DT8211 LCD Back Light Inverter Drive IC Rev July 2008

Transcription

1 D8211 Rev July General description 2. Features 3. Applications he D8211 is a LCD backlight inverter controller for driving CCFL (Cold Cathode Fluorescent Lamp). It drives a half bridge topology symmetrically and provides a near sinusoidal current waveform. It operates at a single-stage topology, constant frequency PWM (Pulse Width Modulation) mode. he MaxDuty technique achieves the maximum duty ratio of about 48% and hence can provide better efficiency. A typical operating frequency ranges from 30kHz to 300kHz, depending on the CCFL and transformer characteristics. Features such as OLP (Open Lamp Protection) and SCP (Short Circuit Protection) functions are included. It is available in 18-pin SOPW. High Efficiency Single Stage Power Conversion P- and N-channel MOSFE Driver Included Wide Input Supply Voltage Range from 7.5V to 45V Maximum Duty ratio of 48% Extremely Low Number of External Components Extremely Small Size of Board Constant Frequency PWM Operation High Precision Oscillator Analog and Burst Dimming Function Simultaneously Analog Dimming Polarity Selectable Burst Dimming Polarity Selectable Open Lamp Protection Circuit Included Output Short Circuit Protection Circuit Included 18 Pin SOPW LCD Backlight Inverter EEFL Inverter FFL Inverter Advertisement Board Rev July of 10

2 4. Package information ype number Package Name Description Marking D SOPW 18 Lead SOP Wide Body D ypical Application VCC 1 VREF VCC 18 EN 2 EN HOU 17 ADIM 3 ADIM LOU 16 BDIM 4 BDIM GND 15 D RS GND 14 6 R VCMP 13 HV HV HV HV 7 C ICMP 12 8 CB VFB 11 9 PRO IFB 10 GND Rev July of 10

3 6. Pinning information op View 1 VREF VCC 18 2 EN HOU 17 3 ADIM LOU 16 4 BDIM GND 15 5 RS D8211 GND 14 6 R VCMP 13 7 C ICMP 12 8 CB VFB 11 9 PRO IFB 10 Pin Symbol I/O Description 1 VREF O Reference Voltage (VREF) = 6V 2 EN I ON/OFF Control Pin 3 ADIM I Analog Dimming Pin (Positive and Negative Mode) 4 BDIM I Burst Dimming Pin (Positive and Negative Mode) 5 RS O Frequency Setting Resistor for Striking PWM Frequency 6 R O Frequency Setting Resistor for Main PWM Frequency 7 C O Frequency Setting Capacitor for Main PWM Frequency 8 CB O Frequency Setting Capacitor for Burst Dimming Frequency 9 PRO I Protection Pin 10 IFB I Feedback Input for Current Regulation 11 VFB I Feedback Input for Voltage Regulation 12 ICMP O Error Amplifier Output for Current Regulation 13 VCMP O Error Amplifier Output for Voltage Regulation 14,15 GND I Ground 16 LOU O Low Side Gate Driver Output 17 HOU O High Side Gate Driver Output 18 VCC I Supply Voltage Rev July of 10

4 7. Absolute maximum ratings If Military/Aerospace specified devices are required, please contact the DMB technology Sales Office/Distributors for availability and specifications. Parameter Symbol Value Unit Supply Voltage V CC 45 V Power Dissipation P D 1.9 W Operating Ambient emperature A -30~+85 C Operating Junction emperature J -30~+150 C hermal Resistance Junction to Ambient θ JA 66.6 C/W Storage emperature SG -40~+125 C 8. Electrical characteristics A = 25 C, V CC = 15V, unless otherwise specified Parameter Symbol Conditions Min yp Max Unit Reference section Reference Voltage V REF V Max V REF Current I REF 30 ma Voltage Error amplifier section V. Amp. ransconductance G mv us Feedback reference Voltage V V,REF V Output Clamp Voltage V V,CLMP V Maximum Sinking Current I V,SNK μa Maximum Sourcing Current I V,SRC μa High VFB Sinking Current I V,SNKH when VFB > 2.5V μa Current Error amplifier section I. Amp. ransconductance G mi us Max. Feedback Ref. Voltage V I,MAX V Maximum Sinking Current I I,SNK μa Maximum Sourcing Current I I,SRC μa Rev July of 10

5 8. Electrical characteristics A = 25 C, V CC = 15V, unless otherwise specified Parameter Symbol Conditions Min yp Max Unit Main oscillator section R Voltage V R V C Oscillation Frequency F C khz when R >20kΩ Main Oscillation Frequency khz F MAIN riangular High Voltage V HM V riangular Low Voltage V LM V Burst oscillator section Burst Oscillation Frequency F oscb when R >20kΩ Hz riangular High Voltage V HB V riangular Low Voltage V LB V Dimming section ADIM Input Impedance R ADIM KΩ BDIM Input Impedance R BDIM KΩ ADIM Int. Bias Voltage V ADIM,B V BDIM Int. Bias Voltage V BDIM,B V Protection section Init. PRO Discharging I. I PRO,INI 3 ma PRO Charging Current I PRO,CG μa PRO hreshold Voltage V PRO V IFB Open Lamp Detect V. V OLP,IFB V ICMP Striking Mode V. V SK,ICMP when IFB<0.75V V General Enable On Voltage V EN,ON 2.0 V Enable Off Voltage V EN,OFF 0.8 V Quiescent Current I CC 7.0 ma Maximum Oscillation Duty D MAX 48 % Output section P-CH Output High Voltage V POH I SINK =200μA V CC V CC V CC V P-CH Output Low Voltage V POL I SOURCE =200μA V CC - 14 V CC - 12 V CC - 10 V N-CH Output High Voltage V NOH I SINK =200μA V N-CH Output Low Voltage V NOL I SOURCE =200μA V Rev July of 10

6 9. Block Diagram VCMP 13 ICMP 12 EN 2 VCC 18 VFB 11 Fast Response OA Startup and Voltage Reference 6.0V Internal Bias 1 VREF IFB 10 2V Ref. COMP Pulse Distributor and Dead ime Generator GD GD 17 HOU 16 LOU ADIM 3 2.0V Positive & Negative Control Block OA LA 2V Ref. Burst On/Off Open Lamp Detection and Frequency Shift Block 3.0V 1.2V High Precision Dual Oscillator Block (Main/Burst) VREF 0.5uA R S FF Q 0.8V 2.0V BDIM 4 Positive & Negative Control Block COMP EN 3V Ref. COMP 15 GND 14 GND 5 RS 7 C 8 CB 6 R 9 PRO 10. Functional Description Internal Regulator o supply a stable power to internal and external circuit, a high precise regulator is included. It makes 6.0V over the full range of input supply voltage. his also supplies a stable voltage to internal analog critical circuit, to make stable operation. VREF is an output of internal regulator, and can supply over 30mA to external circuit. Chip Enable When EN pin is over V EN,ON, the internal regulator is turned on. herefore internal and external circuits begin to operate. Since it has over 100mV hysteresis, unpredictable operation is protected. Main Frequency Oscillator o generate clear PWM pulse, D8211 includes a precise triangular waveform generator circuit. he voltage of R pin is fixed at 2.0V and the current of R pin is flow through the resistor which is connected between R pin and GND. his current makes charging and discharging current of a capacitor which is connected to C pin and GND. riangular wave is generated at C pin by charging and discharging (repeated operation) to this capacitor. his triangular wave is one of reference signal to generate PWM. he frequency of triangular wave can be calculated approximately as below and is 2 times of lamp frequency fmain[ Hz] = R C Rev July of 10

7 10. Functional Description (Continued) Striking Frequency Striking frequency is generated by increasing charging and discharging current of a capacitor (C). RS pin is normally high impedance, but it goes low when D8211 is in striking mode. If a resistor is connected between RS and R, a striking frequency can be generated by increased current and the equation is as below ( R + RS ) fstriking[ Hz] = R R C S Burst Frequency Oscillator o generate clear PWM pulse, D8211 includes a precise triangular waveform generator circuit. he voltage of R pin is fixed at 2.0V and the current of R pin is flow through the resistor which is connected between R pin and GND. his current makes charging and discharging current of a capacitor which is connected to CB pin and GND. riangular wave is generated at CB pin by charging and discharging (repeated operation) to this capacitor. his triangular wave is one of reference signal to generate PWM. he frequency of triangular wave can be calculated approximately as below fburst[ Hz] = R C B Analog Dimming D8211 includes three kinds of dimming method. One is analog dimming, burst dimming and pulse dimming. Analog dimming command feeds DC level to ADIM pin which is a positive input of internal error amplifier. When 0V<V ADIM <2.0V, D8211 operates in positive polarity mode, but when 3.0V<V ADIM <5.0V, D8211 operates in negative polarity mode as below figure. he negative input of error amplifier for current is IFB pin, and control loop is operated to make IFB level equal to ADIM level. he output of error amplifier for current, which is ICMP pin, is directly connected to main PWM generator. Rev July of 10

8 10. Functional Description (Continued) Burst Dimming D8211 includes three kinds of dimming method. One is analog dimming, burst dimming and pulse dimming. Burst dimming command feeds DC level to BDIM pin which is an input of internal PWM generator. When 0V<V BDIM <2.0V, D8211 operates in positive polarity mode, but when 3.0V<V BDIM <5.0V, D8211 operates in negative polarity mode as below figure. Burst PWM is generated using BDIM and triangular wave of CB. he rising and falling slopes of BDIM operation are adjusted by capacitor which is connected between ICMP pin and GND. he source and sink currents of ICMP are 100uA. We recommend 300usec as rising and falling time. Pulse Dimming D8211 includes three kinds of dimming method. One is analog dimming, burst dimming and pulse dimming. In this mode, PWM pulse of pulse dimming feeds to BDIM pin and a resistor must be connected between CB and GND. When the pulse swings 0V to 2V, D8211 operates in positive polarity mode, but when the pulse swings 3V to 5V, D8211 operates in negative polarity mode. o operate pulse dimming mode, CB must be a constant level. So a resistor is recommended between CB and GND, and its value which makes CB level to about 1.0V is recommended as below equation. R = 3. 5 R CB, PDIM Main PWM Generator he main PWM pulse is generated with ICMP, VCMP and C. ICMP and VCMP are connected to comparator negative inputs of PWM generator, and C is connected to comparator positive input of PWM generator. C decides PWM frequency and ICMP and VCMP decide PWM Duty. Output duty of main PWM is limited approximately 48% when main frequency is 50kHz to prevent shoot-through of Power FEs. Rev July of 10

9 10. Functional Description (Continued) Protection (OLP, SCP) Abnormal status is detected by IFB level. If IFB level goes under 0.75V, D8211 became protection mode. his mode means that one or more of current feedback levels is very low. o change to normal operating mode, IFB level must be higher than 0.75V. In protection mode, a capacitor which is connected PRO pin is charged by 0.5uA. If PRO pin is over 3.0V, D8211 will shutdown the outputs. o restart D8211 after shutdown, EN or VCC must be low and go high. he time of protection is as below. [sec] = PRO C PRO Striking Mode Striking mode is a part of abnormal status. his mode is detected by IFB level and ICMP level. If IFB level goes under 0.75V and ICMP level goes over 3.5V, D8211 became striking mode. (Of course striking mode must be occurred in protection mode.) his mode means lamp open status, so D8211 try to increase output voltage by shifting operating frequency. In this mode, RS goes to 0V and burst dimming signal is ignored. he striking frequency is decided as above description. OVP (Over Voltage Protection) OVP function is implemented by internal voltage error amplifier. he reference voltage is 2.0V and in over voltage status, VFB pin is regulated as 2.0V. Soft Start After enabling D8211, all capacitors which are connected to D8211 are charged to make startup. A capacitor which is connected to VCMP must be chosen as a large value such as 100~300nF for soft start. Gate Driver D8211 includes P channel and N channel gate drivers. he swing voltage of driver output is approximately 12V and D8211 can drive directly PowerFEs without external component. Rev July of 10

10 11. Package outline 18-Lead SOPW 12. Important notices his products and its characteristic can be added or changed without notice. Before considering use or application, No part of this publication may be reproduced or transmitted or copied in any form or by any means without permission Although our product has internal protective circuit, you d better adopt safety circuits or measures externally to prevent undesired probabilistic device failure Rev July of 10