BQ76PL455APFCT datasheet(47/125 Pages) TI1

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bq76PL455A

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SLUSCL0A – SEPTEMBER 2016 – REVISED OCTOBER 2016

Product Folder Links: bq76PL455A

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Device Functional Modes (continued)

If you try to send communications to the bottom device before the UART interface is ready, it can get out of sync.

To fix this, send a comm_clear. This is not necessary for parts on the differential interface, since they will re-

synchronize to the bottom chip on every frame. Therefore, only the bottom chip can lose synchronization.

7.4.6 Soft Reset

Setting the SOFT_RESET bit in the DEV_CTRL register will not power down the device, but it will fully reset and

restart the state machine per the sequence in Power-On Reset (POR) or Wakeup. All ICs in the stack above the

reset part will wake up if in SHUTDOWN and reset if awake.

7.4.7 Wakeup Behavior in IDLE Mode

When the bq76PL455A device receives a WAKEUP tone while it is already awake, it performs a reset. The

device requires a series of pulses of the received WAKEUP tone to begin the reset process. Sending the tone

will wake the device if asleep or reset it if idle. The result is that sending the wakeup tone to parts in the stack

can be used to reset them and cause all to enter the IDLE state whether they were previously in SHUTDOWN or

IDLE. This is another method to reset the state of all devices in the stack.

The device will generate a wakeup tone to the other devices north in the chain as a part of the reset sequence.

As a result, each device above the device receiving the wake tone will in turn reset.

7.5 Command and Response Protocol

This protocol enables a single host, such as a microcontroller, to communicate with one or more bq76PL455A

devices. The host initiates every transaction between the host and one or more bq76PL455A devices. The

bq76PL455A will never send data to the host without first receiving a command frame from the host.

NOTE

After each command frame is transmitted, the initiator should always wait for all expected

responses to be returned (or a timeout in case of error) before initiating a new command

frame.

The phrases Write without Response and Write or write are equivalent and synonymous,

unless otherwise noted.

The phrases Write with Response and Read or read are equivalent and synonymous,

unless otherwise noted.

7.5.1 Transaction Frame Description

The transaction frame format includes both Command Frames and Response Frames. There are five field types

used within a transaction frame:

1. Frame Initialization

2. Device Address or Group ID

3. Register Address

4. Data

5. Cyclic Redundancy Check (CRC)

Note that not all byte types are part of every transaction frame.

BQ76PL455APFCT Datasheet(PDF) 47 Page - Texas Instruments

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