33910 Datasheet, PDF (23/44 Pages) Freescale Semiconductor, Inc – LIN System Basis Chip with 2x60mA High Side Drivers

FUNCTIONAL DEVICE OPERATIONS
OPERATIONAL MODES
FUNCTIONAL DEVICE OPERATIONS
OPERATIONAL MODES
INTRODUCTION
The 33910 offers three main operating modes: Normal
(Run), Stop, and Sleep (Low Power). In Normal Mode the
device is active and is operating under normal application
conditions. The Stop and Sleep Modes are low power modes
with wake-up capabilities.
In Stop Mode the voltage regulator still supplies the MCU
with V_DD (limited current capability) and in Sleep Mode the
voltage regulator is turned off (V_DD = 0 V).
Wake-up from Stop Mode is initiated by a wake-up
interrupt. Wake-up from Sleep Mode is done by a reset and
the voltage regulator is turned back on.
The selection of the different modes is controlled by the
MOD1:2 bits in the mode control register (MCR).
Figure 15 describes how transitions are done between the
different operating modes and Table 5, 25, gives an overview
of the Operating Mode.
RESET MODE
The 33910 enters the Reset Mode after a power up. In this
mode, the RST pin is low for 1ms (typical value). After this
delay, the 33910 enters the Normal Request Mode and the
RST pin is driven high.
The Reset Mode is entered if a reset condition occurs (V_DD
low, watchdog trigger fail, after a wake-up from Sleep Mode,
Normal Request Mode time-out occurs).
NORMAL REQUEST MODE
This is a temporary mode automatically accessed by the
device after the Reset Mode or after a wake-up from Stop
Mode.
In Normal Request Mode, the VDD regulator is ON, the
Reset pin is high and the LIN is operating in Rx Only Mode.
As soon as the device enters the Normal Request Mode
an internal timer is started for 150ms (typical value). During
these 150ms, the MCU must configure the timing control
register (TIMCR) and the MCR with MOD2 and MOD1 bits
ste = 0 to enter in Normal Mode. If within the 150ms timeout
the MCU does not command the 33910 to Normal Mode, it
will enter in Reset Mode. If the WDCONF pin is grounded in
order to disable the watchdog function, the 33910 goes
directly in Normal Mode after the Reset Mode. If the
WDCONF pin is open, the 33910 stays typically for 150ms in
Normal Request before entering in Normal Mode.
NORMAL MODE
In Normal Mode, all 33910 functions are active and can be
controlled by the SPI and the PWMIN pin.
The VDD regulator is ON and delivers its full current
capability.
If an external resistor is connected between the WDCONF
pin and the Ground, the window watchdog function will be
enabled.
The wake-up input (L1) can be read as a digital input or
have its voltage routed through the analog-multiplexer.
The LIN interface has slew rate and timing compatible with
the LIN protocol specification 2.0. The LIN bus can transmit
and receive information.
The high side switches are active and have PWM
capability according to the SPI configuration.
The interrupts are generated to report failures 5 for V_SUP
over/under-voltage, thermal shutdown or thermal shutdown
prewarning on the main regulator.
SLEEP MODE
The Sleep Mode is a low power mode. From Normal
Mode, the device enters the Sleep Mode by sending one SPI
command through the MCR. All blocks are in their lowest
power consumption condition. Only some wake-up sources
(wake-up input with or without cyclic sense, forced wake-up
and LIN receiver) are active. The 5V regulator is OFF. The
internal low-power oscillator may be active if the IC is
configured for cyclic-sense. In this condition, one of the high
side switches is turned on periodically and the wake-up
inputs are sampled.
Wake-up from Sleep Mode is similar to a power-up. The
device goes in Reset Mode except that the SPI will report the
wake-up source and the BATFAIL flag is not set.
STOP MODE
The Stop Mode is the second low power mode, but in this
case the 5V regulator is ON with limited current drive
capability. The application MCU is always supplied while the
33910 is operating in Stop Mode.
The device can enter in Stop Mode only by sending the
SPI command. When the application is in this mode, it can
wake-up from the 33910 side (for example: cyclic sense,
force wake-up, LIN bus, wake inputs) or the MCU side (CS,
RST pins). Wake-up from Stop Mode will transition the 33910
to Normal Request Mode and generates an interrupt except
if the wake-up event is a low to high transition on the CS pin
or comes from the RST pin.
Analog Integrated Circuit Device Data
Freescale Semiconductor
33910
23