bq27621-G1 System-Side Fuel Gauge With Dynamic Voltage Correlation
- SLUSBB3E December 2013 – January 2016
  
  PRODUCTION DATA.

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DATA SHEET

bq27621-G1 System-Side Fuel Gauge With Dynamic Voltage Correlation

1 Features

Single-Cell Li-Ion Battery Fuel Gauge
- Resides on System Board
- Supports Embedded or Removable Batteries
- Powered Directly from Battery with Integrated LDO
Easy To Configure Fuel Gauging Based on the Dynamic Voltage Correlation Algorithm
- Reports Remaining Capacity and State of Charge (SOC) with Smoothing Filter
- Automatically Adjusts for Self-Discharge, Temperature, and Rate Changes
Microcontroller Peripheral Supports:
- 400-kHz I²C Serial Interface
- Configurable SOC Interrupt or
  Battery Low Digital Output Warning
- Internal Temperature Sensor or
  Host Reported Temperature
Support 4.2-V, 4.3-V, and 4.35-V Chemistries
9-pin 1.62 × 1.58 mm, 0.5 mm pitch YZF package

2 Applications

Smartphones, Feature Phones, and Tablets
Digital Still and Video Cameras
Handheld Terminals
MP3 or Multimedia Players

3 Description

The Texas Instruments bq27621-G1 is a minimally configured microcontroller peripheral that provides system-side fuel gauging for single-cell Li-Ion batteries. The device requires very little user configuration and system microcontroller firmware development.

The bq27621-G1 uses the Dynamic Voltage Correlation algorithm for fuel gauging. This process eliminates the need for a sense resistor when calculating remaining battery capacity (mAh), state-of-charge (%), battery voltage (mV), and temperature (°C).

Battery fuel gauging with the bq27621-G1 requires connections only to PACK+ (P+) and PACK– (P–) for a removable battery pack or embedded battery circuit. The tiny 9-pin, 1.62 mm × 1.58 mm, 0.5 mm pitch YZF package is ideal for space-constrained applications.

Device Information⁽¹⁾

PART NUMBER	PACKAGE	BODY SIZE (NOM)
BQ27621-G1	YZF (9)	1.62 mm × 1.58 mm

For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

4 Revision History

Changes from D Revision (December 2014) to E Revision

Changed Pin Configurations and Functions Go
Added Community Resources Go
Changed Mechanical, Packaging, and Orderable Information Go

Changes from C Revision (March 2014) to D Revision

Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go
Changed Typical Application to Simplified Schematic and added 1-µF capacitorGo
Added description for connecting 1-µF capacitor Go
Added information for connecting GPOUT Go

Changes from B Revision (January 2014) to C Revision

Updated BIN pin description Go
Updated GPOUT pin description Go
Changed recommend to requiredGo

5 Device Comparison Table

PART NUMBER	BATTERY TYPE	CHEM_ID ⁽¹⁾	FIRMWARE VERSION ⁽²⁾	PACKAGE ⁽³⁾	COMMUNICATION FORMAT
bq27621YZFR-G1	LiCoO₂ (4.2 V maximum charge)	0x1202	1.05 (0x0105)	CSP-9	I²C
	LiCoO₂ (4.3 V maximum charge)	0x1210
	LiCoO₂ (4.35 V maximum charge)	0x354

(1) See the CHEM_ID subcommand to confirm the battery chemistry type. See Alternate Chemistry Selection to select different chemistries.

(2) See the FW_VERSION subcommand to confirm the firmware version.

(3) For the most current package and ordering information see the Package Option Addendum at the end of this document; or, see the TI website at www.ti.com.

6 Pin Configurations and Functions

Pin Functions

PIN		TYPE⁽¹⁾	DESCRIPTION
NAME	NO.	TYPE⁽¹⁾	DESCRIPTION
BAT	C2, C3	PI, AI	LDO regulator input and battery voltage input. Connect to positive battery connector. For highest accuracy, use a Kelvin connection by directly routing to the PACK+ pin and minimizing current flow through the trace. Connect a capacitor (1 µF) between BAT and V_SS. Place the capacitor close to gauge.
BIN	B1	DI	Battery insertion detection input. If Operation Configuration bit [BIE] = 1 (default), a logic low on the pin is detected as battery insertion. For a removable pack, the BIN pin can be connected to V_SS through a pulldown resistor on the pack, typically the 10-kΩ thermistor; the system board should use a 1.8-MΩ pullup resistor to V_DD to ensure the BIN pin is high when a battery is removed. If the battery is embedded in the system, it is recommended to leave [BIE] = 1 and use a 10-kΩ pulldown resistor from BIN to V_SS. If [BIE] = 0, then the host must inform the gauge of battery insertion and removal with the BAT_INSERT and BAT_REMOVE subcommands. A 10-kΩ pulldown resistor should be placed between BIN and V_SS, even if this pin is unused. NOTE: The BIN pin must not be shorted directly to V_CC or V_SS and any pullup resistor on the BIN pin must be connected only to the bq27621 V_DD and not an external voltage rail.
GPOUT	A1	DO	This open-drain output can be configured to indicate BAT_LOW when the Operation Configuration [BATLOWEN] bit is set. By default [BATLOWEN] is cleared and this pin performs an interrupt function (SOC_INT) by pulsing for specific events, such as a change in State of Charge. Signal polarity for these functions is controlled by the [GPIOPOL] configuration bit. This pin should not be left floating, even if unused, so a 10-kΩ pullup resistor is recommended. If the device is in shutdown mode, then toggling GPOUT will make the gauge exit shutdown. Therefore, it is recommended to connect GPOUT to a GPIO of the host MSU.
SCL	A3	DIO	Slave I²C serial communications clock input line for communication with system (Master). Use with 10-kΩ pullup resistor (typical).
SDA	A2	DIO	Slave I²C serial communications data line for communication with system (Master). Open-drain I/O. Use with 10-kΩ pullup resistor (typical).
VDD	B3	PO	1.8-V Regulator Output. Decouple with 0.47-μF ceramic capacitor to V_SS.
VSS	B2, C1	PI	Ground pins. B2 is the actual device ground pin while C1 is floating internally. Therefore, C1 may be used as a bridge to connect to the board ground plane without requiring a via under the device package. Recommend routing B2 to C1 using a top-layer metal trace on the board. Connect to negative battery connector. For highest accuracy, use a Kelvin connection by directly routing to the PACK– pin and minimizing current flow through the trace.

(1) IO = Digital input-output, IA = Analog input, P = Power connection