BD9B301MUV-LB Datasheet, PDF (18/33 Pages) Rohm – Over Current Protection

BD9B301MUV-LB
Datasheet
2. Protection
The protective circuits are intended for prevention of damage caused by unexpected accidents. Do not use them
for continuous protective operation
(1) Over Current Protection (OCP) / Short Circuit Protection (SCP)
Setting of Over current protection is 5.5A (Typ). When OCP is triggered, over current protection is realized by
restricting On / Off Duty of current flowing in upper MOSFET by each switching cycle. Also, if Over current protection
operates 512 cycles in a condition where FB terminal voltage reaches below 70% of internal standard voltage, Short
Circuit protection (SCP) operates and stops switching for 1msec (Typ) before it initiates restart. However, during
startup, Short circuit protection will not operate even if the IC is still in the SCP condition.
Table 1. Over Current Protection / Short Circuit Protection Function
EN terminal PGD
Startup
Over current
protection
L
More than 2.0V
While start up
Startup completed
Valid
Valid
H
＊
Valid
Less than 0.8V ＊
＊
Invalid
Short circuit
protection
Invalid
Valid
Invalid
Invalid
V_OUT
FB
High side
MOSFET gate
Low side
MOSFET gate
OCP threshold
Coil current
1ms(typ.)
Inside IC
OCP signal
PGD
1024 Cycle
Figure 46. Short Circuit Protection (SCP) Timing Chart
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TSZ22111 • 15 • 001
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TSZ02201-0J3J0AJ00830-1-2
2015.04.02 Rev.001