Data Sheet

A111 Pulsed Coherent Radar (PCR)

Datasheet, v2.0 prel.

VIO_3a,b must be turned on before or simultaneously with ENABLE and VIO_1-2a,b. ENABLE and

VIO_1-2a,b can be turned on in any order and independently of each other. A111 should however not

be considered as in state “ON” until all supply voltage levels are stable and ENABLE is high. The

time constant t

in figure 7.4 denotes this time. The actual value of t

depends on the power supply and

the decoupling capacitors used.

Next step in the power up sequence is to have a settling time for the XTAL oscillator to stabilize,

shown as time t

in figure 7.4. This may take up to several milliseconds depending on the XTAL

performance. The sensor does not require any settling time if it is integrated using an external

reference clock. It is advised to have the clock inactive at 0 V while ENABLE is inactive.

Now the A111 radar sensor is ready for SPI communication. All I/Os must never exceed VIO_3

voltage, accordingly if VIO_3 voltage is set to 0V between sensor usage then all I/Os must also be set

to 0V. Otherwise, the internal ESD protection diodes will draw current from the I/O source.

After power up is complete, the sensor is loaded with a program. Up until the point where the sensor’s

program is started, the INTERRUPT is high impedance. However, after the sensor’s program has

started the INTERRUPT is configured to a push-pull CMOS output. Therefore it is required that the

host I/O is configured as input before any programs are started on the sensor.

The power down sequence is recommended to be executed in the following order: First ensure that all

I/O inputs including ENABLE are at 0V. After that, all VIO_1-3a,b can be turned off.

VIO_1 and VIO_2 must never have higher voltage than VIO_3, and it is recommended to

enable/disable the three supplies simultaneously.