OB3309 Highly Integrated U Type CCFL Backlight Controller Product Specification FEATURES It provides a high degree of design flexibility by offering great programmability for key parameters which include operating frequency, striking frequency, striking time, dimming polarity, burst dimming frequency, soft-start time, and soft on/off time for burst dimming. Optimized for U type CCFL solution Adjustable dimming polarity Adjustable striking frequency & time Flexible Dimming mode Control: IV T | Analog dimming control | Internal burst dimming control | External burst (LPWM) dimming control Adjustable minimum duty for internal burst dimming Adjustable minimum reference voltage for analog dimming 0-2V DC voltage direct dimming control without external circuits Comprehensive Protection Coverage: | Output over voltage protection (OVP) | Output over current protection (OCP) id e Various dimming modes control and dimming polarity programmability are offered. Both internal burst and external low frequency PWM (LPWM) dimming methods are available for a wide range of dimming control. Analog dimming is also provided through external DC input control to achieve wide dimming range. High performance push pull topology nt i Operating in push pull configuration, OB3309 converts DC input voltage to the pure sinusoidal voltage and current waveforms, to ignite and operate CCFL lamps. to OB3309 is a highly integrated and high performance U-type Cold Cathode Fluorescent Lamp (CCFL) controller optimized for LCD display backlight application. Comprehensive protection functions are integrated, thus it provides a cost effective yet high reliability LCD backlight solution. al GENERAL DESCRIPTION | | Open lamp protection and short lamp protection Arcing protection nf APPLICATIONS Co The highly integrated OB3309 provides complete protection features covering output over voltage, over output current protection, lamp fail safe function, and IC under voltage lockout. The OB3309 is available in SOP-16 Packages. LCD Monitor LCD TV Flat panel display VIN Br i DIM gh t TYPICAL APPLICATION On - ENA +5V 1 VS DIM ENA 16 2 RI STIME 15 3 RT CMP 14 4 DRC CS 13 BF/DMOD PRT 12 PRT VS 11 VS GND 10 GATE2 9 5 6 POL 7 VDD 8 GATE1 PRT VS OB3309 GND Figure1. OB3309 Typical Application Schematic ©On-Bright Electronics Confidential -1- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control Absolute Maximum Ratings Operating Ambient Temp. TA Operating Junction Temp. TJ Min/Max Storage Temp. Tstg Lead Temp. (10 Sec) Value 4.5V to 5.5V 30K to 150KHz Package Thermal Characteristics Parameter Thermal resistance θJA (SOP) Ordering Information Part Number OB3309QP OB3309QPA Note: Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, functional operation of the device at these or any other conditions beyond those indicated under Value 85 oC /W Description SOP16, pb-free in tube SOP16, pb-free in T&R al “recommended operating conditions” is not implied. Exposure T I/O to GND Parameter VDD Voltage Operating Frequency IV CS to GND Recommended Operating Range Value 7V -1.5V to VDD+0.3V -0.3V to VDD + 0.3V -20 oC ~ 85oC 150oC -55 oC ~150oC 260 oC to Parameter VDD Input Voltage to GND may affect device reliability. Co nf id e nt i to absolute maximum-rated conditions for extended periods On - Br i gh t Package Marking Information ©On-Bright Electronics Confidential -2- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control al to IV T Pin Configuration Terminal Assignment Pin Name I/O Pin Function nt i Number ENA Input Enable control input, active high 2 RI I/O Connected an external resistor to ground to set striking frequency (No Floating) 3 RT I/O Connected an external resistor to ground to set operation frequency Input Dimming range setting. • Connect 0.2V to 2V DC voltage can set minimum burst duty from 100% to 0% for bust dimming; • Connect 0V to 1.25V DC voltage can set minimum Vref_ea from 0V to 1.25V for analog dimming; nf DRC Co 4 id e 1 Connected to VDD to set analog dimming mode I/O POL Connected to GND to set external LPWM dimming mode Connect an external capacitor to GND to set internal burst dimming mode. The burst mode frequency is determined by the external capacitor Input PWM Dimming polarity selection : • POL<2V: Negative analog / burst mode , positive LPWM dimming • POL>2V: Positive burst mode , negative analog / LPWM dimming 7 VDD Power +5V Power supply 8 GATE 1 Output Output drive 9 GATE 2 Output Output drive 10 GND Ground Power ground 11 VS Input Lamp voltage feedback 12 PRT Input Lamp fault detection 13 CS Input Lamp current feedback 14 CMP I/O Loop compensation and soft start time setting 15 STIME I/O Connect an external capacitor to GND to set striking time 16 DIM Input Dimming signal input On - Br i 6 BF/DMOD gh t 5 ©On-Bright Electronics Confidential -3- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control gh t Co nf id e nt i al to IV T Functional Block Diagram On - Br i Figure2. OB3309 Functional Block Diagram ©On-Bright Electronics Confidential -4- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control Electrical Characteristics VDD=5V, ENA=5V, RT=36Kohm, RI=120Kohm, TA=25℃, if not otherwise noted. Parameter Symbol Conditions Min Typ Max Units 8 T Current Consumption Istandby ENA=0V - - uA Operating supply current IVDD No loading, CMP=5V - 4.5 6 mA Operating supply current IVDD Cload=2nF, CMP=5V - 5.5 8 mA IV Standby current to VDD UVLO UVLO on 3.6 UVLO off V 4.4 V al Enable / Disable ON ENA (Enable) threshold voltage 2.0 OFF RENA nt i Pull down resistor FOP Striking frequency FSTK Max. (overlap) duty cycle id e High Frequency Oscillator Operating frequency 0.8 100 - 50 V Kohm - KHz 65 KHz 45 % Burst frequency Max. burst duty DMAX 1 DMIN1 Co Min. burst duty 1 (set by DRC) nf Low Frequency Oscillator for Burst Mode Dimming DMIN2 Min. burst duty 3 (set by DRC) 1 DMIN1 gh t Min. burst duty 2 (set by DRC) 1 Min. burst duty 4 (set by DRC) 1 DMIN2 CBF/DMOD=22nF - 200 - Hz CBF/DMOD=22nF, DIM<0.2V POL=0V, CBF/DMOD=22nF, VDRC=VRT, DIM>2V POL=0V, CBF/DMOD=22nF, VDRC=92%VRT , VDRC <DIM<2V POL=5V, CBF/DMOD=22nF, VDRC =0V, DIM<0.2V POL=5V, CBF/DMOD=22nF, VDRC=9%VRT+0.2,DIM< VDRC - 100 - % - 0 - % - 9 - % - 0 - % - 9 - % - 0 - V - 0.5 - V - 1.25 - V Analog Dimming Control On - Br i Min. Lamp Current Reference Voltage 1 (set by DRC) 1 Min. Lamp Current Reference Voltage 2 1 (set by DRC) Max. Lamp Current Reference Voltage Vref_EA_MAX BF/DMOD=VDD, VDRC=0V , DIM>2V BF/DMOD=VDD, VDRC=25%VRT , DIM>1.28V BF/DMOD=VDD, DIM<0.2V BF/DMOD=0V 0 high BF/DMOD=0V 2.0 low BF/DMOD=0V Vref_EA_MIN1 Vref_EA_MIN2 External LPWM Dimming Control External LPWM duty External LPWM Logic input level ©On-Bright Electronics Confidential -5- - 100 % V 0.8 V Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control Parameter Symbol Conditions Min Typ Max Units 1.25 1.3 V Error Amplifier Vref_EA 1.2 ISOFT_ON ISOFT_OFF 60 350 60 120 ISST 1.3 uA 1.3 3 uA V CMP=15nF Soft start current to Soft start Striking time ISTIME1 Vth_STIME1 al Striking timer current Striking timer threshold CS threshold voltage for OLP (open lamp protection) TOLP 0.85 1.25 2.0 1.25 14 3 V V V uA V 0.8 V 60%*Vref_EA 160 ms Vth_OVP Normal 2.0 V TOVP T_nom Normal Normal Normal, BF/DMOD=0V or CBF/DMOD=22nF 160 0.48 ms Sec 480 uS Co OLP debounce time VS threshold voltage for OVP (over voltage protection) OVP debounce time Normal protection blanking time Dimming_on time for OLP disable Vth_OLP Striking Normal Normal Normal Normal, BF/DMOD=0V or CBF/DMOD=22nF Normal, BF/DMOD=VDD Normal nf VS regulate voltage at Striking Threshold voltage for PRT Fault timer currnet Fault timer threshold id e Vth_CS Vth_PRT Vth_REG Vth_PRT ISTIME2 Vth_STIME2 nt i Control and Protection Threshold / Debounce time Ignition completion threshold dB Hz uA uA T Open loop voltage gain Unity gain bandwidth Soft on current Soft off current CBF/DMOD=22nF or BF/DMOD=0V IV Reference voltage gh t T_dim_on Br i Dimming Polarity Control On - Dimming Polarity Selection RPOL Negative internal burst mode or positive external PWM dimming Positive internal burst mode or negative external PWM dimming Pull down resistor RON RON Isink/Isource=70mA Isink/Isource=70mA Vth_POL - - 2.0 V 2.05 - - 45K ohm Gate Driver Output Gate1 Gate2 - 8 8 12 12 ohm ohm Note: 1 Detail description to see Figure4 of page 8; 2 For analog dimming mode, Vth_OLP tracks with Vref_EA. Vref_EA can be calculated by the following equation: Vref _ EA = ©On-Bright Electronics 25 × (2 − VDIM ) for 0.2V ≤ VDIM ≤ 2V 36 Confidential -6- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control General Operation OB3309 CCFL controller is designed for U-type CCFL’s LCD backlight system applications configured in push pull topology; it converts the DC input voltage to pure sinusoidal waveforms for CCFL operating with high efficiency and low EMI emission. The resonant frequency of the tank is set by the transformer leakage inductance and secondary parallel capacitor. IV T(sec) = 2.31 × C[uF] to After the striking time out, the striking frequency will be switched to normal frequency and last for 64ms, if any one of the lamps still can not be lit, OB3309 will enters the shutdown mode as show in Figure 3. The lamp fault protection functions are integrated to provide a high reliability & simplifier solution with low system cost. Dimming polarity selection can be achieved by setting the voltage level at POL Pin. A typical application scheme is shown in figure 8 on page 10. al 64ms 3V id e OB3309 is activated by applying logic high to the ENA input. It is TTL logic compatible. The controller is enabled when the voltage at ENA pin is higher than 2.0V. Toggling the ENA signal resets the state machine hence restarts the inverter system. Vstime nt i Enable the Controller T lower than 1.25V, then the system enters normal operating mode. Otherwise, the duty cycle of the gate drive signal will increase further to deliver more power to ignite the lamp. Once the duty cycle of gate drive signal reaches maxima of 45%, the internal striking timer will be triggered. If the lamps are lit before the time out, OB3309 enters the normal operation mode. Otherwise, it enters the shutdown mode. The striking time is given by: Function Description 1.5s t 0 Striking frequency Normal frequency Figure 3 Striking mode control nf Normal Operation and Striking Frequency Soft Start and Soft On/off The normal operation frequency, FOP, is set by the resistor connected to RT pin. It is given by Co External capacitor connected to CMP pin provides soft start and soft on/off control. At start up, an internal current source starts to charge the capacitor. Consequently, voltage at CMP pin increases gradually and so as to the pulse width of the PWM Gate signals. This soft start control helps to reduce the MOSFET inrush current and voltage stresses, thus expand the lamp life time. The slope of the soft start ΔV / ΔT can be approximated as: 1800 RT(Kohm) The striking frequency, Fstriking, is set by the resistors connected to both RI and RT pins. It can be calculated by the following equation: gh t FOP (KHz) = 1800 RT//RI(Koh m) 217 ΔV[V] = ΔT[mS] C CMP [nF] × RT//RI[kohm] Br i FSTRIKING (KHz) = Lamp Ignition and Striking Voltage Regulation Once lamps are ignited, the capacitor connected to CMP pin performs the loop compensation function. In internal burst mode dimming or external burst (PWM) mode dimming conditions, the voltage ramping up and down at this pin performs a soft on/off control function in each burst cycle. On - To ignite CCFL, a much higher voltage than that in normal operation is required, especially for aged lamp or in low ambiance temperature. The output voltage is divided by the capacitive voltage divider. A voltage signal is fed into VS pins with diodes and their peaks are compared with internal 2.0V threshold voltage. Consequently, the maximum output voltage is regulated and limited. During ignition, OB3309 monitors the peak voltage levels at CS & PRT pins, it is recognized that all lamps are lit If the peak voltage of CS pin is higher than 0.85V and the voltage level at PRT pin is ©On-Bright Electronics Lamp Current Regulation Lamp current is regulated by the currents feedback loop with an internal transconductance error amplifier. Confidential -7- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control The AC lamp currents are sensed by the sense resistors (refer to R24 in figure 8) connected in series with high voltage coupling inductance. The AC voltage across the sense resistors are fed into the CS pins. The peak of the sensed AC voltage is detected. The peak value is compared with an internal reference voltage. The error is amplified that controls the on time of the push pull switches, as a result, the lamp current is regulated. The lamp current can be calculated by the following equation: 0.2V ≤ V DIM ≤ 2 − 36 × V DRC 25 IV T The minimum voltage of Vref_EA is determined by the voltage at DRC which should be set in the range from 0V to 1.25V for analog dimming mode. 1.33 2 × Rsense al Where N is the coupling inductance turns ratio, N=NLV/NHV, the inductance T2 ,as shown in figure8. nt i Dimming Control Figure. 4 Vref of EA vs DIM voltage Internal burst mode dimming is obtained by connecting a capacitor to BF/DMOD pin. A low frequency triangular waveform generator is formed by the capacitor and internal circuit of IC. The triangular voltage waveform with peak of 2V and valley of 0.2V at this pin is used for the internal low frequency burst PWM generation. Duty cycle so as to lamp brightness is controlled by the analog signal at DIM pin. The burst mode dimming frequency Fburst is set by the following equation: Polarity POL< 2V POL >2V Co Function nf id e Three commonly used dimming modes, analog mode dimming, internal burst mode dimming and external burst (PWM) dimming functions, are supported without any additional components. Different dimming modes are selected by BF/DMOD pin. The lamp brightness is determined by the control signal at DIM pin. Both in internal burst mode dimming and external PWM mode dimming, the polarity can be set by the voltage level at POL pin as shown in the following table: 25 × (2 −VDIM ) for 36 to Ilamp ( A) = N * Vref _ EA(V ) = Negative Negative Internal Burst Negative Positive External LPWM Positive Negative gh t Analog dimming Fburst ( Hz) = 158400 C BF [nF ] × RT[ Kohm] A DC voltage ranging from 0.2V to 2V at DIM pin corresponds to a lamp brightness of approximately 100% to (2 − VDRC ) × 100% , as shown in Figure 5. 1.8 Br i External LPWM burst dimming mode is selected by shorting BF/DMOD pin to ground. OB3309 accepts an external LPWM signal to DIM pin with a swing voltage of 0V to a level greater than 2V. The lamp brightness is controlled by the duty cycle of the LPWM signal. The burst frequency is equal to LPWM frequency. (2 − VDIM ) × 100% for 0.2V ≤ VDIM ≤ VDRC 1.8 On - Duty = Connecting BF/DMOD pin to VDD selects analog mode dimming. A DC voltage ranging from 0.2V to 2V at DIM pin performs analog mode dimming control. The voltage at DIM pin modulates internal error amplifier reference voltage Vref_EA from 1.25V to VDRC, which corresponds to a lamp current of approximately 100% to (VDRC/1.25)×100%. Vref_EA can be calculated by the following equation: Figure. 5 Duty of burst vs DIM voltage (Negative internal burst mode dimming) ©On-Bright Electronics Confidential -8- Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control Duty = Figure. 7 Use DRC PIN to set Dimming Range for V DRC ≤ 0.2V VDRC (V ) = 2 × R2 R1 + R 2 to 0% for V DRC > 0.2V IV (VDRC − 0.2) × 100% 1.8 T If the voltage of POL is higher than 2.05V, the dimming polarity is changed, and DC voltage from 0.2V to 2V at DIM pin corresponds to the lamp’s brightness of approximately minimum duty cycle of burst dimming to 100%, as shown in Figure 6. The minimum duty cycle of burst dimming can be calculated by the following equation: (V DIM − V DRC ) ×100% for 0.2V < VDRC < VDIM 2 − V DRC RT = R1 + R 2 Lamp Fail Safe Functions nt i al The OB3309 provides complete protection features that cover all common lamp fault conditions including: z Lamp open or broken z Two terminals of lamp are short together z High voltage terminal of lamp is short to ground id e The sensed lamp voltage and current signals, CS, VS and PRT are used to monitor and detect the faults. nf Figure. 6 Duty of burst vs DIM voltage During normal operation, if the peak voltage level at CS pin is less than Vth_OLP, the lamp open or lamp broken is recognized and the system will shutdown after 160ms. If the peak voltage level at PRT pin is higher than Vth_PRT, an internal source current (14uA) charges the capacitor which connected STIME pin to ground. Once the voltage at STIME pin reaches 3V, the IC will shut down. But in internal burst mode dimming or external PWM mode dimming, if the dimming_on time is less than 480uS, these two protections are disabled. (Positive internal burst mode dimming) Analog dimming >4.5V External LPWM 0.2V-2V Capacitor 0.2V-2V <0.2V PWM gh t Internal Burst Pin Connection BF/DMOD DIM Co Function Ratio Set by customer Set by customer Set by customer During normal operation, if VS peak voltage is more than 2.0V, it enters latched shutdown mode. On - Br i A DC voltage at DRC pin determines the minimum dimming thus it is used to adjust dimming range for analog mode dimming or internal burst mode dimming. Because the voltage of RT pin is fixed 2V when OB3309 is in operation, the voltage of DRC can be set by RT divided resistors, as shown in Figure 7. (Patent pending) ©On-Bright Electronics Confidential -9- Preliminary Datasheet OB_DOC_DS_330900 ©On-Bright Electronics Confidential - 10 - nf Co id e nt i VIN: 10.8-13.2V ADIM: 0V, Max. Brightness; 5V, Min. Brightness (for analog mode dimming) PWM: 0V, Max. Brightness; 5V, Min. Brightness (for internal burst mode dimming) 100%, Max. Brightness; 30%Min. Brightness (for external burst mode dimming) ENA: Disable, 0-0.8V; Enable, 2-5V gh t Br i On - al to IV T Highly Integrated U Type CCFL Backlight Control OB3309 Reference Application Circuit for 2U Lamps Figure8.OB3309 Reference Application Schematic Preliminary Datasheet OB_DOC_DS_330900 OB3309 gh t Co nf id e nt i al to IV T Highly Integrated U Type CCFL Backlight Control Symbol On - Br i A A1 A2 b c D E E1 e L θ ©On-Bright Electronics Dimensions In Millimeters Min Max 1.350 1.750 0.100 0.300 1.350 1.550 0.330 0.510 0.170 0.250 9.800 10.400 3.800 4.040 5.800 6.240 1.270 (BSC) 0.400 1.270 0º 8º Confidential - 11 - Dimensions In Inches Min Max 0.053 0.069 0.004 0.012 0.053 0.061 0.013 0.020 0.007 0.010 0.386 0.409 0.150 0.159 0.228 0.246 0.050 (BSC) 0.016 0.050 0º 8º Preliminary Datasheet OB_DOC_DS_330900 OB3309 Highly Integrated U Type CCFL Backlight Control Important Notice Right to make changes T On-Bright Electronics Corp. reserves the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. IV Warranty information to On-Bright Electronics Corp. warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with its standard warranty. Testing and other quality control techniques are used to the extent it deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. al On-Bright Electronics Corp. assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using On-Bright’s components, data sheet and application notes. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. Life support nt i On-Bright Electronics Corp.’s products are not designed to be used as components in devices intended to support or sustain human life. On-bright Electronics Corp. will not be held liable for any damages or claims resulting from the use of its products in medical applications. id e Military On - Br i gh t Co nf On-Bright Electronics Corp.’s products are not designed for use in military applications. On-Bright Electronics Corp. will not be held liable for any damages or claims resulting from the use of its products in military applications. ©On-Bright Electronics Confidential - 12 - Preliminary Datasheet OB_DOC_DS_330900