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13. Over Current Protection (ISD)
Detection of current of the output power transistor is incorporated.
Each current flowing through four power transistors is detected individually. When the current exceeds the
detection value, the related output power transistor is turned off. Then all output power transistors are turned
off 1ms(typ) after this related output power transistor is turned off.
Timer is incorporated in this circuit. The motor operation resumes OFF time of 100ms (typ) after the over
current is detected. When state of over current continues, over current protection operates repeatedly. In case
this protection operates 8 times repeatedly, the motor operation does not resume automatically. The output
power transistor keeps turned off. In order to clear this state, VSP or the power supply should be applied again.
Design target value of current limit for over current protection is 2.5A. Masking term of 2 μs (typ) is configured
to avoid malfunction by noisy pulse current.
14. Thermal Shutdown Circuit (TSD)
Thermal shutdown circuit (TSD) operates when T
turned off after a 1ms(typ) PWM OFF term during which upper output power transistor is turned off.
The operation resumes when the temperature falls to 130℃(typ) or less.
Junction
170℃ (typ)
temperature
ジャンクション温度
(T j )
130℃ (typ)
内部TSD信号
Internal TSD signal
OUT1/OUT2
15. Under Voltage Lockout Protection (UVLO)
This IC has an under voltage lockout protection (UVLO).
The power supply voltage of VM and the voltage of VREG are monitored. When each of them falls to 2.9 V (typ)
or less, it is recognized as low voltage and the circuit is turned off. The normal operation resumes when both
voltage recovers to 3.2V (typ) or more.
VM voltage
VM電圧
VREG voltage
VREG電圧
内部UVLO
Internal UVLO
release signal
解除信号
OUT1,OUT2
FG,RDO
通常動作
Normal operation
3.1V (typ)
3.2V
2.9V
2.8V (typ)
通常動作
Normal operation
rises to 170℃(typ) or more. All output power transistors are
j
1ms
PWM
OFF （Hi-Z)
OFF
UVLO動作
UVLO protection
OFF （Hi-Z)
23
TC78B002FNG
通常動作
Normal operation
Normal
通常動作
operation
2013-10-17
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