Datasheet

13

Rev. 1.0, 2009-09-30

SPI Driver for Enhanced Relay Control

SPIDER - TLE7243SL

Input and Power Stages

Figure 5

Output Clamp Implementation

Maximum Load Inductance

During demagnetization of inductive loads, energy has to be dissipated in the SPIDER - TLE7243SL. This energy

can be calculated with following equation:

The maximum energy, which is converted into heat, is limited by the thermal design of the component.

5.2.2

Timing Diagrams

The power transistors are switched on and off with a dedicated slope via the IN bits of the serial peripheral

Figure 6

Switching a Resistive Load

In input mode, a high signal at the input pin is equivalent to a SPI ON command and a low signal to SPI OFF

command respectively. Please refer to Section 8.3 for details on operation modes.

OutputClamp.emf

V

bat

I

D

V

DS (CL)

OUT

V

DS

GND

L,

R

L

–

DS(CL)

------------------------------------ ln

⋅

1

⋅

–

DS(CL)

------------------------------------

–

⎝⎠

⎜⎟

⎛⎞

+

L

------

⋅⋅

=

E

1

2

---

2

1

–

DS(CL)

------------------------------------

–

⎝⎠

⎜⎟

⎛⎞

⋅

=

CS

V

DS

t

SwitchOn.emf

t

ON

t

OFF

t

20%

80%

SPI: ON

SPI: OFF