FUNCTIONAL DEVICE OPERATIONS
OPERATIONAL MODES
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.
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)
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.
The low side switches are controlled by the bit LS1:2 in the
Low Side Control Register (LSCR).
VDD
Interrupt
Control
VDD
HVSE
Module
PWMIN
PWMLSx
active
clamp
LSx
MOD1:2
Low Side Driver
on/off
(active clamp)
LSx
Open-load Detection
Current Limitation
Over-temperture Shutdown (interrupt maskable)
High-voltage shutdown (maskable)
Control
LSxOP
LSxCL
Status
PGND
Figure 18. Low Side Drivers LS1 and LS2
Open Load Detection
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).
Each low side driver signals an open load condition if the
current through the low side is below the open load current
threshold.
If the bit LSM is set in the Interrupt Mask Register (IMR)
than an Interrupt (IRQ) is generated.
The open load condition is indicated with the bit LS1OP
and LS2OP in the Low Side Status Register (LSSR).
A write to the Low Side Control Register (LSCR), when the
over-temperature condition is gone, will re-enable the low
side drivers.
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.
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.
When the drivers operate in current limitation, this is
indicated with the bits LS1CL and LS2CL in the LSSR.
A write to the Low Side Control Register (LSCR), when the
high-voltage condition is gone, will re-enable the low side
drivers.
Note: If the drivers are operating in current limitation mode
excessive power might be dissipated.
Sleep And Stop Mode
Over-temperature Protection (LS Interrupt)
The low side drivers are disabled in Sleep and Stop Mode.
Also see Table 5, Operating Modes Overview.
Both low side drivers are protected against over-
temperature. In case of an over-temperature condition both
33912
Analog Integrated Circuit Device Data
Freescale Semiconductor
31
FREESCALE [ Freescale ]
