TLE8108EM Datasheet, PDF (21/30 Pages) Infineon Technologies AG – Smart 8-Channel Low Side Relay Driver with SPI Interface

TLE 8108 EM
Smart 8-Channel Low Side Switch
Serial Peripheral Interface (SPI)
8
Serial Peripheral Interface (SPI)
The diagnosis and control interface is based on a serial peripheral interface (SPI).
The SPI is a full duplex synchronous serial slave interface, which uses four lines: SO, SI, SCLK and CS. Data is
transferred by the lines SI and SO at the data rate given by SCLK. The falling edge of CS indicates the beginning
of a data access. Data is sampled in on line SI at the falling edge of SCLK and shifted out on line SO at the rising
edge of SCLK. Each access must be terminated by a rising edge of CS. A modulo 8 counter ensures that data is
taken only, when a multiple of 8 bit has been transferred, while the minimum of 16 bit is also taken into
consideration. Therefore the interface provides daisy chain capability even with 8 bit SPI devices.
SO
MSB 14 13 12 11 10 09 08 07 06 05 04 03 02 01
LSB
SI
MSB 14 13 12 11 10 09 08 07 06 05 04 03 02 01
LSB
CS
SCLK
t
SPI interface.vsd
Figure 10 Serial peripheral Interface
The SPI protocol is described in Section 8.3. It is reset to the default values after programming the device into
Standby mode (all the channels in Clear mode).
8.1
SPI Signal Description
There is one internal register where the diagnosis information is stored and a shift register used for transmitting
the information via SO.
CS - Chip Select:
The system microcontroller selects the TLE8108EM by means of the CS pin. Whenever the pin is in low state, data
transfer can take place. When CS is in high state, any signals at the SCLK and SI pins are ignored and SO is
forced into a high impedance state.
CS High to Low transition:
• The information which is stored in the internal diagnosis register is transferred into the shift register.
• SO changes from high impedance state to high or low state depending on the logic OR combination between
the transmission error flag (TER) and the signal level at pin SI. The transmission error flag is set after any kind
of reset, so a reset between two SPI commands is indicated. For details, please refer to Figure 11. This
information stays available till the first rising edge of SCLK.
Data Sheet
21
Rev. 1.0, 2011-03-23