FT825-RT

Fremont Micro Devices Preliminary FT825 Primary-Side Control LED Driver with High PFC FEATURES DESCRIPTION Primary Feedback Control Without Secondary The FT825 is a primary-side-control offline LED feedback Circuit lighting controller which can achieve high power High Power Factor >0.9 Over the Universal factor and accurate LED current for an isolated Input lighting application in a single stage converter. High Current Accuracy ±3% Boundary Conduction Mode Operation The real current control method can control the LED Ultra-low Start Up Current current accurately from the primary side information. Cycle-by-cycle Current Limit It can significantly simplify the LED lighting system Over-voltage Protection design by eliminating the secondary side feedback Short-circuit Protection components and the opto-coupler. Under Voltage Lock Out Available in a SOP8/DIP8 Package The FT825 works in boundary conduction mode for reducing the MOSFET switching losses. The APPLICATIONS Isolated, Solid State Lighting extremely low start-up current and the quiescent current can reduce the power consumption thus lead to an excellent efficiency performance. Industrial and Commercial Lighting Residential Lighting The multi-protection function of FT825 can greatly enhance the system reliability and safety. The FT825 features over-voltage protection, short-circuit protection, cycle-by-cycle current limit, VCC UVLO protection. The FT825 is available in SOP8/DIP8 Package. © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page1 Fremont Micro Devices Preliminary FT825 TYPICAL APPLICATION CIRCUIT Figure 1: Typical Application Circuit ABSOLUTE MAXIMUM RATINGS VCC to GND………………………………………………………………………………………………-0.3V to +27V Analog Inputs and Outputs……………………………………………………………………….……….. -0.3V to 7V ZCD Pin Maximum Current………………………………………………………………-5mA (source) / 5mA(sink) Max. Gate Source Current…………………………………………………………………………………………1.0A Max. Gate Sink Current……………………………………………………………………………………………-1.2A 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 exceed those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. Functional operation of the device at conditions beyond those listed in the specification is not guaranteed. Prolonged exposure to extreme conditions may affect device reliability or functionality. © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page2 Fremont Micro Devices Preliminary FT825 PIN CONFIGURATION Top View NC 1 8 VCC COMP 2 7 GATE MULT 3 6 GND CS 5 ZCD 4 Figure 2: Pin Assignments TERMINAL DESCRIPTION No. PIN 1 NC 2 COMP 3 MULT 4 CS FUNCTION This pin can be NC or connects to GND. Loop Compensation pin. Connects a compensation network to stabilize the LED driver and get an accurate LED current of the LED driver. Main input to the multiplier. This pin is connected to the rectified mains voltage via a resistor divider and provides the sinusoidal reference to the current loop. Current sense pin. The MOSFET current is sensed via a resistor, the resulting voltage compared to the internal sinusoid shaped current reference signal to determine when the MOSFET turns off. Zero current detection pin. A negative going edge triggers the turn on signal of the external MOSFET, connects this pin through a resistor divider from the auxiliary 5 ZCD winding to GND. Over-voltage condition is detected through ZCD, if ZCD voltage is higher than the Over-voltage protection (OVP) threshold after a blanking time 1us, the over-voltage condition is detected. 6 GND Ground. Gate drive output pin. The totem pole output stage is able to drive high power 7 GATE MOSFET with a peak current of 1A source capability and 1.2A sink capability. The high level voltage of this pin is clamped to 13V to avoid excessive gate drive voltage. 8 VCC Supply Voltage of both the signal part of the IC and the gate driver. Table1 © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page3 Fremont Micro Devices Preliminary FT825 ORDERING INFORMATION FT825 x - XX HSF and Packaging Circuit Type RB: RoHS and Tube RT: RoHS and T&R GB: Green and Tube GT: Green and T&R Package Blank: SOP8 a: DIP8 Package Temperature Range HSF Packaging Ordering Code Tube FT825-RB RoHS SOP8 -40 T&R FT825-RT Tube FT825-GB T&R FT825-GT RoHS Tube FT825a-RB Green Tube FT825a-GB -125 Green DIP8 -40 -125 Table 2 MARKING RULE Figure 3 marking rule for internal reference © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page4 Fremont Micro Devices Preliminary FT825 BLOCK DIAGRAM VCC 8 VOLTAGE REGULATOR UVLO + - OVP latch 18V/ 9.2V 13V Zero current detection ZCD 5 Internal reference & bias VCC Starter LOGIC & DRIVER - GATE 7 + 0.9V/0.4V OVP Latch PWM/PFC Control MULT 3 MULTIPLIER Current Sense COMP 2 Real Current Control 4 CS 6 GND 1 FB © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page5 Fremont Micro Devices Preliminary FT825 ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 16V, unless otherwise specified) Symbol Parameter Test Condition Min Typ Max Unit 20 V SUPPLY VOLTAGE VCC Operating Range After turn-on 9.5 VCCon Turn-on Threshold 17.8 V VCCoff Turn-off Threshold 9.2 V VCCOVP VCC over Voltage 24 V 6 uA SUPPLY CURRENT Istart-up Iq Icc Start-up Current Before turn-on,VCC= 16V Quiescent Current After turn-on, No switch 1.3 mA @ 70 kHz 1.8 mA Operating Supply Current MULTIPLIER INPUT IMULT VMULT VCS/ VMULT K Input Bias Current VMULT = 0 to 3 V Linear Operation Range Output Max Slope Gain (1) VMULT = 0 to 1V VCOMP = Upper clamp VMULT = 1 V, VCOMP = 3 V -1 uA 0 to 3 V 2.4 V/V 0.72 1/V 0.4 V ERROR AMPLIFIER VFB Voltage Feedback Input Threshold VEA Voltage Gain 400 V/V GEA Transconductance 100 100uA/V Source Current 45 uA Sink Current -65 uA Upper Clamp Voltage 5.2 V Lower Clamp Voltage 1.2 V 100 ns 2.4 V ICOMP VCOMP CURRENT SENSE COMPARATOR td (H-L) VCS clamp Delay to Output Current Sense Reference Clamp © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page6 Fremont Micro Devices Preliminary FT825 ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 16V, unless otherwise specified) Symbol Parameter Test Condition Min Typ Max Unit ZERO CURRENT DETECTOR VZCD_T VZCD_Hy VZCD_OVP Zero Current Detect (2) 0.4 V (2) 0.5 V 1us delay after turn-off 5.3 V 130 us 300 ns 3.5 us 1 A -1.2 A 12 V Threshold Zero Current Detect Hysterestic Output over Voltage Threshold LOGIC tSTART tLEB Toff_min Start Timer Period Leading Edge Blanking Time Minimum off Time GATE DRIVER Igate-source Max Source Current Igate-sink Max Sink Current Voclamp Output Clamp Voltage Table 4 (1) The multiplier output is given by: Vcs = K * VMULT * (VCOMP – 1.2) (2) Parameters guaranteed by design, functionality tested in production. © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page7 Fremont Micro Devices Preliminary FT825 FUNCTIONAL DESCRIPTION Under-Voltage Lockout(UVLO) The turn-on and turn-off threshold voltages are fixed internally at 17.8V and 9.2V respectively for FT825. This hysteresis behavior will guarantee a one shot start-up, as long as a proper start-up resistor and hold-up capacitor are used. Line Compensation An offset current proportional to instantaneous mains voltage streams out CS pin. A compensation resistor inverse proportional to the offset current is added between ZCD Pin and transformer auxiliary winding to achieve extremely low THD and line compensation, the compensation resistor can be adjusted externally. Zero current switching The IC is switched on when the transformer is demagnetized after MOSFET’s minimum off time about 3.5us typically. Internal circuitry connected to the ZCD pin detects the end of the secondary stroke. After MOSFET’s minimum off time, if no demagnetization signal is detected on the ZCD pin, the controller generates a startup signal 130us typically after the last GATE signal. Leading Edge Blanking (LEB) A turn on spike on CS pin will inevitably appear when the power MOSFET is switched on. At the beginning of each switching pulse, the current-limit comparator is disabled for around 300nsec to avoid premature termination. The gate driver output cannot be switched off during the blanking period. However, it is strongly recommended to add a small RC filter for higher power application to avoid the CS pin from damage by the negative turn-on spike. Output Driver With a low ON-resistance and a high current driving capability, the output driver can easily driver a big MOSFET or IGBT. Cross conduction currents are avoided to minimize heat dissipation, allowing the efficiency and reliability to be improved. Over Voltage Protection (OVP) Under steady-state condition, system output voltage is controlled by load connection, the voltage of ZCD pin set by R1, R2 and auxiliary winding (see figure 4) does not exceeds 5.3V, When system output is open, the voltage of output increases, due to the coupling polarity between auxiliary winding and secondary winding of a transformer, ZCD voltage will increase also. Once the ZCD voltage exceeds 5.3V and last for about 1us to guarantee the leakage inductance ringing has been fully damped, OVP of IC is triggered, the IC stops switching, It can be reset by re-starting the voltage on pin VCC. The OVP voltage can be adjusted by setting R1, R2 and auxiliary winding. © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page8 Fremont Micro Devices Preliminary FT825 ZCD FT825 R1 5 R2 Figure4 Circuit OVP Power Factor Correction The MULT pin is connected to the tap of the resistor divider from the rectified instantaneous line voltage and fed as one input of the Multiplier. The output of the multiplier will be shaped as sinusoid too. This signal provides the reference for the current comparator and comparing with the primary side inductor current which sets the primary peak current shaped as sinusoid with the input line voltage, High power factor can be achieved. The maximum voltage of the multiplier output to the current comparator is clamped to 2.4V to get a cycle-by-cycle current limitation. Minimum off time The FT825 operates with variable switching frequency, the frequency is changing with the input instantaneous line voltage. To limit the maximum frequency and get a good EMI performance, FT825 employs an internal minimum off time limiter—3.5 s. Output Short Circuit Protection When the output short circuit happens, the positive plateau of auxiliary winding voltage is also near zero, the VCC can not be held on and it will drop below VCC UVLO. The IC will shut down and restart again. © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page9 Fremont Micro Devices Preliminary FT825 DIP8 PACKAGE OUTLINE DIMENSIONS Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 3.710 4.310 0.146 0.170 A1 0.510 A2 3.200 3.600 0.126 0.142 B 0.380 0.570 0.015 0.022 B1 0.020 1.524 BSC 0.060 BSC C 0.204 0.360 0.008 0.014 D 9.000 9.400 0.354 0.370 E 6.200 6.600 0.244 0.260 E1 7.320 7.920 0.288 0.312 e 2.540 (BSC) 0.100 BSC L 3.000 3.600 0.118 0.142 E2 8.400 9.000 0.331 0.354 © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page10 Fremont Micro Devices Preliminary FT825 SOP8 PACKAGE OUTLINE DIMENSIONS Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 b 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 e L 1.270 (BSC) 0.050 (BSC) 0.400 1.270 0.016 0.050 0° 8° 0° 8° © 2013 Fremont Micro Devices Inc. Confidential Rev0.82 DS825-A-page11 Fremont Micro Devices Preliminary FT825 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 Rev0.82 DS825-A-page12