Fremont Micro Devices
FT838NB/FT838RNA
Low-Power Off-Line CC/CV Switch
FEATURES
DESCRIPTION
The FT838NB/FT838RNA controller device is
optimized
for
high-performance,
low
power
Constant-Current (CC) and Constant-Voltage
(CV) with Primary Side Control
Proprietary technology enabling high
efficiency and fast dynamic response
No audible noise over entire operating range
Built-in power NPN
Built-in Cable Compensation
Built-in Line Compensation
Primary-side feedback eliminates
opto-coupler and TL431
Cycle-by-Cycle Current Limiting
Over Temperature Protection
VCC Over Voltage Protection
Open Circuit Protection
design by eliminating an opto-coupler and TL431.
Voltage Lockout (UVLO), Leading Edge Blanking
(LEB) and built-in cable compensation offer the
AC/DC power applications.
Power supplies built with FT838NB can achieve
both highest average efficiency and fast dynamic
TYPICAL APPLICATION
Adapter/Charger for Cell/Cordless Phones,
PDAs, MP3 and Other Portable Apparatus
Standby and Auxiliary Power Supplies
Set Top Boxes (STB)
AC/DC LED Driver applications
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standby current.
load response. FT838RNA is optimized for LED
driver applications with slightly higher (~22uA)
Furthermore, FT838NB/FT838RNA features fruitful
protections like Open Circuit Protection and Over
Temperature Protection to eliminate the external
protection circuits and provide reliable operations.
FT838NB/FT838RNA is available in SOP8 package.
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users a high efficiency and low cost solution for
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Its highly integrated functions such as Under
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FT838NB/FT838RNA facilitates CC/CV charger
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switching mode power supply applications. The
Fremont Micro Devices
FT838NB/FT838RNA
TYPICAL APPLICATION CIRCUIT
Figure 1: Typical Application Circuit
ABSOLUTE MAXIMUM RATINGS
FB to GND………………………………...………………………………….…….……….….... -0.3V to +7V
VCC to GND………………………………….………….…………………………………………-0.3V to +30V
C to GND…………………………………...…………………………….……….…………......-0.3V to +700V
Operating Temperature Range……………………...………………………………………...-40℃ to +125℃
Junction Temperature………………………………..…………………………………….... -40℃ to +150℃
Storage Temperature Range ……………………………..……………………………….….-60℃ to +150℃
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ESD Protection HBM……………….....……………………………………………….……………………….2000V
ESD Protection MM………………..…………………………………………………………….………………….200V
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings
only. Functional operation above the Recommended Operating Conditions is not implied. Extended
exposure to stresses above the Recommended Operating Conditions may affect device reliability
.
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CS to GND………………………………………...……………………………………….…….....-0.3V to +7V
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Fremont Micro Devices
FT838NB/FT838RNA
PIN CONFIGURATION
TERMINAL DESCRIPTION
Pin
1
2
3
4
5
6
7
8
Name
CS
FB
VCC
NC
GND
Primary current sense
Output voltage feedback pin
Supply voltage
No connection
Ground.
Description
C
The collector of the power NPN. This pin is connected to the primary lead of the
transformer
ORDERING INFORMATION
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FT838NB X X - XX
Circuit Type
Cable Comp
0: 0%
1: 3%
2: 6%
3: 9%
HSF and Packaging
RB: RoHS and Tube
RT: RoHS and T&R
GB: Green and Tube
GT: Green and T&R
Package
Blank: SOP8
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Figure 2: Pin Assignments
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Fremont Micro Devices
FT838RNA X - XX
Circuit Type
Package
Blank: SOP8
FT838NB/FT838RNA
HSF and Packaging
RB: RoHS and Tube
RT: RoHS and T&R
GB: Green and Tube
GT: Green and T&R
FT838NB
①
/FT838RNA
Device
FT838NB①
①
DESIGNATOR
SYMBOL
0
1
2
3
FT838RNA
⁄
⁄
Cable Comp = 0%
Cable Comp = 3%
Table 2
MARKING RULE
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①:
Represents Version (0,1,2 or 3)
②③④⑤:
for internal reference
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Figure 3: Marking Rule
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Cable Comp = 6%
Cable Comp = 9%
Cable Comp = 0%
For LED driver applications
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Fremont Micro Devices
FT838NB/FT838RNA
Block Diagram
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Figure4: FT838NB/FT838RNA Block Diagram
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