MSP430F423IPM datasheet(45/59 Pages) TI1

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Time TMS Goes Low After POR

TMS

TDI/TCLK

MSP430F427, MSP430F425, MSP430F423

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SLAS421B – APRIL 2004 – REVISED NOVEMBER 2016

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Product Folder Links: MSP430F427 MSP430F425 MSP430F423

Detailed Description

6.10.7 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(TF)) of 1.8 mA at 3 V can flow from the TDI/TCLK pin to ground if the fuse

is not burned. Take care 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 flows only when the fuse check mode is active and the TMS pin is in a low state

(see Figure 6-16). Therefore, the additional current flow can be prevented by holding the TMS pin high

(default condition). The JTAG pins are terminated internally and therefore do not require external

termination.

Figure 6-16. Fuse Check Mode Current

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