BQ76PL455APFCT datasheet(43/125 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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7.3.12.10 Communications Timeout Counters

Check the communication timeout counters by setting and reading the 24 most-significant bits of the timeout

counter using COMM_TIM_CNT. A 4-kHz clock source drives the timeout counter. To aid this testing,

CCNT_RST_OFF may be set so the communication sent to either set or monitor the counter does not reset the

counter. The counter value may be set using COMM_TIM_CNT to enable faster testing of long periods. The bits

that are not accessible are set to '1' by writing to this register, to test the counter rollovers quickly.

7.3.13 Built-in-Test Functions

To access the built-in-test functions, set bits in the various registers. The identification of these bits are in the

descriptions of the appropriate registers and their bits in Register Details.

7.3.13.1 Safety Manual and FMEDA

The Safety Manual for bq76PL455A-Q1 (SLUUB67) is available on ti.com. Please contact your TI Sales

Associate or Applications Engineer for the bq76PL455A-Q1 FMEDA (SLUUB93).

7.4 Device Functional Modes

The bq76PL455A device has three power states (modes):

•

SHUTDOWN (sleep)—The lowest power state used for long periods of inactivity to extend battery life.

•

IDLE—The default condition when awake and ready to receive and execute commands.

•

ACTIVE—The highest power state while communicating; that is, IDLE + communications activity.

7.4.1 SHUTDOWN

SHUTDOWN is the lowest power state available in the part. In this state, power is off and monitoring disabled for

most internal blocks. Typically, SHUTDOWN is for long periods of inactivity when the battery is not being

charged or discharged. The part must receive a high signal on the WAKEUP pin or a WAKEUP tone through the

vertical communications bus to transition to the IDLE state.

To enter SHUTDOWN, remove external voltage sources of VP, VDIG, and all input voltage sources to AUX pins

and other I/O pins. VIO can remain while in SHUTDOWN mode and GPIO can remain if based on VIO. While in

SHUTDOWN mode, VP and VDIG must remain off or be disabled to avoid back powering the bq76PL455A

through internal ESD structures. When VIO is lowered, the bq76PL455A will immediately go into reset. Holding

VIO for longer than VIOSD_DLY MAX will cause the device to enter SHUTDOWN mode.

The WAKEUP pin must be held in the low state to allow the device to enter and remain in the SHUTDOWN state

(setting the pin low does not place the device in SHUTDOWN). If the WAKEUP pin remains in the high state, the

device will cycle off and immediately back on. Operation is unpredictable if the WAKEUP pin floats, so take care

to keep this pin in a defined state. This is not harmful to the device, but may not provide the expected behavior in

the system.

If the NPN circuit is not used (external supply), VP and VDIG should turn off immediately after entering shutdown

mode. Lowering VP and VDIG will also put the device in SHUTDOWN mode.

The part will enter SHUTDOWN when any of the following conditions occur:

•

The user requested SHUTDOWN through a command by asserting DEV_CTRL[PWRDN], usually with a

broadcast form of the command. The WAKEUP pin on the base bq76PL455A must remain in the low state.

•

There was a communications timeout caused by the timer set in register CTO[COMM_PD_PER] due to:

–

No valid frames (packets) received in the set period, <OR>

–

TSTCONFIG[CCNT_RST_OFF] is set and the timer expired whether valid frames were received or not,

usually as a part of BIST.

•

TSTCONFIG[VDIG_TEST] was set at some time since the last SHUTDOWN <AND> VDIG dropped below its

SHUTDOWN threshold (DDIEPOR). Once set, subsequently clearing TSTCONFIG[VDIG_TEST] will not

disable this control even though the bit will read 0. It will not disable until the device enters shutdown.

•

One of the two thermal shutdown (TSD) circuits sensed an overtemperature condition (there is one sensor on

each die that operates separately, with separate register flag indicators).

•

VIO was below its VIOPOR threshold for longer than VIOSD_DLY.

•

V5VAO was below the V5VAOSD POR threshold.

BQ76PL455APFCT Datasheet(PDF) 43 Page - Texas Instruments

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