VD5377 datasheet(21/88 Pages) STMICROELECTRONICS

21 / 88 page

Doc ID 022952 Rev 2

21/88

VD5377

System overview

4.2

AUTOMATIC power management

AUTOMATIC power mode is the advanced power saving mode of the VD5377. When this

mode is activated, the sensor automatically enters low power modes (called SLEEP states)

after a given time if the sensor does not detect any motion.

Figure 9. Automatic power mode flow diagram

A SLEEP state is a low power state where the internal system clock is disabled, the analog

block is powered down and only the internal 50 kHz oscillator is running to wake the sensor

up periodically. Each time the sensor wakes up, a single frame is captured and the motion

versus previous frame is estimated. If motion is detected the system resumes in RUN mode;

otherwise if no motion is detected the sensor goes back to SLEEP. Up to three SLEEP

states (default) can be selected. The sleep time-out and wake-up latency periods are

programmable.

BOOT

SW STBY

MANUAL

RUN

MODE

AUTOMATIC

host_config_done = 1

automatic = 0

host_config_done = 1

automatic = 1

POWERDOWN

AUTOMATIC POWER MODE

SLEEP 1

SLEEP 2

SLEEP 3

POWERDOWN=0

POWERDOWN=1

50 ms

8 secs

10mins

10 ms

100 ms

500 ms

Default sleep time-outs and

wakeup latencies are shown.

These parameters are

POWER UP

programmable.

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