DA9021 datasheet(115/142 Pages) DIALOG

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DA9021/22

System PMIC with high efficiency USB power manager

Datasheet

Revision 2.5

17-Feb-2017

CFR0011-120-00 Rev 5

115 of 142

20.3 Automatic measurements scheduler

The automatic measurement scheduler allows monitoring of the system voltage VDDOUT, the

charging current ICH, the battery temperature TBAT and the touch screen interface XY. Additionally,

the auxiliary channels ADCIN4 to ADCIN6 are able to be automatically monitored with upper and

lower thresholds set by power manager registers to give an nIRQ event if a measurement is outside

these levels. All measurements are handled by the scheduler system detailed below.

The scheduler performs a sequence of 10 slots continually repeated according to the configured

mode. If the TSI is enabled the first half slot performs either an automatic or a manual conversion.

The second half slot performs TSI actions and measurements. If the TSI measurement is disabled

there is no split of the slot and only the first conversion is performed. A slot requires 100 µs. The

pattern of measurements over the 10 slots depends upon the charging mode. Automatic

measurements of VDDOUT, ICH and TBAT are made during charging. These cease when not

charging. When automatic measurements are disabled, the manual measurements are made

immediately and unused automatic measurements will handle manual conversion requests.

Slot No

Example sequence of AUTO-ADC measurements

Each Slot allows 1 automatic or manual measurement and 1 TSI measurement to be made

A0 - Automatic measurement of VDDOUT (mux channel 0)

A1 - Automatic measurement of ICH (mux channel 1)

A2 - Automatic measurement of TBAT (mux channel 2)

A4 - Automatic measurement of ADCIN4 (mux channel 4)

A5 - Automatic measurement of ADCIN5 (mux channel 5)

A8 - Automatic measurement of Tjunc with gain 3 (mux channel 8)

M indicates time slots when a Manual measurement can be made

No charging

With charging

Figure 47: ADC sequence

20.3.1

A0: VDDOUT low voltage nIRQ measurement mode

VDDOUT is measured and compared with a threshold. If the reading is below this level for three

consecutive readings an error event is generated. After an nIRQ assertion, the automatic

measurement of channel VDDOUT is paused for reading. The host must clear the associated event

flag (the event causing value is kept inside the result register) to re-enable the supervision of

VDDOUT. If no action is taken to restore the VDDOUT voltage (discharging the battery is continued)

the host may consider to switch off. Optional Always On blocks (backup battery charger or supplies,

that are not disabled when powering down to RESET mode) to save energy later on. The multiple

reading provides a debouncing of the VDDOUT voltage before issuing a nIRQ. The assertion of nIRQ

can be masked by IRQ mask.

20.3.2

A1: ICH (and ICH_BAT average) measurement mode

When the battery is being charged in FAST CHARGE mode the ICH current is measured

automatically every 1 or 10 ms and an average value is determined by adding the result to an 18-bit

accumulator and latching the top 8 bits every 1024 samples (during high speed mode nine

measurements are ignored before performing an update). This provides an average charging current

value every 10.24 s, as long as the system load current is less than the maximum current provided

from the external supply. When the ICH_BAT falls below the value set (and the other requirements

for charging end detection is met), an IRQ will be flagged. The IRQ can be masked.

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