Datasheet

Time TMS Goes Low After POR

TMS

TEST

MSP430F23x0

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SLAS518E –AUGUST 2006– REVISED AUGUST 2011

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, I

, 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.

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 flows only when the fuse check mode is active and the TMS pin is in a low state (see

Figure 30). Therefore, the additional current flow can be prevented by holding the TMS pin high (default

condition).

Figure 30. Fuse Check Mode Current