ꢀ ꢁꢂꢃ ꢄ ꢅ ꢆ ꢇ ꢄ ꢆ ꢈ ꢀ ꢁꢂꢃ ꢄ ꢅ ꢆ ꢇ ꢃ ꢆ ꢈ ꢀ ꢁꢂꢃ ꢄꢅ ꢆꢇꢃ ꢆꢇ
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SLAS272F − JULY 2000 − REVISED JUNE 2004
APPLICATION INFORMATION
JTAG fuse check mode
MSP430 devices that have the fuse on the TDI/TCLK 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, I , of 1 mA at 3 V, 2.5 mA at 5 V can flow from the TDI/TCLK pin to ground if the fuse is not burned.
TF
Care must be taken to avoid accidentally activating the fuse check mode and increasing overall system power
consumption.
Activation of the fuse check mode occurs with the first negative edge on the TMS pin after power up or if the
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 16). Therefore, the additional current flow can be prevented by holding the TMS pin high (default
condition).
Time TMS Goes Low After POR
TMS
I
TF
I
TDI/TCLK
Figure 16. Fuse Check Mode Current: MSP430F13x, MSP430F14x(1)
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