33912 Datasheet, PDF (31/47 Pages) Freescale Semiconductor, Inc – LIN System Basis Chip with DC Motor Pre-driver and Current

FUNCTIONAL DEVICE OPERATIONS
OPERATIONAL MODES
LOW SIDE OUTPUT PINS LS1 AND LS2
These outputs are two low side drivers intended to drive
relays incorporating the following features:
• PWM capability (software maskable)
• Open load detection
• Current limitation
• Over-temperature shutdown (with maskable interrupt)
• Active clamp (for driving relays)
• High-voltage shutdown (software maskable)
The low side switches are controlled by the bit LS1:2 in the
Low Side Control Register (LSCR).
HVSE
Interrupt
Control
Module
To protect the device against over-voltage when an
inductive load (relay) is turned off. An active clamp will re-
enable the low side FET if the voltage on the LS1 or LS2 pin
exceeds a certain level.
PWM Capability (direct access)
Each low side driver offers additional (to the SPI control)
direct control via the PWMIN pin.
If both the bits LS1 and PWMLS1 are set in the Low Side
Control Register (LSCR), then the LS1 driver is turned on if
the PWMIN pin is high and turned off if the PWMIN pin is low.
The same applies to the LS2 and PWMLS2 bits for the LS2
driver.
VDD
VDD
PWMLSx
active
clamp
PWMIN
LSx
MOD1:2
LSx
LSxOP
LSxCL
Control
on/off
Status
Low Side Driver
(active clamp)
Open-load Detection
Current Limitation
Over-temperture Shutdown (interrupt maskable)
High-voltage shutdown (maskable)
Figure 18. Low Side Drivers LS1 and LS2
PGND
Open Load Detection
Each low side driver signals an open load condition if the
current through the low side is below the open load current
threshold.
The open load condition is indicated with the bit LS1OP
and LS2OP in the Low Side Status Register (LSSR).
Current Limitation
Each low side driver has a current limitation. In
combination with the over-temperature shutdown the low
side drivers are protected against over-current and short-
circuit failures.
When the drivers operate in current limitation, this is
indicated with the bits LS1CL and LS2CL in the LSSR.
Note: If the drivers are operating in current limitation mode
excessive power might be dissipated.
Over-temperature Protection (LS Interrupt)
Both low side drivers are protected against over-
temperature. In case of an over-temperature condition both
low side drivers are shut down and the event is latched in the
Interrupt Control Module. The shutdown is indicated as an LS
Interrupt in the Interrupt Source Register (ISR).
If the bit LSM is set in the Interrupt Mask Register (IMR)
than an Interrupt (IRQ) is generated.
A write to the Low Side Control Register (LSCR), when the
over-temperature condition is gone, will re-enable the low
side drivers.
High-voltage Shutdown
In case of a high-voltage condition and if the high-voltage
shutdown is enabed (bit HVSE in the Mode Control Register
(MCR) is set) both low sides drivers are shut down.
A write to the Low Side Control Register (LSCR), when the
high-voltage condition is gone, will re-enable the low side
drivers.
Sleep And Stop Mode
The low side drivers are disabled in Sleep and Stop Mode.
Also see Table 5, Operating Modes Overview.
Analog Integrated Circuit Device Data
Freescale Semiconductor
33912
31