PIFE32251B-R68MS datasheet(69/157 Pages) TI1

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TPS650830

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SLVSCF4A – DECEMBER 2014 – REVISED JULY 2016

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Detailed Description

6.3.13.10 Undervoltage Lockout

An undervoltage lockout function prevents the PMIC from operating if the supply voltage on the VIN pin of

the PMIC is lower than the undervoltage lockout threshold (see Electrical Characteristics table). During

operation, if the supply voltage on the VIN pin drops below the undervoltage lockout threshold, the

system/PMIC will shutdown.

6.3.14 Coincell Selector

6.3.14.1 Functional Description of RTC Powerpath and LDO

In case where the main system battery is removed and there is no alternate power source, the RTC data,

configuration and status registers, oscillator and timekeeping path of the RTC block are backed up by

either a super capacitor or a coin cell battery. If the coincell/ super capacitor battery voltage falls below the

minimum operational voltage and there is no input voltage (AC/ DC above the PMIC UVLO), the RTC data

registers will be invalid. As the Intel RTC cannot handle a max voltage higher than 3.2 V, when AC/DC is

present and is higher than the UVLO threshold, the RTC is supplied by the AC/DC rather than from the

coincell - thus maximizing the stored charge in the coincell battery. When AC/DC is present, the internal

coincell selector selects the higher of the coincell voltage and the AC/DC voltage. When AC/DC is chosen

as a source, there is a coincell LDO which is driven from the 5-V PMIC LDO to regulate The output

voltage is fixed at 3.1 V to ensure the maximum voltage is kept below 3.2 V.

The main power source for the RTC LDO is the 5-V PMIC internal LDO, when the main system battery

(VDC) is greater than 5.4 V. The RTC LDO will be bypassed and the RTC supply will be powered by the

coincell when VDC falls below this threshold - to maximize the coincell battery life. The coincell is used as

a last resort. All power routing of the source selection for the RTC power is done internally and no external

connections other than the coin cell or super cap is required.

PIFE32251B-R68MS 데이터시트(PDF) 69 Page - Texas Instruments