1 Features
1• Supports current sense resistors down to 1 mΩ
• SHA-256 authentication responder for increased
battery pack security
• Two independent ADCs
– Support for simultaneous current and voltage
sampling
– High-accuracy coulomb counter with input
offset error < 1 μV (typical)
• Low-voltage (2 V) operation
• Supports pack-side gauging
• Wide-range current applications (1 mA to > 5 A)
• Active high or low interrupt pin
• Reduced power modes (typical battery pack
operating range conditions)
– Typical SLEEP mode: < 11 μA
– Typical DEEP SLEEP mode: < 9 μA
– Typical OFF mode: < 1.9 μA
• Internal and external temperature sense functions
• 400-kHz I2C bus communications interface for
high-speed programming and data access
• HDQ one-wire for communication with host
• Compact 12-pin DSBGA package (YPH)

2 Applications
• Smart phones
• Digital still and video cameras
• Tablet computing
• Portable and wearable health devices and
portable audio devices

3 Description
The Texas Instruments BQ27Z561 Impedance
Track™ gas gauge solution is a highly integrated,
accurate 1-series cell gas gauge with a flash
programmable custom reduced instruction-set CPU
(RISC) and SHA-256 authentication for Li-Ion and Li-
Polymer battery packs. The 1-series cell capability
includes parallel cells for increased capacity.
The BQ27Z561 gas gauge communicates via I2Ccompatible
and HDQ one-wire interfaces and
includes several key features that can help facilitate
accurate gas gauging applications. Integrated
temperature sense functions (internal and external
options) enable system and battery temperature
measurements. The integrated SHA-256 functionality
helps enable secure identification between systems
and packs. The interrupt function facilitates the
BQ27Z561 device to inform the system when a stateof-
charge (SOC), voltage, or temperature fault
occurs. The low-voltage operation enables the
system to continue monitoring the battery even in
deeply discharged conditions. During low-activity
situations, the device can be set to the low power
coulomb counting (CC) mode, which allows the
device to continue its coulomb counting while
reducing operating current significantly.