FUNCTIONAL DESCRIPTION
INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
The 33742 and the 33742S are system basis chips (SBCs)
dedicated to automotive applications. Their functions include
the following:
• Sleep and Stop modes low power operating modes to
reduce an application’s current consumption while
providing a wake-up capability from the CAN interface,
L3:L0 wake-up inputs, or from a timer wake-up.
• Programmable wake-up input and cyclic sense wake-
ups.
• CAN high-speed physical bus interface with TXD and
RXD fault diagnostic capability and enhanced
protection features.
• One fully protected 5.0 V voltage regulator with 200 mA
total output current capability available at the VDD pin.
• VDD regulator undervoltage reset function,
programmable window or time-out software watchdog
function.
• Internal driver (V2) for an external series pass transistor
to implement a second 5.0 V voltage regulator.
• Two running modes: Normal and Standby modes set by
the system microcontroller.
• An SPI interface for use in communicating with a MCU
and Interrupt outputs to report SBC status, perform
diagnostics, and report wake-up events.
FUNCTIONAL PIN DESCRIPTION
RECEIVE AND TRANSMIT DATA (RXD AND TXD)
VOLTAGE SOURCE 2 (V2)
The RXD and TXD pins (receive data and transmit data
pins, respectively) are connected to a microcontroller’s CAN
protocol handler. TXD is an input and controls the CANH and
CANL line state (dominant when TXD is LOW, recessive
when TXD is HIGH). RXD is an output and reports the bus
state (RXD LOW when CAN bus is dominant, HIGH when
CAN bus is recessive).
The V2 pin is the input sense for the V2 regulator. It is
connected to the external series pass transistor. V2 is also
the 5.0 V supply of the internal CAN interface. It is possible to
connect V2 to an external 5.0 V regulator or to the VDD
output when no external series pass transistor is used. In this
case, the V2CTRL pin must be left open. Refer to Figure 31,
SBC Typical Application Schematic, page 52.
Voltage Digital Drain (VDD)
VOLTAGE SOURCE 2 CONTROL (V2CTRL)
The VDD pin is the output pin of the 5.0 V internal
regulator. It can deliver up to 200 mA. This output is protected
against overcurrent and overtemperature. It includes an
overtemperature pre-warning flag, which is set when the
internal regulator temperature exceeds 130°C typical. When
the temperature exceeds the overtemperature shutdown
(170°C typical), the regulator is turned off.
The V2CTRL pin is the output drive pin for the V2 regulator
connected to the external series pass transistor.
VOLTAGE SUPPLY (VSUP)
The VSUP pin is the battery supply input of the device.
HIGH-SIDE OUTPUT (HS)
VDD includes an undervoltage reset circuitry, which sets
the RST pin LOW when VDD is below the undervoltage reset
threshold.
The HS pin is the internal high-side driver output. It is
internally protected against overcurrent and
overtemperature.
RESET OUTPUT (RST)
LEVEL 0-3 INPUTS (L0: L3)
The Reset pin RST is an output that is set LOW when the
device is in reset mode. The RST pin is set HIGH when the
device is not in reset mode. RST includes an internal pullup
current source. When RST is LOW, the sink current capability
is limited, allowing RST to be shorted to 5.0 V for software
debug or software download purposes.
The L0:L3 pins can be connected to contact switches or
the output of other ICs for external inputs. The input states
can be read by SPI. These inputs can be used as wake-up
events for the SBC when operating in the Sleep or Stop
mode.
CAN HIGH AND CAN LOW OUTPUTS
(CANH AND CANL)
INTERRUPT OUTPUT (INT)
The Interrupt pin INT is an output that is set LOW when an
interrupt occurs. INT is enabled using the Interrupt Register
(INTR). When an interrupt occurs, INT stays LOW until the
interrupt source is cleared.
The CAN High and CAN Low pins are the interfaces to the
CAN bus lines. They are controlled by TXD input level, and
the state of CANH and CANL is reported through RXD output.
A 60 Ω termination resistor is connected between CANH and
CANL pins.
INT output also reports a wake-up event by a 10 µs typical
pulse when the device is in Stop mode.
33742
Analog Integrated Circuit Device Data
Freescale Semiconductor
22
FREESCALE [ Freescale ]
