JW7700A
40V, 16m
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Synchronous Rectifier
DESCRIPTION
JW7700A is a synchronous rectifier for Flyback
converters. It integrates a 40V power MOSFET
that can replace Schottky diode for high efficiency.
It turns on the internal MOSFET if the
V
SW
<-500mV and turns it off before the current
from GND to SW is lower than zero.
FEATURES
Supports DCM and Quasi-Resonant Flyback
converter
Integrated 16m 40V Power MOSFET
Supports High-side and Low-side
Rectification
No need external power supply
APPLICATIONS
Flyback converters
Adaptors
TYPICAL APPLICATION
Note 1: R
VCC
is recommended in case IC is damaged in CCM.
Note 2: D
VCC
is recommended if VCC voltage is too low in light load.
JW7700A Rev.0.1
JoulWatt Proprietary Information. Patent Protected.
Unauthorized Photocopy and Duplication Prohibited.
1
JW7700A
ORDER INFORMATION
TOP
LEAD FREE FINISH
JW7700ASOPB#PBF
TAPE AND REEL
JW7700ASOPB#TRPBF
PACKAGE
MARKING
SOP8
JW7700A
JoulWatt
Note
PIN CONFIGURATION
TOP VIEW
SW PIN .................................................................................................................................................40V
Maximum Power Dissipation
2)
.... .............................................................................2.5W
Junction Temperature
3)
.......................................................................................................................150ºC
Lead Temperature ..........................................................................................................................260ºC
Storage Temperature .........................................................................................................-65ºC to150ºC
RECOMMENDED OPERATING CONDITIONS
SW Pin.......................................................................................................................................20V to 35V
VCC PIN........................................................................................................................................7V to 9V
Operation Junction Temp. ................................................................................................ -40ºC to 125ºC
cJ
AJ
SOP8 .....................................................................................................................................96 ...45ºC/W
Note
3)
JW7700A Rev.0.1
℃
1)
2)
Exceeding these ratings may damage the device.
TA=25 . The maximum allowable power dissipation is a function of the maximum junction temperature T
J
(MAX), the
junction-to-ambient thermal resistance θ
JA
, and the ambient temperature T
A
. The maximum allowable continuous
power dissipation at any ambient temperature is calculated by P
D
(MAX)=(T
J
(MAX)-T
A
)/ θ
JA
. Exceeding the maximum
allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown.
Internal thermal shutdown circuitry protects the device from permanent damage.
Measured on JESD51-7, 4-layer PCB.
JoulWatt Proprietary Information. Patent Protected.
Unauthorized Photocopy and Duplication Prohibited.
）4
）4
）4
THERMAL PERFORMANCE
）1
）1
）1
）1
ABSOLUTE MAXIMUM RATING
：
θ
θ
：
：
：
：
2
JW7700A
ELECTRICAL CHARACTERISTICS
TA = 25ºC, unless otherwise stated.
Item
VCC Section
VCC Operation Voltage
VCC Start up Voltage
VCC UVLO
Quiescent Current
Internal MOS Section
Internal MOS R
dson
Maximum Peak Current
Internal MOS turn on delay
Internal MOS turn off delay
Internal MOS turn on minimum time
Internal MOS turn off minimum time
SW Section
Internal MOS turn on Threshold
SW to GND Breakdown Voltage
V
MOS_ON
V
(BR)DSS
VCC=9V, I
SW
=250uA
40
-0.5
R
dson
I
peak
T
DON
T
DOFF
T
ON_MIN
T
OFF_MIN
VCC=10V, Isw=10A
16
8
24
10
500
2.5
V
CC
V
CC_STAR UP
V
CC_UVLO
I
Q
V
CC
=6.5V, C
VCC
=0.1uF
68
SW=30V, VCC=0.1uF
7.8
3.85
3.6
85
JoulWatt
Symbol
Condition
Min.
Typ.
Max.
Units
V
V
V
102
uA
m
A
ns
ns
ns
uS
JW7700A Rev.0.1
JoulWatt Proprietary Information. Patent Protected.
Unauthorized Photocopy and Duplication Prohibited.
℃
T
J
=25
V
V
3
JW7700A
PIN DESCRIPTION
Pin No.
SOP
1
2
3
JoulWatt
Name
GND
VCC
Ground
Description
BLOCK DIAGRAM
JW7700A Rev.0.1
、、、
5
、、
4
6
7
Power supply, Bypass a capacitor between VCC and GND.
Internal Power MOSFET Drain.
8
SW
JoulWatt Proprietary Information. Patent Protected.
Unauthorized Photocopy and Duplication Prohibited.
4
JW7700A
FUNCTIONAL DESCRIPTION
Operation
JW7700A is a synchronous rectifier, it can
replace the Schottky to improve the efficiency in
Flyback converters. It supports operation in
DCM and Quasi-Resonant Flyback converters.
It can power itself through the internal LDO
during the turn-off period, a 0.1uF capacitor is
needed between VCC and GND.
JoulWatt
Turn-on Blanking Time
The control circuitry contains a blanking function.
When the internal MOSFET is turned on, it at
least last for some time, the turn on blanking
time is about 500ns. During the turn on blanking
period, the turn off threshold is not totally
blanked, but changes the threshold current.
This assures that the internal MOSFET can
always be turned off even during the blanking
period.
Turn on and turn off delay
Startup
During the startup period, when the VCC is
lower than startup voltage, the internal MOSFET
is turned off. The current flows though body
diode until the VCC exceeds the startup voltage.
RC Snubber Circuit
In some applications (output short circuit
protection), the inductor current may go into
slight CCM condition. To avoid the voltage spike
across the synchronous rectifier, we suggest
RC snubber should be placed between SW and
GND, and a resistor should be paralleled with
VCC capacitor.
Under-Voltage Lockout (UVLO)
When the VCC is below UVLO threshold, the
internal MOSFET is turned off and never turned
on before the VCC exceeds the startup voltage.
Turn On Phase
The switch current first flows through the body
diode of integrate MOSFET, which generates a
negative V
SW
. When the V
SW
is higher than 0.7V
and then V
SW
is lower than
V
MOS_ON
, it turns on
the integrate MOSFET after 24ns delay.
Turn Off Phase
The JW7700A senses the current of the internal
MOSFET I
SW
, before I
SW
is lower than Internal
MOS turn off threshold, the driver voltage of the
switch is pulled down to zero after 10ns delay.
RC Snubber circuit
PCB Layout Guidelines
1. The VCC pin must be locally bypassed with a
capacitor.
JW7700A Rev.0.1
JoulWatt Proprietary Information. Patent Protected.
Unauthorized Photocopy and Duplication Prohibited.
5
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