ADE75 datasheet(34/148 Pages) AD

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ADE75xx/ADE71xx

Preliminary Technical Data

Rev. PrE | Page 34 of 148

operating mode. When battery switchover occurs, the analog

circuitry used in the ADE energy measurement DSP is disabled.

To reduce power consumption, the user code can initiate a

transition to PSM2.

Entering Sleep Mode (PSM1 to PSM2)

To reduce power consumption when VSW is connected to VBAT,

user code can initiate sleep mode, PSM2, by setting bit 4 in the

Power Control SFR (POWCON, 0xC5) to shut down the MCU

core. Events capable of waking the MCU can be enabled—see

the 3.3V Peripherals and Wakeup Events section.

Servicing Wakeup Events (PSM2 to PSM1)

The ADE75XX/ADE71XX may need to wake up from PSM2 to

service wakeup events – see the 3.3V Peripherals and Wakeup

Events section. PSM1 code execution will begin at the power on

reset vector. After servicing the wakeup event, the

ADE75XX/ADE71XX can return to PSM2 by setting bit 4 in the

Power Control SFR (POWCON, 0xC5) to shut down the MCU

core.

Automatic Switch to VDD (PSM2 to PSM0)

If the conditions to switch VSW from VBAT to VDD occur (see the

Battery Switchover section), the operating mode will switch to

PSM0. When this switch occurs, the MCU core and the analog

circuitry used in the ADE energy measurement DSP will start

up again automatically. PSM0 code execution will begin at the

power on reset vector.

Automatic Switch to VDD (PSM1 to PSM0)

If the conditions to switch VSW from VBAT to VDD occur (see the

Battery Switchover section), the operating mode will switch to

PSM0. When this switch occurs, the analog circuitry used in the

ADE energy measurement DSP will start up automatically. Note

that code execution will continue normally. A software reset can

be performed to start PSM0 code execution at the power on

reset vector.

USING THE POWER MANAGEMENT FEATURES

Since program flow is different for each operating mode, the

status of VSW must be known at all times. The VSWSOURCE bit

in the Power Management Interrupt Flag SFR (IPSMF, 0xF8)

indicates what VSW is connected to. This bit can be used to

control program flow on wakeup. Since code execution always

starts at the power on reset vector, bit 6 of the Peripheral

Configuration SFR (PERIPH, 0xF4) can be tested to determine

which power supply is being used and to branch to normal code

execution or to wakeup event code execution. Power supply

events can also occur when the MCU core is active. To be aware

of events that change what VSW is connected to:

Enable the battery switchover interrupt (EBSO) if VSW=VDD

at power up.

Enable the power supply restored interrupt (EPSR) if

VSW=VBAT at power up.

An early warning that battery switchover is about to occur is

provided by SAG detection and possibly low VDCIN detection—

see the Battery Switchover section.

For a user controlled battery switchover, enable automatic

battery switchover on low VDD only. Then enable the low VDCIN

event to generate the PSM interrupt. When a low VDCIN event

occurs, start data backup. Upon completion of the data backup,

enable battery switchover on low VDCIN. Then battery switchover

will occur TBDms later.

PSM0

Normal Mode

VSW connected to VDD

PSM1

Battery Mode

VSW connected to VBAT

PSM2

Sleep Mode

VSW connected to VBAT

User code directs MCU

to shutdown core after

servicing wakeup event

Automatic Battery

Switchover

Power Supply

Restored

Wakeup

Event

Power Supply

Restored

Figure 15: Transitioning between Operating Modes

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