Datasheet

TPS65950

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SWCS032E–OCTOBER 2008–REVISED JANUARY 2011

5 Real-Time Clock and Embedded Power Controller

The TPS65950 device contains an RTC to provide clock and timekeeping functions and an EPC to

provide battery supervision and control.

5.1 RTC

The RTC provides the following basic functions:

• Time information (seconds/minutes/hours) directly in binary-coded decimal (BCD) code

• Calendar information (day/month/year/day of the week) directly in BCD code

• Interrupt generation periodically (1 second/1 minute/1 hour/1 day) or at a precise time (alarm function)

• 32-kHz oscillator drift compensation and time correction

• Alarm-triggered system wake-up event

5.1.1 Backup Battery

The TPS65950 implements a backup mode in which a backup battery can keep the RTC running to

maintain clock and time information even if the main supply is not present. If the backup battery is

rechargeable, the device also provides a backup battery charger so it can be recharged when the main

battery supply is present.

The backup domain powers the following:

• Internal 32.768-kHz crystal oscillator

• RTC

• Eight GP storage registers

• Backup domain low-power regulator (VBRTC)

5.2 EPC

The EPC provides five system states for optimal power use by the system, as listed in Table 5-1.

Table 5-1. System States

System State Description

NO SUPPLY The system is not powered by any battery.

BACKUP The system is powered only with the backup battery and maintains only the VBRTC supply.

WAIT-ON The system is powered by the main battery and maintains only the VRRTC supply. It can

accept switch-on requests.

ACTIVE The system is powered by the main battery; all supplies can be enabled with full current

capability.

SLEEP The main battery powers the system; selected supplies are enabled, but in low consumption

mode.

Three categories of events can trigger state transitions:

• Hardware events: Supply/battery insertion, wake-up requests, USB plug, and RTC alarm

• Software events: Switch-off commands, switch-on commands, and sleep-on commands

• Monitoring events: Supply/battery level check, main battery removal, main battery fail, and thermal

shutdown

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