Rohm TO-247N User manual

4th Generation SiC MOSFET
Half Bridge Evaluation Board
User’s Manual

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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
© 2022 ROHM Co., Ltd.
No. 63UG060E Rev.001
2022.2
<High Voltage Precautions>
◇Before you start operation!
This document describes only how to handle evaluation boards for SiC MOSFETs
(P04SCT4018KE-EVK-001, P05SCT4018KR-EVK-001).
Please refer to the product specifications for detailed information on schematics, BOM,
layout, etc.
In order to ensure safe operation, please read this document thoroughly
before using the evaluation board!
Also, depending on the voltage used and the structure of the board,
life-threatening voltages may be generated.
Be sure to strictly observe the precautions in the box below.
<Before Use>
①Make sure that no parts are damaged or missing, for example because the board has been dropped.
②Make sure that no conductive objects have fallen on the board.
③When soldering the module to the evaluation board, be careful of solder splattering.
④Make sure that there is no condensation or water droplets on the board.
<During Energization>
⑤Make sure that no conductive objects come into contact with the board.
⑥During operation, even a brief accidental contact or discharge due to bringing your
hand near the board may result in serious or life-threatening injury.
Never touch the board with bare hands or bring it too close to your hand.
Also, be careful when working with conductive instruments such as tweezers or screwdrivers, as
described above.
⑦If a higher voltage than the rated voltage is applied, the parts may explode depending on the
specification conditions such as short circuit. Also consider the danger of parts scattering.
⑧During operation, be careful of discoloration of the board and components due to heat, liquid
leakage, etc., and condensation when evaluating at low temperature.
<After Use>
⑨The evaluation board may contain a circuit that stores high voltage. Even if the connected power
supply circuit is disconnected, it still stores electric charge, so be sure to discharge it after use and
confirm that it is discharged before handling.
⑩Be careful of burns, etc. caused by contact with overheated components.
This evaluation board is to be used in research and development facilities and can only be
used by persons who are authorized to handle high voltage in each facility. When
working with high voltages, it is recommended to install signage such as “high voltage work
underway,” to use a cover with interlocks, etc., and to wear protective goggles to ensure a
safe working environment. Please read the cautionary note on short circuit protection for
this board at the beginning of this document.

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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
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No. 63UG060E Rev.001
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SiC MOSFET Evaluation Board
4th Generation MOSFET Evaluation Board
User’s Manual
This user guide explains how to use the evaluation board to evaluate 4th Generation SiC MOSFETs.
SiC MOSFETs handle high voltage and high current and need to be evaluated under various conditions to determine the
operating conditions for optimizing EMC noise and power supply efficiency. However, creating an appropriate evaluation
environment is not an easy task. To solve this problem, we have prepared an evaluation board that allows you to easily set various
conditions for evaluating the switching characteristics, so that you can efficiently evaluate SiC MOSFETs.
This user guide explains how to handle the evaluation boards for the TO-247N package and TO-247-4L. For detailed information
on product specifications, please refer to “4th generation SiC MOSFET Evaluation Board Product Specifications”
1. Introduction
Since this board has multiple voltage and signal sources supplied from external sources, be sure to follow the on/off sequence
specified below to avoid problems such as destruction.
Figure 1 On/Off sequence
Vcc
12 V
CLK
5.0V
HVdc
800 V
Power On
Sequence
Power Off
Sequence
Vcc
12 V
CLK
5.0V
HVdc
800 V
This evaluation board does not have a short circuit protection function for the evaluation
device.
Therefore, even with the normal evaluation method, if the usage deviates from the electrical
specifications (maximum current, etc.) of the evaluation device selected by the customer, the
device may be severely damaged with a popping sound. Therefore, never use the evaluation
board in a way that deviates from the specifications of the evaluation device. Also, take
precautions to prevent fragments from scattering and use protective equipment in case severe
damage occurs.

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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
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No. 63UG060E Rev.001
2022.2
In addition, this board is designed with the optimum gate drive circuit for "SCT4018KE" or "SCT4018KR" as a default setting,
surely other devices in "TO-247N" or "TO-247-4L" packages can also be mounted and evaluated. In this case, change the gate
drive circuit constants according to the characteristics of each device, referring to "4. How to set the gate drive voltage" and "5.
How to set the gate resistance”.
Table.1 shows the lineup and specifications of the 4th generation SiC MOSFET series.

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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
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No. 63UG060E Rev.001
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2. LED Display
The board is equipped with a number of LEDs to make it easy to monitor the board’s operating status.
The approximate locations of the LEDs are shown in Figure 2 and their details are shown in Table 2.
(a) PCB004P for TO-247N
(b) PCB005P for TO-247-4L
Figure 2. LED Location
HV alive
+5V ON
HS_Vcc2 ON
LS_Vcc2 ON
HS_Vcc2 ON
LS_Vcc2 ON
+5V ON
HV alive

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User’s Guide
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No. 63UG060E Rev.001
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Table 2 LED lights and their meanings
3. Connector Pin Assignment
Connector pin assignments are shown in Figure 3.
The definitions of each signal and power pin are shown in Table 3 and Table 4.
(1) CN1 (H-side signal input connector)
(2) CN101 (L-side signal input connector)
(3) CN201 (Control power supply power connector)
(4) JP51 (H-side negative bias/0 V switching connector)
(5) JP151 (L-side negative bias/0 V switching connector)
Figure 3 Connector pin assignment (Top view)
Silkscreen
notation
LED
LED lighting
Details
HV alive
Red
Lit
The LED lights up when there is a voltage of 20 V or more in the high-voltage
power supply HVdc. Never touch the board when this LED is lit, as it may be
lit even when the high-voltage power supply is disconnected.
Off
HVdc voltage is 20 V or less.
+5V_ON
Green
Lit
Lit during normal operation. When lit, control power (+12 V) is being output.
Off
No control power is applied.
HS_Vcc2_ON
LS_Vcc2_ON
Green
Lit
Lit during normal operation. The gate drive isolated power supply is rising
normally.
Off
No gate drive isolated power supply is being output.
VEE_HS
SOURCE_HS
GND2_HS
VEE_LS
SOURCE_LS
GND2_LS

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Table 3 Definition of power supply pins
Power supply
pin
Signal
Details
T1
HVdc
High-voltage input pin
The input pin during buck or inverter operation, but the output pin during boost
operation.
T2
Vsw
Power source pin of H-side MOSFET and drain pin of L-side MOSFET
This pin is connected in the board and cannot be disconnected.
T3
PGND
Power GND pin
Connected to SGND on the input signal side.
Table 4 Definition of signal lines
Connector
Pin
No.
Signal
I/O
Details
CN1
01
IN_H_CLK
I
Signal to turn on/off the H-side MOSFET. Turns on when at “H” level.
When open, it is pulled down with a 2.2 kΩ resistor.
02
SGND
--
Input signal side GND. Completely separated from the DUT side GND.
CN101
01
IN_L_CLK
I
Signal to turn on/off the L-side MOSFET. Turns on when at “H” level.
When open, it is pulled down with a 2.2 kΩ resistor.
02
SGND
--
Input signal side GND.
CN201
01
Vcc
--
Power supply pin for driver IC and internal control. The gate drive power
supply is generated internally from this power supply.
02
SGND
--
Input signal side GND.
JP51
01
SOURCE_HS
--
PCB004P: SOURCE signal of H-side DUT.
PCB005P: DRIVER SOURCE signal of H-side DUT.
02
GND2_HS
--
GND2 signal of H-side driver IC.
03
VEE_HS
--
H-side negative bias power supply.
JP151
01
SOURCE_LS
--
PCB004P: SOURCE signal of L-side DUT.
PCB005P: DRIVER SOURCE signal of L-side DUT.
02
GND2_LS
--
GND2 signal of L-side driver IC.
03
VEE_LS
--
L-side negative bias power supply.

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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
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No. 63UG060E Rev.001
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4.How to Set the Gate Drive Voltage
The gate drive voltage is supplied by an isolated flyback power supply mounted on-board. This flyback power supply uses a
photo-coupler-less control IC (BD7F200EFJ) manufactured by ROHM, and is equipped with transformers that output positive and
negative drive voltages on the HS and L-sides, respectively.
Figure 4 shows the layout of the on-board power supply.
Figure 4 Gate power supply configuration (Top view of PCB004P)
4.1 How to adjust the positive bias (VCC2)
The transformer (TX1, TX101) outputs of the isolated flyback power supply have a positive voltage and a negative voltage.
VCC2, which is the drive voltage (positive bias) of the MOSFET, is generated from the transformer positive output through LDO,
and the output voltage of LDO can be adjusted by the variable resistors RV51 and RV151. Rotating the variable resistors clockwise
increases the output voltage.
4.2 How to adjust the negative bias (VEE2)
The negative bias VEE2, which is the bias voltage when the MOSFET is off, is adjusted from the negative output of
transformers TX1 and TX101 by the shunt regulators SR1 and SR101 (TIV431 manufactured by TI) and by the variable resistors
RV51 and RV151 can be set in the range of -4.5 V to -2 V. VEE2 is supplied via the negative bias switching pins JP51 and JP151
to select between zero bias and VEE2 bias. The setting method is shown in Table 5.
Connector
Pin No.
Signal
Setting method
JP51
JP151
01
SOURCE
DRIVER_SOURCE
02
GND2
03
VEE
H-side VCC2
Adjustment
(RV51)
L-side isolation
Power supply
IC (U101)
L-side VCC2
Adjustment
(RV151)
L-side negative
bias switching
(JP151)
H-side isolation
Power supply
IC (U1)
L-side VEE2
Adjustment
(RV152)
H-side VEE2
Adjustment
(RV52)
H-side negative
bias switching
(JP51)
Table 5 Negative bias (VEE2) setting method
Pin 1-2 connection: 0 V bias
setting
Pin 2-3 connection: Negative
bias setting

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No. 63UG060E Rev.001
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Figure 5 Gate drive power supply circuit (HS-side)
VCC2
SOURCE
VEE
GND2

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User’s Guide
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No. 63UG060E Rev.001
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5. How to Set the Gate Resistance
A gate resistor is provided to adjust the switching speed of the MOSFET, and diodes (D52, D152) are connected in order to
set the turn-off side low, so that the switching speed of turn-on and turn-off can be adjusted separately.
Turn-on: H-side R55
L-side R155
Turn-off: H-side R56, D52
L-side R156, D152
Figures 6 (a) and (b) show the mounted state of the gate drive circuits of TO-247N and TO-247-4L, respectively, and Figure 7
shows the circuit diagram of TO-247N.
The output signal of the ROHM MOSFET driver IC (BM61M41RFV-C) directly drives the MOSFET via the gate resistor. Since
the pattern inductance of the driver circuit affects the surge voltage characteristics of the gate-source signal, it is recommended
to keep the wiring length as short as possible, so the circuit is composed of a minimum number of adjustment components.
Since the pin assignment of the gate pin is different between TO-247N and TO-247-4L, the board layout is optimized for each
package.
(a) For TO-247N (PCB004P)(b) For TO-247-4L (PCB005P)
Figure 6 Gate drive circuit mounted state
H-side
L-side
L-Side Gate
Resistor
H-Side Gate
Resistor
H-side Gate
Resistor
Driver IC
(BM61M41RFV-C)
H-side
L-side
L-Side Gate
Resistor
Driver IC
(BM61M41RFV-C)
Driver IC
(BM61M41RFV-C)
Driver IC
(BM61M41RFV-C)

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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
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No. 63UG060E Rev.001
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In the default setting, the turn-on and turn-off adjustment resistors have the same circuit configuration and are adjusted by
R55. However, if you want to set individual switching speeds for turn-on and turn-off, mount R56 and transmit the drive signal to
the MOSFET through resistor R55 for turn-on, and through D52 and R56 for turn-off. In this case, the gate resistor R55 is used
for turn-on, and R55 // R56 are connected in parallel for turn-off, resulting in faster turn-off.
Note that the footprint of diode D52 is for the anode and cathode, so it can be mounted in reverse. If the anode is connected
to the OUT pin of the driver IC (U2), the turn-on speed can be increased, so it can be used in different ways depending on the
characteristics of the device used.
Figure 7 Gate driver circuit (PCB004P)
6.Gate-source voltage measurement using an optical isolation probe
This evaluation board has patterns CX51 and CX151 near the gate terminals at the H-side and L-side DUT, respectively, and
by mounting the connectors, gate-source voltage measurement using an optical isolation probe can be performed. By using an
optically isolated probe, interference from common-mode noise can be removed and more accurate waveforms can be obtained.
(a) Connector mounting pattern b) Measurement using an optical isolation probe (c) Probe connections
Figure 8. Measurement method with Coaxial type shunt resistor
Gate
Resistor
CX51
CX151

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No. 63UG060E Rev.001
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7.How to Measure the Device Current
7.1 Measurement with a Rogowski-type current probe
This evaluation board has one through-hole (without plating) on each of the HS and L-sides, and a notch on the edge of the
board, so that the current flowing to each device can be easily measured using a Rogowski-type current probe. The H-side can
measure the current at the drain pin, and the L-side can measure the current at the power source side. Figure 9 shows the
appearance of the probe-related connections during measurement, and the enlarged photo shows the attachment of the current
probe.
The head of the Rogowski-type current probe is available in various sizes, and the applicable head is shown in Figure 10, with
a diameter of 25 mm to 30 mm and a wire diameter of 3 mm or less.
Figure 10 Applicable head part of Rogowski-type current probe
Figure 9 Current measurement with a Rogowski-type current probe (PCB005P)
Rogowski
Probe
L-side
L-side
H-side
Rogowski
Probe
H-side
(II)
(I)

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No. 63UG060E Rev.001
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7.2 Measurement with a coaxial-type shunt resistor
Rogowski-type current probes can be used for measurement without breaking up the current path during measurement, so
that waveforms can be observed while reproducing the circuit used in the device. On the other hand, the frequency band of the
measurement is not very wide.
In addition to the Rogowski-type current probe, there are other methods for observing current waveforms, such as using a
clamp-type current probe or a shunt resistor, and it is necessary to select the measuring instrument that matches the
measurement conditions. Clamp-type current probes are not recommended because they require an extension of the wiring to
attach the probe, which affects the switching characteristics of the DUT to some extent. In addition, general shunt resistors
generate a large amount of noise due to their own package inductance, making it impossible to accurately measure the current
waveform during switching. Therefore, a coaxial-type shunt resistor that can measure the rise in current at the ns level should
be used to measure the switching characteristics of the DUT.
Table 6 shows a comparison of the characteristics of a general Rogowski-type current probe and a coaxial-type shunt
resistor. While the Rogowski-type has a measurement bandwidth of several tens of MHz, the coaxial type supports up to several
GHz.
Table 6 Comparison of the characteristics of a Rogowski-type current probe and a coaxial-type shunt resistor
Rogowski
Coaxial
Model
(Manufacturer)
SS-285A
(IWATSU)
CWT3
(PEM)
TRCP0600
(Tektronix)
SDN-414-01
(T&M Research)
SDN-414-025
(T&M Research)
SDN-414-10
(T&M Research)
HF frequency
30MHz
16MHz
30MHz
400MHz
1200MHz
2000MHz
di/dt or rise time
(Peak Value)
4A/ns
(N/A)
4A/ns
(40A/ns)
N/A
1ns
0.3ns
0.18ns
This evaluation board has a layout that allows measurement with coaxial-type shunt resistors. Remove the resistor R321
(0.1 mΩ) shown in Figure 11(a), disconnect the source line of the lower arm, solder the coaxial-type shunt resistor as shown in
(b), and measure the source current of the lower arm DUT. At that time, the GND side of the coaxial-type shunt resistor should
be the source side of the DUT, and the GND of the coaxial-type shunt resistor (GND in the oscilloscope) should be based on the
source side of the DUT. This is to prevent mismatch of the GND level when measuring the gate-source voltage VGS of the lower
arm DUT with a general passive probe.
(a) R321 mounting position (b) Replaced with coaxial-type shunt resistor
Figure 11 Measurement method with coaxial-type shunt resistor
R321
Coaxial

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8. How to Mount the Heat Sink
When performing power conversion of several kW using this board, such as when taking efficiency measurements based on
the power supply topology, cooling by a heat sink or similar is essential because the power consumption of the device itself
reaches several tens of Watts. To install a heat sink, the device must be mounted on the solder side. The DUT is laid out on the
same side so that the commutation device can also be installed on the same heat sink. Figure 12 shows a schematic of the
mounting example, and Figure 13 shows a photograph of the mounted state. An equivalent product (33BS136) is available from
Sankyo Thermo-Tech with a thermal resistance of 1.16ºC/W.
Figure 12 Heat sink installation diagram
Figure 13 Example of heat sink
installation

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No. 63UG060E Rev.001
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Figure 14 Measurement view of heat sink installation
Figure 15 Efficiency
(SCT4036KR, BUCK, Rg=3.3Ω)
DUT
(Mounted on the
solder side)
Inductor
Heat Sink
Input Bulk
Capacitor
Output Bulk
Capacitor

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9.Evaluation Board Connection Example
9.1 Double-pulse test for H-side MOSFET
Figure 16 shows a double-pulse test circuit using a MOSFET on the H-side.
Figure 16 H-side double-pulse circuit
Prepare a pulse generator and connect the CLK signal to the IN_H_CLK pin (CN1 pin 1). Connect the 12 V power supply for
control to the Vcc pin (CN201) and the high-voltage HVdc power supply to the HVdc pin (T1). The operating procedure is as
follows.
①Turn on the power supply in the order of +12 V to HVdc.
②Input a pulse signal using the pulse generator.
The maximum current ID(peak) flowing through the inductor (L) can be roughly calculated by the following formula.
ID(PEAK) ≈ HVdc/L*TDP_TTL [A].
HVdc: Applied voltage [V]
L: Inductor value [µH].
TDP_TTL: Total time of double-pulse signal [µs]
Normally, the double-pulse signal is a single shot, but when it is applied periodically, it is necessary to ensure sufficient reset
time for the inductor current ID (PEAK). Since the reset voltage is only equal to the forward voltage VF of the flywheel diode,
determine the rough time using:
TRST = ID(PEAK)*L/VF [µs]
and ensure that the reset time TRST is about twice that value. Note that a heat sink is not necessary, but be careful not to raise
the temperature of the flywheel diode when performing repeated double-pulse tests.
+12V
Power
Supply
Pulse
Generator
(+5V output)
PGND
HVdc
DUT_HS
DUT_LS
HS-GADJ
LS-GADJ
IN_H_CLK
IN_L_CLK
LDO
Vcc1
DCR
Vsw
Vcc
ICAP
SNB
SGND
PGND
PGND
PGND PGND
SGND
HS_GD
PRIMERY
SECONDERY
BD7F200
HS
Gate Power
LS_GD
LS
Gate Power
BM61M41
BD7F200
BM61M41
VEE2
VCC2
VEE2
VCC2
Vcc1
HS_GSC
LS_GSC
UVLO2
UVLO2
RCD-SNB
RCD-SNB
HS-
VEESEL
LS
-
VEESEL
SGND
VEE2
GND2
GND2
UVLO
UVLO1
UVLO
UVLO1
LS_CS

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9.2 Double-pulse test with L-side MOSFET
Figure 17 shows the double-pulse test circuit using the L-side MOSFET.
Figure 17 L-side double-pulse circuit
After preparing the pulse generator and connecting the external CLK signal to the IN_L_CLK pin (CN101 pin 1), the procedure
is the same as for the H-side.
Pulse
Generator
(+5V output)
PGND
HVdc
DUT_HS
DUT_LS
HS-GADJ
LS-GADJ
IN_H_CLK
IN_L_CLK
LDO
Vcc1
DCR
Vsw
Vcc
ICAP
SNB
SGND
PGND
PGND
PGND PGND
SGND
HS_GD
PRIMERY
SECONDERY
BD7F200
HS
Gate Power
LS_GD
LS
Gate Power
BM61M41
BD7F200
BM61M41
VEE2
VCC2
VEE2
VCC2
Vcc1
HS_GSC
LS_GSC
UVLO2
UVLO2
RCD-SNB
RCD-SNB
HS-
VEESEL
LS
-
VEESEL
SGND
VEE2
GND2
GND2
UVLO
UVLO1
UVLO
UVLO1
LS_CS

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9.3 Boost power supply circuit
Figure 18 shows the boost operation test circuit in which the L-side MOSFET is switched.
Figure 18 Operation test circuit based on boost circuit
First, prepare a pulse generator and connect the CLK signal to the IN_L_CLK pin (CN101 pin 1). Connect the 12 V power
supply for control to the Vcc pin (CN201), the load inductance to the Vsw pin (T2), the high-voltage HVdc power supply to the
load inductance, and the electronic load to the HVdc pin (T1) as shown in Figure 17. The HVdc side is the output, and since the
output capacitor is mounted on the board, it is basically not necessary. However, if the oscillation frequency is low, it is
recommended to add an appropriate value externally. In this case, ensure that the rated voltage of the capacitor is sufficient.
The operating procedure is as follows.
①Turn on the +12 V power supply.
②Set the switching frequency and duty ratio using the pulse generator and input the CLK signal.
③Turn on the HVdc power supply.
④Adjust the output current with an electronic load device.
In CCM mode, where the inductor current is continuous, the output voltage will be approximately as follows.
Vout=Vin/(1-Duty)
If the inductor current is discontinuous (output current is small), the output voltage will increase out of proportion to the duty ratio
(output voltage varies with load current). This is because the pulses are not thinned out due to the open-loop control, but since
the output voltage reaches several tens of times the input voltage, care must be taken to gradually increase the input voltage
while keeping track of the output voltage value. When increasing the load current, pay attention to the heat generation of the
evaluation device, and if necessary, install a heat sink capable of sufficient cooling or consider the ambient temperature.
Pulse
Generator
(+5V output)
PGND
HVdc
DUT_HS
DUT_LS
HS-GADJ
LS-GADJ
IN_H_CLK
IN_L_CLK
LDO
Vcc1
DCR
Vsw
Vcc
ICAP
SNB
SGND
PGND
PGND
PGND PGND
SGND
HS_GD
PRIMERY
SECONDERY
BD7F200
HS
Gate Power
LS_GD
LS
Gate Power
BM61M41
BD7F200
BM61M41
VEE2
VCC2
VEE2
VCC2
Vcc1
HS_GSC
LS_GSC
UVLO2
UVLO2
RCD-SNB
RCD-SNB
HS-
VEESEL
LS
-
VEESEL
SGND
VEE2
GND2
GND2
UVLO
UVLO1
UVLO
UVLO1
LS_CS
Load

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9.4 Two-level inverter circuit
Figure 19 shows the operation test circuit for a 2-level inverter with a half-bridge configuration.
Figure 19 Operation test circuit for a 2-level inverter circuit
First, prepare a pulse generator and connect CLK signals to the IN_H_CLK and IN_L_CLK pins (CN1, CN101 pin 1).
Connect the 12 V power supply for control to the Vcc pin (CN201) and the load inductance to the Vsw pin (T2). Prepare two
high-voltage HVdc power supplies with the same voltage, connect them in series, and connect the upper one to the HVdc pin
(T1) and the lower one to the PGND pin (T3). Connect a smoothing capacitor and an AC load to one side of the load inductance
and connect its return line to the middle point of the series-connected high-voltage HVdc power supply.
When the AC output is on the + side, the H-side switches, and when it is on the - side, the L-side switches, and by controlling
the duty cycle of the CLK signal, a sinusoidal voltage is output.
The operating procedure is as follows.
①Turn on the +12 V power supply.
②Set the switching frequency and duty ratio using the pulse generator and input the CLK signal.
③Turn on the HVdc power supply.
④Adjust the output current with an AC load device.
When increasing the load current, pay attention to the heat generation of the evaluation device, and if necessary, install a heat
sink capable of sufficient cooling or consider the ambient temperature.
Pulse
Generator
(+5V output)
AC
Load
PGND
HVdc
DUT_HS
DUT_LS
HS-GADJ
LS-GADJ
IN_H_CLK
IN_L_CLK
LDO
Vcc1
DCR
Vsw
Vcc
ICAP
SNB
SGND
PGND
PGND
PGND PGND
SGND
HS_GD
PRIMERY
SECONDERY
BD7F200
HS
Gate Power
LS_GD
LS
Gate Power
BM61M41
BD7F200
BM61M41
VEE2
VCC2
VEE2
VCC2
Vcc1
HS_GSC
LS_GSC
UVLO2
UVLO2
RCD-SNB
RCD-SNB
HS-
VEESEL
LS
-
VEESEL
SGND
VEE2
GND2
GND2
UVLO
UVLO1
UVLO
UVLO1
LS_CS

19/27
TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
© 2022 ROHM Co., Ltd.
No. 63UG060E Rev.001
2022.2
9.5 Synchronous rectification-type buck power circuit
Figure 20 shows the buck operation test circuit using an H-side MOSFET.
Figure 20 Operation test circuit based on synchronous rectification-type buck power supply circuit
Prepare a pulse generator and connect CLK signals from outside to the IN_H_CLK pin (CN1, pin 1) and IN_L_CLK pin
(CN101, pin 1). Connect the 12 V power supply for control to the Vcc pin (CN201), the high-voltage HVdc power supply to the
HVdc pin (T1), and the load inductance to the Vsw pin (T2). Connect the smoothing capacitor and load to one side of the load
inductance. Since the HVdc side is the input, the input capacitor is mounted on the board and is basically not necessary.
However, if the oscillation frequency is low, it is recommended to add an appropriate value externally. In this case, ensure that
the rated voltage of the capacitor is sufficient.
The operating procedure is as follows.
①Turn on the +12 V power supply.
②Set the switching frequency and duty ratio using the pulse generator and input the CLK signal.
③Turn on the HVdc power supply.
④Adjust the output current with an electronic load device.
In CCM mode, where the inductor current is continuous, the output voltage will be approximately as follows.
Vout=Duty*Vin
On the other hand, in DCM mode, where the inductor current is discontinuous, the output voltage is equal to the input voltage
because the pulses are not thinned out due to open loop control. Since the output voltage is equal to the input voltage, pay
attention to the withstand voltage of the electronic load device.
To prevent the H-side and L-side MOSFETs from being turned on simultaneously, make sure there is enough dead time
between the IN_H_CLK and IN_L_CLK signals. When increasing the load current, pay attention to the heat generation of the
evaluation device, and if necessary, install a heat sink capable of sufficient cooling or consider the ambient temperature.
Pulse
Generator
(+5V output)
Load
PGND
HVdc
DUT_HS
DUT_LS
HS-GADJ
LS-GADJ
IN_H_CLK
IN_L_CLK
LDO
Vcc1
DCR
Vsw
Vcc
ICAP
SNB
SGND
PGND
PGND
PGND PGND
SGND
HS_GD
PRIMERY
SECONDERY
BD7F200
HS
Gate Power
LS_GD
LS
Gate Power
BM61M41
BD7F200
BM61M41
VEE2
VCC2
VEE2
VCC2
Vcc1
HS_GSC
LS_GSC
UVLO2
UVLO2
RCD-SNB
RCD-SNB
HS-
VEESEL
LS
-
VEESEL
SGND
VEE2
GND2
GND2
UVLO
UVLO1
UVLO
UVLO1
LS_CS