4/38
TO-247-4L Half-Bridge Evaluation Board
User’s Guide
©
2019 ROHM Co., Ltd.
No. 61UG047E Rev.001
August.2019
3.
OCP Setting
3.1 OCP Detection Signal
Over Current Protection (OCP) circuit detects the voltage drop across the current sense resistor mounted between LS MOSFET
Source and PGND, inputs the OCP detection signal to VTSIN input (pin 01) of LS MOSFET driver IC (U102), generates the FLT
signal at the input signal side, and makes all the CLK signals invalid including at the HS side.
OCP circuit is shown in Figure 3.
Figure 3.
OCP Circuit
In order to minimize the power consumed by the current sense resistor, the OCP circuit is designed to be able to operate with
negative bias drive, but VTSIN signal takes GND2 (pin 03) as a base, thus, it is not possible to input the OCP detection signal
directly to VTSIN input in case of negative bias drive. Resistors (R341, R342, R359) for level-shifting are interconnected with OCP
signal to the VTSIN pin, it is required to adjust this level-shifting circuit when changing the bias voltage. Resistor value for each bias
voltage is shown in Table 3. Furthermore, OCP detected point can be adjusted during the negative bias, remove the resistor R361 to
make it possible. Also R353 has to be changed in value at the same time due to a change of the OCP adjustable range.
OCP
220 Ω
47 mΩ
1/2W
R321~R330
R342
R350
R349
1k Ω
Q303
RV301
1.5kΩ
Q301
C313
1.5k Ω
100pF
1.5k Ω
1.5kΩ
Q302
Q304
R348
R347
R346
1000pF
4.7k Ω
R343
C312
C311
3.3kΩ
R345
C310
1
3
2
Q305
TP303
Current
Limit Adjust
4.7kΩ
100 Ω
R353
C309
R352
1.5k Ω
1000pF
C314
NOP
15k Ω
68kΩ
To MOSFET
Drain
4.7uF
R153
R151
R152
C163
TP154
C157
8.2 kΩ
100pF
VIN
VOUT
S-19700A00A-E8
U151
PGND
1000pF
R344
1.5kΩ
R358
R354
LED302
4.7kΩ
Q306
1.5kΩ
R356
SW301
1
3
4
2
OCP
RESET
R355
1.5kΩ
4.7kΩ
10kΩ
1.5kΩ
R357
R340
Q307
470 Ω
R359
6
5
3
2
10
13
9
EE2225
04398-T256
8T
8T
6T
12
11
4
32T
TX101
1
7
8
14
R361
470 Ω
R363
R362
0 Ω
NOP
R364
0 Ω
R365
NOP
NOP
C315
100pF
NOP
JP151
3
1
JP152
OUT2
VTSIN
VCC2
VREG
GND2
SCPIN
VEE2
01
BM6101FV-
CE2
To MOSFET
Source
ZD151
1000pF
6.8kΩ
0 Ω
10uF
TFZVTR2.0B
R341
Drain LS
②
OCP detection signal
Gate OFF signal
OCP
Latch
signal
OCP_GND
U102