes

of operation with VBUS being discharged (select states 5

and 20), the STATUS pin indicates the discharge state.

Refer to the Bus Reset Modes of Operation section for

more details.

Data Pass Through Modes of Operation

The LT8698S implements several modes of operation that

close the dataline switches to allow data to pass through

the LT8698S but otherwise do not tie any resistor termi-

nation to the datalines. Select states 9, 10 and 11 activate

various versions of the data pass through modes. What is

common to these states is that the dataline switches are

closed. These data pass through modes differ by allow-

ing the user to power VBUS, not power VBUS or discharge

VBUS. See Table 6.

For data pass through mode of operation with VBUS in reg-

ulation (select state 10), STATUS high indicates IBUS load

> 120mA and STATUS low indicates IBUS load <100mA.

For data pass through mode of operation with VBUS dis-

abled (select state 9), STATUS high indicates VBUS < 0.5V

and STATUS low indicates VBUS > 0.85V. For data pass

through mode of operation with VBUS being discharged

(select state 11), the STATUS pin indicates the discharge

state. Refer to the Bus Reset Modes of Operation section

for more details.

Charger Modes of Operation

The LT8698S implements several common USB char-

ger profiles. These charger profiles have the datalines

switches open and do not allow data communication.

These charger profiles allow compatible devices to draw

IBUS current in excess of the 0.5A that a standard USB

socket allows. The LT8698S includes the USB BC 1.2

Dedicated Charger Port (DCP) profile and vendor propri-

etary 2.0A, 2.4A, 2.1A and 1.0A profiles. These profiles

tie various combinations of resistor dividers from VBUS to

the datalines or short the datalines together. See Table 6.

Select state 21 accesses the USB BC 1.2 DCP profile. This

mode of operation connects a 100Ω short from D+ to D–

and a 500kΩ resistor from D+ and D– to ground. This state

allows compatible devices to draw 1.5A of charge current.

Select state 22 accesses the 2.0A vendor charger profile.

This mode of operation connects a 100Ω short from D+

to D– and a 1.25V resistive divider from VBUS to D+ and

D–. This state allows compatible devices to draw 2.0A of

charge current.

Select State 24 accesses the 2.4A vendor charger profile.

This mode of operation connects two separate 2.7V resis-

tive dividers from VBUS to D+ and D–. This state allows

compatible devices to draw 2.4A of charge current.

Select State 25 accesses the 2.1A vendor charger profile.

This mode of operation connects a 2.7V resistive divider

from VBUS to D+ and a 2.0V resistive divider from VBUS

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