MAX17043 Просмотр технического описания (PDF) - Maxim Integrated

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MAX17043

1-Cell/2-Cell Fuel Gauge with ModelGauge and Low-Battery Alert

Maxim Integrated 

MAX17043/MAX17044

1-Cell/2-Cell Fuel Gauge with

ModelGauge and Low-Battery Alert

IC Power-Up

When the battery is first inserted into the system, there is

no previous knowledge about the battery’s SOC. The IC

assumes that the battery has been in a relaxed state for

the previous 30min. The first A/D voltage measurement is

translated into a best “first guess” for the SOC. Initial error

caused by the battery not being in a relaxed state fades

over time, regardless of cell loading following this initial

conversion. Because the SOC determination is conver-

gent rather than divergent (as in a coulomb counter), this

initial error does not have a longlasting impact.

Quick-Start

A quick-start allows the MAX17043/MAX17044 to restart

fuel-gauge calculations in the same manner as initial pow-

er-up of the IC. For example, if an application’s power-up

sequence is exceedingly noisy such that excess error

is introduced into the IC’s “first guess” of SOC, the host

can issue a quick-start to reduce the error. A quick-start

is initiated by a rising edge on the QSTRT pin, or through

software by writing 4000h to the MODE register.

ALERT Interrupt

The MAX17043/MAX17044 have an interrupt feature that

alerts a host microprocessor whenever the cell’s state of

charge, as defined by the SOC register, falls below a pre-

defined alert threshold set at address 0Dh of the CONFIG

register.

When an alert is triggered, the IC drives the ALRT pin to

logic-low and sets the ALRT bit in the CONFIG register

to logic 1. The ALRT pin remains logic-low until the host

software writes the ALRT bit to logic 0 to clear the inter-

rupt. Clearing the ALRT bit while SOC is below the alert

threshold does not generate another interrupt. The SOC

register must first rise above and then fall below the alert

threshold value before another interrupt is generated.

Note that the alert function is not disabled at IC powerup.

If the first SOC calculation is below the threshold setting,

an interrupt is generated. Entering Sleep mode does not

clear the interrupt.

Sleep Mode

Holding both SDA and SCL logic-low forces the MAX17043/

MAX17044 into Sleep mode. While in Sleep mode, all IC

operations are halted and power drain of the IC is greatly

reduced. After exiting Sleep mode, fuel-gauge operation

continues from the point it was halted. SDA and SCL must

be held low for at least 2.5s to guarantee transition into

Sleep mode. Afterwards, a rising edge on either SDA or

SCL immediately transitions the IC out of Sleep mode.

Alternatively, Sleep mode can be entered by setting the

SLEEP bit in the CONFIG register to logic 1 through I2C

communication. If the SLEEP bit is set to logic 1, the only

way to exit Sleep mode is to write SLEEP to logic 0 or

power-on reset the IC.

Power-On Reset (POR)

Writing a value of 0054h to the COMMAND register

causes the MAX17043/MAX17044 to completely reset as

if power had been removed. The reset occurs when the

last bit has been clocked in. The IC does not respond with

an I2C ACK after this command sequence.

Registers

All host interaction with the MAX17043/MAX17044 is han-

dled by writing to and reading from register locations. The

MAX17043/MAX17044 have six 16-bit registers: SOC,

VCELL, MODE, VERSION, CONFIG, and COMMAND.

Register reads and writes are only valid if all 16 bits are

transferred. Any write command that is terminated early

is ignored. The function of each register is described

as follows. All remaining address locations not listed in

Table 1 are reserved. Data read from reserved locations

is undefined.

Table 1. Register Summary

ADDRESS

(HEX)

02h–03h

04h–05h

06h–07h

08h–09h

0Ch–0Dh

FEh–FFh

REGISTER

VCELL

SOC

MODE

VERSION

CONFIG

COMMAND

DESCRIPTION

Reports 12-bit A/D measurement of battery voltage.

Reports 16-bit SOC result calculated by ModelGauge algorithm.

Sends special commands to the IC.

Returns IC version.

Battery compensation. Adjusts IC performance based on

application conditions.

Sends special commands to the IC.

READ/

WRITE

R

R

W

R

R/W

W

DEFAULT

(HEX)

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971Ch

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