MAX1667 Datasheet, PDF (18/28 Pages) Maxim Integrated Products – Chemistry-Independent, Level 2 Smart Battery Charger

Chemistry-Independent,
Level 2 Smart Battery Charger
Table 3. ChargerMode() Bit Functions
BIT NAME
BIT
POR
POSITION* VALUE**
INHIBIT_CHARGE
0
(LSB)
0
FUNCTION
0 = Allow normal operation; clear the CHG_INHIBITED status bit.
1 = Turn the charger off; set the CHG_INHIBITED status bit.
ENABLE_POLLING
POR_RESET
RESET_TO_ZERO
N/A
1
—
Not implemented. Write 0 into this bit.
0 = No change in any non-ChargerMode() settings.
2
—
1 = Change the voltage and current settings to 0xFFFF and 0x0007
respectively; clear the THERMISTOR_HOT and ALARM_INHIBITED bits.
3
—
Not implemented. Write 0 into this bit.
4
—
Not implemented. Write 1 into this bit.
BATTERY_PRESENT_MASK
5
0
0 = Interrupt on either edge of the BATTERY_PRESENT status bit.
1 = Do not interrupt because of a BATTERY_PRESENT bit change.
POWER_FAIL_MASK
6
1
0 = Interrupt on either edge of the POWER_FAIL status bit.
1 = Do not interrupt because of a POWER_FAIL bit change.
N/A
7–9
—
Not implemented. Write 1 into this bit.
HOT_STOP
10
1
0 = The THERMISTOR_HOT status bit does not turn the charger off.
1 = THERMISTOR_HOT turns the charger off.
N/A
11–15
(MSB)
—
*Bit position in the D15–D0 data. **Power-on reset value.
N/A = Not applicable
Not implemented. Write 1 into this bit.
age is too high by comparing CCV to REF/4. If
CCV_LOW = 1 (when CCV < REF/4), IOUT shuts off.
This prevents the output voltage from exceeding the
voltage set point specified by the ChargingVoltage()
register. VOLTAGE_NOTREG = 1 whenever the internal
clamp pulls down on CCV. (The internal clamp pulls
down on CCV to keep its voltage close to CCI’s volt-
age.)
With the switching regulator on, the current through R1
(Figure 7) is regulated by sensing the average voltage
between CS and BATT. Figure 10 shows the relation-
ship between the ChargingCurrent() data and the aver-
age voltage between CS and BATT.
When the switching regulator is off, DHI is forced to
LX and DLO is forced to ground. This prevents current
from flowing through inductor L1. Table 6 shows the
relationship between the ChargingCurrent() register
value and the switching regulator current DAC code
(DA4–DA0).
To ensure that the actual output current matches the
data value programmed with the ChargingCurrent()
command, R1 should be as close as possible to 40mΩ.
The SEL pin setting affects the full-scale current but not
the step size. ChargingCurrent() values above the full-
scale setting set the CURRENT_OR status bit. Note that
whenever any current DAC bits are set, the linear-cur-
rent source is turned off.
The power-on reset value for the ChargingCurrent() reg-
ister is 0x0007. Any time the BATTERY_PRESENT status
bit is clear (battery removed), the ChargingCurrent()
register returns to its power-on reset state. This ensures
that upon insertion of a battery, the initial charging cur-
rent is 7mA.
AlarmWarning()
The AlarmWarning() command uses Write-Word protocol
(Figure 8a). The command code for AlarmWarning() is
0x16 (0b00010110). The AlarmWarning() command sets
the ALARM_INHIBITED status bit. The MAX1667 responds
to the following alarms: OVER_CHARGED_ALARM (D15),
TERMINATE_CHARGE_ALARM (D14), and OVER_TEMP_
ALARM (D12). Table 7 summarizes the AlarmWarning()
command’s function. The ALARM_INHIBITED status bit
remains set until BATTERY_PRESENT = 0 (battery
removed), a ChargerMode() command is written with the
POR_RESET bit set, or a new ChargingVoltage() or
ChargingCurrent() is written.
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