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TLE7236SE Datasheet, PDF (17/37 Pages) Infineon Technologies AG – SPI Driver for Enhanced Relay Control | |||
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SPI Driver for Enhanced Relay Control
TLE7236SE
Power Stages
6.3
Inductive Output Clamp
When switching off inductive loads with low-side switches, the potential at pin OUT rises to VDS(CL) potential,
because the inductance intends to continue driving the current. For the high-side channels, the potential at pin
OUT drops below ground potential to VS(CL). The voltage clamping is necessary to prevent destruction of the
device, see Figure 5 for details. Nevertheless, the maximum allowed load inductance is limited by the max.
clamping energy EAR see electrical characteristics âEARâ on Page 10.
Vbb
high side
channel
V DS( CL )
VS(CL)
GND
VBB
low side
channel
OUT I S
VS
L,
IL
RL
VDS(CL)
L,
IL
RL
OUT ID
VD
GND
Figure 5 Output Clamp Implementation
OutputClamp.emf
Maximum Load Inductance
During demagnetization of inductive loads, energy has to be dissipated in the TLE7236SE. This energy can be
calculated with following equations:
E = VDS(CL) â
V-----b--b-----â----V----D----S---(-C----L--)
RL
â

ln 1
ï£
â
----------R----L----â
---I---L----------
Vbb â VDS(CL)



+ IL
â
--L----
RL
Low-side
(1)
E = (Vbb â VS(CL)) â
V-----S---(-C----L--)
â

ln 
1
â
R-----L----â
---I--L-
RL
ï£ VS(CL)
+ IL
â
--L----
RL
High-side
(2)
These equations simplify under the assumption of RL = 0:
E
=
1--
2
LIL2
â


1
â
-------------V-----b--b--------------


ï£ Vbb â VDS(CL) 
Low-side
(3)
E
=
1--
2
LIL2
â

1
ï£
â
----V----b---b----
VS(CL)
High-side
(4)
The maximum energy, which is converted into heat, is limited by the thermal design of the component.
Data Sheet
17
Rev. 1.0, 2010-02-18
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