FUNCTIONAL DESCRIPTION
INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
The 33911 was designed and developed as a highly
integrated and cost-effective solution for automotive and
industrial applications. For automotive body electronics, the
33911 is well suited to perform relay control in applications
like window lift, sunroof, etc. via a LIN bus.
which include a voltage sense port and two wake-up capable
pins. An internal voltage regulator provides power to a MCU
device.
Also included in this device is a LIN physical layer, which
communicates using a single wire. This enables this device
to be compatible with 3-wire bus systems, where one wire is
used for communication, one for battery, and one for ground.
Power switches are provided on the device configured as
high side and low side outputs. Other ports are also provided,
FUNCTIONAL PIN DESCRIPTION
See Figure 1, 33911 Simplified Application Diagram,
page 1, for a graphic representation of the various pins
referred to in the following paragraphs. Also, see the pin
diagram on page 3 for a description of the pin locations in the
package.
microcontroller. Data on this output pin changes on the
negative edge of the SCLK. When CS is High, this pin will
remain in high-impedance state.
CHIP SELECT (CS)
CS is an active low digital input. It must remain low during
a valid SPI communication and allow for several devices to
be connected in the same SPI bus without contention. A
rising edge on CS signals the end of the transmission and the
moment the data shifted in is latched. A valid transmission
must consist of 8 bits only.
RECEIVER OUTPUT (RXD)
The RXD pin is a digital output. It is the receiver output of
the LIN interface and reports the state of the bus voltage:
RXD Low when LIN bus is dominant, RXD High when LIN bus
is recessive.
While in STOP Mode a low-to-high level transition on this
pin will generate a wake-up condition.
TRANSMITTER INPUT (TXD)
The TXD pin is a digital input. It is the transmitter input of
the LIN interface and controls the state of the bus output
(dominant when TXD is Low, recessive when TXD is High).
ANALOG MULTIPLEXER (ADOUT0)
The ADOUT0 pin can be configured via the SPI to allow
the MCU A/D converter to read the several inputs of the
Analog Multiplexer, including the VSENSE, L1, L2 input
voltages and the internal junction temperature.
This pin has an internal pull-up to force recessive state in
case the input is left floating.
LIN BUS (LIN)
PWM INPUT CONTROL (PWMIN)
The LIN pin represents the single-wire bus transmitter and
receiver. It is suited for automotive bus systems and is
compliant to the LIN bus specification 2.0.
This digital input can control the high side and low side
drivers in Normal Request and Normal Mode.
The LIN interface is only active during Normal and Normal
Request Modes.
To enable PWM control, the MCU must perform a write
operation to the High Side Control Register (HSCR), or the
Low Side Control Register (LSCR).
SERIAL DATA CLOCK (SCLK)
This pin has an internal 20µA current pull-up.
The SCLK pin is the SPI clock input pin. MISO data
changes on the negative transition of the SCLK. MOSI is
sampled on the positive edge of the SCLK.
RESET (RST)
This bidirectional pin is used to reset the MCU in case the
33911 detects a reset condition, or to inform the 33911 that
the MCU was just reset. After release of the RST pin Normal
Request Mode is entered.
MASTER OUT SLAVE IN (MOSI)
The MOSI digital pin receives SPI data from the MCU. This
data input is sampled on the positive edge of SCLK.
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 VDD or
to GND during software development without the risk of
destroying the driver.
MASTER IN SLAVE OUT (MISO)
The MISO pin sends data to a SPI-enabled MCU. It is a
digital tri-state output used to shift serial data to the
33911
Analog Integrated Circuit Device Data
Freescale Semiconductor
20
FREESCALE [ Freescale ]
