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| OZ965 High-Efficiency Inverter Controller FEATURES * * * * * * * * * * Single-stage power conversion, requiring only a +5 V voltage source Reduces the number of components and board size by 30% compared with conventional design Supports both floating and grounded secondary designs 90% efficiency vs. typical 75% efficiency of conventional designs Internal open-lamp and short-circuit protections Wide dimming range Supports multiple CCFLs Simple and reliable 2-winding transformer design Eliminates leakage current when used in a floating secondary design Constant-frequency design eliminates interference with LCDs dimming function with an analog voltage or low frequency Pulse Width Modulation (PWM) control. Operating Principle: The CCFL tube, transformer secondary, and capacitor form a resonant circuit. The OZ965 utilizes the low energy loss resonate mode principle to deliver a very high efficiency inverter. The OZ965 drives the transformer primary with a variable pulse width voltage directly from the +5v supply. The resultant primary drive current is alternately reversing with zero-voltage-switching. Because of the transformer leakage inductance and the secondary resonant circuit, the secondary voltage and current are approximately sinusoidal. This sinusoid results in very little harmonic emi/rfi emissions. The OZ965 operates at a single, constant frequency in a PWM mode. Typical operating frequency ranges between 30 KHz to 200 KHz, dependent upon the CCFL and transformer characteristics. Intelligent open-lamp protection provides design flexibility so various transformer models/manufacturers may be used. Its high driving capability allows the OZ965 to drive high power MOSFETs. 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 OZ965 is available in 16-pin SOP and TSSOP packages. It is specified over the commercial temperature range of 0C to +70C, and the industrial temperature range of -40C to +85C. ORDERING INFORMATION OZ965G - 16-pin plastic SOP OZ965R - 16-pin plastic TSSOP OZ965IG - 16-pin plastic SOP OZ965IR - 16-pin plastic TSSOP GENERAL DESCRIPTION The OZ965 is a single chip, high-efficiency, Cold Cathode Fluorescent Lamp (CCFL) backlight inverter controller whose primary function is to convert +5 volt DC power to approximately 600 VAC. Additionally, the OZ965 performs the lamp Figure 1. Typical Application Circuit J1 5V 5V ENA DIM GND GND 1 2 3 4 5 6 100k R1 C2 22u C1 0.1u R3 150k C3 10u R4 20k R5 15k C4 0.1u R2 22 C5 U1 1 2 3 4 5 6 7 8 C9 0.01u C8 0.1u REF HCLMP LCLMP SCP ADJ FB CMP GND OZ965 VDD RT CT OPS ENA NDR PDR SST 16 15 14 13 12 11 10 9 C10 2.2u R6 59.0k U2 2 1 470p C6 4 3 Q2 Si4532 3 Q1 6 5 8 7 2 17:2200 5 T1 C7 10u 6 7 68p 3kv 1 2 J2 HV RTN 2 C11 0.1u R13 510k CR3 BAV99L R15 4.3k R16 100k C12 0.1u R17 1.02k 06/20/00 Copyright 2000 by O2Micro OZ965-SF-3.0 All Rights Reserved 1 Page 1 U.S. Patent #5,619,402 OZ965 FUNCTIONAL BLOCK DIAGRAM Refer to the functional block diagram in Figure 2, below, and the Pin Description Table on page 3. Power is transferred to the transformer primary by the N-MOSFET, driven by the MOSFET gate driver out of pin NDR. The P-MOSFET resets the primary field, driven by pin PDR. The usual design results in approximately 50% duty cycle at full lamp intensity. Terminating the NDR signal earlier than the full brightness lamp pulse width performs lamp dimming, using the analog dimming. The voltages on pins HCLMP and LCLMP set a threshold voltage for the ramp comparator setting the maximum duty cycle for NDR. A pulse generator circuit creates the clock signal with the frequency determined by an external, constant current setting resistor (RT) and timing capacitor (CT). The "soft-start" circuit ensures a reliable and long lamp life starting condition. REF 1 2.50V IBIAS & REFERENCE POFF "Soft start" gradually increases the energy delivered to the secondary. When the OZ965 is enabled at pin ENA, the capacitor on pin SST determines the duration of the "soft-start" period, gradually increasing the NDR pulse width to the regulated brightness. The "soft-start" period provides sufficient time for the lamp to ignite. For system reliability there are several circuit protections provided. To ensure a controlled output, the secondary current is monitored on pin FB and is compared to a reference voltage on pin ADJ. The NDR signal is shortened or lengthened dependent upon this feedback. Protection is provided by the resultant signal, CMP, monitoring for a lamp removal condition. Short circuit protection is provided at pin SCP. The OPS signal selects either HCLMP or LCLMP providing current protection against an "Open Lamp" condition at start-up. The OPS signal also allows adjustment to different transformer models. To reduce power dissipation, the switch (MOSFET) drive signals are "break-before-make" with a short, fixed off time between activation of NDR or PDR. Vdd 16 HCLMP 2 Vset + Vmax=2.6V-Vset Vmax V V>Vmax -- -> Vmax Vmin + RAMP COMP. RAMP COMP. PULSE RT 15 LCLMP 3 - + COMP 2.5V PULSE GEN Vmin (fix value) + COMP CT 0.5V 14 SCP CLK 4 + COMP 0.6V LAMP ON/OFF OPS 13 ADJ Vdd 5 RESET - + FB 6 EA SS1 UNDER VOLTAGE UVLO LOCKOUT ENABLE COMP t1 ENA + 12 R1 300k ACTIVE "HIGH" (slow start) ZVS CONTROLLER 1.5V PDR 11 Pgate PDRV CMP 7 R4 70k NDR Ngate COMP OLPROT PROTECTION NDRV + 2.5V R5 630k 10 POFF SS2 I=12uA I=2.5uA GND SS1 8 V_SS2 t1+t2 (slow start) R2 4K 9 SST Note: OVP - Over Voltage Protection SCP - Short-Circuit Protection UVL - Under Voltage Lockout POFF MN1 Figure 2. Functional Block Diagram OZ965-SF-3.0 Page 2 OZ965 PIN DESCRIPTION Names REF HCLMP LCLMP SCP ADJ FB CMP GND SST PDR NDR ENA OPS CT RT VDD Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 I/O O I I I I I O GND I O O I I I/O I/O PWR Description Reference voltage output. Nominal voltage is 2.5 V. Clamping maximum duty cycle under normal operation. Clamping maximum duty cycle under open-lamp condition. Short-circuit protection input (VTH=0.6V) Reference voltage input for dimming control. Current sense feedback. Compensation for the current sense feedback. Ground. Soft-start ensures lamp current pulses gradually increases to its normal value Gate drive output for the P-MOSFET. Gate drive output for the N-MOSFET. Enable input, active high (VTH=1.5V) Output current sense (VTH=0.6V) Timing capacitor. CT and RT set the clock frequency. Timing resistor. Fosc = 1.91 / (Rt * Ct) Supply voltage input. ABSOLUTE MAXIMUM RATINGS VDD GND Logic inputs 5.5V +/- 0.3V -0.3 V to VDD+0.3V Power dissipation 16-pin SOP 16-pin TSSOP Thermal Impedance 16-pin SOP 16-pin TSSOP OZ965 .720W .690W 111 C/W o 115 C/W o OZ965I .580W .550W 111 C/W o 115 C/W o OZ965 Operating temp. 0 C to 70 C o o OZ965I -40 C to 85 C 150 C -55 C to 150 C o o o o o Operating junction temp. Storage temp. RECOMMENDED OPERATING RANGE VDD Fosc Rosc 5.0 V +/- 5% 30 KHz to 200 KHz 50 k to 150 k OZ965-SF-3.0 Page 3 OZ965 FUNCTIONAL SPECIFICATIONS Parameter Symbol Test Conditions 4.75 V < VDD < 5.25 V Reference Voltage Nominal voltage Line regulation Load regulation Oscillator Initial accuracy Ramp peak Ramp valley Temp. stability Error Amplifier Input bias current Input offset voltage Input voltage range Open loop voltage gain Unity gain bandwidth Power supply rejection Under-Voltage Lockout Positive-going threshold voltage Negative-going threshold voltage Supply Supply current - Enable Low Supply current - Enable High NDR output Output high voltage Output low voltage Output resistance PDR output Output high voltage Output low voltage Output resistance Break-Before-Make Qn off to Qp on delay Qp off to Qn on delay High Clamp Duty cycle of NDR HCLMP OPS=1 V VHCLMP=0V OPS=1 V, VHCLMP=1.8V Low Clamp Duty cycle of NDR LCLMP OPS=0 V, VLCLMP=0V OPS=0 V, VLCLMP=1.8V Max. / Min. Duty cycle Duty cycle of NDR 6 95 92 94 14 96 92 94 14 96 THL TLH 250 220 ns Ns VOH VOL ROUT Isource = 10 mA, VDD = 5V Isink = 10 mA, VDD = 5V 4.7 0.5 15 V V VOH VOL ROUT Isource = 10 mA, VDD = 5V Isink = 10 mA, VDD = 5V 4.75 0.25 10 0.5 V V IOFF ION VDD = 5.0 V 195 1.0 See Table 1, page 5 See Table 1, page 5 ADJ=FB=2.0 V VFB = 4.0 V 0 0.25 5 65 1.5 60 10 VDD1.5 uA mV V dB MHz dB TA = -40oC to 85oC fosc Ct = 470 pF, Rt = 49.9 k 81 2.54 0.48 200 KHz V V ppm/ oC Iload = 0.2 mA to 1.0 mA Vref Iload = 0.1 mA, 2.37 2.50 6 1 2.63 V mV/V mV/mA Min Limits Typ Max Unit A mA % % % OZ965-SF-3.0 Page 4 OZ965 OZ965 Parameter Test Conditions 4.75V < VDD < 5.25V Under-Voltage Lockout Positive-going threshold voltage Negative-going threshold voltage 3.2 3.9 3.4 4.3 V V 3.0 3.9 3.4 4.5 V V Min Limits Typ Max Unit Min OZ965I Limits Typ Max Unit Table 1. Under-Voltage Lockout for OZ965 and OZ965I OZ965-SF-3.0 Page 5 OZ965 PACKAGE INFORMATION A2 16 A A1 TSSOP-16 PACKAGE E E1 1 D 2 R1 b Gauge Plane e b c c1 L 3 DIM A A1 A2 L D E1 E R R1 b b1 c c1 L1 e 1 2 3 INCHES MIN MAX 0.043 0.002 0.006 0.031 0.041 0.020 0.030 0.169 0.177 0.252BSC 0.004 0.004 0.007 0.012 0.007 0.010 0.004 0.008 0.004 0.006 0.039REF 0.026BSC 0 8 12REF 12REF R 1 b1 Lead Cross Section L1 MILLIMETERS MIN MAX 1.20 0.05 0.15 0.80 1.05 0.45 0.75 4.90 5.10 4.30 4.50 6.40BSC 0.09 0.09 0.19 0.30 0.19 0.25 0.09 0.20 0.09 0.16 1.0REF 0.65BSC 0 8 12REF 12REF OZ965-SF-3.0 Page 6 OZ965 DIM A A1 B C D E e H L EH SOP-16 PACKAGE INCHES MIN MAX 0.0532 0.0688 0.0040 0.0098 0.013 0.020 0.0075 0.0098 0.3859 0.3937 0.1497 0.1574 0.050 BCS. 0.2284 0.244 0 0.016 0.050 0 8 MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.33 0.51 0.19 0.25 9.80 10.00 3.80 4.00 1.27 BCS. 5.80 6.20 0.40 0 1.27 8 D A B e A1 D L C OZ965-SF-3.0 Page 7 |
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