TLE7237SL Datasheet, PDF (20/36 Pages) Infineon Technologies AG – SPI Driver for Enhanced Relay Control

SPI Driver for Enhanced Relay Control
TLE7237SL
Protection Functions
7
Protection Functions
The device provides embedded protective functions. Integrated protection functions are designed to prevent IC
destruction under fault conditions described in this data sheet. Fault conditions are considered as “outside” normal
operating range. Protection functions are not designed for continuous repetitive operation.
7.1
Over Load Protection
The TLE7237SL is protected in case of over load or short circuit of the load. After time t_OFF(OVL), the over loaded
channel n switches off and the according diagnosis flag Dn is set. The channel can be switched on after clearing
the protection latch by command CMD.CPL = 1. The CPL command clears itself with the next valid SPI
communication frame. Please refer to Figure 7 for details.
IN
I_D0
I _{D0(OV L)}
t_{OFF(OV L)}
Figure 7
D0 = 1_b
Shut Down at Over Load
CPL = 1
b
D0 = 00_b
t
t
OverLoad.emf
7.2
Over Temperature Protection
A temperature sensor for each channel causes an overheated channel to switch off to prevent destruction. The
according diagnosis flag is set. This flag is also set in OFF state, if the regarding channel temperature is too
high.The channel can be only switched on after clearing the protection latch by SPI command CMD.CPL = 1. The
CPL command clears itself with the next valid SPI communication frame. Please refer to “Diagnostic Features”
on Page 23 for information on diagnosis features.
7.3
ESD protection
There is a designed in protection against ESD disturbances up to the specified limit by using the defined model.
Please see electrical characteristics “ESD susceptibility on all pins” on Page 11
7.4
Reverse Polarity Protection
There is a reverse polarity protection implemented in the TLE7237SL. This protection has to be divided into two
parts. First the protection of the control circuits and second in the protection of the power transistors.
The control circuits are reverse polarity protected by protective measures in the ground connection. In case of
reverse polarity, there is no current flow through the control circuits. To ensure this functionality, the GND pin and
the substrate connections SUB must not be connected to the same potential. This means, the copper area
dedicated for cooling should be connected at SUB and needs to be electrically isolated from GND.
The power transistors contain intrinsic body diodes that cause power dissipation. The reverse current through
these intrinsic body diodes has to be limited by the connected loads. The over temperature and over load
protection are not active during reverse polarity.
7.5
Loss of V_bb
In case of loss of V_bb connection in on-state, all inductances of the loads have to be demagnetized through the an
additional path from V_bb to ground. Usually this path is given somewhere in the PCB circuitry, for example, as a
suppressor diode like in the application diagram (see D1 in Figure 14 “Application Diagram” on Page 35).
Data Sheet
21
Rev. 1.0, 2010-02-18