VC5

Vss

SRP

SRN

CHG

DSG

TS

VTB

CTRD

CTRC

LD

VDD

VC5

Vss

SRP

SRN

CHGU

DSG

TS

VTB

LD

VDD

bq77094/5

bq77094/5

PACK+

PACK-

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

bq77904, bq77905

SLUSCM3E – JUNE 2016 – REVISED MARCH 2017

bq77905, bq77904 3-5S Ultra Low-Power Voltage, Current, Temperature,

and Open Wire Stackable Lithium-ion Battery Protector

1

1 Features

1

•

Normal Mode: 6 µA (bq77904/bq77905)

•

Full suite of voltage, current and temperature

protections

•

Scalable cell count from 3 S to 20 S or more

•

Voltage Protection (Accuracy ±10 mV)

–

Overvoltage: 3 V to 4.575 V

–

Undervoltage: 1.2 V to 3 V

•

Open Cell and Open Wire Detection (OW)

•

Current Protection

–

Overcurrent Discharge 1: –10 mV to –85 mV

–

Overcurrent Discharge 2: –20 mV to 170 mV

–

Short Circuit Discharge: –40 mV to 340 mV

–

Accuracy ±20% for

≤ 20 mV, ±30% for > 20

mV across full temperature

•

Temperature Protection

–

Overtemperature Charge: 45°C or 50°C

–

Overtemperature Discharge: 65°C or 70°C

–

Undertemperature Charge: –5°C or 0°C

–

Undertemperature Discharge: –20°C or –10°C

•

Additional Features

–

Independent Charge (CHG) and Discharge

(DSG) FET Drivers

–

36-V Absolute Maximum Rating Per Cell Input

–

Built-In-Self-Test Functions For High Reliability

•

Shutdown Mode: 0.5 µA Maximum

2 Applications

•

Power Tools, Garden Tools

•

Start-Stop Battery Packs

•

Lead-Acid (PbA) Replacement Batteries

•

Light Electric Vehicles

•

Energy Storage Systems, Uninterruptible Power

Supplies (UPS)

•

10.8 V to 72 V Packs

3 Description

The bq77904 and bq77905 devices are low-power

battery pack protectors that implement a suite of

voltage, current, and temperature protections without

microcontroller (MCU) control. The device's stackable

interface provides simple scaling to support battery

cell applications from 3 S to 20 S or more. Protection

thresholds and delays are factory-programmed and

available in a variety of configurations. Separate

overtemperature and undertemperature thresholds for

discharge (OTD and UTD) and charge (OTC and

UTC) are provided for added flexibility.

The device achieves pack protection through the

integrated independent CHG and DSG low-side

NMOS FET drivers, which may be disabled through

two control pins. These control pins may also be used

to achieve cell protection solutions for higher series

(6 S and beyond) in a simple and economical

manner. To do this, simply cascade a higher device

CHG and DSG outputs to the immediate lower device

control pins. For reduced component count, all

protection faults use internal delay timers.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

bq77904

TSSOP (20)

6.50 mm × 4.40 mm

bq77905

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Simplified Schematic