33912 Datasheet, PDF (22/47 Pages) Freescale Semiconductor, Inc – LIN System Basis Chip with DC Motor Pre-driver and Current

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
RESET PIN (RST)
This bidirectional pin is used to reset the MCU in case the
33912 detects a reset condition, or to inform the 33912 that
the MCU has just been reset. After release of the RST pin,
Normal Request Mode is entered.
The RST pin is an active low filtered input and output
formed by a weak pull-up and a switchable pull-down
structure which allows this pin to be shorted either to V_DD or
to GND during software development, without the risk of
destroying the driver.
INTERRUPT PIN (IRQ)
The IRQ pin is a digital output used to signal events or
faults to the MCU while in Normal and Normal Request Mode
or to signal a wake-up from Stop Mode. This active low output
will transition to high only after the interrupt is acknowledged
by a SPI read of the respective status bits.
WATCHDOG CONFIGURATION PIN (WDCONF)
The WDCONF pin is the configuration pin for the internal
watchdog. A resistor can be connected to this pin to configure
the window watchdog period. When connected directly to
ground, the watchdog will be disabled. When this pin is left
open, the watchdog period is fixed to its lower precision
internal default value (150ms typical).
GROUND CONNECTION PINS (AGND, PGND,
LGND)
The AGND, PGND and LGND pins are the Analog and
Power ground pins.
The AGND pin is the ground reference of the voltage
regulator and the current sense module.
The PGND and LGND pins are used for high current load
return as in the relay-drivers and LIN interface pin.
Note: PGND, AGND and LGND pins must be connected
together.
CURRENT SENSE AMPLIFIER INPUT PINS
(ISENSEH AND ISENSEL)
The ISENSEH and ISENSEL pins are the input pins of a
ground compatible differential amplifier designed to be used
to sense the voltage drop over a shunt resistor. The main
purpose of this amplifier is to implement accurate current
sensors. The gain of the differential amplifier can be set by
SPI.
LOW SIDE PINS (LS1 AND LS2)
LS1 and LS2 are the low side driver outputs. Those
outputs are short-circuit protected and include active clamp
circuitry to drive inductive loads. Due to the energy clamp
voltage on this pin, it can raise above the battery level when
switched off. The switches are controlled through the SPI and
can be configured to respond to a signal applied to the
PWMIN input pin.
Both low side switches are protected against overheating.
DIGITAL/ANALOG PINS (L1, L2, L3 AND L4)
The Lx pins are multi purpose inputs. They can be used as
digital inputs, which can be sampled by reading the SPI and
used for wake-up when 33912 is in low power mode or used
as analog inputs for the analog multiplexer. When used to
sense voltage outside the module, a 33kohms series resistor
must be used on each input.
When used as wake-up inputs L1-L4 can be configured to
operate in cyclic-sense mode. In this mode one of the high
side switches is configured to be periodically turned on and
sample the wake-up inputs. If a state change is detected
between two cycles a wake-up is initiated. The 33912 can
also wake-up from Stop or Sleep by a simple state change on
L1-L4.
When used as analog inputs, the voltage present on the Lx
pins is scaled down by an selectable internal voltage divider
and can be routed to the ADOUT0 output through the analog
multiplexer.
Note: If an Lx input is selected in the analog multiplexer, it
will be disabled as a digital input and remains disabled in low
power mode. No wake-up feature is available in that
condition.
When an Lx input is not selected in the analog multiplexer,
the voltage divider is disconnected from that input.
HIGH SIDE OUTPUT PINS (HS1 AND HS2)
These two high side switches are able to drive loads such
as relays or lamps. Their structures are connected to the VS2
supply pin. The pins are short-circuit protected and both
outputs are also protected against overheating.
HS1 and HS2 are controlled by SPI and can respond to a
signal applied to the PWMIN input pin.
HS1 and HS2 outputs can also be used during low-power
mode for the cyclic-sense of the wake inputs.
POWER SUPPLY PINS (VS1 AND VS2)
Those are the battery level voltage supply pins. In an
application, VS1 and VS2 pins must be protected against
reverse battery connection and negative transient voltages
with external components. These pins sustain standard
automotive voltage conditions such as a load dump at 40V.
The high side switches (HS1 and HS2) are supplied by the
VS2 pin. All other internal blocks are supplied by VS1 pin.
33912
22
Analog Integrated Circuit Device Data
Freescale Semiconductor