User Manual
933
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
High-Side Switch
26.3.1
Normal Operation
In normal operation mode (CPU normal mode, CPU slow down mode) the high-side switch provides
functionalities and protection functions which are:
•
selectable Slew Rate Control
for improved EMI behavior.
•
Overcurrent Detection
with four different thresholds (min.): 25 mA, 50 mA, 100 mA and 150 mA.
•
Overtemperature Protection
, to protect the switch against overtemperature.
•
On-State Open Load Detection
with threshold lower than 1.5 mA typ.
In device stop mode and device sleep mode the high-side driver is switched off and disabled. The user
software does not need to take care about the proper power down sequence of this module. This is done by
hardware.
In stop mode, the configuration of the driver is kept inside the corresponding sfrs. If the driver was switched
on before entering stop mode, after a wakeup its status is restored automatically.
26.3.1.1 Slew Rate Configuration
The high-side switch provides two slew rate configuration possibilities:
• 10V/µs (recommended up to 5 kHz PWM frequency).
• 30V/µs (recommended above 10 kHz PWM frequency).
The intermediate range has to be evaluated in the application. The setting depends on load current demand.
Power dissipation analysis is recommended.
The configuration can be done by flag HSx_SRCTL_SEL. The slew rate configuration is also taken for the pwm
mode.
26.3.1.2 Overcurrent Detection
To configure the proper overcurrent threshold the corresponding bits
HSx_OC_SEL
in the
HSx_CTRL - SFR
have to be set. If an overcurrent condition is present, the high-side switch will be automatically turned off. In
parallel the flag
HSx_OC_IS
is set and the HSx_ON flag and HSx_PWM flag is cleared. To enable the high-side
switch again, it is recommended to clear the
HSx_OC_IS
flag and then set the
HSx_ON
bit to reactivate the
switch. Clearing only the
HSx_OC_IS
flag, would not turn the switch automatically on. If the overcurrent
condition is still present, the switch will be disabled once again.
26.3.1.3 Overtemperature Detection
If overtemperature condition appears, the switch will shutdown and the corresponding bit
HSx_OT_STS
is
set. To reenable the high-side switch, the same procedure as for the overcurrent condition has to be applied.
Due to the fact that overtemperature condition is removed very slowly (device has to cool down) in
comparison to the CPU time base, it is recommended to clear the status flag and to check if it is set again
immediately after clearing, before trying to switch the driver on again.
26.3.1.4 ON-State Open Load Detection
The high-side open load detection in ON State is mainly performed by the overcurrent detection and its fixed
threshold of typ. 1.5 mA. If the current flowing through the output stage of the high-side switch falls below the
value of typ. 1.5 mA, the corresponding status flag
OL_STS
is set. The open load detection has no influence on
operation of the high-side switch.
The open load condition will cause an interrupt if enabled by the user.