BTS54040-LBF_15 Datasheet, PDF (34/67 Pages) Infineon Technologies AG – SPI Power Controller

BTS54040-LBF
Protection Functions
7
Protection Functions
The device provides embedded protective functions, which are designed to prevent IC destruction under fault
conditions described in this data sheet. Fault conditions are considered as “outside” normal operating range.
Protective functions are neither designed for continuous nor for repetitive operation.
7.1
Over Load Protection
The load current I_L is limited by the device itself in case of over load or short circuit to ground. All channels have
2 steps of current limitation which are selected automatically depending on the voltage V_DS across the power
DMOS as show in Figure 17. Please note that V_OUT = V_S - V_DS. The current limitation threshold when V_DS = 5 V is
taken as reference.
Current limitation to the value I_L(LIM) is realized by increasing the resistance of the output channel, which leads to
fast DMOS temperature rise.
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
4
Current limitation variation ("1" = I_L(LIM) @ V_DS = 5 V)
8
12
16
20
24
28
Drain Source Voltage (V)
Figure 17 Typical Current Limitation variation according to V_DS voltage
7.2
Over Temperature Protection
Each channel incorporates both an absolute (T_j(SC)) and a dynamic (∆T_j(SW)) temperature sensor. An increase of
junction temperature T_j above one of the two thresholds (T_j(SC) or ΔT_j(SW)) switches OFF an overheated channel to
prevent destruction. Any protective switch OFF deactivates the output until the temperature has reached an
acceptable value.
Each protective switch OFF event increments the error counter by one. The number of automatic reactivations is
limited by n_retry. If this number of retries is reached the channel turns OFF and latches OFF.
The error information related to the given channel is available on the Standard Diagnosis and Errors Diagnosis.
Executing HWCR.CTC = 1_B will clear all thermal counters and errors on all channels. If the channel is active (either
OUT.OUTn = 1_B or INn = “high” and DCR.MUX ≠ 111_B) it is turned on immediately after the SPI command. In
addition the execution of the reset command (HWCR.RST = 1_B) will clear the thermal counters.
Data Sheet
34
Rev. 2.1, 2014-12-05