TLE7236G Datasheet, PDF(13/38 Page) Infineon Technologies AG – 8 Channel High-Side and Low-Side Relay Switch with Limp Home Mode and Cranking

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TLE7236G Datasheet, PDF (13/38 Pages) Infineon Technologies AG – 8 Channel High-Side and Low-Side Relay Switch with Limp Home Mode and Cranking

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TLE7236G

Power Supply

The TLE7236G is supplied by two supply voltages Vbb and VDD. The Vbb supply line is connected to a battery feed

and used by the power switches and by an integrated power supply for the register banks. The internal power

supply is designed to hold the state of the power switches including the configuration stored in the control register

bank during cranking down to 4V. There is an under voltage reset function implemented for the Vbb power supply.

After start-up of the power supply, all SPI registers are reset to their default values and the device is in sleep mode

(standby). The SPI command CMD.WAKE = 1 is switching the device to operation mode (ON), while a command

CMD.STB = 1 send the device to sleep mode (standby) again.

The VDD supply line is used by the SPI shift register related circuitry and for driving the SO line. As a result, the

daisy chain function is available as soon as VDD is provided in the specified range independent of Vbb. A capacitor

between pins VDD and GND is recommended (especially in case of EMI).

5.1

Operation Modes

There is a limp home functionality implemented in the TLE7236G, which is activated via pin LHI. Please refer to

Section 5.2 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 . The sleep mode current is minimized only when limp

home is inactive. After limp home, the device enters sleep mode automatically.

The internal power supply is designed for low voltage cranking condition down to Vbb = 4 V. During cranking, the

output channels keep their state as before configured via SPI independent of VDD supply voltage. If VDD = 0 V the

SPI can not be used as the output and input levels refer to VDD, but the device keep the current state until either

the limp home mode is triggered or the VDD voltages comes back and therefore the SPI Interface works again.

The following table shows the operation modes depending on Vbb, VDD and the limp home input signal LHI.

Operation Modes

VBB

VDD

LHI

Switches operating

Limp Home

SPI & daisy-chain

Diagnostic functions

0V 0V 0V 4V

0V 5V 5V 0V

0V 5V 0V

reset reset reset â

4V 4V

0V 3V

4V 0V

reset â

12 V

reset

12 V

reset

5.2

Limp Home Mode

The TLE7236G offers the capability of driving dedicated channels during fail-safe operation of the system. This

limp home mode is activated by a high signal at pin LHI. In limp home mode, the SPI registers are reset and the

input pins are directly routed to the auto configuring channels (channel 4 and 5). As a result, the limp home

operation can be chosen for high-side and low-side driven loads.

Due to the integrated power supply, limp home operation is independent of digital power supply VDD. In case of

stand-by, a high signal at pin LHI will wake up the device. After limp home operation, the device enters sleep mode

in any case.

Data Sheet

Rev. 1.0, 2008-10-30

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