908E625 Datasheet, PDF (30/48 Pages) Freescale Semiconductor, Inc – Integrated Quad Half H-Bridge with Power Supply, Embedded MCU, and LIN Serial Communication

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
HxEN
HxF
Three-Terminal Hall-Effect Sensor
Vs
Sense
Hx
Out
Circuitry
V
GND
GND
Figure 15. Hall-Effect Sensor Input Terminal Connected to Three-Terminal Hall-Effect Sensor
CYCLIC WAKE-UP
Interrupts
The Hall-effect sensor input terminals are interrupt
capable. How and when an interrupt occurs is dependent on
the operating mode, RUN or Stop.
RUN Mode
In RUN mode the Hall-effect sensor input terminal interrupt
flag (HPF) will be set if a state change on the hallflags (HxF)
is detected. The interrupt is maskable with the HPIE bit in the
Interrupt Mask Register. Before enabling the interrupt, the
flag should be cleared in order to prevent a wrong interrupt.
The Hall-effect sensor inputs can be used to wake up the
system. This wake-up function is provided by the cyclic check
wake-up feature of the AWD (Autonomous Watchdog).
If the cyclic check wake-up feature is enabled (AWDCC bit
is set), the AWD switches on the enabled Hall-effect sensor
terminals periodically. To ensure that the Hall-effect sensor
current is stabilized after switching on, the inputs are sensed
after ~40 µs. If a 1 is detected (I_{Hall sensor} > I_HSCT) and the
interrupt mask bit HPIE is set, an interrupt is performed. This
wakes up the MCU and starts the main voltage regulator.
The wake-up function via this input is available when all
three conditions exist:
STOP Mode
• The two-terminal Hall-effect sensor input is enabled
(HxEN = 1)
In STOP mode the Hall-effect sensor input terminals are
disabled independent of the state of the HxEN flags.
• The cyclic wake-up of the AWD is enabled (AWDCC =
1); see Figure 16
• The Hall-effect sensor input terminal interrupt is
enabled (HPIE = 1)
908E625
30
Analog Integrated Circuit Device Data
Freescale Semiconductor