米6体育平台手机版

ZHCSGI9 August 2017

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机械数据 (封装 | 引脚)

PW|14
- MPDS360A

散热焊盘机械数据 (封装 | 引脚)

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7 Detailed Description

7.1 Overview

The bq34210-Q1 incorporates fuel gauging and an End-of-Service (EOS) Determination function for use in 1-series cell packs with support for multiple battery chemistries, including Lithium-Ion (Li-Ion), Lithium Iron Phosphate (LiFePO4), and Nickel Metal Hydride (NiMH). The gas gauging function uses Compensated End-of-Discharge Voltage (CEDV) technology to accurately predict the battery capacity and other operational characteristics of the battery, and can be interrogated by a host processor to provide cell information, such as remaining capacity, full charge capacity, and average current.

See the bq34210-Q1 Technical Reference Manual (TRM, SLUUBE8) for further details.

NOTE

The following formatting conventions are used in this document:

Commands: italics with parentheses() and no breaking spaces, for example, Control().

Data Flash: italics, bold, and breaking spaces, for example, Design Capacity.

Register bits and flags: italics with brackets [ ], for example, [TDA]

Data flash bits: italics, bold, and brackets [ ], for example, [LED1]

Modes and states: ALL CAPITALS, for example, UNSEALED mode.

7.2 Functional Block Diagram

7.3 Feature Description

Information is accessed through a series of commands called Standard Commands. The Extended Commands set provides additional capabilities. Both sets of commands, indicated by the general format Command(), are used to read and write information in the control and status registers, as well as its data locations. Commands are sent from the system to the gauge via the I²C serial communications engine, and can be executed during application development, system manufacture, or end-equipment operation.

The integrated End-of-Service (EOS) Determination function is specifically intended for applications where the battery is rarely discharged, such as in eCall systems, uninterruptible power supplies (UPS), enterprise server backup systems, and telecommunications backup modules. In such systems, the battery may remain in a fully (or near-fully) charged state for much of its lifetime, with it rarely or never undergoing a significant discharge. If the health of the battery in such a system is not monitored regularly, then it may degrade beyond the level required for a system backup/discharge event, and thus fail precisely at the time when it is needed most.

The EOS Determination function monitors the health of the battery through the use of infrequent learning phases, which involve a controlled discharge of ~1% capacity, and provides an alert to the system when the battery is approaching the end of its usable service. By coordinating battery charging with the learning phases, the battery capacity available to the system can be maintained above a preselected level, which helps to avoid compromising the battery's ability to support a system discharge event.

NOTE

The following sections offer a brief overview of the content available in the bq34210-Q1 Technical Reference Manual (TRM, SLUUBE8), and should be used only as references to the respective sections in the TRM for full details.

7.3.1 Device Configuration

The device must select the correct CEDV profile, interrupt functions (enables, levels), and more during its initial configuration setup. The bq34210-Q1 includes two CEDV profiles (XYZ and ABC), which are stored in ROM. If neither of these profiles matches the battery used, a new configuration must be stored in RAM using Texas Instruments tools (see Getting Started for more details). Changing batteries also requires a new initialization of the configuration settings. This enables the device to be reconfigured for different battery chemistries or capacities through the host. If another battery is chosen, the parameters must be generated using TI's web-based tool, Gauge Parameter Calculator for CEDV Gauges (GAUGEPARCAL). The TRM provides further details.

7.3.2 ALERT Interrupt and SHUTDOWN Wake-up

The interrupt function of the ALERT pin enables the bq34210-Q1 to communicate with the main system.

Even if the host is not using the ALERT functionality, it is recommended that ALERT be connected to a GPIO of the host so that in cases where the device is in SHUTDOWN, toggling ALERT can wake up the gauge from the SHUTDOWN state.

7.3.3 Voltage Measurement and Calibration

Voltage measurements and calibration are done automatically. The Battery Management Studio bqStudio tool aids in setting up this function to match system requirements.

7.3.4 Temperature Measurement

The device can be configured to use an external thermistor (103AT type) to measure temperature or use its internal temperature sensor.

7.3.5 Charging and Termination

The bq34210-Q1 monitors charging and detects termination. The termination works for Li-Ion, LiFePO4, and NiMH systems.

7.3.6 Accumulated Charge Measurement

The device measures the accumulated charge and reports the duration over which that charge was accumulated. The AccumulatedCharge() and AccumulatedChargeTime() registers can be used to send an alert to the host when a certain threshold is achieved.

7.3.7 Gas Gauging

The bq34210-Q1 device features the Compensated End-of-Discharge Voltage (CEDV) gauging algorithm. This algorithm uses the accumulated measured quantities for charge and discharge in addition to estimating self-discharge of the battery. Registers including Remaining Capacity, Design Capacity, Full Charge Capacity, and Discharge Count Register (DCR) are used in this algorithm.

7.3.8 Battery Condition Warnings

Battery status indications are stored in registers and are used by the device to take action and provide warnings. Examples of indicator parameters are state-of-charge low detection, overtemperature-in-charge, and battery voltage high/low.

7.3.9 Configuration Update

CONFIG UPDATE mode is used when updating the configuration data of the fuel gauge. Gauging is disabled during this mode. This is required when a new battery is inserted.

7.3.10 End-Of-Service Determination

The bq34210-Q1 device incorporates the End-of-Service (EOS) Determination function to calculate the end of useful service of the battery and to provide alerts based on this detection. Learning phases are used to gather information about the present state of the battery through its cell resistance.

7.3.11 Battery Level Threshold

The Battery Level Threshold (BLT) feature indicates when the SOC of a battery pack has depleted to a certain value stored in a register. The thresholds can be set for the charge and discharge conditions.

7.3.12 Communications

7.3.12.1 I²C Interface

The slave-only fuel gauge supports the standard I²C read, incremental read, quick read, one-byte write, and incremental write functions. The 7-bit device address (ADDR) is the most significant 7 bits of the hex address and is fixed as 1010101. The first 8 bits of the I²C protocol are, therefore, 0xAA or 0xAB for write or read, respectively.

7.3.12.2 I²C Time Out

The I²C engine releases SDA and SCL if the I²C bus is held low for 2 seconds. If the fuel gauge is holding the lines, releasing them frees them for the master to drive the lines. If an external condition is holding either of the lines low, the I²C engine enters the low-power SLEEP mode.

7.3.12.3 I²C Command Waiting Time

To ensure proper operation at 400 kHz, a t_(BUF) ≥ 66 μs bus-free waiting time must be inserted between all packets addressed to the fuel gauge. In addition, if the SCL clock frequency (f_SCL) is > 100 kHz, use individual 1-byte write commands for proper data flow control.

7.3.12.4 I²C Clock Stretching

A clock stretch can occur during all modes of fuel gauge operation. In SLEEP mode, a short ≤ 100-µs clock stretch occurs on all I²C traffic as the device must wake up to process the packet. In the other modes (INITIALIZATION, NORMAL), a ≤ 4-ms clock stretching period may occur within packets addressed for the fuel gauge as the I²C interface performs normal data flow control.

7.3.13 Additional Data Memory Parameter Descriptions

The calibration method requires a correction due to offset errors, using a number of samples to get a statistical average for the golden image.

7.4 Device Functional Modes

To minimize power consumption, the fuel gauge has four power modes:

INITIALIZATION
NORMAL
SLEEP
SHUTDOWN

The fuel gauge passes automatically between these modes, depending upon the occurrence of specific events, though a system processor can initiate some of these modes directly. The bq34210-Q1 Technical Reference Manual (SLUUBE8) provides more details.

7.4.1 INITIALIZATION Mode

The bq34210-Q1 enters INITIALIZATION mode at power up. This mode prepares the device to enter NORMAL mode through its internal power-on reset sequence. When the reset sequence is complete, the device automatically moves to NORMAL mode.

7.4.2 NORMAL Mode

The bq34210 NORMAL mode is entered from INITIALIZATION mode when the power-on reset is complete. When the charge and discharge currents are above the programmable level, the device will remain in NORMAL mode. If the measured currents are below the programmable level, SLEEP mode is entered. Once the currents increase above the threshold, the device will reenter NORMAL mode. The device will enter SHUTDOWN mode through a command sequence.

7.4.3 SLEEP Mode

SLEEP mode is entered from NORMAL mode if enabled and the current is below a programmable level. Once the current increases above that level, NORMAL mode is reentered.

7.4.4 SHUTDOWN Mode

The lowest power mode is SHUTDOWN mode. In this mode, the device is completely off. It is entered through an I²C command. Exiting from SHUTDOWN mode can be done by battery removal and replacement or through the ALERT pin. Pulling ALERT low for t_SHUP and then above V_IH(OD) enables the bq34210 device to go through its standard power-up sequence (into INITIALIZATION mode).