SPI Driver for Enhanced Relay Control

TLE7238SL

Power Supply

Data Sheet

13

Rev. 1.0, 2010-02-18

5

Power Supply

The TLE7238SL is supplied by two supply voltages

V

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

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

CMD.WAKE = 1 before this time is elapsed. A SPI frame send during

t

The

V

result, the daisy chain function is available as soon as

V

A capacitor between pins

V

5.1

Operation Modes

There is a limp home functionality implemented in the TLE7238SL, which is activated via pin LHI. Please refer to

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

V

5.2

Limp Home Mode

The TLE7238SL 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

V

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 and the device is in sleep mode.

Under Voltage Reset:

Operation Modes

VBB

0 V0 V0 V

12 V

12 V

12 V

12 V

VDD

0 V5 V5 V

0 V

0 V5 V5 V

LHI

X

0V

5V

0V

5 V

0 V

5 V

Switches operating

-

-

-

✓✓✓✓

Limp Home

-

-

-

-

✓

-

✓

SPI & daisy-chain

-

✓

✓

--

✓

✓

Register Banks

reset

reset

reset

✓

reset

✓

reset

Diagnostic functions

-

-

-

✓

-

✓

-