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AS3935

Datasheet - Detailed Descr i p ti on

8 Detailed Description

The AS3935 can detect the presence of an approaching storm with lightning activities and provide an estimation of the distance to the leading

edge of the storm, where the leading edge of the storm is defined as the minimum distance from the sensor to the closest edge of the storm. The

embedded hardwired distance estimation algorithm of the AS3935 issues an interrupt on the IRQ pin (see Interrupt Management on page 22)

every time a lightning is detected. The estimated distance which is displayed in the distance estimation register does not represent the distance

to the single lightning but the estimated distance to the leading edge of the storm. A graphical representation is shown in the Figure 9.

Figure 9. Storm

As shown in Figure 10, Figure 11, Figure 12, and Figure 13, the system integration consists mainly of the AS3935 and an external control unit

(e.g. MCU) for the IC initialization and interrupt management (IRQ).

The choice of interface type (SPI vs. I²C) is accomplished using pin 9, SI (Select Interface). When the SI is connected to GND, the SPI is

selected. When the SI is connected to VDD, the I²C is selected. Pins ADD0 and ADD1 are used to select among 4 different I²C address.

The internal voltage regulator can be enabled by connecting EN_VREG to VDD. If the internal regulator is not used, capacitor C3 is not needed

and VREG must be connected to VDD. In this case, the AS3935 can be directly supplied by VREG and VDD (EN_VREG to GND).

AS3935 needs the following external components:



Power supply capacitor – CBAT – 1µF



Load capacitor on the ACG and VREG pins; the latter is needed only in case the voltage regulator is enabled



One, RLC resonators for the antenna



One resistor on the I2CL pin to VDD, if I²C is active (R2 > 10k

Ω)

Time

Single lightning events

Distance estimation of the AS3935