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LV8731V-TLM-H

PWM Current Control Stepping Motor Driver

ON Semiconductor 

LV8731V

4-3) Auto reset type

In the automatic reset mode, when the output current exceeds the detection current level, the output waveform

changes to the switching waveform.

As with the latch system, when the output short-circuited state is detected, the short-circuit protection circuit is

activated. When the operation of the short-circuit detection circuit exceeds the timer latch time (Tcem) described later,

the output is changed over to the standby mode and is reset to the ON mode again in 2ms (typ). In this event, if the

over current mode still continues, the switching mode described above is repeated until the over current mode is

canceled.

4-4) Unusual condition warning output pins (EMO, MONI)

The LV8731V is provided with the EMO pin which notifies the CPU of an unusual condition if the protection circuit

operates by detecting an unusual condition of the IC. This pin is of the open-drain output type and when an unusual

condition is detected, the EMO output is placed in the ON (EMO = Low) state.

In the DC motor driver mode (DM = High), the MONI pin also functions as a warning output pin.

The functions of the EMO pin and MONI pin change as shown below depending on the state of the DM pin.

When the DM is low (STM mode) :

EMO : Unusual condition warning output pin

MONI : Excitation initial position detection monitoring

When the DM is high (DCM) mode) :

EMO : Channel 1 warning output pin

MONI : Channel 2 warning output pin

Furthermore, the EMO (MONI) pin is placed in the ON state when one of the following conditions occurs.

1. Shorting-to-power, shorting-to-ground, or shorting-to-load occurs at the output pin and the output short-circuit

protection circuit is activated.

2. The IC junction temperature rises and the thermal protection circuit is activated.

Unusual condition

Channel 1 short-circuit detected

Channel 2 short-circuit detected

Overheating condition detected

DM = L (STM mode)

EMO

MONI

ON

-

ON

-

ON

-

DM = H (DCM mode)

EMO

MONI

ON

-

-

ON

ON

ON

4-5) Timer latch time (Tcem)

The time taken for the output to be set to OFF when the output has been short-circuited can be set using capacitor

Ccem, connected between the CEM pin and GND. The value of capacitor Ccem is determined by the formula given

below.

Timer latch : Tcem

Tcem ≈ Ccem × Vtcem/Icem [sec]

Vtcem : Comparator threshold voltage, typ 1V

Icem : CEM pin charge current, typ 10μA

5. Thermal shutdown function

The thermal shutdown circuit is included, and the output is turned off when junction temperature Tj

exceeds 180°C and the abnormal state warning output is turned on at the same time.

When the temperature falls hysteresis level, output is driven again (automatic restoration)

The thermal shutdown circuit doesn’t guarantee protection of the set and the destruction prevention

of IC, because it works at the temperature that is higher than rating (Tjmax=150°C) of the junction

temperature

TTSD = 180°C (typ)

∆TSD = 40°C (typ)

No.A1482-22/26

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