MAX1660 Datasheet, PDF (15/20 Pages) Maxim Integrated Products – Digitally Controlled Fuel-Gauge Interface

Digitally Controlled
Fuel-Gauge Interface
Table 5. ReadStatus( ) Bit Functions
BIT NAME
—
—
—
—
—
—
—
—
ODSTATUS
OCSTATUS
COMPSTATUS
COUNTSTATUS
SHDNSTATUS
CHARGESTATUS
DIRCHANGE
—
BIT
POSITION
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
POWER-ON
RESET STATE
DESCRIPTION
1
Unused. Always returns 1.
1
Unused. Always returns 1.
1
Unused. Always returns 1.
1
Unused. Always returns 1.
1
Unused. Always returns 1.
1
Unused. Always returns 1.
1
Unused. Always returns 1.
1
Unused. Always returns 1.
Overcurrent-Interrupt Status. This bit sets when an overcurrent condition
0
occurs in the discharging direction. This bit clears in soft shutdown, following a
power-on reset, or when the configuration word’s CLRINT bit is set.
Overcurrent-Interrupt Status. This bit sets when an overcurrent condition
0
occurs in the charging direction. This bit clears in soft shutdown, following a
power-on reset, or when the configuration word’s CLRINT bit is set.
COMPINT-Interrupt Status. This bit sets upon generation of the COMPINT
0
interrupt. This bit clears in soft shutdown, on a power-on reset, or when the
configuration word’s CLRINT bit is set.
—
SETCOUNT Status Indicator. This bit sets when the configuration word’s
SETCOUNT bit is set. This bit clears when SETCOUNT clears.
0
Soft-Shutdown Status Indicator. Returns 1 when the device is in soft-shutdown
mode; returns 0 when it is not in soft-shutdown mode.
0
Charge-Status Indicator. This bit sets upon detection of charging current. The
bit clears upon detection of discharging current.
The bit sets when the current flow changes direction. This bit clears when the
0
configuration word’s CLRINT or SOFTSHDN bit is set, or following a power-on
reset. See Direction-Change Detection Function section.
—
Unused. Always returns 1.
WriteConfig() Command
The host configures the MAX1660 using the
WriteConfig() command. Table 6 describes each of the
configuration word’s bits.
Applications Information
Choosing R_CS
For greatest accuracy, choose R_CS to ensure that the
product of the maximum current to be measured (I_MAX)
and R_CS does not exceed 120mV. Calculate the proper
sense-resistor value as follows:
R _CS
=
120mV
I_MAX
ceptable results. Be sure to consider power dissipation
when choosing the current-sense resistor to avoid
resistor self-heating.
Setting the Overcurrent Threshold
Set the current at which the voltage on CS exceeds the
voltage on OCI with a voltage divider placed between
REF and GND (Figure 10a). To set the overcharge
threshold, choose R5 in the 1MΩ range and calculate
R6 from:
R6 =
R5
 _VREF
 ^ICHG,MAX^RCS

- 1_
where I_MAX is the maximum current to be accurately
measured. Use only surface-mount metal-film resistors;
wire-wound resistors are too inductive to provide ac-
where V_REF = 2.00V, I_CHG,MAX is the maximum allow-
able charging current, and R_CS is the current-sense
resistor value.
*Patent pending
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