FT838D2-BL-RT

Fremont Micro Devices FT838D/FT838R Low-Power Off-Line CC/CV Controller FEATURES DESCRIPTION Constant-Current (CC) and Constant-Voltage The FT838D/FT838R controller device is optimized (CV) with Primary Side Control for high-performance, low power switching mode Proprietary technology enabling high power supply applications. The FT838D/FT838R efficiency and fast dynamic response facilitates CC/CV charger design by eliminating an No audible noise over entire operating range opto-coupler and TL431. Its highly integrated Applications from 1W to more than 18W functions such as Under Voltage Lockout (UVLO), output Leading Edge Blanking (LEB) and built-in cable Direct drive of BJT or MOS switch compensation offer the users a high efficiency and Built-in Cable Compensation low cost solution for AC/DC power applications. Built-in Line Compensation Primary-side feedback eliminates Power supplies built with FT838D can achieve both opto-coupler and TL431 highest average efficiency and fast dynamic load Cycle-by-Cycle Current Limiting response. FT838R is optimized for LED driver Over Temperature Protection applications with slightly higher (~22uA) standby VCC Over Voltage Protection current. Open Circuit Protection Furthermore, TYPICAL APPLICATION Adapter/Charger for Cell/Cordless Phones, PDAs, MP3 and Other Portable Apparatus Standby and Auxiliary Power Supplies FT838D/FT838R features fruitful protections like Open Circuit Protection and Over Temperature Protection to eliminate the external protection circuits and provide reliable operations. FT838D/FT838R is avilabel in SOT23-5 package. Set Top Boxes (STB) AC/DC LED Driver applications © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page1 Fremont Micro Devices FT838D/FT838R TYPICAL APPLICATION CIRCUIT Figure 1: Typical Application Circuit ABSOLUTE MAXIMUM RATINGS FB to GND………………………………...…………………………………….…….……….….... -0.3V to +7V CS to GND…………………………………………...……………………………………….…….....-0.3V to +7V VCC to GND…………………………………..………….…………………………………………-0.3V to +30V OUT to GND…………………………………...…………………………….……….…………......-0.3V to +7V Operating Temperature Range……………………...……………………………………………...-40 to +125 Junction Temperature………………………………..………………………………………….... -40 to +150 Storage Temperature Range ……………………………..………… ……………………….….-60 to +150 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 . © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page2 Fremont Micro Devices FT838D/FT838R PIN CONFIGURATION Figure 2: Pin Assignments Pin Definition Pin #. Name I/O 1 FB I Output voltage feedback pin Pin Description 2 GND I Ground. 3 CS I Primary current sense 4 OUT O NPN base or MOS gate driver 5 VCC I Supply voltage Table1: Pin Definition ORDERING INFORMATION FT838D X X - BL - XX HSF and Packaging Circuit Type -RT: RoHS and T&R Cable Comp -GT: Green and T&R 0: 0% 1: 3% Internal Code 2: 6% 3: 9% Package Blank: SOT23-5 FT838R X - BL - XX Circuit Type HSF and Packaging -RT: RoHS and T&R -GT: Green and T&R Package Blank: SOT23-5 © 2013 Fremont Micro Devices Inc. Internal Code Confidential Rev0.81 DS838D/838R-A-page3 Fremont Micro Devices Device FT838D/FT838R DESIGNATOR FT838D SYMBOL Options 0 Cable Comp = 0% 1 Cable Comp = 3% 2 Cable Comp = 6% 3 Cable Comp = 9% Cable Comp = 0% FT838R For LED driver applications Table 2 MARKING RULE Figure 3 marking rule : Represents Version (0,1,2 or 3) : Represents Device (D or R) : for internal reference © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page4 Fremont Micro Devices FT838D/FT838R BLOCK DIAGRAM Figure 4: FT838D/FT838R Block Diagram © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page5 Fremont Micro Devices FT838D/FT838R 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 2.944 V Current Sense Feedback Section Feedback Voltage Threshold Vfb CCM protection Threshold Level Vcp 2.856 2.9 100 mV Supply Section Start Up Threshold Voltage Vcc_on 16.5 Under Voltage Lockout Voltage Vcc_off 6 6.6 18.5 V 7 V 2 5 14 22 30 Iop 0.4 0.5 0.7 mA Feedback Loop Open Protection Ifb_open 120 140 160 uA VCC Over Voltage Protection Vcc_OVP 26 27.5 29 V Over Temperature Protection T_OTP 145 Output low level ON-resistance Rdson 2 Output Maximum Source current Isource 35 mA Output sourcing current after pre-off Is_preoff 1.4 mA Output clamp voltage Vbase 9 V VCC Start Up Current FT838D 17.6 Istart_up FT838R Operating Current uA Protection Section Base Driver 25 30 Compensation Line Compensation (Ifb=1mA) Vline 30 0 Cable compensation 1 2 33 36 mV 0 Kcab 3 3 6 % 9 Table 3 © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page6 Fremont Micro Devices FT838D/FT838R FUNCTIONAL DESCRIPTION Operating Description FT838D/FT838R 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,. Start up Control Start-up current of FT838D 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. FT838R increases the start-up current slightly to ensure the smooth shutting down operations in LED lighting applications with relaxed requirement on external board design. Operating current The operating current of FT838D/FT838R 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. Constant voltage (CV) and constant current (CC) Operation The FT838D/FT838R 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 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 discharger time, which determines the off-time of the base or gate driver to make the output average current constant. Primary peak current modulation 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 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. Leading edge blanking Each time the power 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 disabled and cannot switch off the base or gate driver. Under voltage lockout (UVLO) FT838D/FT838R 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 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. © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page7 Fremont Micro Devices FT838D/FT838R Protection control With rich protection features of FT838D/FT838R, 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. Base or gate driver To minimize loss in the primary power NPN and to prevent it from secondary breakdown, the driving current profile is carefully controlled. The driving current is nominally 30mA.The FT838D/FT838R can also drive power MOS for high power applications. 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 increases from no-load to the peak current load, the voltage drop introduced across the output cable is compensated by increasing the feedback pin reference voltage. © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page8 Fremont Micro Devices FT838D/FT838R PACKAGE INFORMATION SOT23-5 Package Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 e 0.95 (BSC) 0.116 0.037 (BSC) e1 1.800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 0° 8° 0° 6° © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page9 Fremont Micro Devices FT838D/FT838R 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 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 Fax: (852) 27811144 Fremont Micro Devices (USA), Inc. 42982 Osgood Road Fremont, CA 94539 Tel: (1-510) 668-1321 Fax: (1-510) 226-9918 Web Site: http://www.fremontmicro.com/ * 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 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. © 2013 Fremont Micro Devices Inc. Confidential Rev0.81 DS838D/838R-A-page10