USB3500 datasheet(31/45 Pages) MICROCHIP

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DS00002103A-page 31

USB3500

The Chirp K-J-K-J-K-J sequence occurs too slow to propagate through the serial data path, therefore LINESTATE signal

transitions must be used by the Link to step through the Chirp K-J-K-J-K-J state diagram, where “K State” is equivalent

to LINESTATE = K State and “J State” is equivalent to LINESTATE = J State. The Link must employ a counter (Chirp

Count) to count the number of Chirp K and Chirp J states. Note that LINESTATE does not filter the bus signals so the

requirement that a bus state must be “continuously asserted for 2.5µs” must be verified by the Link sampling the LIN-

ESTATE signals.

FIGURE 6-4:

CHIRP K-J-K-J-K-J SEQUENCE DETECTION STATE DIAGRAM

FIGURE 6-5:

HS DETECTION HANDSHAKE TIMING BEHAVIOR (HS MODE)

Detect K?

Start Chirp

K-J-K-J-K-J

detection

INC Chirp

Count

K State

Detect J?

INC Chirp

Count

J State

Chirp Count != 6

& !SE0

Chirp Count

= 0

Chirp Count != 6

& !SE0

Chirp Valid

Chirp

Invalid

SE0

Chirp Count

USB3500 Datasheet(PDF) 31 Page - Microchip Technology