TLE7234EM Datasheet, PDF (13/36 Pages) Infineon Technologies AG – SPI Driver for Enhanced Relay Control

SPI Driver for Enhanced Relay Control
TLE7234EM
Power Supply
5
Power Supply
The TLE7234EM is supplied by two supply voltages V_bb and V_DD. The V_bb supply line is connected to a battery
feed and used by the power switches and by an integrated power supply for the register banks. There is an under
voltage reset function implemented for the V_bb power supply, which is triggered if V_bb is below the undervoltage
threshold. After start-up of the power supply, all SPI registers are reset to their default values and the device is in
sleep mode (standby). Sending the SPI command CMD.WAKE = 1 switches the device to operation mode (ON),
while a command CMD.STB = 1 send the device to sleep mode (standby) again. Please note that the device
needs the time t_wu(Sleep) to initialize itself. No SPI command should be send after changing the power state via
CMD.WAKE = 1 before this time is elapsed. A SPI frame send during t_wu(Sleep) could be ignored.
The V_DD supply line is used to power the circuitry related to the SPI shift register and for driving the SO line. As a
result, the daisy chain function is available as soon as V_DD is provided in the specified range independent of V_bb.
A capacitor between pins V_DD and GND is recommended (especially in case of EMI disturbances).
Please see Figure 14 “Application Diagram” on Page 35 for details.
The device provides a sleep mode (stand by) to minimize current consumption, which also resets the register
banks. It is entered and left by dedicated SPI commands or by turning off the VDD supply.
The following table shows the operation modes depending on V_bb, V_DD .
Operation Modes
VBB
VDD
Switches operating
SPI & daisy-chain
Register Banks
Diagnostic functions
0V
0V
-
-
reset
-
0V
5V
-
✓
reset
-
12 V
0V
✓
-
✓
✓
12 V
5V
✓
✓
✓
✓
5.1
Reset
There are several reset trigger implemented in the device. A reset switches off all channels and sets the registers
to default values. After any kind of reset, the transmission error flag (TER) is set and the device is in sleep mode.
Under Voltage Reset:
During this device condition a read on SPI delivers the Standard Diagnostic Frame with a TER flag, if V_DD is above
the under voltage threshold already, if not SPI is not working.
This under voltage reset is released when V_DD and V_bb supply voltage levels are above under voltage threshold.
Reset Command: There is a reset command available to reset all register bits of the register bank and the
diagnosis registers. As soon as CMD.RST = 1, a reset is triggered.
Data Sheet
13
Rev. 1.0, 2010-02-18