UPD360 datasheet(107/221 Pages) MICROCHIP

107 / 221 page

 2016-2017 Microchip Technology Inc.

DS00002084C-page 107

UPD360

10.0

BASEBAND CC INTERFACE (BCI)

The device integrates a Baseband CC Interface (BCI) to facilitate USB Power Delivery communication. This module

bridges between the PD MAC/BMC and the analog front end. Baseband communication is initiated by the PD MAC,

which interfaces to the BCI. The BCI implements the digital functions required to control TX baseband components.

10.1

Baseband TX Data-flow

The key responsibility of the BCI is to generate the wave form required for baseband communication. To this end, the

BMC has a group of eight registers that define the Lo-Hi and Hi-Lo transitions for the generated BMC signal.

When instructed to transition from Lo-Hi, the BCI steps through all BB TX Risex Registers (BB_RX_RISEx). Likewise

when instructed to transition from Hi-Lo, the BCI steps through all BB TX Fallx Registers (BB_TX_FALLx). The BCI

always presents the value at BB_TX_RISE0 or BB_RX_FALL0 first.

APPLICATION NOTE: The user may replicate values if it is desired to use less than twelve unique values for this

purpose.

The following steps should be followed to program the BCI for data transmission:

Software programs the BB TX Risex Registers (BB_RX_RISEx) and BB TX Fallx Registers (BB_TX_FALLx) to

define the slew rate for rising and falling transitions.

Software enables the PD MAC.

The PD MAC initiates, either via firmware, or autonomously via a data transmission (GoodCRC). The PD MAC

instructs the BCI to take the BB TX analog components out of power-down.

After a sufficient time elapses for the analog to power up, the PD MAC begins transmission to the BMC encoder

which drives the analog components.

If the MAC requests a rising transition, the BCI steps through the BB TX Risex Registers (BB_RX_RISEx). Alter-

natively, if the MAC requests a falling transition, the BCI steps through the BB TX Fallx Registers (BB_TX_-

FALLx).

When the PD MAC indicates the transmission has completed, the BCI powers down the TX analog components.

10.2

Baseband RX Data-flow

Baseband RX data is received by the BCI from the RX analog front end where it is compared to a threshold programmed

by software. The CC RX DAC Value defines the trip point used for reception of baseband data. The field shall be pro-

grammed to be 175 mV below the RX Eye center, as defined in the PD Specification for the mode in which the device

is operating (Sourcing Power, Sinking Power, Power Neutral).

In order to program the required trip point, the RX DAC Enable bit must be set and the CC RX DAC Value field in the

CC RX DAC Control Register (CC_RX_DAC_CTL) must be programmed.

UPD360 датащи(PDF) 107 Page - Microchip Technology