FT838NB2-RT

Fremont Micro Devices FT838NB/FT838RNA Low-Power Off-Line CC/CV Switch DESCRIPTION FEATURES Constant-Current (CC) and Constant-Voltage The FT838NB/FT838RNA controller device is (CV) with Primary Side Control optimized Proprietary technology enabling high switching mode power supply applications. The efficiency and fast dynamic response FT838NB/FT838RNA facilitates CC/CV charger  No audible noise over entire operating range design by eliminating an opto-coupler and TL431.  Built-in power NPN Its highly integrated functions such as Under  Built-in Cable Compensation Voltage Lockout (UVLO), Leading Edge Blanking  Built-in Line Compensation (LEB) and built-in cable compensation offer the  Primary-side feedback eliminates users a high efficiency and low cost solution for opto-coupler and TL431 AC/DC power applications. low power y high-performance, O nl  for se  Cycle-by-Cycle Current Limiting  Over Temperature Protection Power supplies built with FT838NB can achieve  VCC Over Voltage Protection both highest average efficiency and fast dynamic  Open Circuit Protection load response. FT838RNA is optimized for LED SA U  driver applications with slightly higher (~22uA) TYPICAL APPLICATION U  standby current. Adapter/Charger for Cell/Cordless Phones, PDAs, MP3 and Other Portable Apparatus Standby and Auxiliary Power Supplies Set Top Boxes (STB) ic AC/DC LED Driver applications Temperature Protection to eliminate the external protection circuits and provide reliable operations. FT838NB/FT838RNA is available in SOP8 package. Fr em on tm  protections like Open Circuit Protection and Over ro  Furthermore, FT838NB/FT838RNA features fruitful © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page1 Fremont Micro Devices FT838NB/FT838RNA SA U se O nl y TYPICAL APPLICATION CIRCUIT ro U Figure 1: Typical Application Circuit ic ABSOLUTE MAXIMUM RATINGS FB to GND………………………………...………………………………….…….……….….... -0.3V to +7V tm CS to GND………………………………………...……………………………………….…….....-0.3V to +7V VCC to GND………………………………….………….…………………………………………-0.3V to +30V C to GND…………………………………...…………………………….……….…………......-0.3V to +700V on Operating Temperature Range……………………...………………………………………...-40℃ to +125℃ Junction Temperature………………………………..…………………………………….... -40℃ to +150℃ em Storage Temperature Range ……………………………..……………………………….….-60℃ to +150℃ ESD Protection HBM……………….....……………………………………………….……………………….2000V Fr 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. © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page2 Fremont Micro Devices FT838NB/FT838RNA O nl y PIN CONFIGURATION se Figure 2: Pin Assignments U TERMINAL DESCRIPTION Pin Name 1 CS Primary current sense 2 FB Output voltage feedback pin 3 VCC Supply voltage 4 NC No connection 7 C Ground. SA The collector of the power NPN. This pin is connected to the primary lead of the transformer Table 1 on tm ic 8 U GND 6 ro 5 Description Fr em ORDERING INFORMATION FT838NB X X - XX Circuit Type HSF and Packaging RB: RoHS and Tube Cable Comp RT: RoHS and T&R 0: 0% GB: Green and Tube 1: 3% GT: Green and T&R 2: 6% 3: 9% © 2012 Fremont Micro Devices Inc. Package Blank: SOP8 Confidential Rev. 0.8 DS838NB/838RNA-A-page3 Fremont Micro Devices FT838NB/FT838RNA FT838RNA X - XX Circuit Type HSF and Packaging RB: RoHS and Tube Package RT: RoHS and T&R Blank: SOP8 GB: Green and Tube O nl y GT: Green and T&R FT838NB①/FT838RNA SYMBOL FT838NB① ① 0 Cable Comp = 0% 1 Cable Comp = 3% 2 Cable Comp = 6% Cable Comp = 9% Cable Comp = 0% SA 3 FT838RNA Options se DESIGNATOR U Device ⁄ ⁄ For LED driver applications ro U Table 2 em on tm ic MARKING RULE Figure 3: Marking Rule Fr ①: Represents Version (0,1,2 or 3) ②③④⑤: for internal reference © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page4 Fremont Micro Devices FT838NB/FT838RNA U SA U se O nl y Block Diagram Fr em on tm ic ro Figure4: FT838NB/FT838RNA Block Diagram © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page5 Fremont Micro Devices FT838NB/FT838RNA ELECTRICAL CHARACTERISTICS (For typical values Tj=25℃, Vcc=12V, unless otherwise noted) Characteristic Symbol Min Typ Max Unit Maximum Current Threshold Vcs_max 541 552 563 mV Leading Edge Blanking Duration Tleb 350 400 450 ns Propagation Delay (OUT=1.0nF to GND) Tpd 200 ns y Current Sense Feedback Section Vfb CCM protection Threshold Level Vcp 2.856 2.9 100 Vcc_on 16.5 Under Voltage Lockout Voltage Vcc_off 6 FT838NB 18.5 V 6.6 7 V 2 5 uA 14 22 30 Iop 0.4 0.5 0.7 mA Ifb_open 120 140 160 uA Vcc_OVP 26 27.5 29 V Istart_up FT838RNA Operating Current Protection Section SA Feedback Loop Open Protection VCC Over Voltage Protection Over Temperature Protection T_OTP U Compensation Line Compensation (Ifb=1mA) Vline 30 1 tm 36 mV % 6 ic 2 Characteristic 33 ℃ 3 Kcab 3 Power NPN Section 145 0 ro 0 Cable compensation 17.6 mV se Start Up Threshold Voltage V U Supply Section VCC Start Up Current 2.944 O nl Feedback Voltage Threshold 9 Test condition Symbol Min Ic=0.1mA Vcbo 700 V Ic=1mA Vceo 400 V IE=0.1mA Vebo 9 V IB=0.25A,IC=1A VCEsat 0.3 0.9 V Base-Emitter saturation voltage IB=0.25A,IC=1A VBEsat 0.9 1.2 V Maximum collector current Vc=2V Icm Collector-Base breakdown on voltage Collector-Emitter breakdown em voltage Emitter-Base breakdown voltage Fr Collector-Emitter saturation voltage 0.4 Typ 0.45 Max Unit A Table 3 © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page6 Fremont Micro Devices FT838NB/FT838RNA FUNCTIONAL DESCRIPTION Operating Description FT838NB/FT838RNA is a cost effective and high-performance AC-DC power supply controller for off-line low power AC-DC applications including battery chargers, adaptors and LED lighting. The constant voltage (CV) and constant current (CC) control are achieved accurately without the secondary feedback circuit. y Start up Control O nl Start-up current of FT838NB is very low so that a start-up resistor with high resistance and low-wattage is allowed to supply the start-up power for the controller. The large value startup resistor minimizes the power loss in operations and allows quick start up. FT838RNA increases the start-up current slightly to ensure the smooth shutting down operations in LED lighting applications with relaxed requirement on external board se design. Operating current U The operating current of FT838NB/FT838RNA is as low as 500uA. Good efficiency is achieved with the low operating current. Low operating current also reduces the Vcc hold-up capacitance requirement. SA Constant voltage (CV) and constant current (CC) Operation The FT838NB/FT838RNA can accurately achieve CV/CC characteristic output without secondary side voltage and current-feedback circuits. It operates in CV mode to regulate the output voltage by capturing the U auxiliary winding feedback voltage at FB pin. The auxiliary winding feedback voltage is proportional to secondary winding, so it provides controller the feedback signal from secondary side and achieves constant-voltage output. In CC mode, the controller detects the secondary discharger peak current and the ro discharger time, which determines the off-time of the base driver to make the output average current ic constant. Primary peak current modulation tm Primary peak current is constant at constant current mode. And primary peak current is modulated at constant voltage mode for the purposes of good dynamic load response and no audible noise over entire operating on range. According to the output loading current the current threshold voltage is modulated from 0.55V to 0.27V. The current threshold voltage is 0.55V at rated load and 0.27V at light load. em Leading edge blanking Each time the power NPN transistor is switched on, a turn-on spike occurs at the sense resistor. To avoid premature termination of the switching pulse, a 400ns leading edge blanking time is built in. Conventional RC filtering can therefore be omitted. During this blanking period, the current limit comparator is disabling and Fr cannot switch off the base driver. Under voltage lockout (UVLO) FT838NB/FT838RNA turn-on Vcc_on and turn-off Vcc_off are 17.6 V and 6.6 V, respectively. During start-up, the hold-up capacitor must to be charged to 17.6V through the start-up resistor. The hold-up capacitor continues to supply Vcc until power can be delivered from the auxiliary winding of the transformer. Vcc must not drop below 6.6 V during this start-up process. This UVLO hysteresis window ensures that hold-up capacitor is sufficient to supply Vcc during start-up. © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page7 Fremont Micro Devices FT838NB/FT838RNA Protection control With rich protection features of FT838NB/FT838RNA, excellent power supply system reliability can be achieved. The protection features including cycle by cycle current limiting, Vcc over voltage protection and clamp, over temperature protection, feedback loop open circuit protection and Vcc under voltage lockout. Integrated NPN y Power NPN is integrated in FT838NB/FT838RNA for low cost and/or space limited applications. O nl Output cable compensation The output cable compensation provides a constant output voltage at the end of the cable over the entire load rang in constant voltage mode. As the converter load increase from no-load to the peak current load, the voltage drop introduced across the output cable is compensated by increasing the feedback pin reference Fr em on tm ic ro U SA U se voltage. © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page8 Fremont Micro Devices FT838NB/FT838RNA DIP8 PACKAGE OUTLINE DIMENSIONS Symbol ro U SA U se O nl y SOP8 Package Dimensions In Millimeters Min Max 1.750 0.053 0.069 0.100 0.250 0.004 0.010 1.350 1.550 0.053 0.061 0.330 0.510 0.013 0.020 c 0.170 0.250 0.006 0.010 D 4.700 5.100 0.185 0.200 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 A2 em on b 1.350 tm A1 ic Max A Min e Fr Dimensions In Inches 1.270 (BSC) 0.050（BSC） L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page9 Fremont Micro Devices FT838NB/FT838RNA Fremont Micro Devices (SZ) Limited #5-8, 10/F, Changhong Building, Ke-Ji Nan 12 Road, Nanshan District, Shenzhen Tel: (86 755) 86117811 Fax: (86 755) 86117810 O nl y Fremont Micro Devices (Hong Kong) Limited #16, 16/F, Blk B, Veristrong Industrial Centre, 34-36 Au Pui Wan Street, Fotan, Shatin, Hong Kong Tel: (852) 27811186 se Fax: (852) 27811144 U Fremont Micro Devices (USA), Inc. 42982 Osgood Road Fremont, CA 94539 Tel: (1-510) 668-1321 U em on tm ic ro Web Site: http://www.fremontmicro.com/ SA Fax: (1-510) 226-9918 * Information furnished is believed to be accurate and reliable. However, Fremont Micro Devices, Incorporated (BVI) assumes no responsibility for the consequences of use of such information or for any Fr infringement of patents of other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent rights of Fremont Micro Devices, Incorporated (BVI). Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. Fremont Micro Devices, Incorporated (BVI) products are not authorized for use as critical components in life support devices or systems without express written approval of Fremont Micro Devices, Incorporated (BVI). The FMD logo is a registered trademark of Fremont Micro Devices, Incorporated (BVI). All other names are the property of their respective owners. © 2012 Fremont Micro Devices Inc. Confidential Rev. 0.8 DS838NB/838RNA-A-page10