TLE8108EM Datasheet, PDF (12/30 Pages) Infineon Technologies AG – Smart 8-Channel Low Side Relay Driver with SPI Interface

TLE 8108 EM
Smart 8-Channel Low Side Switch
Electrical and functional Description of the Device
5.2
Power Outputs
5.2.1 Inductive Output Clamp
When switching off inductive loads, the potential at pin OUT rises to V_DS(CL) potential, because the inductance
intends to continue driving the current. The voltage clamping is necessary to prevent destruction of the device.
See Figure 6 for more details. Nevertheless, the maximum allowed load inductance is limited. If a dedicated
output enters clamping mode, the channel can be turned on again after clamping has disappeared.
OUT
I_L
V_DS(CL)
GND
R_L
L_L
LOAD
V_BAT
Figure 6 Internal Clamping Principle
Clamping Principle.vsd
Clamping Energy
During demagnetization of inductive loads, energy has to be dissipated in the TLE8108EM. This energy can be
calculated with following equation:
E
=
V_DS(CL)
⋅
-^L---^L-
R_L
⋅
I_L
–
V_{----D----S--(--C----L--)---–-----}V_{----B---A---T-}
R_L
⋅
ln
⎝⎛ ¹
+
V^----_D^----_S^--₍^--R_C^---L-_L^--₎^{-⋅--–-I---L-}V^----_B^---_A^---_T^{-⎠⎞}
(1)
The maximum energy which is converted into heat, is limited by the thermal design of the component.
• Application hint: It is recommended to consider the real behavior of the load (R_L and L_L vs. temperature and
vs. current) at each operating condition. Typical small signal parameters provided in the Datasheet of the load
(actuator) might not represent the real behavior under operating conditions.
Data Sheet
12
Rev. 1.0, 2011-03-23