BL8080 BELLING | Alldatasheet
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Technical content
www.belling.com.cn 1 BL8080 HIGH INTEGRATED PWM CONTROLLER GENERAL DISCRIPTION The BL8080 is a PWM controller designed to drive high voltage NPN transistors. It integrates an oscillator, cycle -by-cycle current limit, thermal protection and over voltage protection, great reducing the number of external components and system level cost. Compared to conventional controller, BL8080 has a significantly smaller startup current of less than 20uA , which allows large startup resistor that enabes further power saving. The frequency can be adjusted from a n external capcitor. At light load condition the frequency of BL8080 can b e varied according to the load, which improves the light load efficiency.
FEATURES
Low start up current Easy programmable frequency Compact SOT23-6 package Universal voltage range: 85VAC -264VAC Thermal shutdown Cycle by cycle current limit Slope current drive Low standby power consumption
APPLICATIONS
Cell phone charger DVD player power supply MP3 charger LED lighting driver TYPICAL APPLICATION CIRCUIT OB OE VCC GND FB CT LC8100 AC Input DC Output Figure1: BL8080 Typical Application Circuit BL8080
www.belling.com.cn 2 BL8080 BLOCK DIAGRAM Figure2: Block Diagram PIN CONFIGURATION 3 4 6OB OE VCC FB GND CT SOT23-6 Figure3:BL8080 Top View PIN DISCRIPTIONS Pin # Name Description
1 OB Output of the drive, connects t his pin to the base of the external power
transistor. 2 OE Connects this pin to the emmiter of the external power transistor. 3 VCC The power supply. This pin provides power for the internal circuitry and driver. 4 FB Feedback. Need put a capacitor between this pin and the ground. 5 GND Ground. 6 CT Oscillator input pin. Need put a capacitor between this pin and the ground. The oscillator frequency varied with the capacitor value.
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ORDERING INFORMATION
BL8080 □1 □2 □3 Code Description Temperature & Rohs: C: -40~85° C, Pb Free Rohs Std. Package Type: B6: SOT-23-6 Packing Type: TR: Tape & Reel (Standard) MARKING INFORMATION Product Classification BL8080CB6TR Marking AA Product code Y Year W Week ABSOLUTE MAXIMUM RATINGS Parameter Symbol Min Max Unit Supply Power Voltage VCC -0.3 15 V Voltage at CT, FB, OB, OE -0.3 12 V Power Dissipation PD 0.25 W Operating Junction Temperature TJ -40 150 ℃ Storage Temperature Ts -55 150 ℃ Electronic static discharg ESD 2000 V Notes: 1. Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. 2. All voltage values are given with respect to GND pin. RECOMMENDED OPERATING CONDITIONS The recommended operating conditions table defines the condition for acture device operation. Recommended operating conditions are specified to ensure the optimal performance to the datasheet specifications. Parameter Symbol Min Max Unit Supply Power Voltage VCC 5.5 9 V Operating Ambient Temperature TA -25 85 ℃ AAYW 1 2 3 4 5 6
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ELECTRICAL CHARACTERISTICS
(All the data tested under the condition: Ta=25℃, unless it is specially noted) Parameter Test Condition Min Type Max Unit Reference Section Reference voltage Oscillator worked 2.4 2.5 2.6 V Line regulation VCC range 4.5V-9V 4 % Load regulation 2 % Temperature coefficient -40℃--120℃ 0.2 mV/℃ Feedback Section Source current VFB=1V,Vcc=8V 500 600 700 uA Pull down resistor 23k Ω Sink current VFB =2V, VCC=11V mA PFM threshold VPFM 1.5 1.8 2.0 V Oscillator stop threshold Vstart 0.8 1 1.2 V Oscillator Section Frequency CCT=330pF 42 45 48 KHZ Voltage stability 4.5V≤VCC≤9V Amplitude VCT peak to peak 2.4 V Temperature stability -40≤Ta≤125 -10 +10 % Falling slop time CCT=330pF 0.8 1 1.3 uS Source current 37 uA Sink current 500 uA PWM Section Max duty cycle 60 75 % Min duty cycle 0 % Current Sense Section Current sense voltage 0.6 V Peak current limit IPK 450 520 600 mA IPK temperature coefficient -40≤Ta≤125 -10 10 % Propagation delay time 250 nS Minimum on time 0.5 1.2 uS Output Section OB source current IOC=0A (VCC=8V) IOC=0.5A mA OB sink current VOB=1V VOB=2V 100 mA Power Section Startup current by OB 30 50 uA Quiescent current VCC=8V, VFB=0.6V(note1) 3.5 mA VCC startup threshold 8.4 8.8 9.2 V
www.belling.com.cn 5 BL8080 ELECTRICAL CHARACTERISTICS (continued) Parameter Test Condition Min Type Max Unit VCC shut down threshold 4 4.5 5 V OVP threshold 9.5 10 10.5 V Others Over temperature shut down threshold 135 145 ℃ TYPICAL PERFORMANCE INFORMATION Figure4．Constant operating frequency VS Temperature Figure5. VCC Over Voltage Protection Point VS Temperature Figure6. VCC Startup Voltage VS Temperature Figure7. VCC Shutdown Voltage VS Temperature
www.belling.com.cn 6 BL8080 TYPICAL PERFORMANCE INFORMATION Figure8. Reference Voltage VS Temperature Figure9. Oscillator Frequency VS Feedback Voltage Figure10. Oscillator Frequency VS CT Cap TA=25
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APPLICATION INFORMATION
LC 8100 starts to work once VCC reaches the start up thresh old voltage (typically 8.8V). The device has a build -in diode of which the anode connects to the OE pin and the cathod to the VCC pin. Through the external power transistor, the VCC storage capacitor can be charged, and the base current of the transistor is supplyed by a resistor connects to the DC bus.because the base current is amplified by transistor, this will greatlly reduce the cosumption. After start up the auxillary power supply take over. Feedback and control The FB voltage value controls the peak current of primary side. The oscillator begins to work once VFB exceeds th e threshold voltage of 1V . By comparing the voltage across the current sense resistor with a preset value of VFB*k (k is a coefficient less than 1), the internal comparator controls the on/off state of the transistors in the cycle. BL8080 can automatically adjust the operating mode according to the load condition. If VFB is larger than 1.8V, BL8080 works at constant frequency mode which frequ encyset by the CT capacitor, otherwisethe oscillator operates invaried frequency mode. Oscillator frequency(kHZ) FB Voltage(V) 1V 1.8V Constant frequency VFM Figure11．Feedback Control of BL8080 Cycle by cycle current limit Cycle is terminated when the peak current exceeds 0.6A. In normal operation, Ipk should be less than 0.6A. When the power supply output is overload or the control loop is open, the internal OCP(over current protection) function circuit istriggered and shuts down the external transistor-pulling down the FB voltage in the rest time of this cycle to decrease the pea k current.If FB voltage in one cycle is pulled down to 1.8V, then FB voltage will be clamped to this level till this cycle ended , if the next cycle the fault still exist, FB voltage will continue to be pull down to keep the transistor and transformer work at a save zone. Leading edge blanking At the instant the power transistor is turn on, there usually exists a current spike through the transistor caused by primary side capacitor and secondary rectifier reverse recovery which can lead to incorrect OCP ac tion.For this reason, BL8080 employs a leading edge blanking circuit to inhibit the current sense comparator for a short time after the transistor is on. Over Voltage Protection (OVP) BL8080 integrates VCC OVP circuit to improve the system stability. When the VCC voltage exceeds 10V due to abnormal condition, the OVP circuit is triggered and shut down the device . When VCC drops bellow UVLO, BL8080 starts again. As the output winding couple s with the auxiliary winding, when the output voltage exceeds the s et value, the auxiliary voltage rise linearly with the output voltage, if VCC exceeds 10V, PWM pulse is disabled to proventthe system from damage.
www.belling.com.cn 8 BL8080 Over Temperature Protection (OTP) BL8080 integrates a temperature detection circuit that will shut down PWM output when the junction temperature exceeds 135 ℃. s When the temperature drops down and the VCC voltage is still over the UVLO voltage, the device resumes operation. Under Voltage Lockout (UVLO) The turn-on and turn -off threshold voltage are fixed internally at 8.8V and 4.5V, respectivelly. ICC Supply Current(mA) Supply Voltage(V) VCC 4.5 8.8 Turn OnTurn Off Figure12. UVLO of BL8080 During start up, the hold -up capacitor should be charged up to 8.8V by the start up resistor and external transistor to enable the BL8080. The hold-up capacitor supplies VCC until the auxiliary winding of transformer takes over. When VCC drops below 4.5V, BL8080 stops work. This UVLO hysterisis ensures that the hold -up capacitor is adequate to supply VCC during normal operation. Built-in Slope Compensation The voltage across the current sense resistor is collected for current mode control and cycle by cycle current limit. Built -in slope compensation improves the stability and prevents sub-harmonic oscillations when the device works in continue conduction mode -especially when the duty cycle exceeds 50%.
www.belling.com.cn 9 BL8080 Aplication Design Example Figure13. 5W (5V/1A) Application Circuit BOM Designator Part Type Designator Part Type D1 IN5822 R1,R9 100 D2,D3,D4,D6,D7 IN4007 R2,R6 3M D5 IN4148 R3 270K C1 1nF R5 5.1K C2 1nF,250V R7 10 C3,C4 470uF,10V R8 300 C5 6.8uF,400V R10 1K C6 3.3uF,400V R11 20K C7 22uF,16V R12,R13 27K C8 33nF L1c 1mH C9 10nF(optional) L2 1.5uH C10 330pF L3 10uH C11 0.1uF U1 BL8080 Q1 MJE13003 U2 PC817 IC2 TL431 T1 EE16 RF1 10, 2W BL8080
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