Intelligrnt CCFL Inverter Controller

www.DataSheet4U.com OZ960 Intelligent CCFL Inverter Controller FEATURES • • • • • • • • • • • Supports wide-range voltage input applications (8v to 20v) Built-in intelligence to manage ignition and normal operation of CCFLs Reduces the number of components and board size by 30% compared with conventional designs 85% efficiency vs. typical 70% efficiency of conventional designs Zero-voltage-switching full bridge topology Built-in internal open-lamp and over-voltage protections Integrated burst mode control, and wide dimming range (10% to 100%) with integrated burst mode control Supports multiple CCFL lamps Simple and reliable 2-winding transformer design Constant-frequency design eliminates interference with LCDs Low stand-by power quality waveform received, at the CCFL voltage and current. The OZ960 operates at a single, constant frequency in a phase-shift PWM mode. Intelligent open-lamp and over-voltage protections provide design flexibility so various transformer models/manufacturers may be used. The built-in burst mode control provides a wide dimming range and simplifies the application circuit designs. Both operating and burst-mode frequencies are user-programmable parameters. The single stage design results in a low cost, reliable transformer without expensive, less reliable secondary fold-back treatment. The transformer does not require a more expensive center tapped primary. The OZ960 is available in a 20-pin SSOP package. It is specified over the commercial temperature range of 0°C to +70°C, and the industrial temperature range of -40°C to +85°C. ORDERING INFORMATION OZ960S - 20-pin plastic SSOP 150mil OZ960IS - 20-pin plastic SSOP 150mil OZ960G - 20-pin plastic SOP 300mil OZ960IG - 20-pin plastic SOP 300mil OZ960D - 20-pin plastic DIP 300mil OZ960ID - 20-pin plastic DIP 300mil FUNCTIONAL BLOCK DIAGRAM Refer to the functional block diagram in Figure 2, page 3, and the Pin Description Table on page 4. A precision reference provides a reference voltage for both internal and external uses. An oscillator circuit generates a user-programmable operating frequency with an external capacitor and a timing resistor. In addition, another resistor to program striking frequency is provided. The drive circuit consists of four outputs. These are designed to achieve zero-voltage switching, fullbridge applications. An error amplifier is provided to regulate the CCFL current. The Soft-start circuit offers a gradual increase of the power to the CCFL during the ignition period. The overvoltage protection block offers a regulated striking voltage for CCFLs. The striking time is programmable simply through an external component. The open-lamp protection is integrated in the protection block. This block intelligently differentiates the striking condition and open-lamp condition. ENA circuitry enables the operation of the IC through a TTL signal interface. Wide-dimming control is achieved through the burst-mode control block. GENERAL DESCRIPTION The OZ960 is a unique, high-efficiency, Cold Cathode Fluorescent Lamp (CCFL) backlight inverter controller that is designed for wide input voltage inverter applications. Additionally, the OZ960 performs the lamp dimming function with an analog voltage or low frequency Pulse Width Modulation (PWM) control. Operating Principle: Operating in a zero-voltage switching, full-bridge configuration, the inverter circuit achieves a very high efficiency power conversion. In addition, the transformer in the OZ960 does not require any specific gap-less arrangement. The simple, low cost transformer provides designers a high degree of design flexibility in specifying transformers. Setting the switching frequency higher than the resonant frequency of a highquality-factor resonant tank circuit yields a good- 10/23/01 Copyright 2000 - 01 by O2Micro OZ960-DS-1.6 All Rights Reserved Page 1 U.S. Patent #6,259,615 www.DataSheet4U.com J1 FUSE 1A R2 5.1K 10U U1 U2 OZ960 0.047u NDR_B PDR_A CT RT PGND LCT DIM LPWM PDR_C NDR_D F1 C1 Vin VIN DIM 5VDC ENA GND R1 22 1.0u C3 1 8 C4 2 QB C2 Si5504 D1 4.7V 1 CTIMR OVP ENA SST VDDA GNDA REF RT1 FB CMP 20 19 18 17 16 15 14 C12 0.047u QD 7 6 C6 5 QA 100P J2 C7 22P T1 C11 32:2200 0.033U 1 2 2 3 4 C9 0.47u 7 C13 0.1u 10 C14 0.015u U3 R6 33k Si5504 4 QC C5 220P 4 RT 4.7V 10K 1 2 3 7 6 5 8 52.3K D2 R3 2.2U R4 3 C8 6 RT 8 R5 240K 9 11 12 13 C10 6.8nF 5 1.0u CR1 BAV99L TYPICAL APPLICATION CIRCUIT Figure 1: An 8-22V Application Circuit of OZ960 OZ960-DS-1.6 C15 0.1u R7 1M R8 51k CR2 BAV99L R9 499 VIN: 8.0V---22V ENA: 0V--1.0V Disable;2.0V---3.3V Enable DIM: 3V Max. Brightness; 1.2V Min. Brightness Striking frequency: 74KHz - 82KHz Operating frequency: 56KHz - 64KHz OZ960 Page 2 www.DataSheet4U.com OZ960 I=3uA CTIMR 1 2V + I=6uA OVP Protection POFF Soft Start NDR_B 20 NDR_B OVP 2 - hys. COMP PDR_A 19 PDR_A ENA ACTIVE "HIGH" 3 1.5V + ENA hys. COMP 18 HF OSC 17 CT SST 4 RT VDDA 5 Reference POFF 16 PGND GNDA 6 2.75V 2.50V 15 OPLAMP + ZVS Phase-Shift Controller BurstMode Control LCT REF 7 14 DIM RT1 8 - Ignition 13 LPWM FB 9 + EA 1.25V PDR_C 12 PDR_C CMP 10 NDR_D 11 NDR_D Figure 2. Functional Block Diagram OZ960-DS-1.6 Page 3 www.DataSheet4U.com OZ960 PIN DESCRIPTION Names CTIMR OVP ENA SST VDDA GNDA REF RT1 FB CMP NDR_D PDR_C LPWM DIM LCT PGND RT CT PDR_A NDR_B Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 I/O I I I I I I O I I O O O O I I I I I O O Description Capacitor for CCFL ignition duration Output voltage sense Vth=2.0V Enable input; TTL signal is applicable Soft-start capacitor Voltage source for the IC Analog signal ground reference Reference voltage output; 2.5V typical Resistor for programming ignition frequency CCFL current feedback signal Compensation output of the current error amplifier NMOSFET drive output PMOSFET drive output Low-frequency PWM signal for burst-mode dimming control Input analog signal for burst-mode dimming control Triangular wave for burst-mode dimming; frequency Power ground reference Timing resistor set operating frequency Timing capacitor set operating frequency PMOSFET drive output NMOSFET drive output ABSOLUTE MAXIMUM RATINGS WITH RESPECT TO INPUT POWER SOURCE RETURN REFERENCE VDDA GNDA, PGND Logic inputs 7.0V (1) +/- 0.3V -0.3V to VDD +0.3V OZ960 Operating temp. 0 C to 70 C o o OZ960I -40 C to 85 C o o Operating junction temp. Storage temp. o 150 C -55 C to 150 C o o RECOMMENDED OPERATING RANGE VDDA Fosc Rosc 4.7V ~ 5.5V 30 KHz to 150 KHz 50 k to 150 k Note : The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The “Functional Specifications” table will define the conditions for actual device operation. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. (1) OZ960-DS-1.6 Page 4 www.DataSheet4U.com OZ960 FUNCTIONAL SPECIFICATIONS Parameter Symbol Test Conditions VDDA=5V; Tamb = 25 C Reference Voltage Nominal voltage Line regulation Load regulation High Frequency Oscillator Initial accuracy Ramp peak Ramp valley Temp. stability Low Frequency Oscillator Initial accuracy Ramp peak Ramp valley Low Frequency PWM Duty Cycle Range Error Amplifier Input offset voltage Input voltage range Offset current at FB pin Reference voltage at noninverting input pin (internal) Open loop voltage gain Unity gain bandwidth Power supply rejection Threshold Over Voltage Protection Supply Supply current IOFF ENA = low ENA = high; VDDA = 5V; Supply current ION Vdim = 2V; LPWM = 50k(2) Ca=Cb=Cc=Cd=2nF(3) HF = 60kHz; LF = 185Hz SST current CTIMR current NDR-PDR Output Output resistance Output resistance Rp Rn Current source Current sink 27 14 Ω Ω See Table 1, page 6 See Table 1, page 6 4.4 5.5 mA 150 200 1.90 2 2.15 V VADJ 0 1.19 7 1.25 80 1.0 60 VDD-1.5V 100 1.31 mV V nA V dB MHz dB 0 100 % 2.85 0.94 See Table 1, page 6 3.0 1.0 3.15 1.06 V V TA = 0 oC to 70oC fosc CT = 100pF, RT = 120k(1) 53 57 3.0 1.0 200 60 KHz V V ppm/ oC Vref Iload = 0.1mA VDDA = 4.7V – 5.3V Iload = 0.025 mA to 0.25 mA 2.37 2.5 4 2 2.63 V mV/V mV/mA o Limits Min Typ Max Unit µA OZ960-DS-1.6 Page 5 www.DataSheet4U.com OZ960 Parameter Max. / Min. Overlap VDDA = 5V; Tamb = 25oC Min. Overlap between diagonal switches Max. Overlap between diagonal switches Brake before Make PDR_A / NDR_B PDR_C / NDR_D See Table 1, below See Table 1, below HF = 60kHz Ca=Cb=Cc=Cd=2nF(3) HF = 60kHz Ca=Cb=Cc=Cd=2nF(3) Min 3.0 78 Typ 4.5 81 Max 5.5 84 Symbol Test Conditions Limits Unit % % OZ960 Parameter Symbol Test Conditions Min Low Frequency Oscillator Initial accuracy Supply SST current CTIMR current Brake before Make PDR_A / NDR_B PDR_C / NDR_D Threshold Enable 1.35 1.50 1.65 V 1.25 HF = 60kHz HF = 60kHz 250 250 380 380 530 520 ns ns 250 250 ISST ICTIMR 4.9 2.2 7.5 3.3 10 4.5 fosc LCT = 6.8nF, LPWM = 50k(2) 160 220 250 Hz 150 Limits Typ Max Unit Min OZ960I Limits Typ Max Unit 220 340 Hz µA µA 4.9 2.0 6.0 3.0 12 5.2 µA µA 380 380 565 545 ns ns 1.50 1.65 V Table 1. Low Frequency Oscillator, Supply and Brake before Make Specifications for OZ960 and OZ960I Note (1) CT: capacitor from CT (Pin 18) to ground RT: resistor from RT (Pin 17) to ground Note (2) LCT: capacitor from LCT (Pin 15) to ground LPWM: resistor from LPWM (Pin 13) to ground Note (3) Ca: capacitor from PDR_A (Pin 19) to VDDA Cb: capacitor from NDR_B (Pin 20) to ground Cc: capacitor from PDR_C (Pin 12) to VDDA Cd: capacitor from NDR_D (Pin 11) to ground OZ960-DS-1.6 Page 6 www.DataSheet4U.com OZ960 FUNCTIONAL INFORMATION 1. Steady-State Operation Refer to the schematic shown in Figure 1, the OZ960 drives a full-bridge power train where the transformer couples the energy from the power source to the secondary CCFL load. The switches in the bridge denoted as QA, QB, QC and QD are configured such that QA and QB, QC and Q