SPI Driver for Enhanced Relay Control

SPIDER - TLE7231G

Power Stages

Datasheet

12

Rev. 1.2, 2014-05-09

6

Power Stages

The TLE7231G is a four channel low-side relay switch.

The power stages are made of N-channel vertical power MOSFET transistors.

6.1

Input Circuit

The TLE7231G has an input pin, that can be configured to be used for control of the output stages. The INn

parameter of the SPI provide the following operation modes:

•

channel is in off mode without diagnosis

(if all channels are programmed to this mode, the device goes into idle mode)

•

channel is switched according to signal level at input pin IN

•

channel is switched on

•

channel is switched off with active diagnosis

Figure 4 shows the input circuit of TLE7231G.

Figure 4

Input Multiplexer

The current sink to ground ensures that the channels switch off in case of open input pin. The zener diode protects

the input circuit against ESD pulses. After power-on reset, the device enters idle mode.

6.2

Inductive Output Clamp

When switching off inductive loads, the potential at pin OUT rises to

V

intends to continue driving the current. The voltage clamping is necessary to prevent destruction of the device,

see Figure 5 for details. Nevertheless, the maximum allowed load inductance is limited.

Figure 5

Output Clamp Implementation

Channel 3

Channel 2

Channel 1

IN

I

IN

Channel 0

1

IN0

InputLogic.emf

0

0

D0

&

OutputClamp.emf

OUT

V

DS

GND

L,

R

L