Apprication Note (PDF: 1.9MB)

Quasi-Resonant type AC/DC converter IC
BD768xFJ-LB series Quasi-Resonant converter Technical Design
24V / 1A ( SIC TO-3PFM SCT2H12NZ)
This application note describes the design of Quasi-Resonant converters using ROHM’s AC/DC converter IC BD768xFJ-LB
series devices. It explains the selection of external components and PCB layout guidelines.
● Description
The BD768xFJ-LB series are Quasi-Resonant switching AC/DC converter for driving SiC (Silicon Carbide)–MOSFET. Using
external switching MOSFET and current detection resistors provides a lot of flexibility in the design. Power efficiency is
improved by the burst function and the reduction of switching frequency under light load conditions.
This is the product that guarantees long time support in the Industrial market.
● Key features
Quasi-resonant method(Maximum frequency control 120kHz)/Current mode
Low power when load is light ( Burst operation) / Frequency reduction function
VCC pin : under voltage protection / over voltage protection
Leading-Edge-Blanking function
Over-current protection (cycle-by-cycle)
ZT trigger mask function
ZT Over voltage protection
AC voltage correction function
Soft start
Brown IN/OUT function
Gate Clamp circuit
MASK Function
● Basic specifications
Operating power supply voltage range(VCC):
Operating current
:VCC:15.0V~27.5V
Normal mode
:0.80mA (Typ.)
Burst mode
:0.50mA(Typ.)
Maximum frequency
:120kHz(Typ.)
Operating temperature range
:-40℃ to +105℃
(*) Product structure:Silicon monolithic integrated circuit This product has no designed protection against radioactive rays
(*) Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between
pins or an open circuit between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures,
such as adding a fuse, in case the IC is operated over the absolute maximum ratings.
● BD768xFJ-LB Series line-up
BD7682FJ
BD7683FJ
BD7684FJ
BD7685FJ
FBOLP
AutoRestart
Latch
AutoRestart
Latch
VCCOVP
Latch
Latch
AutoRestart
AutoRestart
● Applications
Industrial equipment, AC Adaptor, Household appliances
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
1/24
2016.04.06
Rev.A
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
● Block Diagram
VH
FUSE
Filter
VOUT
Rstart
RH
Diode
Bridge
Va
RL
Cvcc
8
7
BO
VCC
BO
Comp.
VCC UVLO
+
+
-
-
15uA
1.0V
4.0V
Regulator Internal
18.5V/14.0V
18.0V
Clamper
Supply
NOUT
+
-
ZT ACSNS Comp.
+
VCC OVP
+
-
Rzt1
ZT
1
ZT OVP Comp.
(LATCH)
ZT
Comp.
+
TimeOut
( 15 usec )
7V
Rzt2
ZT Blanking
OUT(H->L)
0.60us
100mV
/400mV
OSC
+
-
ERROR
AMP
OR
POUT
AND
S Q
NOUT
FBOLP_OH
AND
OR
MAX
Blanking
Frequency
(120kHz)
+
VREF(4V)
OSC
1 shot
AND
-
Czt
28.0V
5 OUT
PRE
Driver
NOUT
R
1.00V
20k
FB
2
+
Burst
Comp.
-
0.50V
Cfb
6
OLP
+
-
Timer
(128ms)
MASK
0.5μs
Delay
FBOLP_OH
NOR
Soft Start
200kΩ
200kΩ
FB/2
1.00V
-
DCDC
Comp.
SS1ms
SS4ms
+
CURRENT SENSE (V-V Change)
Normal : ×1.0
Leading Edge
Blanking
3
CS
RS
4
GND
PC
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
2/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
Contents
1. Design of Isolated Fly-buck Quasi-Resonant convertor
1-1.Transformer T1 design
1-1-1.Determination of fly-back voltage VOR
1-1-2.Determination of Minimum frequency fsw and calculation of primary -side winding inductance Lp
1-1-3.Determination of transformer size
1-1-4.Calculation of primary-side turn count Np
1-1-5.Calculation of secondary-side turn count Ns
1-1-6.Calculation of VCC turn count Nd
1-1-7.Transformer design
1-2.Selection of main components
1-2-1.MOSFET:Q1
1-2-2.Input capacitor: C2,C3,C4
Balance resistance: R1,R2,R3,R4,R5,R6
1-2-3.Current-sensing resistor: R19
Resistance for noise protection of CS terminal:R22
1-2-4.Overload protection correction setting resistor : R20
1-2-5.Setting resistor for ZT terminal voltage: R21
1-2-6.ZT terminal capacitor: C11
1-2-7.VCC-diode: D18
1-2-8.VCC winding surge-voltage limiting resistor: Rvcc1
1-2-9.VCC starter resistance ;R11,R12,R13,R14 capacitance;C5,C6 and Rectifier diode;D19
1-2-10.Brown IN/OUT resistance: R7,R8,R9,R10,R15 and BO capacitor: C8
1-2-11.Snubber circuits: Csnubber1,Rsnubber1,D13,D14,D15,D16
1-2-12.FB terminal capacitor: C12
1-2-13.MOSFET gate circuit: R16,R17,R18,D17
1-2-14.Output rectification diode: ND1
1-2-15.Output capacitors: Cout1,Cout2,Cout3,Cout4
1-2-16.Output voltage setting resistors: R25,R26,R28
1-2-17.Parts for adjustment of control circuit: R24,R27,R32,C15
1-3.EMI countermeasures
1-4.Output noise countermeasures
1-5.Proposed PCB layout
2. Evaluation result
2.1. Evaluation circuit and parts list
2.2. Evaluation Result (Efficiency)
2.3. Evaluation Result (Waveform)
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
3/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1.Design of Isolated Fly-buck Quasi-Resonant convertor
Quasi-resonant converter is self-excited fly-back converter power supply system using the voltage resonance of the transformer
primary winding inductor and resonant capacitor.
Generally, Quasi-resonant converter is possible to reduce the loss and noise than the PWM fly-back converter.
Quasi-Resonant Converter becomes DCM (Discontinuous Conduction Mode) under light load, and switching frequency
increases with the load increasing. When the load increased further, Quasi-Resonant Converter becomes BCM (Boundary
Conduction Mode), and switching frequency decreases with the load increasing.
The relation of switching Frequency and output load characteristics is shown in Figure 1-2. The Switching waveform at DCM and
CCM is shown in Figure 1-2.
Switching
Frequency
Boundary
point
DCM
BCM
Output
Load
Figure 1-1.Switching Frequency – Output Load Characteristics
IC detects Bottom and controls a timing of
switching turn ON.
BCM
DCM
Figure 1-2.Switching waveform (MOSFET Vds,Ids)
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
4/24
2016.04.06
Rev.A
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
1-1.Transformer T1 design (24V1A, Vin(DC)=300V~900V)
1-1-1.Determination of fly-back voltage VOR
Turns-ratio Np:Ns and duty-ratio is determined along
with Fly-back voltage VOR
Np ton

 VIN
Ns toff
Np VOR


Ns
VO
VOR
 Duty 
VIN  VOR
VOR  VO 
VIN→
VOR
When VIN(MIN)=300V, VOR=204V, Vf=1.5V:
GND→
Np VOR
VOR
204V



 8.0
Ns
VO
Vout  Vf 24V  1.5V
VOR
204V
Duty(max) 

 0.405
VIN(min)  VOR 300V  204V
Figure1-3.MOSFET Vds
(*) VOR is adjusted to set it below 0.5 in consideration of MOSFET’s loss.
1-1-2.Determination of Minimum frequency fsw and calculation of primary side winding inductance Lp
The primary side maximum current Ippk and the primary side winding inductance Lp is determined from the minimum
input voltage(VIN=300V) and the minimum frequency (Fsw=92kHz).
Other’s parameter is following:
Po=24V × 1A=24W, Po (max)=30W(de-rating 0.8) in consideration of over current protection.
Transformer efficiency:η=85%
Resonance capacitor: Cv=100pF
2




VIN
(min)

Duty
(max)
  1755uH Lp  
 2  Po(max)  fsw

 VIN(min)  Duty (max)  fsw    Cv 




Ippk 
2  Po (max)
 0.662 A
η Lp  fsw
1-1-3.Determination of transformer size
Core size of the transformer is determined to EFD30 by the condition of Po(max)=30W.
Table 1-1. Output Voltage and Transformer Core
Core sectional area
Ae (mm2)
~30
EI25/EE25
41
~50
EFD30
68
~60
EI28/EE28/EER28
84
~80
EI33/EER35
107
(*) The above is guideline values. For details, check with the transformer manufacturer, etc.
Output power Po(W)
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
Core size
5/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-1-4.Calculation of primary-side turn count Np
Generally, the maximum magnetic flux density B(T) for an ordinary ferrite core is 0.4T @100°C, so Bsat = 0.3T.
Np 
Lp  Ippk 1750uH  0.66A

 57turns Ae  Bsat
68mm 2  0.3T
In order not to cause a magnetic saturation, the IC must be used
in areas that do not saturate from AL-Value-NI characteristics.
In the case of Np=50 turns:
AL  Value 
Np=50turns
AL-Value=700nH/turns2
NI=33A・turns
Lp
1750uH

 700nH / turns 2
Np 2 50turns 2
NI  Np  Ippk  50turns  0.66A  33A・turns
Transformer is saturated based on the AL-value-NI characteristics.
Set the number of primary winding so as not to be saturation region.
In the case of Np=64 turns:
AL  Value 
Lp
1750uH

 427nH / turns 2
Np 2 64turns 2
Np=64turns
AL-Value=427nH/turns2
NI=42.2A・turns
Figure 1-4.
NI  Np  Ippk  64turns  0.66A  42.2A・turns
AL-Value-NI Limit
Reference Characteristics
In this case, this point is within the tolerance range
Np = 64 turns is determined
1-1-5.Calculation of secondary-side turn count Ns
Np
64
 8  Ns 
 8 turns Ns
8
1-1-6.Calculation of VCC turn count Nd
When VCC=24V, Vf_vcc=1V,
Nd  Ns 
VCC  Vf_vcc
24V  1.0V
 8turns 
 7.8turns Vout  Vf
24V  1.5V
(*)In the case of driving SiC-MOSFET, since it is necessary to control the Gate voltage, VCC is required more than 22V.
As a result, the transformer specifications are as follows.
Table 1-2. Transformer Specifications
Core
EFD30 compatible
Lp
1750uH
Np
64 turns
Ns
8 turns
Nd
8 turns
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
6/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-1-7. Transformer design
White
Marking
dot
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
7/24
2016.04.06
Rev.A
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
1-2.Selection of main components
1-2-1.MOSFET:Q1
For MOSFET selection, it must be considered maximum voltage between the drain and source, peak current, losses due to
Ron, maximum power dissipation of the package.
At low input voltage, the ON time of the MOSFET becomes long and the heat generated by Ron loss is bigger.
Be sure to confirm the state incorporated in the product and execute the heat dissipation of the heat sink as needed.
Current rating should be selected twice about Ippk.
Vds (max)  VIN (max)  VOR  Vspike  VIN (max)  Vout  Vf  
Np
64turns
 Vspike  DC900V  (24V  1.5V ) 
 Vspike
Ns
8turns
 1104V  Vspike
Calculation of Vspike is difficult. MOSFET breakdown voltage is 1700V by using a snubber circuit.
In this design example, ROHM’s MOSFET SCT2H12NZ(1700V 4A 1.15Ω) is selected .
Below show the typical characteristics of SCT2H12NY. Please refer to the SCT2H12NY data sheet for formal data.
○ABSOLUTE MAXIMUM RATINGS
[Tj=25oC]
・・・
1700V
GATE-SOURCE VOLTAGE
VDSS
VGSS
・・・
-6V ~ +22V
DRAIN CURRENT CONTINUOUS
ID
・・・
±4A (Limited by Tj)
RAIN CURRENT PULSED
IDP
・・・
±10A PW≦10µs
SOURCE CURRENT CONTINUOUS
IS
・・・
4A (BODY DIODE. Limited by Tj.)
SOURCE CURRENT PULSED
ISP
・・・
10A PW≦10µs
DRAIN-SOURCE VOLTAGE
DUTY CYCLE≦1%
DUTY CYCLE≦1%
(BODY DIODE.)
TOTAL POWER DISSIPATION
PD
JUNCTION TEMPERATURE
Tj
RANGE OF STORAGE TEMPERATURE Tstg
PARAMETER
GATE-SOURCE LEAKAGE CURRENT
GATE-SOURCE LEAKAGE CURRENT
DRAIN-SOURCE BREAKDOWN VOLTAGE
ITEM
・・・
44W
・・・
175 oC
・・・
-55~175 oC
CONDITION
MIN.
TYP.
MAX.
-
-
100nA
IGSS+
VGS=+22V/VDS=0V
IGSS-
VGS=-6V/VDS=0V
-
-
-100nA
V(BR)DSS
ID=1mA/VGS=0V
1700V
-
-
ZERO GATE VOLTAGE DRAIN
CURRENT
IDSS
VDS=1700V/VGS=0V
-
0.1μA
10μA
GATE THRESHOLD VOLTAGE
VGS(th)
VDS= VGS /ID=410μA
STATIC DRAIN-SOURCE
ON-STATE RESISTANCE
RDS(on)
*PULSED
ID=1.1A/VGS=18V
Tj=25oC
ID=1.1A/VGS=18V
Tj=125oC
TRANSCONDUCTANCE
gfs
*PULSED
VDS=10V/ID=1.1A
INPUT CAPACITANCE
Ciss
OUTPUT CAPACITANCE
Coss
REVERSE TRANSFER CAPACITANCE
Crss
GATE INPUT RESISTANCE
Rg
TURN-ON DELAY TIME
RISE TIME
TURN-OFF DELAY TIME
FALL TIME
TOTAL GATE CHARGE
GATE-SOURCE CHARGE
GATE-DRAIN CHARGE
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
td(on)
*PULSED
tr
*PULSED
td(off)
*PULSED
tf
*PULSED
Qg
*PULSED
Qgs
*PULSED
Qgd
*PULSED
VDS=800V/VGS=0V
f=1MHz
f=1MHz open Drain
VDD=500V
ID=1.1A
VGS=18V/0V
RL=455Ω
RG=0Ω
VDD=500V
ID=1A
VGS=18V
RL=500Ω
8/24
1.6V
-
4.0V
0.80Ω
1.15Ω
1.50Ω
-
1.71Ω
-
-
0.4S
-
-
184pF
-
-
16pF
-
-
6pF
-
-
64Ω
-
-
16.3ns
-
-
20.9ns
-
-
35.1ns
-
-
73.8ns
-
-
14nC
-
-
4nC
-
-
5nC
-
2016.04.06
Rev.A
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
1-2-2.Input capacitor: C2,C3,C4
Balance resistance: R1,R2,R3,R4,R5,R6
Use Table 1-3 to select the capacitance of the input capacitor.
Cmain:1x25=25 → 33uF
Since Pout=24Vx1.1A≒25W
Table 1-3. Input Capacitor
Input voltage(Vdc)
Cin(uF)
Selection
Table
< 300
2 x Pout(W)
300<
1 x Pout(W)
(*)When selecting, also consider other specifications such as the retention-time.
The breakdown voltage of the capacitor is required above the maximum input voltage.
VIN(MAX)/de-rating=900V/0.8=1125V
Using three 450V breakdown voltage capacitors in series, the breakdown voltage of the capacitor is 450V × 3 = 1350V.
As noted, when connecting the capacitors in series, the balanced resistance is required for a constant voltage applied to all
capacitors. Since the resistance is in loss, it is recommended to use more resistance 470kohm.
CN2
R1,R2,R3,R4,R5,R6’s loss is below.
VDC:300~1000V
1
D21
1
D20
2 1
2
1N4007 IN4007
P11_12_13_14_15_16=VN(MAX)×VIN(MAX)/R=900V×900V/2.82Mohm=0.287W
DC_IN
2
It is shown in Figure 1-5.
HV+
3
1
2
D5
D9
R7
R11
470k
1M
2
200K
D15
Csnubber1
2200pF
R31
D16
10
1.5KE
2
2 1
C2
100uF
R2
2
2
IN4007
2 1
IN4007
2 1
1
D1
IN4007
2
2
2
R1
470k
1.5KE
Rsnubber1
1mH
1
1
L1
R8
5.1
CN1
470k
VAR2
D13
1M
UF4007
D14
VAR1
R3
UF4007
5.1
C1
3
0.33uF
VAR3
470k
100uF
R9
R13
470k
470k
C9
R4
2
RT3
t
VAC:400~690V
C3
1
RT2
1
2
2
AC_IN
t
1
1
R12
2 1
t
RT1
470k
1
D10
1N4007
1
D6
1N4007
1
D2
1N4007
470k
5.1
2
0.33uF
R10
470k
1
IN4007
2
IN4007
D11
470k
150
10
D8
D12
1N4007
1N4007
R1
10
470k
CIN4
1
2200p
L2
R19
2
1mH
R22
1.5
1k
L4
1
2
Figure 1-5.Input capacitor and Balance resistance
2200p
C7
C6
C5
0.1uF
4.7uF
22uF
5
6
0
OUT
MASK
VCC
BO
7
U1
8
CY3
Resistance for noise protection of CS
2200p terminal:R22
The current-sensing resistor limits the current that flows on the primary side to provide protection against output overload.
47pF
R15
10k
C11
C12
4
CS
3
FB
2
ZT
1
C8
Sensing resistor loss P_R19:
GND
BD7682FJ
Vcs
1.0V
R19 

 1.515Ω Ippk 0.66 A
C13
47pF 2200pF
47pF
P_R19(peak)  Ippk2  R19  0.66 A2  1.5Ω  0.6534W
2


Duty(max) 
0.404 
  R19   0.66A 
  1.0  0.0586W P_R19(rms)  Iprms2  R19   Ippk


3
3 



Set the value 1W or above in consideration of pulse resistance.
The structure of the resistance may vary the pulse resistance even with the same power rating.
Check with the resistor manufacturers for details.
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
9/24
2016.04.06
1
10
0
2
Rvcc1
1
Rev.A
2
2200p
1-2-3.Current-sensing resistor: R19
D19
CY2
1
CY1
2
HV+
1G
R6
D4
1N4007
1
100uF
R16
IN4007
2 1
D7
2 1
D3
2
2200p
R5
Q
R17
2 1
2200p
C4
1
1
2200p
R14
470k
2
CIN1
1
CIN2
2
CIN3
D17
RB160L-60
2
2
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
1-2-4. Overload protection correction setting resistor: R20
BD768xFJ-LB series has overload protection correction function in the input voltage. After the IC detects overload, there is
a delay time to stop the switching operation. This delay is to increase the overload protection point with an increase
input voltage. Correction function reduces the current detection level when it equals or exceeds an input voltage value. This
function corrects the overload.
Since the input voltage range is DC300V ~ DC900V, switching voltage is set to DC400V. Izt is the current flowing from the IC
to the transformer Nd winding in time of the switching ON.
Izt lower the current detection level at the top than 1mA, overload protection point is lowered.
R20  VIN (change) 
Nd 1
8turns
1

 500V 

 62.5kΩ Np Izt
64turns 1mA
Check whether the rating load can be taken after the point of over load protection is switched.
When the IC switches CS over current voltage level, it is changed from 1.0V to 0.7V.
VIN (change)  R20 
Ippk ' 
ton ' 
Np
64turns
 Izt  56kΩ
 1mA  448V
Nd
8turns
Vcs 0.70V

 0.466 A R19 1.5Ω
tdelay
toff’
Lp  Ippk '
1750uH  0.466 A

 1.64us
VIN (change)
496V
Ispk ' 
ton’
Np
64turns
 Ippk ' 
 0.466 A  3.728 A
Ns
8turns
2
 Ns 
 8turns 
  1750uH  
Ls  Lp  
  27.34uH
 64turns 
 Np 
toff ' 
2
Ls  Ispk ' 27.34uH  3.728 A

 3.997us
Vout  Vf
24V  1.5V
tdelay    Lp  Cv  3.14  1750uH  100 pF  1.31us
fsw' 
Po' 
1
1

 143kHz
ton 'toff 'tdelay 1.64us  3.997us  1.31us
Figure 1-6.The waveform of Switching
1
1
 Lp  Ippk '2  fsw'   1750uH  0.466 A2  120kHz  0.85  19.38W Transformer efficiency:η=0.85
2
2
When Po’ is under the rated output power, R19 has to be adjusted.
In this board, furthermore, if the over load point is adjusted by a resistor of 100 kHz, the point is changed to 816V
because the maximum frequency of the IC is restricted to 120 kHz. Regarding the over load protection point, please
check in an actual product.
Figure 1-7. Input voltage correction circuit of overcurrent detection (reference value)
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
10/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-2-5.Setting resistor for ZT terminal voltage: R21
The ZT bottom detected voltage is Vzt1=100mV(typ)(ZT fall), Vzt2=200mV(typ)(ZT rise), and ZT OVP(min) is 3.30V, so as
a guide, set Vzt to 1V to 3V.
Vzt  Vout  Vf  
Nd
R21

 2.7V    R21  11.84kΩ
Ns R20  R21
1-2-6.ZT terminal capacitor: C11
C11 is a capacitor for stability of ZT voltage and timing adjustment of the bottom detection.
Check the waveform of ZT terminal and the timing of bottom detection, and adjust it as necessary.
1-2-7.VCC-diode: D18
A high-speed diode is recommended as the VCC-diode.
When D13_Vf=1V, reverse voltage applied to the VCC-diode:
Vdr  VCC(max) +Vf  VINmax 
Nd
Np
This IC has VCC OVP function, VCC OVP (max) = 31.5V.
Reverse voltage of the diode is set so as not to exceed the Vr of diode in conditions of VCC OVP (max).
Vdr  31.5V+1.0V  900V 
8turns
 145V 64turns
With a design-margin taken into account, 145V/0.7≒ 200V → 200V component is selected.
(Example: ROHM’s RF05VAM2S 200V 0.5A)
1-2-8.VCC winding surge-voltage limiting resistor: Rvcc1
Based on the transformer’s leakage inductance (Lleak), a large surge-voltage (spike noise) may occur during the instant
when the MOSFET is switched from ON to OFF. This surge-voltage is induced in the VCC winding, and as the VCC voltage
increases the IC’s VCC overvoltage protection may be triggered.
A limiting resistor R16 (approximately 5Ω to 22Ω) is inserted to reduce the surge-voltage that is induced in the VCC winding.
Confirm the rise in VCC voltage while the resistor is assembled in the product.
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
11/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-2-9.VCC starter resistance ;R11,R12,R13,R14 capacitance;C5,C6 and Rectifier diode;D18, D19
Start resistance RSTART is the resistance required to start the IC.
When the start resistance RSTART value is reduced, the standby power is increased and the startup time is shortened.
Conversely, when the start resistance RSTART value is increased, the standby power is reduced and the startup
time is lengthened. When BD768xFJ is in standby mode, current I OFF becomes 40µA (Max)
However, this is the minimum current required to start the IC. In this case current IOFF is 40µA( Max) with margin.
Input voltage VIN_start=180V: VCCUVLO(max)=20V: Ivcc-protected(min)=0.3mA:
Rstart  (Vcc _ start  VCCuvlo(min)) / Istart(max)  (180V  20V ) / 40uA  4000kohm Rstart  (Vin _ max  Vcc _ ovp(max)) / Icc _ protect  (900V  31.5V ) / 0.3mA  2895kohm 2895kohm  Rstart  4000kohm From the above results, set Rstart = 2940kohm (1Mohm × 2 + 470kohm × 2 series).
Start-up time is shown in Figure 1-8.
Start up time VS Input Voltage
START UP TIME ( SEC)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
180V
300V
600V
900V
4.7uF
1.8
1.0
0.4
0.3
14.7uF
4.3
2.7
1.3
0.9
Figure 1-8. Start up time
A VCC capacitor is needed to stabilize the IC’s VCC voltage.
Capacitance of 2.2μF or above is recommended.
This example is recommended circuit of Figure 1-9 for the start-up time and stability.
At startup, only the C6 works for fast start. After starting, after the output voltage is above a certain voltage, C5 operates.
D18 is recommended Low IR Switching diode. (Example Rohm 1SS355VM)
R11
1M
R12
1M
R start
C start
Figure1-9. resistance of Starter and VCC capacitor
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
12/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-2-10.Brown IN/OUT resistance: R7,R8,R9,R10,R15 and BO capacitor: C8
When the input VH value is low, the brown out function stops the DC/DC operations (The IC itself continues to operate).
In the following example, VHON is the operation start VH voltage (L to H), and VHOFF is the operation stop VH voltage (H to L).
IC operation start (OFF => ON)
(VHON-1.0) /RH = 1.0/RL +15*10e-6
IC operation stop (ON => OFF)
(VHOFF-1.0) /RH = 1.0/RL
Based on the above, RH and RL can be calculated as follows.
RH  VHON  VHOFF  / 15 * 10e  6, RL  1.0 / VHOFF  1.0 * RH
VHON=90V、VHOFF=60V: It becomes the circuit shown in Figure 1-10.
It should be noted that the BO terminal is required capacitor C8.
BO line is weak in noise for high impedance. Recommended is 0.01uF ~ 0.1uF.
VIN
R7
470k
R8
470k
R9
470k
5
OUT
6
MASK
CS
GND
4
2
1
ZT
FB
C8
0.1uF
3
7
VCC
BO
R15
33k
8
R10
470k
GND
Figure 1-10. Broun IN/OUT setting
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
13/24
2016.04.06
Rev.A
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
1-2-11.Snubber circuits: C snubber 1, R snubber1, D13,D14, D15,D16
Based on the transformer’s leakage inductance (Lleak), a large surge-voltage (spike noise) may occur during the instant
when the MOSFET is switched from ON to OFF. This surge-voltage is applied between the MOSFET’s Drain and Source, so
in the worst case damage to MOSFET might occur. RCD snubber circuits are recommended to suppress this surge-voltage.
(1) Determination of clamp voltage (Vclamp) and clamp ripple-voltage (Vripple)
The clamp voltage is determined by the MOSFET’s withstand voltage considering a design margin.
Vclamp = 1700V × 0.8 = 1360V
The clamp ripple-voltage (Vripple) is set about 50V.
(2) Determination of R snubber 1
R snubber 1 is selected according to the following conditions.
R snubber 1  2  Vclamp 
Vclamp - VOR
Lleak  Ip 2  fsw(max)
Lleak = Lp x 10% = 1750uH x 10% = 175uH
In the case of Po=25W, VIN(max)=900V,
Ip、fsw is calculated
1
 Lp  Ip 2  fsw  
2
1
Vcs
fsw 

Ip 
ton  toff  tdelay  Lp
 
Rcs
 Ip   

Po 
1
Ls
  Vo  Vf
 VIN

Np

 Ip     Lp  Cv
Ns

⇒ Vcs=0.7V, Ip=0.466A, fsw=161kHz
Rsnubber 1  2  1360V 
1360V - 204V
 253kΩ
175uH  0.466 2  120kHz
R snubber 1 loss P_ R snubber 1 is expressed as
P_R snubber 1 
Vclamp
- VIN 
1360 - 900  1.05W

R snubber 1
200kΩ
2
2
A more than 2W component is determined with consideration for design margin.
(3) Determination of C snubber 1
Csnubber1 
Vclamp
1360V

 1607pF
Vripple  fsw(min)  Rsnubber
50V  120kHz  200kΩ
The voltage applied to C snubber 1 is 1360V-900=460V.
C snubber 1 is set 600V or above with design margin.
(4) Determination of D13,D14
Choose a fast recovery diode as the diode, with a withstand voltage that is at or above the MOSFET’s Vds (max) value.
The surge-voltage affects not only the transformer’s leakage inductance but also the PCB substrate’s pattern.
Confirm the Vds voltage while assembled in the product, and adjust the snubber circuit as necessary.
(5) TVS: D15, D16
For excellent protection performance, it is possible to cramp the transient noises. Please determine after checking the
withstand voltage and operation waveform.
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
14/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-2-12.FB terminal capacitor: C12
C12 is a capacitor for stability of FB voltage (approximately 1000pF to 0.01uF).
1-2-13.MOSFET gate circuit: R16,R17,R18,D17
The MOSFET’s gate circuits affect the MOSFET’s loss and the generation of noise. The Switching speed for turn-on
is adjusted using R16+R17, and for turn-off is adjusted using R16, via the drawing diode D17.
(Example: R16:10Ω 0.25W、R17:150Ω、D17:SBD 60V 1A)
In the case of Quasi-Resonant converters, switching-loss basically does not occur during turn-on, but it occurs
predominantly during turn-off. To reduce switching-loss when the IC turned off, turn-off speed can be increased by reducing
R16 value, but sharp changes in current will occur, which increases the switching-noise. Since there is a trade-off relation
between loss (heat generation) and noise, measure the MOSFET’s temperature rise and noise while it is assembled in the
product, and adjust it as necessary.
Also, since a pulse current flows to R16, check the pulse resistance of the resistors being used.
R18 is the resistance to pull down the gate of the MOSFET. The recommended value is 10kohm ~ 100kohm.
1-2-14.Output rectification diode: DN1
Choose a high-speed diode (Schottky barrier diode or fast recovery diode) as the output rectification diode.
When Vf=1.5V, reverse voltage applied to output diode is
Vdr  Vout(max)  Vf +VINmax 
Ns
Np
When Vout(max)=24.0V+5%=25.2V:
Vdr  25.2V+1.5V  900V 
8
 139.2V 64
139.2V/0.7=198V → 200V component is determined with consideration for design margin.
Also, diode loss (approximate value) becomes Pd=Vf x Iout=1.5V x 1.0A=1.5W
(Example: ROHM’s RFN10T2D:200V 10A, TO-220FN package)
Using a voltage margin of 70% or less and current of 50% or less is recommended.
Check the rise in temperature while assembled in the product. If necessary, reconsider the component and radiate heat by a
heat sink or similar to dissipate the heat.
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
15/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-2-15.Output capacitors: C out 1,C out 2,C out 3, C out 4
Determine the output capacitors based on the output load‘s allowable peak-to-peak ripple voltage (ΔVpp) and ripple-current.
When the MOSFET is ON, the output diode is OFF. At that time, current is supplied to the load from the output capacitors.
When the MOSFET is OFF, the output diode is ON. At that time, the output capacitors are charged and a load current is also
supplied.
When ΔVpp = 200mV,
ΔVpp
ΔVpp
0.2V
Z_C<


 0.0379 Ω at 60kHz (fsw min) Np
64
Ispk
 Ippk
 0.66 A
Ns
8
With an ordinary switching power supply electrolytic-capacitor (low-impedance component), impedance is rated at 100 kHz,
so it is converted to 100kHz.
60
Z_C<0.0379 Ω 
 0.02274 Ω at 100kHz 100
Ripple-current Is (rms):
Is(rms)  Ispk 
1 - Duty 64
1 - 0.261

 0.66A   2.62A
3
8
3
The capacitor’s withstand voltage should be set to about twice the output voltage.
Vout x 2 = 24V x 2 = 48V → 50V over
Select an electrolytic capacitor that is suitable for these conditions.
(Example: low impedance type 50V, 470 μF × 3 parallel for switching power supply )
(*) Use the actual equipment to confirm the actual ripple-voltage and ripple-current.
1-2-16.Output voltage setting resistors: R25,R26,R28
When Shunt regulator IC2:Vref=2.495V,
R25  R26 
82k  4.3k 


Vo  1 
  Vref  1 
  2.495V  24.02V
R
28
10k




1-2-17.Parts for adjustment of control circuit: R24,R27,R32,C15
R27 and C15 are parts for phase compensation. Approximately R27=1k~30kΩ、C15=0.1uF, and adjust them while they are
assembled in the product.
R32 is a resistor which limits a control circuit current. Approximately R32:300 to 2kΩ, and adjust it while it assembled in the
product.R24 is a resistor for adjustment of minimum operating current of shunt regulator IC2.
In case of IC2: TL431, minimum operating current is 1mA. And when Optocoupler:PC1_Vf is 1V,
R24 = 1V / 1mA = 1kΩ
1-3.EMI countermeasures
Confirm the following with regard to EMI countermeasures.
(*) Constants are reference values. Need to be adjusted based on noise effects.
-
Addition of filter to input block
-
Addition of capacitor between primary-side and secondary-side (approximately CY1,CY2+CY3: Y-Cap 2200pF)
-
Addition of RC snubber to secondary diode
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
16/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-4.Output noise countermeasures
As an output noise countermeasure, add an LC filter
(approximately L:10μH, C: 10μF to 100μF) to the output.
(*) Constants are reference values.
Need to be adjusted based on noise effects.
VOUT
+
+
+
+
GND
R32
R25
R24
R26
C15 R27
PC
1
2
TL431
R28
Figure1-11.LC Filter Circuit
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
17/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
1-5.Proposed PCB layout
A proposed layout (example) for these circuits is shown in Figure 1-12.
・Double-sided board, lead component view
Figure 1-12.Proposed PCB Layout (Example)
Figure 1-13. Evaluation board
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
18/24
2016.04.06
Rev.A
Application Note
BD768xFJ-LB series Quasi-Resonant converter Technical Design
2. Evaluation result
2.1.
Evaluation circuit and parts list
The evaluation circuit is shown in Figure 2-1, parts list is shown in Table 2-1.
2
2 1
IN4007
82
T1
CN3
C14
R23
1
330pF
2
2
Vout
3
L1
1
1
9
8
7
220uF
470uF
470uF
24V/1A
1
1
1
1
2
1.5KE
Cout3 Cout4
2
1M
VOUT
2
Cout1 Cout2
2
470k
10
L3
2.2uH
0.1uF
GND
R2
2
2
100uF
1
2
R31
D16
DN1
12
11
10
2
R11
3
Csnubber1
2200pF
D15
2
1
R7
200K
1
2
2
C2
IN4007
IN4007
2 1
2 1
470k
D9
D5
2 1
2
R1
D1
IN4007
1.5KE
Rsnubber1
1mH
GND
HV+
3
Vout
1N4007
2
DC_IN
D20
D21
1
1
1
VDC:300~1000V
CN2
D10
1N4007
1N4007
1N4007
R8
1
1
D6
1
470k
5.1
CN1
D13
1M
UF4007
Vout
UF4007
R3
RT3
t
VAC:400~690V
VAR3
R9
470k
100uF
R30
R13
C9
27K
470k
0.33uF
2
R4
R14
470k
2
2
2
R5
100uF
470k
R29
10
0
N.C
R18
10k
R6
D8
D12
1N4007
1N4007
470k
1
D4
CIN4
1
L2
R19
2
1.5
R22
1mH
2200p
1k
L4
1
2
D19
Rvcc1
1
11
1
CY2
C7
C6
C5
0.1uF
4.7uF
22uF
2
2200p
2200p
2
CY1
1
HV+
LED1
N.C
1G
IN4007
IN4007
1N4007
1
C4
150
470k
1
2 1
D11
D7
Q1
R16
2 1
D3
IN4007
2 1
CIN1
2200p
1
CIN2
2200p
2
CIN3
C10
R17
R10
2200p
1
RB160L-60
470k
5.1
D17
1
3
470k
2
C3
0.33uF
D 2
C1
5.1
3S
RT2
1
2
2
AC_IN
t
1
1
R12
D14
VAR1
VAR2
0
2 1
t
RT1
470k
D2
2
2
D18
5
1
6
0
0
OUT
4
1
2
3
4.7k
1k
R27
100k
1K
4
CS
3
FB
ZT
GND
R20
R26
R24
PC817
BD7682FJ
2
82k
2k
U2
C15
0.1u
C3
1
R25
R32
5
6
7
MASK
2200p
VCC
BO
U1
8
CY3
1
H2
鏍孔
H3
鏍孔
H4
鏍孔
H6
H5
光學點 光學點
47pF
R15
10k
2A
R
C8
H1
鏍孔
C11
C12
47pF 2200pF
C13
R21
47pF
12k
U3
R28
10K
0
Figure 2-1.Isolated Fly-buck Quasi-Resonant convertor(24V1A=24W)
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
19/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
Table 2-1.Isolated Fly-buck Quasi-Resonant convertor(24V1A=24W)
ROHM BD7682FJ-LB Application Board
Bill of Materials # 1
Item
Part Description
Quantity
Manufacturer
Manufacturer part number
CN1
Terminal Block, 3x1, 9.52MM, TH
1
Phoenix Contact
1714984
CN2
Terminal Block, 3x1, 9.52MM, TH
1
Phoenix Contact
1714968
1
WURTH ELECTRONIK
69110171002
CN3
WR-TBL_5.0mm_Horizontal
Serie101_THT
VAR1
VARISTOR 1080V 10KA DISC 20MM
1
Littelfuse Inc
TMOV20RP750E
VAR2
VARISTOR 1080V 10KA DISC 20MM
1
Littelfuse Inc
TMOV20RP750E
VAR3
VARISTOR 1080V 10KA DISC 20MM
1
Littelfuse Inc
TMOV20RP750E
RT1,RT2,RT3
Fusible ResistorResistor, 2W, 5%
3
Max-Quality Co., LTD
FKN2W10JTB
C1,C9
Film Cap 0.033UF 1.6KV_DC TH
2
TDK_EPCOS Inc
B32672L1333J
CAP, X1Y1, 250VAC
3
Rise Power Corp
WDE222M9HL
C2,C3,C4
AL CAP, 100uF, 450V, +/-20%
3
Nichicon
UPT2W101MHD
CY1,CY2,CY3
CAP, X1Y1, 1KV
3
Shinyspace Co.,Ltd
DY5P222K1K08D
L1,L2
HV Inductor, Shielded , 1mH, TH
2
Wurth Elektronik
768772102
Rsnubber1
RES 200K OHM 3W 1% AXIAL
1
Faithful link corp
CFSJ100K
RVCC1
RES, 11 ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF11R0
R1
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
MCR18ERTF4703
R2
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
MCR18ERTF4703
R3
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
MCR18ERTF4703
R4
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
MCR18ERTF4703
R5
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
MCR18ERTF4703
R6
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
MCR18ERTF4703
R7
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF4703
R8
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF4703
R9
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF4703
R10
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF4703
R11
RES, 1M ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF1004
R12
RES, 1M ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF1004
R13
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF4703
R14
RES, 470k ohm, 1%, 0.25W, 1206
1
ROHM
KTR18EZPF4703
R15
RES, 33k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF3302
R16
RES, 10 ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF10R0
R17
RES, 150 ohm, 1%, 0.125W, 0805
1
ROHM
MCR10PZPZF1000
R18
RES, 10k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1002
R19
RES, 1 ohm, 5%, 2W, DIP
1
Panasonic
ERX-2SJ1R0
CIN1, CIN2,
CIN3,CIN4
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
20/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
R20
RES, 100k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1003
R21
RES, 12k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1202
R22
RES, 1k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1001
R23
RES, 82 ohm, 1%, 0.75W, 1210
1
ROHM
MCR100PZHZF82R0
R24
RES, 1k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1001
R25
RES, 82k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF8202
R26
RES, 4.7k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF4701
R27
RES, 1k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1001
R28
RES, 10k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1002
R29
N.C
1
ROHM
R30
RES, 30k ohm, 1%, 0.1W, 0603
1
ROHM
MCR03ERTF3002
R31
RES, 10 ohm, 1%, 1W, 2512
1
ROHM
MCR100JZHF10R0
R32
RES, 1k ohm, 1%, 0.125W, 0805
1
ROHM
MCR10ERTF1001
Diode, P-N, 1000V, 1A, TH
14
Pan Jit Inc
1N4007
DIODE FAST REC 1KV 1A DO41
2
Taiwan Semiconductor
UF4007
2
Micro Commercial Components
1.5KE200A
D1,D2,D3,D4,D5
,D6,D7,D8,D9,D
10,D11,D12,D20
,D21
D13,D14
D15,D16
TVS DIODE
274VC AXIAL
D17
Schottky diode 40V 1A PMDS
1
ROHM
RB160L-40TE25
D18
Super fast diode 200V 0.5A TUMD2M
1
ROHM
RF05VAM2STR
D19
Diode 90V 0.1A UMD2
1
ROHM
1SS355VMTE17
DN1
Schottky Diode 200V 10A ITO-220AB
1
Diodes, Inc
MBR20200CT
1
JOHANSON DIELECTRICS INC
202S41W222KV4E.
Csnubber1
Cerm CAP,2200pF, 2KV, 10%, X7R,
1210
C5
AL CAP, 22uF, 35V, +/-20%, TH
1
Nichicon
UVR1V220MDD1TD
C6
AL CAP, 4.7uF, 35V, +/-20%, TH
1
Nichicon
UVR1V4R7MDD1TD
1
Murata
GRM21BR71H104JA01L
1
Murata
GQM2195C1H470JB01D
1
Murata
GQM2195C1H470JB01D
1
AVX
08055C222JAT2A
1
Murata
GQM2195C1H470JB01D
1
Yageo
225000111543
1
Taiyo Yuden
UMK212BJ104KGHT
C7
C8
C10
C11
C12
C13
C14
C15
Cerm CAP, 0.1uF, 35V, +/-10%, X7R,
0805
Cerm CAP, 47pF, 50V, +/-5%, X7R,
0805
N.C
Cerm CAP, 47pF, 50V, +/-5%, X7R,
0805
Cerm CAP, 2200pF, 50V, +/-5%, X7R,
0805
Cerm CAP, 47pF, 50V, +/-5%, X7R,
0805
Cerm CAP, 330pF, 1KV, +/-5%, X7R,
1206
Cerm CAP, 0.1uF, 50V, +/-10%, X5R,
0805
Cout1
AL CAP 470uF 35V +/-20% RADIAL
1
HERMEI CORP., LTD
LER471M1VG16VR6
Cout2
AL CAP 470uF 35V +/-20% RADIAL
1
HERMEI CORP., LTD
LER471M1VG16VR6
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
21/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Cout3
Cout4
AL CAP 220uF 35V +/-20% RADIAL
Cerm CAP, 1uF, 50V, +/-10%, X5R,
0805
Application Note
1
HERMEI CORP., LTD
LER221M1VG16VR6
1
Taiyo Yuden
UMK212BJ105KG-T
U1
IC QR-flyback controller 7SOIC
1
ROHM
BD7682FJ-LB
U2
Photocoupler 5mA DIP4
1
SHARP
PC817
U3
TL431 TO-92
1
UNISONIC CO., LTD
TL431
T1
EFD-30 10pin
1
G-CHAN CO., LTD
GC-1528
1
Wurth Elektronik
7447462022
L3
Inductor, Shielded core, Metal, 2.2uH
4.3A
L4
NC
1
Wurth Elektronik
74476626
HS1
HEATSINK
1
MEICON. CO., LTD.
MI-301G-25.4
HS1
HEATSINK
1
MEICON. CO., LTD.
MB-217-25
LED1
Smart LED RED 569NM
1
ROHM
SML-P11UTT86-RG
1
ROHM
SCT2H12NZ
Q1
SIC MOSFET N-CH 1700V 4A
TO-3PFM
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
22/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
2.2. Evaluation Result ( Efficiency, switching frequency)
Output Power (W)
Figure 2-2. Efficiency vs Output Power
Figure 2-3 Switching Frequency vs Output Power
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
23/24
2016.04.06
Rev.A
BD768xFJ-LB series Quasi-Resonant converter Technical Design
Application Note
2.3. Evaluation Result (Waveform)
VIN(DC)=300V
VIN(DC)=600V
VIN(DC)=900V
Figure 2-4. Drain Voltage and Drain current waveform (VO=24V,IO=1.0A, PO=24W)
CH1: Vdrain (200V/div),
VIN(DC)=300V
CH4: Idrain (200mA/div)
VIN(DC)=600V
Figure 2-5. Drain Voltage and Drain current waveform
CH1: Vdrain (200V/div),
www.rohm.com
© 2016 ROHM Co., Ltd. All rights reserved.
VIN(DC)=900V
(VO=24V,IO=2.1A, PO=50W)
CH4: Idrain (500mA/div)
24/24
2016.04.06
Rev.A
Notice
Precaution on using ROHM Products
1.
Our Products are designed and manufactured for application in ordinary electronic equipments (such as AV equipment,
OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you
(Note 1)
intend to use our Products in devices requiring extremely high reliability (such as medical equipment
, transport
equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car
accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or
serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.
Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any
damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific
Applications.
(Note1) Medical Equipment Classification of the Specific Applications
JAPAN
USA
EU
CHINA
CLASSⅢ
CLASSⅡb
CLASSⅢ
CLASSⅢ
CLASSⅣ
CLASSⅢ
2.
ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3.
Our Products are designed and manufactured for use under standard conditions and not under any special or
extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way
responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any
special or extraordinary environments or conditions. If you intend to use our Products under any special or
extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of
product performance, reliability, etc, prior to use, must be necessary:
[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents
[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust
[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,
H2S, NH3, SO2, and NO2
[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves
[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items
[f] Sealing or coating our Products with resin or other coating materials
[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of
flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning
residue after soldering
[h] Use of the Products in places subject to dew condensation
4.
The Products are not subject to radiation-proof design.
5.
Please verify and confirm characteristics of the final or mounted products in using the Products.
6.
In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,
confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power
exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect
product performance and reliability.
7.
De-rate Power Dissipation depending on ambient temperature. When used in sealed area, confirm that it is the use in
the range that does not exceed the maximum junction temperature.
8.
Confirm that operation temperature is within the specified range described in the product specification.
9.
ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in
this document.
Precaution for Mounting / Circuit board design
1.
When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product
performance and reliability.
2.
In principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method must
be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,
please consult with the ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Notice-PGA-E
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.003
Precautions Regarding Application Examples and External Circuits
1.
If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the
characteristics of the Products and external components, including transient characteristics, as well as static
characteristics.
2.
You agree that application notes, reference designs, and associated data and information contained in this document
are presented only as guidance for Products use. Therefore, in case you use such information, you are solely
responsible for it and you must exercise your own independent verification and judgment in the use of such information
contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses
incurred by you or third parties arising from the use of such information.
Precaution for Electrostatic
This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper
caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be
applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,
isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).
Precaution for Storage / Transportation
1.
Product performance and soldered connections may deteriorate if the Products are stored in the places where:
[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2
[b] the temperature or humidity exceeds those recommended by ROHM
[c] the Products are exposed to direct sunshine or condensation
[d] the Products are exposed to high Electrostatic
2.
Even under ROHM recommended storage condition, solderability of products out of recommended storage time period
may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is
exceeding the recommended storage time period.
3.
Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads
may occur due to excessive stress applied when dropping of a carton.
4.
Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of
which storage time is exceeding the recommended storage time period.
Precaution for Product Label
A two-dimensional barcode printed on ROHM Products label is for ROHM’s internal use only.
Precaution for Disposition
When disposing Products please dispose them properly using an authorized industry waste company.
Precaution for Foreign Exchange and Foreign Trade act
Since concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign
trade act, please consult with ROHM in case of export.
Precaution Regarding Intellectual Property Rights
1.
All information and data including but not limited to application example contained in this document is for reference
only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any
other rights of any third party regarding such information or data.
2.
ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the
Products with other articles such as components, circuits, systems or external equipment (including software).
3.
No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any
third parties with respect to the Products or the information contained in this document. Provided, however, that ROHM
will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to
manufacture or sell products containing the Products, subject to the terms and conditions herein.
Other Precaution
1.
This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.
2.
The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written
consent of ROHM.
3.
In no event shall you use in any way whatsoever the Products and the related technical information contained in the
Products or this document for any military purposes, including but not limited to, the development of mass-destruction
weapons.
4.
The proper names of companies or products described in this document are trademarks or registered trademarks of
ROHM, its affiliated companies or third parties.
Notice-PGA-E
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.003
Datasheet
General Precaution
1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.
ROHM shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s
representative.
3.
The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccur acy or errors of or
concerning such information.
Notice – WE
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.001
Similar pages