BD9610AMUV-E2 Datasheet, PDF (14/30 Pages) Rohm – 60V Synchronous Step-down Switching Regulator(Controller type)

BD9610AMUV
(11)PROGRAMING OCP
This IC monitors the voltage between CLH and CLL for turning on High-side driver (HG=ON).When this voltage is
over the threshold adjusted by RRCL, the output is turned off immediately. The switching current is detected by the
current detect resistor Rs connected the high side FET drain side usually.
The value of the OCP current is decided by the following .
IOCP= VOCPTH / Rs
(8)
IOCP：OCP detect current
VOCPTH：Threshold voltage between CLH and CLL programmed using RCL.
Rs：Current detect resistor
The OCP threshold is set by a single resistor RCL to ground. Please refer the following graph.
Using RRCL>12.5kΩ, take into consideration the increase of OCP variability.
VOCPTH = ( 0.8 / RRCL ) × 1850 [mV] RRCL: RCL pin connected resistor [kΩ]
40
30
20
10
0
-10
-20
-30
-40
0
OCP Production Tolerance Range
5
10
15
20
25
RRCL[kΩ]
Fig.29 OCP Variability vs RRCL
Recommend to fix OCP threshold voltage using Rs connecting between VCC and Drain of hi side Nch-FET and CR
filter between CLH and CLL.
It is available to response stability for control detected variation when connecting CLH and CLL trying not to are
common impedance between large current pass line and Rs both ends, and inserting CR filter between CLH and CLL.
CR filter for CLH and CLL is consist of following figure, the impedance of Cocp the lowest possible around noise
frequency(adjust noise frequency and self-resonant frequency ) and fixed filter constant with Rocp.
VCC
CLH
BD9610AMUV
CLL
HG
Put CR filter near IC
Vin
Wiring which separates sense
line from large current line.
Cocp
Rs
Rocp
Rgate
Take care of difference noise
Fig.30 Caution for CLH,CLL filter
Please note that selecting FET and wiring pattern when OCP detection using Ron of FET.
Because of variable Ron and large switching noise false detection, it is false detection.
Please connect CLH and CLL to VCC or line became voltage LX when FET is ON.
Connect RCL to REG5 and CLH,CLL to VCC with shortest wiring not to be used
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TSZ22111・14・001
14/27
TSZ02201-0Q1Q0AJ00010-1-2
24.OCT.2014 Rev.002