LTC3300-1 Datasheet, PDF(13/44 Page) Linear Technology – High Effciency Bidirectional Multicell Battery Balancer

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LTC3300-1 Datasheet, PDF (13/44 Pages) Linear Technology – High Effciency Bidirectional Multicell Battery Balancer

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TIMING DIAGRAM

SCKI

Timing Diagram of the Serial Interface

LTC3300-1

SDI

CSBI

SDO

33001 TD

OPERATION

Battery Management System (BMS)

The LTC3300-1 multicell battery cell balancer is a key

component in a high performance battery management

system (BMS) for series-connected Li-Ion cells. It is de-

signed to operate in conjunction with a monitor, a charger,

and a microprocessor or microcontroller (see Figure 1).

The function of the balancer is to efficiently transfer charge

to/from a given out-of-balance cell in the stack from/to

a larger group of neighboring cells (which includes that

individual cell) in order to bring that cell into voltage or

capacity balance with its neighboring cells. Ideally, this

charge would always be transferred directly from/to the

entire stack, but this is impractical for voltage reasons

when the number of cells in the overall stack is large. The

LTC3300-1 is designed to interface to a group of up to 6

series cells, so the number of LTC3300-1 ICs required

to balance a series stack of N cells is N/6 rounded up to

the nearest integer, with no limitation imposed on how

large N can be. For connecting an individual LTC3300-1

in the stack to fewer than 6 cells, refer to the Applications

Information section.

Because the balancing function entails switching large

(multiampere) currents between cells, precision voltage

monitoring in the BMS is better served by a dedicated

monitor component such as the LTC6803-1 or one of its

family of parts. The LTC6803-1 provides for high precision

A/D monitoring of up to 12 series cells. The only voltage

monitoring provided by the LTC3300-1 is a coarse âout-

of-rangeâ overvoltage and undervoltage cell balancing

disqualification, which provides a safety shutoff in the

event Kelvin sensing to the monitor component is lost.

In the process of bringing the cells into balance, the over-

all stack is slightly discharged. The charger component

provides a means for net charging of the entire stack from

an alternate power source.

The last component in the BMS is a microprocessor/

microcontroller which communicates directly with the

balancer, monitor, and charger to receive voltage, current,

and temperature information and to implement a balanc-

ing algorithm.

For more information www.linear.com/product/LTC3300-1

33001f

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