BQ25872 Datasheet, PDF (18/68 Pages) Texas Instruments – Battery Switch Charger

bq25872
SLUSCQ6 – OCTOBER 2016
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Feature Description (continued)
The user application has the option of selecting which parameters (voltage, current, temperature) the ADC needs
to convert when the ADC is set to continuous conversion mode (ADC_RATE is set to ‘1’) or in 1-shot mode
(ADC_RATE is set to ‘0’). By default, all parameters (VUSB_ADC, IBUS_ADC, VBUS_ADC, IBAT_ADC,
VBAT_ADC, VOUT_ADC, VDROP_ADC, TBUS_ADC, TBAT_ADC, TDIE_ADC) will be converted in 1-shot and
continuous conversion mode unless disabled in the ADC_MASK register. If an ADC parameter is masked (by
setting the corresponding bit in the ADC_MASK_x register), then the value in that register will be from the last
valid ADC conversion or the default POR value (which is all zeros if no conversions have taken place). If an ADC
parameter is masked in the middle of an ADC measurement cycle, the device will finish the conversion of that
parameter in the current conversion cycle and will not convert that parameter starting the next conversion cycle.
Even though no conversion takes place when all ADC measurement parameters are masked off, the ADC
circuitry is active and ready to begin conversion as soon as one of the bits in the ADC_MASK register is set to
‘0’.
The ADC_DONE bit signals when a 1-shot mode conversion is completed. During continuous conversion mode,
this bit is always set to ‘0’.
The ADC_EN bit controls when the ADC is enabled for a conversion. Upon enabling the ADC, the ADC
conversion will follow the settings in ADC_AVG_EN, ADC_SAMPLE, and ADC_RATE.
ADC conversion operates independently of the faults present in the device. ADC conversion will continue even
after a fault has occurred (that causes the battery switch to be disabled), and the host must set ADC_EN = ‘0’ to
disable ADC.
ADC readings are only valid for DC states of the signals, not for transients.
8.3.4 Linear Regulation Mode (LDO)
The device employs LDO mode that helps regulate VOUT voltage, battery voltage, input current and battery
current. In an event that the VOUT_REG, VBAT_REG, IBUS_REG or IBAT_REG threshold is exceeded, the
battery switch will act as an LDO and will regulate VOUT, VBAT, IBUS and IBAT (depending upon which
threshold is exceeded). The purpose of LDO mode is to provide temporary protection until the host is able to
read the EVENT_x registers (upon INT trigger), ADC output registers, and then update the adapter voltage
accordingly.
When VOUT_REG, VBAT_REG, or IBAT_REG threshold is exceeded, the response time of the LDO will be
1ms. Depending upon which LDO mode event occurs, the corresponding bit (VBAT_REG_LDO,
IBAT_REG_LDO, VOUT_REG_LDO) will be set in EVENT_1 register and INT will be asserted low to alert the
host (if the corresponding bit is not masked in EVENT_1_MASK register).
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