Preliminary BW7385A High Power Factor & Accuracy Constant Current LED Driver Features Description TM (Transition Mode) Fixed On -Time PFC The BW7385A is a highly-integrated, low startup Control current, TM (Transition Mode), fixed on- time PFC Accuracy Constant Current control and PWM controller. These functions enable the Low BOM Cost LED driver to easily meet the accuracy average LED Inductor Size Reduction current and high power factor requirements. The CT Pin Adjust Frequency Range for integrated functions also include the LED short Optimization protection, over voltage protection, over load Over Voltage Protection (OVP)-Auto Recovery protection. The COMP pin controls the duty by LED Short Protection (SCP) -Auto Recovery connected an RC compensation network to ground Over Load Protection (OLP) -Auto Recovery and forming the closed loop feedback control. SOT-26 Package The BW7385A improves the performance and Compatible Inductance Ballast reduces the cost of the LED driver. It is a 6-pin Incompatible Electronic Ballast SOT-26 package. Application GU10 /E14 LED Bulb Others LED Lighting Applications 1 Preliminary BW7385A Pin Configuration Pin Description Pin No. Name Function 1 VCC Power Supply Pin 2 GND Ground Pin 3 DRV 4 CT 5 CS 6 COMP The DRV pin is connected to the totem pole gate driver to drive the external power switch. The CT pin is connected to the current source to charge the external capacitor and compare the COMP voltage to terminate the power switch. Current Sense Pin Feedback Compensation Network Absolute Maximum Ratings Supply Voltage VCC --------------------------------------------------------------------------------------------------------CT, COMP, CS ---------------------------------------------------------------------------------------------------- 30V -0.3V ~ 7V DRV ------------------------------------------------------------------------------------------------------- 15V ℃ Operating Ambient Temperature ------------------------------------------------------------------------------ -20℃ ~ 85℃ Storage Temperature Range ---------------------------------------------------------------------------------- -65℃ ~ 150 ℃ SOT-26 Package Thermal Resistance (junction to ambient) ----------------------------------------------- 250℃/W Power Dissipation (SOT-26, at ambient temperature = 85℃) ------------------------------------------------ 250mW Lead Temperature (All Pb free packages, soldering, 10 sec) -------------------------------------------------- 260℃ Junction Temperature ------------------------------------------------------------------------------------------------------- 150 ESD Voltage Protection, Human Body Model -------------------------------------------------------------------------ESD Voltage Protection, Machine Model ----------------------------------------------------------------------------- 2KV 200V 2 Preliminary BW7385A Function Block VCC UVLO Internal Bias & Vref All Blocks Vref OK VCC OK EN VCCOVP + 31.5 V debounce - Protection OCP + Current Limit - COMP CS R + VREF gm On Time Controller - Q Driver stage OUT R S CT Sawtooth Generator STARTER Current Detector GND 3 Preliminary BW7385A Application Circuit 4 Preliminary BW7385A Electrical Characteristics (VCC = 15.0V & TA = +25℃, unless otherwise specified.) Parameter Pin Min. Typ. Max. Unit SUPPLY VOLTAGE Startup Current (VCC=UVLO on - 1V) 1 10 50 uA Operating Current (with 1nF load on OUT pin), Vcomp = 2.5V 1 2.5 3.2 mA 1 1.6 2.5 mA Operating Current (with 1nF load on OUT pin), Protection Tripped (OVP, SCP,) UVLO(off) 1 5.5 6.5 7.5 V UVLO(on) 1 14 15 16 V OVP Level on VCC Pin 1 29.5 31.5 33.5 V OVP De-Bounce Time 1 40 us VOLTAGE FEEDBACK Feedback Reference Voltage 6 0.195 0.200 0.205 V Tran-Conductance 6 300 uS Output Sink Current 6 300 uA Output Source Current 6 60 uA CURRENT SENSING Input Over Voltage Protection 5 1.8 2.0 2.2 V Open Loop Voltage, CS Pin Open 5 5 V Leading-Edge Blanking Time 5 450 nS Delay to Output 5 130 220 nS Rising Time, Load Capacitance = 1000pF 3 280 500 nS Falling Time, Load Capacitance = 1000pF 3 80 150 nS VGATE-Clamp (VCC = 25V ) 3 12.5 15 V 200 uA GATE DRIVER OUTPUT CT OUTPUT SECTION CT Pin Current 4 160 180 5 Preliminary BW7385A Application Information threshold voltage 31.5V, the output gate driver circuit will Start-up Current The typical start-up current is around 10uA. Very low start-up current allows the PWM controller to increase the value of start-up resistor and then reduce the power dissipation on it. UVLO (Under Voltage Lockout) A hysteresis UVLO comparator is implemented in BW7385A, then the turn-on and turn-off thresholds be shut down immediately to stop the switching of power MOSFET. The VCC pin OVP function is an auto recovery type protection. If the OVP condition happens, the pulses will be stopped and never recovery unless the VCC pin voltage is down to the UVLO off level. The BW7385A is working in an auto-recovery mode as shown in Fig.2. level are fixed at 15V and 6.5V respectively. This hysteresis shown in Fig.1 ensures that the start-up capacitor will be adequate to supply the chip during start-up. For quickly startup the LED driver, the start-up resistor should be matched with the startup capacitor. Due to the low UVLO on level, so the turn-on delay time will also never greater than the general PWM IC. Fig. 2 Gate Clamp Driver is clamped to 15V by an internal clamping circuit. Those damages usually come from undesired over-voltage gate signals. Under the Fig.1 conditions listed below, the gate output will turn off immediately to protect the power circuit. LEB (Leading-Edge Blanking) Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the sense resistor. To avoid fault trigger, a 450ns 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 can not switch off the gate driver. OVP (Over Voltage Protection) on VCC To prevent the LED driver from being damaged, the BW7385A is implemented an OVP function on VCC. When the VCC voltage is higher than the OVP 6 Preliminary BW7385A Package Information SOT-26 SOT-26 SYMBOL MILLIMETERS MIN. INCHES MAX. A MIN. MAX. 1.45 0.057 A1 0.00 0.15 0.000 0.006 A2 0.90 1.30 0.035 0.051 b 0.30 0.50 0.012 0.020 c 0.08 0.22 0.003 0.009 D 2.70 3.10 0.106 0.122 E 2.60 3.00 0.102 0.118 E1 1.40 1.80 0.055 0.071 e 0.95 BSC 0.037 BSC e1 1.90 BSC 0.075 BSC L θ 0.30 o 0 0.60 8 o 0.012 o 0 0.024 8 o Note: 1. Followed from JEDEC TO-178 AB. 2. Dimension D and E1 do not include mold flash, protrusions or gate burrs. Mold flash, protrusions or gate burrs shall not exceed 10 mil per side 7 Preliminary BW7385A Carrier Tape & Reel Dimensions SOT-26 Application A H 178.0±2.00 50 MIN. P0 P1 P2 D0 D1 4.0±0.10 4.0±0.10 2.0±0.05 1.5+0.10 -0.00 1.0 MIN. SOT-26 Application SOT -26 T1 C d 8.4+2.00 13.0+0.50 1.5 MIN. -0.00 -0.20 D W E1 20.2 MIN. 8.0±0.30 1.75±0.10 T A0 B0 F 3.5±0.05 K0 0.6+0.00 -0.40 3.20±0.20 3.10±0.20 1.50±0.20 Carrier Width Cover Tape Width Devices Per Reel 8 5.3 3000 (mm) 8 Preliminary BW7385A Tape and Specification Reel SOT 26 Direction of feed 9