33742_08 Datasheet, PDF (36/70 Pages) Freescale Semiconductor, Inc – System Basis Chip with Enhanced High Speed CAN Transceiver

FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
MCU FLASH PROGRAMMING CONFIGURATION
To allow for new software to be loaded into a SBC’s MCU
NVM or to standalone EEPROM or Flash, the 33742 is
capable of having (1) VSUP applied to it to from an external
power 5.0V supply and (2) having the RST and the WDOG
outputs pins eternally forced to 0.0V or 5.0V without
damaging the device.
This allows the SBC to be externally powered and off-
board signals to be applied to the reset pins. No functions of
the 33742 are operating. Figure 18 illustrates a typical
configuration for the connection of programming and
debugging tools.
VSUP (Open or > 5.0V
33742
VDD
RST
WDOG
The VSUP should be left open or forced to a value equal
to or above V.
The VDD regulator uses an internal pass transistor
between VSUP and the VDD output pin. Biasing the VDD
output pin with a voltage greater than VDD potential will force
current through the body diode of the internal pass transistor
to the VSUP pin.
The RST pin is periodically pulled LOW for the t _RSTDUR
time (device in Reset mode), before being pulled to VDD for
350ms typical (device in Normal Request mode). During the
time reset is LOW, the RST pin sinks 5.0mA maximum
(I_PDW).
MCU with
Flash Memory
5.0 V
Programming Tool
Programming Bus
Note External supply and sources applied to VDD, RST, and WDOG test points on application circuit board.
Figure 18. Simplified Schematic for Microcontroller Flash Programming
33742
36
Analog Integrated Circuit Device Data
Freescale Semiconductor