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OZ9938
Change Summary
CHANGES
No. 1. 2. Applicable Section Electrical Characteristics Throughout datasheet Description Update rotection release threshold in Timer & protection parameter Min & Max limits Miscellaneous changes Page(s) 3 ---
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REVISION HISTORY
Revision No. 0.60 0.65 Description of change Initial release 1. Electrical Characteristics: a. Modify general test conditions in line 1; b. Modify Driver Frequency Striking & Normal Operation Typ limit; c. Modify PWM Dimming Control LCT frequency. 2. Reference Application Circuit: Modify C14, C9 & R9 values 1. Ordering Information: Add OZ9938G, IG, D & DN. 2. Recommended Operating Range: a. Add Dimming Range; b. Fill in Thermal Impedance. 3. Electrical Characteristics: a. Update Supply Current limits; b. Update Soft Start limits; c. Update Under Voltage Lockout limits; d. Update Reference Voltage limits; e. Update Driver Frequency limits; f. Update Timer & Protection limits; g. Update Drivers parameter name & limits; h. Update PWM Dimming Control limits; i. Delete Analog Dimming Control. 4. Function Description: Update formula in NO. 4 Ignition, No. 6 Normal Operation & No. 9 Dimming Control. 5. Package Information: Add DIP package drawing. Release Date 5/12/2005 6/27/2005
1.0
9/22/2005
10/14/2005 OZ9938-DS-1.1 Copyright 2005 by O2Micro All Rights Reserved Patent#6,559,606, #6,856,519 & #6,809,938
Page 0 CONFIDENTIAL
OZ9938
LCDM Inverter Controller
FEATURES
Positive PWM dimming polarity Constant operating frequency Drives positive/negative-impedance lamps during ignition High drive current for external MOSFETs User-defined ignition time and shutdown delay time Multiple mode dimming control Built-in intelligence for ignition and normal operation of CCFLs Built-in open-lamp protection and overvoltage protection for backlight system Optimized soft-start function The control logic provides a regulated ignition voltage and appropriate protection features for over-voltage or over-current conditions. The OZ9938 offers a high level of integration, while maintaining flexibility and high-efficiency operation that reduces external component heating, resulting in higher reliability and longer CCFL life. The proprietary design technique provides a simple, low-cost system solution.
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PIN DIAGRAM
ORDERING INFORMATION
Part Number OZ9938G OZ9938GN OZ9938IG OZ9938IGN OZ9938D OZ9938DN Temp Range -20oC to 85oC -20 C to 85 C -40oC to 85oC -40 C to 85 C -20oC to 85oC -20 C to 85 C
o o o o o o
Package 16-pin SOIC 16-pin SOIC Lead-Free 16-pin SOIC 16-pin SOIC Lead-Free 16-pin DIP 16-pin DIP Lead-Free
GENERAL DESCRIPTION
The OZ9938 is a high performance, cost-effective CCFL (Cold Cathode Fluorescent Lamp) controller designed for driving large-size Liquid Crystal Display (LCD) applications requiring 2 to 6 CCFLs. The controller converts unregulated DC voltages into a nearly sinusoidal lamp voltage and current waveforms. The OZ9938 provides two drive signals for most power conversion topologies while maintaining high-efficiency operation. The PWM controller provides a soft-start operation, current and voltage regulation, over-voltage and over-current protection, high drive capability and multiple dimming functions (internal PWM or external PWM or analog dimming functions).
SIMPLIFIED APPLICATION CIRCUIT
10/14/2005 OZ9938-DS-1.1 Copyright 2005 by O2Micro All Rights Reserved Patent#6,559,606, #6,856,519 & #6,809,938
Page 1 CONFIDENTIAL
OZ9938
PIN DESCRIPTION
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Names DRV1 VDDA TIMER DIM ISEN VSEN OVPT NC NC ENA LCT SSTCMP CT GNDA DRV2 PGND Description Drive output Supply voltage input Timing capacitor to set striking time and shutdown delay time Analog dimming or Internal LPWM dimming or external PWM pulse input for dimming function Current sense feedback Voltage sense feedback Over-voltage/ over-current protection threshold setting pin No connection No connection ON/OFF control of IC Timing capacitor to set internal PWM dimming frequency and also a pin for analog dimming selection Capacitor for soft start time and loop compensation Timing resistor and capacitor for operation and striking frequency Ground for analog signals Drive output Ground for power paths
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ABSOLUTE MAXIMUM RATINGS(1)
Input Voltage VDDA GNDA Signal Inputs 7.0V +/- 0.3V -0.3V to VDDA +0.3V
Operating Temp.
OZ9938 -20oC to 85oC
OZ9938I -40oC to 85oC
Operating Junction Temp. Storage Temp.
125oC -55 C to 150oC
o
RECOMMENDED OPERATING RANGE
VDDA - Input Voltage 4.5V to 5.5V 20KHz to 150KHz 0.7V to 2.1V
fop - Operating Frequency
Analog Dimming Range Thermal Impedance (
J-A)
(1)
16-pin SOP 16-pin DIP
86 oC/W 56 oC/W
Note : The bsolute 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 lectrical Characteristics?table defines the conditions for actual device operation. Exposure to absolute maximum rated conditions for extended periods may affect device reliability.
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OZ9938-DS-1.1
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OZ9938
ELECTRICAL CHARACTERISTICS
Parameter Symbol Test Conditions VDDA=5V; Ta=25 C RCT =39Kohm, CCT=470pF RLCT =3.3Mohm, CLCT=4.7nF Supply Current Stand By Idds ENA=0V & aCapacitance at DRV1h S DRV2=2nF 2.0 5.0 A Min Typ Max
o
Limits
Unit
w
w
w
. Operating
Soft Start
D
a
tdd I
e 1.5
e 2.0
t 2.5
4 mA
U
.
c
Current Source Under Voltage Lockout Lock out Resume Reference Voltage
ISSTCMP
1.83
2.29
2.75
A
UVLO UVLO
VDDA 5V 0V VDDA 0V 5V 4.0
3.2
V V
ISEN=SSTCMP ISEN reference voltage Temperature Coefficient VSEN reference voltage during striking Driver Frequency Striking Normal operation Timer and Protection Striking current Source Open lamp and over voltage protection current Source Protection release threshold Drivers DRV1/2 source DRV1/2 sink Maximum duty cycle Ron Ron ISEN =0V SSTCMP > 3.3V or VSEN>OVPT fstr Fop VSEN=SSTCMP Temperature Coefficient
1.12
1.18 360
1.23
V ppm/ OC
2.78
2.92 310
3.06
V ppm/ C
O
62.6 Temperature Coefficient 50.0 Temperature Coefficient
65.8 290 52.0 110
69.0 54.0
KHZ ppm/ OC kHz ppm/ OC
2.3 8.0 2.60
2.9 10.0 2.81
3.5 12.0 3.02
uA uA V
12 5 45
18 9
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OZ9938-DS-1.1
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OZ9938
ELECTRICAL CHARACTERISTICS (Continued)
Parameter Symbol Test Conditions VDDA=5V; Ta=25 C RCT =39Kohm, CCT=470pF RLCT =3.3Mohm, CLCT=4.7nF PWM Dimming Control LCT frequency 194 200 206 Hz Min Typ Max
o
Limits
Unit
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ENA Threshold On Off 1.0 2.0 V V
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OZ9938-DS-1.1
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OZ9938
FUNCTIONAL BLOCK DIAGRAM
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Figure 1
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OZ9938-DS-1.1
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OZ9938
FUNCTIONAL DESCRIPTION
1. Power Conversion
The OZ9938 controller is designed to suit various power conversion topologies and provides symmetrical drive pulses to the tank circuit that includes the transformer(s), output capacitors and the CCFL/panel load that yields quasisinusoidal CCFL voltage and current waveforms. High efficiency operation of the OZ9938 yields lower heat dissipation for the inverter system resulting in higher reliability. To illustrate the controller functions, refer to Figures 1 and 2 on pages 5 and 8, respectively for the following sections. (Pin 6). When the voltage at VSEN reaches a threshold of approximately 3.0V, the IC regulates the output voltage at the transformer secondary. If the lamps are not ignited when the voltage at TIMER (pin 3) reaches a threshold of approximately 3V, the IC will shutdown and latch The approximate striking time is calculated by the following equation. Tstr [Sec] = CTIMER [uF] To resume normal operation, toggle the ENA signal or reset VDDA.
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6. Normal Operation
Once the lamps are ignited and the voltage at ISEN (pin 5) is >0.7V, the IC enters the normal operation mode and the PWM dimming control is activated. The operating frequency is determined by resistor (R9) and capacitor (C9) connected to CT (pin 13). The control loop regulates the average current through the lamps by adjusting the duty cycle of the output drives. Constant frequency operation eliminates interference with the inverter and LCD panel that often occurs in a variable frequency inverter system. The peak and valley of the CT waveform are 2V and 0V respectively. The approximate operating frequency calculated by the following equation.
9.53 x105
2. Enable
Applying a voltage level greater than 2V to ENA (pin 10) enables the IC. A voltage less than 1V will disable the IC.
3. Soft-Start (SST)
Utilizing a patented multi-task technique, the softstart function and the loop compensation function are combined to provide a good start-up characteristic. Connecting an external capacitor to SSTCMP (pin 12) provides the functions. In the start-up mode, current charges capacitor C13 connected to SSTCMP. The voltage at the capacitor controls the gradual increase in power to the transformer and subsequently to the output load. This reduces in-rush current and provides reliable operation to the CCFL.
is
fop =
[KHz]
RCT [K ]*CCT[pF]
4. Ignition
When the VDDA voltage exceeds the undervoltage lockout threshold, the IC is enabled an internal striking timer is activated. The approximate striking frequency is calculated by the following equation.
7. Open Lamp Protection
If a CCFL is removed or damaged during normal operation, the voltage at SSTCMP (pin 12) rises rapidly. When the voltage at SSTCMP reaches a threshold of approximately 2.5V, a current source charges the capacitor (C17) connected to TIMER (pin 3). Once the voltage level at the TIMER pin reaches a threshold of approximately 3V, the drive outputs shut down and latch. The shutdown delay feature avoids inverter shutdown due to a VIN transient or if a lamp has a positive impedance characteristic. The approximate shutdown delay calculated by the following equation. Td [Sec] = 0.33 XCTIMER [uF] time is
fst =
3812/ RCT [K ] + 26 X1000 4 *CCT[pF]
[KHz]
5. Aged CCFL Ignition
OZ9938 provides a striking timer function to ensure that any aged, slow-turn-on CCFL is provided with sufficient voltage and time to ignite. The transformer output voltage is sensed at VSEN
CONFIDENTIAL
OZ9938-DS-1.1
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OZ9938
To resume operation, toggle the ENA signal or restart VDDA.
8. Over-Voltage and Over-Current Protection
Over-voltage and over-current protection are monitored by the voltage on VSEN (pin 6). During normal operation, if a CCFL is damaged or removed, the voltage at VSEN (pin 6) increases. Once the voltage at VSEN exceeds the user-defined, preset voltage set by OVPT (pin 7), the driver output duty cycle is regulated and the shutdown delay timer is activated. OVPT sets the overall protection threshold voltage that is lower than ~3V (VSEN threshold). Once the voltage at TIMR pin reaches ~3V, the IC will shut down and latch. OVPT voltage setting is determined by a resistor divider (R13 and R16) connected to the OVPT. The approximate shutdown delay calculated by the following equation. Td [Sec] = 0.33 XCTIMER [uF] To resume operation, toggle the PWM signal or restart VDDA. time is
External PWM dimming is implemented by setting LCT to a DC voltage between 0.5V to 1.0V using a resistor divider (R8 and R17) between VDDA and GND. Apply the external PWM pulse to DIM (pin 4). .
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9. Dimming Control
A built-in function enables the user to select one of the following dimming controls: analog, internal LPWM or external PWM signal. Analog dimming control is activated when the voltage to LCT (pin 11) is greater than 3V. A voltage of 0.5V to 1.25V applied to DIM (pin 4) controls the amplitude of the lamp current. Internal LPWM dimming control is determined by resistor R8 and capacitor C14 connected to LCT. The low frequency sawtooth waveform is compared with the voltage at DIM to generate the LPWM signal. The peak and valley of the waveform are 1.5V and 0.1V respectively. The frequency is approximated by the following equation:
3102
f LOSC =
[Hz]
RLCT [M ]*CLCT[nF]
With positive PWM dimming polarity, the LPWM duty cycle will be 100% when DIM pin voltage is higher than 1.5V. LCD panel will have maximum brightness. When DIM pin voltage is lower than 0.1V, the LPWM duty cycle will be 0%. LCD panel will be totally dark.
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OZ9938-DS-1.1
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OZ9938
Figure 2
OZ9938
PACKAGE INFORMATION ? 16-PIN SOP: OZ9938G (150mil)
D
w w w . D a t a S
Eh H
e
e
t
4
U
.
c
o
m
A B e A1
C L
DIM A A1 B C D E e H L 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. 0.244 0.2284 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 0.40 0 6.20 1.27 8
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OZ9938-DS-1.1
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OZ9938
PACKAGE INFORMATION ? 16-PIN DIP: OZ9938D (300mil)
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OZ9938-DS-1.1
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OZ9938
IMPORTANT NOTICE
No portion of O2Micro specifications/datasheets or any of its subparts may be reproduced in any form, or by any means, without prior written permission from O2Micro. O2Micro and its subsidiaries reserve the right to make changes to their datasheets and/or products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability.
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O2Micro warrants performance of its products to the specifications applicable at the time of sale in accordance with O2Micros standard warranty. Testing and other quality control techniques are utilized to the extent O2Micro deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customer acknowledges that O2Micro products are not designed, manufactured or intended for incorporation into any systems or products intended for use in connection with life support or other hazardous activities or environments in which the failure of the O Micro products could lead to death, bodily 2 injury, or property or environmental damage (High Risk Activities). O2Micro hereby disclaims all warranties, and O2Micro will have no liability to Customer or any third party, relating to the use of O Micro products in 2 connection with any High Risk Activities. Any support, assistance, recommendation or information (collectively, Support) that O2Micro may provide to you (including, without limitation, regarding the design, development or debugging of your circuit board or other application) is provided AS IS. O2Micro does not make, and hereby disclaims, any warranties regarding any such Support, including, without limitation, any warranties of merchantability or fitness for a particular purpose, and any warranty that such Support will be accurate or error free or that your circuit board or other application will be operational or functional. O2Micro will have no liability to you under any legal theory in connection with your use of or reliance on such Support. COPYRIGHT ? 2005, O2Micro International Limited
CONFIDENTIAL
OZ9938-DS-1.1
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