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Lock Detection

Hall Input

Motor Output

LD

AL

Motor

locked

On

Off

Clamp voltage

Comparator voltage

Motor lock

cleared

Motor lock

detected

t

ON

t

OFF

Return to

normal operation

Power

AL

A few hundred milliseconds

TMP821

SLDS152 – JANUARY 2008

When a motor lock is detected, the TMP821 automatically shuts down its output current. When the motor lock is

removed, the TMP821 automatically restarts. Motor lock is detected when the Hall signal stops switching, as

shown in Figure 2.

Figure 2.

Where:

NOTE:

After power is supplied to the device, the the lock detection pin (AL) may remain high

for a few hundred milliseconds (see Figure 3).

Figure 3. Power-On to AL Delay

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