TLE7232G Datasheet, PDF (12/36 Pages) Infineon Technologies AG – SPI Driver for Enhanced Relay Control

SPI Driver for Enhanced Relay Control
SPIDER - TLE 7232G
Block Description and Electrical Characteristics
The input signal can be configured to be used as control signal of the output stages for
each channel separately. The channels 0 to 3 differ from the channels 4 to 7 in the
mapping behavior. Please refer to Figure 4 for details.
The current sink to ground at the input pin ensures that the channels switch off in case
of open pin. The zener diode protects the input circuit against ESD pulses.
4.1.3 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 5 for details. Nevertheless,
the maximum allowed load inductance is limited.
V_bat
V_DS(CL)
OUT
L,
I_D
R_L
V_DS
GND
Figure 5 Output Clamp Implementation
OutputClamp .emf
Maximum Load Inductance
During demagnetization of inductive loads, energy has to be dissipated in the SPIDER -
TLE 7232G. This energy can be calculated with following equation:
E = V_DS(CL) ⋅
V_{-----b--a---t---–----}V_{-----D---S---(--C---L--)}
⋅

ln1
–
----------^R-----^L----^â‹---^I--^D-----------


R_L
 ^V_bat ^{– V}_DS(CL) 
+ I_D
⋅ --^L----
R_L
(1)
The equation simplifies under the assumption of R_L = 0:
E
=
1_--
2
LI_D
2
⋅

1

–
-------------^V-----^b--^a---^t------------


V_bat – V_{DS(CL) }
(2)
The energy, which is converted into heat, is limited by the thermal design of the
component.
Data Sheet
12
V1.0, 2005-09-30