FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
Stop
VDD: ON
(Limited Current
Capability),
CAN, SPI, L0:L3,
Cyclic Sense,
Forced Wake-Up,
Normally HIGH.
Signal 33742S
wake-up and
Running if
enabled.
Not running if
disabled
Low power.
Wake-up capability
if enabled
Active LOW if WDOG
(40)
I
DD > IDDS-WU
V2: OFF,
HS:OFF or Cyclic Sense
I
DD Overcurrent (39) or VDD undervoltage (not maskable)
occurs
Sleep
VDD: OFF,
V2: OFF,
HS: OFF or Cyclic
CAN, SPI,
L0:L3, Cyclic Sense
Forced Wake-Up
LOW
Not Active
Not running
Low power.
Wake-up capability
if enabled
Normal
Same as Normal
Same as Standby
Same as Stop
–
Normally HIGH.
Active LOW if VDD
undervoltage occurs
Same as Normal Not running
Same as Normal
Debug (38)
Standby
–
Normally HIGH.
Active LOW if VDD
undervoltage occurs
Same as Standby Not running Same as Standby
Debug (38)
Stop
Same as Stop
Normally HIGH.
Active LOW if VDD
undervoltage occurs
Same as Stop
Not operating
Not running
Same as Stop
Not operating
Debug (38)
Flash
Forced externally
–
Not operating
Not operating
Programming
Notes
38. Mode entered via special sequence described under the heading Debug Mode: Hardware and Software Debug with the 33742 beginning
on page 30.
39. IDD overcurrent always enabled.
40. WDOG if enabled.
mode overcurrent situation or from forced wake-up, no bits
are set. After the INT pulse, the 33742 accepts SPI command
after a time delay (tS-1STSPI).
APPLICATION WAKE-UP FROM THE 33742
When the application is in Stop mode, it can be awakened
from the SBC side. When a wake-up condition is detected by
the SBC (for example, CAN, wake-up input), the 33742
enters the Normal Request mode and generates an interrupt
pulse at the INT pin.
WATCHDOG SOFTWARE IN STOP MODE
If the SBC watchdog is enabled, the application must
provide a “system ok” response before the end of the 33742
watchdog time. Typically an MCU initiates the wake-up of the
33742 through the SPI wake-up (CS activation). The SBC will
awaken and jump into the Normal Request mode. The MCU
has to configure the 33742 to go to either Normal or Standby
mode. The MCU can then decide to return to the Stop mode.
APPLICATION WAKE-UP FROM THE MCU
When the device is in the Stop mode, a wake-up event
may come from the system MCU. In this case the MCU
selects the device the using a LOW-to-HIGH transition on the
33742 CS pin. Then the 33742S goes into Normal Request
mode and generates an interrupt pulse at the INT pin.
If no MCU wake-up occurs within the watchdog time
period, the SBC activates the RST pin and jumps into the
Normal Request mode. The MCU can then be re-initialized.
STOP MODE CURRENT MONITOR
If the VDD output current exceeds an internal set threshold
(IDDS-WU), the SBC automatically enters the Normal Request
mode and generates an interrupt at the INT pin. The interrupt
is a non-maskable and the INTR register will have no flag set.
STOP MODE ENTER COMMAND
Stop mode is entered at the end of the SPI message at the
rising edge of the CS. (Refer to the t CS-STOP data in the
Dynamic Electrical Characteristics table on page 17.) Once
Stop mode is entered, the SBC can wake up from a VDD
regulator overcurrent detection state. In order to allow time
for the MCU to complete the last CPU instruction and enter
its low power mode, a deglitcher time of 40 µs typical is
implemented.
INTERRUPT GENERATION WHEN WAKE-UP
FROM STOP MODE
When the SBC wakes from Stop mode, it first enters the
Normal Request mode before generating a 10 µs typical
pulse on the INT pin. These are non-maskable interrupts with
the wake-up event read through the SPI registers, the
CANWU bit in the CAN Register (CANR), or the LCTRx bit in
the Wake-Up Register (WUR). In case of wake-up from Stop
Figure 11, page 27, depicts the operation of entering the
Stop mode.
33742
Analog Integrated Circuit Device Data
Freescale Semiconductor
26
FREESCALE [ Freescale ]
