OZ968 SMBus Smart Inverter Controller FEATURES GENERAL DESCRIPTION • • The OZ968 is a unique single-stage, highefficiency, CCFL backlight controller. It drives a zero-voltage-switching circuit and provides a near sinusoidal output voltage and current waveforms for a CCFL backlight. Typical operating frequency ranges from 30KHz to 100KHz. These advances drive the OZ968 beyond comparable conventional inverter designs with two power conversion stages (one operates at a variable frequency, the other at a constant frequency). • • • • • Single-stage power conversion Constant frequency design eliminates interference with LCDs Built-in open-lamp protection and shortcircuit protection Reliable 2-winding transformer design eliminates arcing failures and the need for foldback wiring 32-level dimming and 256-level contrast control via SMBus High efficiency, 90% typical Supports both floating secondary and grounded secondary designs Operating in a PWM push-pull drive, the transformer in an OZ968 backlight inverter requires only one primary winding and one secondary winding. The secondary winding requires no foldback treatment. ORDERING INFORMATION The OZ968 supports a bi-directional, two-wire bus, data transmission protocol to control dimming (32 levels) and contrast (256 levels). Supply current is 1mA in active mode, 150µA in standby mode. OZ968G - 16-pin plastic SOP The OZ968 is available in a 16-pin SOP package. It is specified over the commercial temperature range 0oC to +70oC. TYPICAL APPLICATION CIRCUIT 20V SMBCLCK SMBDATA C1 ENABLE 47u/ 25v 5V OZ968 CONTRAST C5 1:40 1 FB VDD 22p/3KV R3 3.3k C2 2 CMP SCP 15 3 SST VSEQ 14 4 ADJ SMBD 13 C6 0.1u 16 Q4 3904 CCFL 0.1u C3 Q2 Si4559EY/P D1 0.47u 5 CNT SMBC 12 6 RT OVP 11 7 CT PDR 10 Q3 3906 R6 2.2k R4 200k C7 1N4148 D2 1N4148 4.7u Q1 Si4559EY/ N R8 R2 120k Q5 3904 R5 10k R7 0.1ohm 10k C4 220p 8 GND NDR R10 100k R9 1k 9 Figure 1. Typical Application Circuit 06/15/00 Copyright 1999 by O2Micro OZ968-SF-1.5 All Rights Reserved Page 1 U.S. Patent #5,619,402 OZ968 FUNCTIONAL BLOCK DIAGRAM IBIAS REF clki RT OSC ramp CT clk set Reset Comparator + FB - Qp PDR Qn NDR 160K - EA 40K ADJ reset Break Before Make F/F + CMP + OVP OVP vd Slow Start SST poff iss CNT pofbr lcd_susp Protections pofcnt csusp Brightness DAC SMBC SMBD See P.8, Section 9 5bit data Contrast DAC 8bit data SMB INTERFACE + SCP - bsusp SCP 0.5V xolp_ok xscp_ok VSEQ CLAMP OVP OVP Figure 2. Functional Block Diagram OZ968-SF-1.5 Page 2 OZ968 PIN CONFIGURATION Pin No. 1 2 3 Name FB CMP SST 4 ADJ 5 CNT 6 7 8 9 10 11 12 13 14 15 16 RT CT GND NDR PDR OVP SMBC SMBD VSEQ SCP VDD Description Current sense feedback. Compensation for the current sense feedback. Soft start in two steps. Two-interval current sources of 50µA and 0.6µA provide 1:26.6 ratio between the two time intervals of soft start. Connect a capacitor between this pin and the ground to adjust the soft-start timing. The output of the brightness D/A converter. The brightness has 32 adjustable levels. The default range is between 0.9V to 2.5V. The output of the contrast D/A converter. The contrast has 256 levels from 0.8V to 2.8 V (8mV per step). This output has a current capability of up to 2mA. Timing resistor. Timing capacitor. CT and RT set the clock frequency. Fs = 1.60 / (RT * CT). Ground. Gate drive output for the N-MOSFET. Gate drive output for the P-MOSFET. Over-voltage protection sense input. SMBus Clock Input/Output SMBus Data Input/Output. Vee power sequence input. Short-circuit protection sense input. Supply voltage input. ABSOLUTE MAXIMUM RATINGS VDD GND Storage temp. Operating temp. Operating junction temp. 7.0 V +/- 0.3 V -55 to 150 oC 0 to 70 oC 150 oC Logic inputs -0.3 V to VDD+0.3 V RECOMMENDED OPERATING RANGE VDD Fosc Rt 4.75 V to 5.25 V 30 KHz to 100 KHz 50 K to 150 K OZ968-SF-1.5 Page 3 OZ968 FUNCTIONAL SPECIFICATIONS Parameter Test Conditions Limits Typ Unit VDD = 5V, Tj =25, Test Circuit Min Max Initial accuracy Ct = 270pF, Rt = 100k 54 59 64 KHz Temp. stability TA = 0oC to 70oC - 200 500 ppm/ oC Line regulation 4.5 V < VDD <5.5V - 2 3 % - 2.5 5 µA Oscillator Error Amplifier Bias current Input offset voltage Open loop voltage gain Unity gain bandwidth - 2.0 5.0 mV 60 80 - dB - 2.0 - MHz 2.40 2.50 2.65 V Dimming D/A Output (ADJ – floating) Maximum level Minimum level 0.8 0.9 1.0 V Power-on reset default 2.40 2.5 2.65 V Settling time - 10 - µs D/A output levels - 32 - Contrast D/A Output Maximum level 2.70 2.80 2.95 V Minimum level 0.75 0.80 0.90 V Power-on reset default V 0.75 0.80 0.90 Settling time - 10 - µs Maximum output current - 2.0 2.2 mA Load regulation - 50 100 mV/mA D/A output levels - 256 - 3.8 4.0 4.2 V - 0.3 - V - 400 - ns - 150 - µA - 1 2 mA 4.75 - - V Under-voltage Lockout Power-on Voltage Hysteresis Break-before-Make Delay (between NDR and PDR) 100KHz, 800pF loading Supply Supply current – Standby Mode Supply current – Active Mode 100KHz, 800pF loading Output (NDR and PDR) Output high voltage VDD = 5.0V Output low voltage VDD = 5.0V - - 0.25 V Output resistance VDD = 5.0V - 50 - Ω OZ968-SF-1.5 Page 4 OZ968 TWO-WIRE BUS REGISTER DESCRIPTION The following register map describes the SMBus interface between SMBus Host and the OZ968 Register Map For Write commands. Function Slave Address (7-bit) 0101 000 0101 000 Contrast Brightness Register Index (Hex) A9 AA Data byte byte Contrast (A9) SMBus Protocol: Read or Write Byte Input/Output: Byte -- bit flags mapped as follows: Bit # 7:0 Name D7-D0 R/W r/w Default 0000 0000 Description Bits D7-D0 contain the contrast level setting. When D7-D0 = FF, the CNT pin of the OZ968 outputs 2.8V. When D7D0 = 00, the CNT pin outputs 0.8V. Brightness (AA) SMBus Protocol: Read or Write Byte Input/Output: Byte -- bit flags mapped as follows: Bit # 7:0 Name D7-D0 R/W r/w Default 0000 0000 Description Bits D7-D0 contain the brightness level setting. When D7D0 = FF, the OZ968 inverter outputs miniimum brightness. When D7-D0 = 00, the OZ968 inverter outputs maximum brightness. OZ968-SF-1.5 Page 5 OZ968 PACKAGE INFORMATION DIM SOP-16 PACKAGE E H A A1 B C D E e H L α 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 0.2440 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 1.27 0° 8° D A B e A1 C D L OZ968-SF-1.5 Page 6