lv8740v ON Semiconductor, lv8740v Datasheet - Page 19

• Manufacturer Part Number: lv8740v
• Description: Pwm Current Control Stepping Motor Driver
• Manufacturer: ON Semiconductor

Output short-circuit protection circuit
(1) Output short-circuit protection operation changeover function
(2) Latch method
(3) Automatic return method
(4) Abnormal state warning output pin
• When a voltage short, the earth fault or the load is short-circuited and the output short-circuit protection circuit
• When the junction temperature of IC rises, and the overheating protection circuit operates
This output short protection circuit that makes the output a standby mode to prevent the thing that IC destroys when
the output is short-circuited by a voltage short and the earth fault, etc. , and turns on the warning output to IC is built
into.
Changeover to the output short-circuit protection of IC is made by the setting of EMM pin.
In the latch mode, the output is turned off when the output current exceeds the detection current, and the state is
maintained.
The output short protection circuit starts operating so that IC may detect a short output. When the short-circuit is the
consecutive between internal timers (≈4μs), the output where the short-circuit is first detected is turned off. Even if
the following time (Tcem) of the timer latch is exceeded, the output is turned ON again, and afterwards, when the
short-circuit is detected, all the outputs of correspondence ch side are still switched to the standby mode, and the state
is maintained. This state is released by making it to ST ="L".
In the automatic return mode, the output wave type changes into the switching wave type when the output current
exceeds the detection current.
The short-circuit detection circuit operates when a short output is detected as well as the latch method. The output is
switched to the standby mode when the operation of the short-circuit detection circuit exceeds the following time
(Tcem) of the timer latch, and it returns to the turning on mode again after 2ms(TYP). At this time, the
above-mentioned switching mode is repeated when is still in the overcurrent mode until the overcurrent mode is made
clear.
When IC operates the protection circuit detecting abnormality, the EMO pin has been installed as a terminal that
outputs this abnormality to CPU side. This pin is an open drain output, and if abnormality is detected, the EMO output
becomes (EMO="L") of ON.
EMO pin enters on a state in the following.
operates, the output pin
Connect
detection status
Internal counter
CEM voltage
H bridge
output status
Low or Open
EMM
High
First counter
biginning
Conn-
ection
First counter
interruption
release
Auto reset method
Latch method
First counter
biginning
Output ON
State
Connection
LV8740V
First counter
end
Output OFF
Suresshu voltage
Second counter
biginning
Output ON
Second counter
Standby status
end
No.A1864-19/23