AS3935-BQFT ams, AS3935-BQFT Datasheet - Page 18

• 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
8.5.2 I²C Register Read
To read data from the slave device, the master has to change the transfer direction. This can be done either with a repeated START condition
followed by the device-read address, or simply with a new transmission START followed by the device-read address, when the bus is in IDLE
state. The device-read address is always followed by the 1st register byte transmitted from the slave. In Read Mode, any number of subsequent
register bytes can be read from the slave. The word address is incremented internally.
Figure 19. I²C Page Read
Random Read and Sequential Read are combined formats. The repeated START condition is used to change the direction after the data transfer
from the master.
The word address transfer is initiated with a START condition issued by the master while the bus is idle. The START condition is followed by the
device-write address and the word address.
In order to change the data direction, a repeated START condition is issued on the 1st CLK pulse after the ACKNOWLEDGE bit of the word
address transfer. After the reception of the device-read address, the slave becomes the transmitter. In this state, the slave transmits register data
located by the previous received word address vector. The master responds to the data byte with a NOT ACKNOWLEDGE, and issues a STOP
condition on the bus.
In contrast to the Random Read, in a sequential read the transferred register-data bytes are responded by an acknowledge from the master. The
number of data bytes transferred in one sequence is unlimited (consider the behavior of the word-address counter). To terminate the
transmission, the master has to send a NOT ACKNOWLEDGE following the last data byte and subsequently generate the STOP condition.
8.5.3 Direct Command
It is possible to send direct commands writing 0x96 in the registers REG0x3C and REG0x3D, as shown in the table below:
8.6 Voltage Regulator
The AS3935 can be either supplied by a voltage regulator or directly.
If the voltage regulator is used, an additional current consumption (around 5μA) will have to be considered. In this case the pin EN_VREG must
be connected to VDD and the AS3935 is supplied by the pin VDD, while the regulated voltage is at the pin VREG (output of the voltage
regulator). In order to fulfil the stability requirements of the voltage regulator a capacitance greater than 1μF on the pin VREG to ground is
needed. The nominal output regulated voltage is 3V.
If the voltage regulator is not used, the pin EN_VREG must be connected to ground and the pins VDD and VREG must be connected together to
the supply voltage (e.g. battery).
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PRESET_DEFAULT
Direct Command
CALIB_RCO
Register
0x3C
0x3D
Revision 1.2
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