LVC125A datasheet(32/46 Pages) TI

32 / 46 page

MSP430C11x1, MSP430F11x1A

MIXED SIGNAL MICROCONTROLLER

SLAS241H − SEPTEMBER 1999 − REVISED SEPTEMBER 2004

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

JTAG fuse check mode

MSP430 devices that have the fuse on the TEST terminal have a fuse check mode that tests the continuity of

the fuse the first time the JTAG port is accessed after a power-on reset (POR). When activated, a fuse check

current, ITF, of 1 mA at 3 V, 2.5 mA at 5 V can flow from the TEST pin to ground if the fuse is not burned. Care

must be taken to avoid accidentally activating the fuse check mode and increasing overall system power

consumption.

When the TEST pin is taken back low after a test or programming session, the fuse check mode and sense

currents are terminated.

Activation of the fuse check mode occurs with the first negative edge on the TMS pin after power up or if TMS

is being held low during power up. The second positive edge on the TMS pin deactivates the fuse check mode.

After deactivation, the fuse check mode remains inactive until another POR occurs. After each POR the fuse

check mode has the potential to be activated.

The fuse check current will only flow when the fuse check mode is active and the TMS pin is in a low state (see

Figure 13). Therefore, the additional current flow can be prevented by holding the TMS pin high (default

condition).

Time TMS Goes Low After POR

TMS

ITF

ITEST

Figure 13. Fuse Check Mode Current, MSP430F11x1A and MSP430C11x1

NOTE:

The CODE and RAM data protection is ensured if the JTAG fuse is blown and the 256-bit bootloader

access key is used. Also, see the bootstrap loader section for more information.

LVC125A Datasheet(PDF) 32 Page - Texas Instruments