VD5377 datasheet(22/88 Pages) STMICROELECTRONICS

22 / 88 page

System overview

VD5377

22/88

Doc ID 022952 Rev 2

In AUTOMATIC power mode, if the use_standby_pin register is set, the STANDBY pin is

configured as a chip select (active low) to perform I2C communications. This allows the host

to perform I2C communications to the VD5377 at anytime even during SLEEP modes. If the

use_standby_pin register is not set, the host can only perform I2C communications when

motion data is pending.

Low power states:

•

SLEEP states: Typical power consumption in the various sleep states is shown in

Table 10.

•

POWERDOWN pin: if set, this signal immediately disables the internal 1.8 V core

regulator. After power down, the system needs to be re-initialized. Power consumption

is typically <1 µA in this state.

Figure 10 describes the power-up sequence of the VD5377 in AUTOMATIC power

management mode. After the MCU boot sequence is completed, the system enters SW

STDBY state and the MOTION pin is set to 1 indicating that the device is ready to receive

commands from the host. After initialization by the host over I2C, the device enters the

AUTO RUN state and the MOTION pin will go low.

Note:

The MOTION pin polarity is programmable. If active low polarity is selected during

initialization, the MOTION pin will remain high.

After a time, motion is detected and the MOTION PIN goes high. Once motion is detected

the device can no longer enter SLEEP until all pending motion data has been read. The host

deasserts the STANDBY pin to enable I2C comms (if use_standby_pin register was set in

initialization routine); motion data is read and the STANDBY pin is re-asserted. After the

RunningTimeout period, if no further motion is detected, the device enters the SLEEP1

state. After the Sleep1Latency period, the device wakes up for 1 frame to detect any

movement. No motion is detected so the device remains in the SLEEP1 state.

If the POWERDOWN pin is asserted, the internal 1.8 V regulator is disabled and the 1.8 V

core supply is switched off. When the POWERDOWN pin is deasserted, the internal 1.8 V

regulator is re-enabled and the MCU re-initializes as at power-up before entering the SW

STBY state. The device must be re-configured after POWERDOWN.

Table 10. Typical power consumption(1) - automatic mode

1. Includes LED (maximum exposure)

Run(2)

2. Internal clock = 44 MHz; led_dac 14 mA; Maximum exposure

Sleep1

Sleep2

Sleep3

Power down

3.3 kf/s

2 kf/s

1 kf/s

10.2 mA

6.9 mA

4.5 mA

350 µA

60 µA

20 µA

<1 µA

VD5377 数据表(PDF) 22 Page - STMicroelectronics

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