Rectification Controller. N3867V Datasheet

N3867V Controller. Datasheet pdf. Equivalent

N3867V Datasheet
Recommendation N3867V Datasheet
Part N3867V
Description Synchronous Rectification Controller
Feature N3867V; NIKO-SEM Synchronous Rectification Controller N3867V N3867P GENERAL DESCRIPTION The N3867 is a low.
Manufacture NIKO-SEM
Datasheet
Download N3867V Datasheet




NIKO-SEM N3867V
NIKO-SEM Synchronous Rectification Controller
N3867V
N3867P
GENERAL DESCRIPTION
The N3867 is a low cost, high efficiency,
synchronous rectification controller that
specifically designed for the synchronous
rectification applications of the Fly-back
AC/DC PWM mode switching power supply.
The N3867 is included a totem pole output
ideally suited for driving a synchronous
rectification power MOSFET. In the QR mode
or discontinuous mode operating, the current
detector properly turns off the synchronous
rectification power MOSFET by detecting the
dropout voltage between source and drain pin.
In continuous mode operating, it provides the
Aout pin for turning off the GATE output while
receive a turn-off signal from the primary side.
The operation of N3867 prevents secondary
side shoot-through condition by a cycle by
cycle control method.
FEATURES
High efficiency operating.
Decrease areas of heatsink or PCB.
Solved heat dissipation.
Sensitive current detecter(about 20mV)
Suited for discontinuous,QR or continuous
mode operation.
Auto frequency tracking with PWM
frequency.
Suited for fixed or variable frequency
SOIC-8 and DIP-8 package.
APPLICATION
Fly-back AC/DC power supply
Pin to pin compatible with N3856
DEVICE SELECTION GUIDE
SnPb
N3867P
DIP-8
Pb Free
N3867PG
SnPb
N3867V
SOP-8
Pb Free
N3867VG
THERMAL DATA
PARAMETER
Thermal Resistance Junction to Ambient
Thermal Resistance Junction to Case
SYMBOL
θja
θjc
DIP-8
53
23
UNIT
/W
/W
ABSOLUTE MAXIMUM RATING
PARAMETERS
Vcc to GND
Drain to Other Pin
Power Dissipation at Ta = 25 ,Derate 8mV/ for Ta
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperture(Soldering) 10 sec
25
SYMBOL
Vcc
PD
Tj
TSTG
TLEAD
LIMITS
-0.3 to 30
180
725
-40 to +150
-65 to +150
300
UNITS
V
V
mW
1 FEB-10-2006



NIKO-SEM N3867V
NIKO-SEM Synchronous Rectification Controller
N3867V
N3867P
ELECTRICAL CHARACTERISTICS (TC = 25 °C)
PARAMETER
TEST CONDITIONS
Supply Voltage
Supply Current
GATE Sink Current
GATE Source Current
Rise Time
Fall Time
Delay Time
Max Duty Cycle
Vcc
CL= 1.0nF
CL= 1.0nF
LIMITS
UNIT
MIN TYP MAX
7 12 30 V
- 4.5 - mA
1A
1A
40 nS
40 nS
200 300 nS
90 95
%
BLOCK DIAGRAM
VCC PIN8
PGND PIN2
10K
PIN7 NC
PIN6 Aout
GND PIN3
20mV
DRAIN PIN5
ADJ.
SLOPE CURRENT
DETECTOR
BUFFER
DRIVER
PIN1 GATE
PIN4 BIAS
2 FEB-10-2006



NIKO-SEM N3867V
NIKO-SEM Synchronous Rectification Controller
N3867V
N3867P
OPERATION DESCRIPTION
•Discontinuous
In discontinuous or QR mode applications, the N3867 is detecting the MOSFET current to
control the MOSFET be ON or OFF by a internal current detector , the current of the
secondary winding flows through the Source and Drain of the MOSFET is changing from
maximum level to zero , It cause a voltage drop of the MOSFET from the maximum level
down to zero , the voltage drop is compared with internal reference voltage 20mV, if voltage
dropout is over 20mV ,will make the MOSFET turn-on, if the voltage drop is under 20mV, will
make the MOSFET become turn-off.
For the various MOSFET applications , different RDS(ON) will cause a different voltage drop
between the MOSFET,s Source and Drain , the BIAS pin provided the “adjustable slope”
function delaying turn-off the MOSFET for better efficiency , the BAIS pin is connected a
resistor with VCC used to adjust the gate output slope , change the resistance will get the
different slope ,a higher resistance will get the smoother slope, and MOSFET turn-off become
slower , a smaller resistance will get the sharper slope , and MOSFET turn-off become
quicker .
Considering of Bias setting, first, adjust output to heavy load but still in discontinuous mode ,
changing the Bias resistor make the Gate waveform of MOSFET is sloping to connect the
resonant waveform of LC tank of the output circuit, second,adjust output to the minimum load
and check the Gate waveform is OK or not , to decrease the resistance until waveform is
normal .
•Continuous mode
In continuous mode application , the current detector can not turn-off the MOSFET directly,
the N3867 is using a synchronous signal from the primary side to control the Aout pin , pull
the Aout pin to low will turn off the output of Gate driver . Aout pin also can be used to
increase Gate drive capability when two parallel MOSFET application , connected a resistor
to VCC if need .
3 FEB-10-2006





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