LV8731V
4. Output short-circuit protection function
This IC incorporates an output short-circuit protection circuit that, when the output has been shorted by an event such
as shorting to power or shorting to ground, sets the output to the standby mode and turns on the warning output in
order to prevent the IC from being damaged. In the stepping motor driver (STM) mode (DM = Low), this function
sets the output to the standby mode for both channels by detecting the short-circuiting in one of the channels. In the
DC motor driver mode (DM = High), channels 1 and 2 operate independently. (Even if the output of channel 1 has
been short-circuited, channel 2 will operate normally.)
4-1) Output short-circuit protection mode switching function
Output short-circuit protection mode of IC can be switched by the setting of EMM pin.
EMM
State
Low or Open
Latch method
High
Auto reset method
4-2) Latch type
In the latch mode, when the output current exceeds the detection current level, the output is turned OFF, and this state
is held.
The detection of the output short-circuited state by the IC causes the output short-circuit protection circuit to be
activated.
When the short-circuited state continues for the period of time set using the internal timer (approximately 2μs), the
output in which the short-circuiting has been detected is first set to OFF. After this, the output is set to ON again as
soon as the timer latch time (Tcem) described later has been exceeded, and if the short-circuited state is still detected,
all the outputs of the channel concerned are switched to the standby mode, and this state is held.
This state is released by setting ST to low.
H-bridge
output state
Output ON
Output OFF
Output ON
Standby state
Threshold voltage
2μs
CEM voltage
Short-circuit
detection state
Short- Release
circuit
Short-circuit
Internal counter
1st counter 1st counter 1st counter
start
stop
start
1st counter
end
2nd counter 2nd counter
start
end
No.A1482-21/26