33742 datasheet(32/65 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33742

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 5.0 V supply and (2) having the RST and the WDOG

outputs pins eternally forced to 0.0 V or 5.0 V 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.

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 tRSTDUR

time (device in Reset mode), before being pulled to VDD for

350 ms typical (device in Normal Request mode). During the

time reset is LOW, the RST pin sinks 5.0 mA maximum

(IPDW).

Figure 18. Simplified Schematic for Microcontroller Flash Programming

33742

MCU with

VDD

RST

WDOG

VSUP (Open or > 5.0 V

Programming Bus

Note External supply and sources applied to VDD, RST, and WDOG test points on application circuit board.

5.0 V

Programming Tool

Flash Memory

33742 Datasheet(PDF) 32 Page - Freescale Semiconductor, Inc