BD49101ARFS-M Datasheet, PDF (32/45 Pages) Rohm – Multi-channel Power Supply IC for Car Audio Systems

BD49101ARFS-M
(4) Setting of REG4 Over Current Protection Threshold and Cable Impedance Calibration
① Setting of Over Current Protection Threshold
The over current protection threshold (IRG4OCP) can be set by the resistance connected with CLCAL (RCLCAL).
The threshold can be obtained by the following formula (Typical Characteristic)
RCLCAL[Ω] = 5.1k x 1.96A / IRG4OCP[A]
The relation between resistance and the threshold is decided as shown in the figure below.
2.0
1.96
1.79
1.5
1.47
1.22
1.0
1.00
0.83
0.67
0.5
0.56
0.45
0.37 _{0.30 0.26 0.21 0.18}
0.0
0
10
20
30
40
50
60
OCP Threshold Current Setting
Resistance : R_CLCAL [kΩ]
R_CLCAL[kΩ]
5.1
5.6
6.8
8.2
10.0
12.0
15.0
18.0
22.0
27.0
33.0
39.0
47.0
56.0
I_RG4OCP[A]
1.96
1.79
1.47
1.22
1.00
0.83
0.67
0.56
0.45
0.37
0.30
0.26
0.21
0.18
Figure 62. Setting of Over Current Protection Threshold
② Setting of Cable Impedance Calibration
The cable impedance (RCABLE) calibration value can be set by the resistance connected with the VOCAL pin (RVOCAL).
This value can be obtained by the following formula (Typical Characteristic):
RVOCAL[Ω] = RCABLE[Ω] x 2400 / VOUT4
VOUT4: REG4 Output Setting Value(Typ)
250
V_OUT4=5.2V
200
150
100
50
0
0
0.1
0.2
0.3
0.4
0.5
Cable Resistance : R_CABLE [Ω]
R_CABLE[Ω]
0.000
0.022
0.039
0.085
0.163
0.217
0.238
0.260
0.282
0.325
0.347
0.390
0.433
0.477
0.520
R_VOCAL[Ω]
VOUT4=5.2V
0
10
18
39
75
100
110
120
130
150
160
180
200
220
240
Figure 63. Setting of Cable Impedance Calibration
When you set cable impedance, please assume VOUT4 absolute maximum rating(7.0V) and I/O voltage difference(0.4V max)
so that the cable impedance calibration cause rising output voltage.
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