AS3935-BQFT ams, AS3935-BQFT Datasheet - Page 20

• Manufacturer Part Number: AS3935-BQFT
• Description: Interface - Specialized
• Manufacturer: ams

Specifications of AS3935-BQFT

• Rohs: yes
• Operating Supply Voltage: 2.4 V to 5.5 V
• Supply Current: 100 mA
• Maximum Power Dissipation: 0.1 W
• Mounting Style: SMD/SMT
• Package / Case: MLPQ-16
• Supply Voltage - Max: 5.5 V

AS3935
Datasheet - D e t a i l e d D e s c r i p t i o n
8.8 Noise Floor Generator and Evaluation
The output signal of the AFE is also used to generate the noise floor level. The noise floor is continuously compared to a reference voltage (noise
threshold). Whenever the noise floor level crosses the noise threshold, the AS3935 issues an interrupt (INT_NH) to inform the external unit (e.g.
MCU) that the AS3935 cannot operate properly due to the high input noise received by the antenna (e.g. blocker). It is possible to set the
threshold for the noise floor limit with the bits REG0x01[6:4], as defined in the table below.
Table 16. Settings for the Noise Floor Threshold
INT_NH is displayed as long as the input noise level (blocker) is higher than the noise floor threshold. By default the setting REG0x01[6:4] =010
is used.
8.9 Lightning Algorithm
The lightning algorithm consists of hardwired logic. False events (man-made disturbers) which might trigger the AS3935 are rejected, while
lightning events initiate calculations to estimate the distance to the head of the storm.
The Lightning algorithm is broken up into three sub blocks:
If the signal validation fails (the incoming signal does not have the characteristics of lightning), the energy calculation and statistical distance
estimation do not happen and the event is classified as disturber.
8.9.1 Signal Validation
The watchdog enables the lightning algorithm block in the event any activities are detected at the antenna. As this happens the output signal of
the AFE is evaluated by the Signal Validation block, which checks the pattern of the received signal. The signal validation checks the shape of
the received signal. In particular, the AS3935 can reject the impulse signals, like spikes, picked up by the antenna. The AS3935 has the ability to
improve the spike rejection with the register REG0x02[3:0]. By default, register REG0x02[3:0] =0010. Larger values in REG0x02[3:0]
correspond to more robust disturber rejection, with a decrease of the detection efficiency, as shown in the
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1. Signal validation: Verification that the incoming signal can be classified as lightning.
2. Energy calculation: Calculation of the energy of the single event.
3. Statistical distance estimation: According to the number of stored events (lightning), a distance estimate is calculated.
Continuous Input Noise Level
[μVrms] (outdoor)
1100
1140
1570
1800
2000
390
630
860
Continuous Input Noise Level
[μVrms] (indoor)
130
146
112
28
45
62
78
95
Revision 1.2
REG0x01[6]
0
0
0
0
1
1
1
1
Figure
REG0x01[5]
21.
0
0
1
1
0
0
1
1
REG0x01[4]
0
1
0
1
0
1
0
1
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