TLE7235G Datasheet, PDF(13/37 Page) Infineon Technologies AG – 8 Channel High-Side and Low-Side Relay Switch with Limp Home Mode

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TLE7235G Datasheet, PDF (13/37 Pages) Infineon Technologies AG – 8 Channel High-Side and Low-Side Relay Switch with Limp Home Mode

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TLE7235G

Power Supply

The TLE7235G 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. 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 TLE7235G, 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 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

reset

12 V

reset

12 V

reset

5.2

Limp Home Mode

The TLE7235G 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.

5.3

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.

Under Voltage Reset:

During this device condition a read on SPI always delivers the Standard Diagnostic Frame with a TER flag.

This under voltage reset is released when all the supply voltages levels are above under voltage threshold.

Data Sheet

Rev. 1.0, 2008-10-30

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