TLI4970-D025T4_15 Datasheet, PDF (21/29 Pages) Infineon Technologies AG – High precision miniature coreless magnetic current sensor for AC

4
Interfaces
TLI4970-D025T4
Interfaces
4.1
SPI Interface Definition
The TLI4970-D025T4 has a 3-pin serial peripheral interface (SPI). A standard unidirectional 16-bit SPI protocol is
used. Several sensors can be connected to a parallel SPI bus. An example on how to connect multiple sensors is
given in Figure 3-2. The timing parameters are given in Table 4-1.
4.1.1 Logical Interface
All SPI frames are based on a 16-bit word. A parity bit in each SPI frame allows the detection of transmission errors
and increases the reliability of the measured data. The transmission of the data is triggered by the CS-pin.
4.1.1.1 Protocol Description
The internal data register is continuously updated with the internal update rate f_UPDATE. When CS is pulled to low,
the actual value from the data register is written into the SPI output register. Like in standard SPI protocol, the
sensor starts to transmit the data when clock pulses are applied to the SCLK pin and the CS-pin is still low. With
the next 16 clock pulses, the data word is sent out via the DOUT pin. If more than 16 clock pulses are sent by the
SPI-Master and the CS-pin stays low, the sensor sends 0’s for all additional clock pulses. If a new sample should
be read from the sensor, the CS-pin has to return to the high state for at least the time t_CSON before pulling it to low
again in order to trigger the next sample readout.
The clock pulses are ignored and the DOUT pin is in high ohmic state, when the CS-pin is in “high” state. Therefore
multiple chips can be readout on the same data bus by sequentially selecting the addressed sensor via the CS-pin.
4.1.1.2 Description of the SPI Data Frames
There are two different types of SPI frames sent from the sensor. The “Sensor Status Message” and the “Sensor
Value Message”. The two types are distinguished by the STATUS Bit. The DATA section contains different
information. For details see below.
General structure of the 16-bit SPI data frame
GENERAL
16-bit SPI data frame
Offset
00_H
Reset Value
4000_H
15 14 13
0
STAT PAR
DATA
r
r
r
Note: All fields marked as “r” are read-only values.
4.1.1.3 Sensor Current Message
The actual measurement current value is returned in the Sensor Value Message.
Data Sheet
21
Rev. 1.0, 2015-07-02