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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 0C to +70C, and the industrial temperature range of -40C to +85C.

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

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

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

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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

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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 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

A

OZ960-DS-1.6

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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

A A

4.9 2.0

6.0 3.0

12 5.2

A A

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

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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 QD are turned on complementarily. The duration of QA and QD, QB and QC turn on simultaneously determines an amount of energy put into the transformer which in turn delivers to the CCFL. The current in CCFL is sensed via resistor R9 and regulated through the adjustment of the turn-on time for both diagonal switches. This is accomplished through an error amplifier in the current feedback loop. A voltage loop is also established to monitor the output voltage so that a programmable striking voltage is achieved. The OVP represents the peak-detect signal of the voltage on the output of the transformer. A softstart circuit ensures a gradual increase in the input and output power. The soft-start capacitor determines the rate of rise of the voltage on SST pin where the voltage level determines the ontime duration of QA and QD, QB and QC diagonal switches. This minimizes the surge impacts in circuit designs. Apply enable signal to the ENA pin of the IC after the bias voltage applied to VDDA initiates the operation of the circuit. The output drives, include PDR_A, NDR_B, PDR_C and NDR_D put out a complementary square pulse. The frequency is determined by R4 and C5 where they are connected to RT and CT pins respectively. Initially, the energy converted from the power source to the CCFL is low due to the soft start function. It increases as soft start capacitor voltage increases linearly with time. The voltage at the secondary side of the transformer T1 increases correspondingly. This process continues until the CCFL current is detected and reaches a regulated value. The output of the error amplifier, CMP, follows the feedback signal, commands a proper switching among the four output drives to maintain current regulation. The operations of the four switches are implemented with zero-voltage-switching to provide a highefficiency power conversion. In the case of open-lamp condition, the OZ960 provides a programmable striking-frequency intelligence to optimize the ignition scheme. This is implemented through resistor R5. Effectively, R5 is in parallel with R4 to yield a required striking frequency. In addition, the striking time is also programmable through the capacitor C8. Striking voltage, or the open-lamp voltage, is regulated through a voltage feedback loop where output voltage is monitored. The signal, being sent to the OVP pin, commands the output drives to provide the desired output voltage. This design provides high degree of flexibility while maintaining OZ960 a very high integration device. One protection feature needed is removing the lamp during normal operation. The OZ960 senses the missing current signal through current amplifier, it shuts off the output drives and stay in the latched mode. This is differentiated intelligently with turning on the inverter while CCFL is not connected. Recycle of the IC power is necessary to resume normal operation. Dimming control: dimming control of the inverter is implemented by adjusting the amount of energy processed and delivered to the CCFL. A PWM burst-mode scheme is internally generated which provides 0% to 100% wide dimming control. An input analog voltage signal is fed into DIM pin and determines the dimming level of the CCFL. The burst-mode frequency is programmable through a capacitor C10 as shown in the schematic. The OZ960 inverter operates in a constant frequency mode. This eliminates any undesired interference between inverter and LCD panels where the interference is usually associated with variable-frequency designs. Symmetrical drive to the power transformer gives a very dynamic choice of selecting transformers. This vulnerable design offers flexibility to the system designers to choose transformer sources. There is no limitation to the gap-less transformer.

2. CCFL Ignition Time
Ignition time for CCFLs varies with CCFL length, diameter, module package and temperature. The OZ960 provides a flexible design where a capacitor is connected to CTIMR pin to determine the necessary striking time. An approximate of the timing calculation is: T[second] = C[uF] This capacitor remains reset at no charge if lamp is connected and at normal operation.

OZ960-DS-1.6

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OZ960
3. Protection
Open-lamp protection in the ignition period is provided through both OVP and CTIMR to ensure a rated voltage is achieved and a required timing is satisfied. Removal of the CCFL during normal operation will trigger the current amplifier output and shuts off the inverter. This is a latch function. striking voltage and frequency. This add-on feature could optimally accomplish the ignition process so that the CCFL life could be extended. When RT1 is used, it is connected in parallel with RT during the ignition period.

9. Burst-Mode Dimming Control
The OZ960 integrates a burst-mode dimming function to perform a wide dimming control for the CCFLs. The burst-mode frequency is determined by a capacitor C10 connected to LCT pin. The frequency can be calculated approximately by:
1496 f[Hz] = CLCT[nF]

4. OVP
The OVP threshold is set at 2V nominal. When the output voltage reaches the threshold, it commands the PWM controller to maintain the driving level. This ensures that output gets sufficient striking voltage while operating the power transformer safely.

5. ENA
Applying positive TTL logic to the ENA pin enables the operation of the IC. The threshold of the ENA is set at 1.5V. Apply logic low to the ENA pin will disable the operation of the inverter. Toggle this signal allows the on/off tests for the inverter. The Dim pin compares with the triangle wave in LCT and yields a proper pulse width to modulate the CCFL current. This pulse can also be monitored through LPWM pin. The peak and valley of the LCT signal is 3V and 1V respectively.

6. Soft-Start -- SST
The soft-start function is provided with a capacitor connected to SST pin. The soft-start time is not related to the striking time for the CCFL. It simply provides a rate of rise for the pulse width where diagonal switches are turned on. Normally, a 0.47uF capacitor is connected.

10. Output Drives
The four output drives are designed so that switches QA and QB, QC and QD never turn on simultaneously. These include two NMOS and two PMOS transistors. The configuration prevents any shoot-through issue associated with bridge-type power conversion applications. Adjusting the overlap conduction between QA and QD, QB and QC, the CCFL current regulation is achieved. This overlap is also adjusted while the voltage applied from the battery varies. At a specific CCFL current, the input power is maintained almost constant.

7. Error Amplifier
The CCFL current is regulated through this error amplifier. It also provides an intelligence of differentiating open-lamp striking versus removing the lamp during normal operation. The non-inverting reference is at 1.25V nominal.

8. Operating frequency
A resistor RT and a capacitor CT determine the operating frequency of OZ960. The frequency is calculated as:
68.5104 f[kHz] = CT[pF]RT[k]

The OZ960 also provides an optional striking frequency as desired. CCFL in a LCD module possesses parasitic that may require different

OZ960-DS-1.6

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OZ960
PACKAGE INFORMATION (SSOP 150mil)
D

Detail A

E

E1

h x 45 deg

1

c

ZD A2
0.10MM C
SEATING PLANE

e

NOTES: DIMENSION D DOES NOT INCLUDE MOLD PROTRUSIONS OR GATE BURRS MOLD PROTRUSIONS AND GATE BURRS SHALL NOT EXCEED 0.006 INCH PER SIDE

DIM
2

1 Gauge Plane 0.25MM R

R1

L Detail A

A A1 A2 B c e D E E1 L h ZD R1 R 1 2 JEDEC

MILLIMETERS INCHES MIN NOM MAX MIN NOM MAX 1.35 1.63 1.75 0.053 0.064 0.069 0.10 0.15 0.25 0.004 0.006 0.010 1.50 0.059 0.20 0.30 0.008 0.012 0.18 0.25 0.007 0.010 0.635 BASIC 0.025 BASIC 8.56 8.66 8.74 0.337 0.341 0.344 5.79 5.99 6.20 0.228 0.236 0.244 3.81 3.91 3.99 0.150 0.154 0.157 0.41 0.635 1.27 0.016 0.025 0.050 0.25 0.50 0.010 0.020 1.4732 REF 0.058 REF 0.20 0.33 0.008 0.013 0.20 0.008 0 8 0 8 0 0 5 10 15 5 10 15 MO-137 (AD)

OZ960-DS-1.6

A1

B

A

Page 9

OZ960
PACKAGE INFORMATION (SOP 300mil)

b

20

11

D e t a il X

H

E

1 e D

10 c

Y A1
S E A T IN G P L A N E

NOTES: 1 . R E F E R T O J E D E C S T D . M S -0 1 3 A C . 2 . D IM E N S IO N S " D " D O S E N O T IN C L U D E M O L D F L A S H , P R O T R U S IO N S O R G A T E B U R R S . M O L D F L A S H , P R O T R U S IO N S A N D G A T E B U R R S S H A L L N O T E X C E E D 0 .1 5 m m (6 m il) P E R S ID E . 3 . D IM E N S IO N S " E " D O S E N O T IN C L U D E IN T E R L E A D F L A S H O R P R O T U R S IO N S . IN T E R -L E A D F L A S H A N D P R O T R U S IO N S S H A L L N O T E X C E E D 0 .2 5 m m (1 0 m il) P E R S ID E . 4 . C O N T R O L L IN G D IM E N S IO N : M IL L IM E T E R

h x 45

O

SYMBOL A A1 b c D E e H h L Y


L
DETAIL "X"

MM NOM MAX 2.54 2.64 0.20 0.30 0.406 0.48 0.254 0.31 12.80 13.00 7.50 7.60 1.27 BSC 10.00 10.31 10.65 0.25 0.66 0.75 0.51 0.76 1.02 0.075 0 8 MIN 2.36 0.10 0.35 0.23 12.60 7.40

A

MIN 93 4 14 9 496 291 394 10 20 0

MIL NOM 100 8 16 10 504 295 50 BSC 406 26 30

MAX 104 12 19 12 512 299 419 30 40 3 8

OZ960-DS-1.6

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OZ960
PACKAGE INFORMATION (DIP 300mil)
D E1 A2

0.018typ. 0.060typ.

0.100typ.

SYMBOL A A1 A2 D E E1 L eB

A1

L

A

H

SEATING PLANE

MIN 0.015 0.125 0.98

NOR 0.130 1.030 0.300 BSC 0.245 0.250 0.115 0.130 0.335 0.355 0 7

MAX 0.210 0.135 1.060 0.255 0.150 0.375 15

NOTES: 1. JEDEC OUTLINE: MS-001 AD 2. "D", "E" DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH 3. eB IS MEASURED AT THE LEAD TIPS WITH THE LEADS UNCONSTRAINED. 4. POINTED OR ROUNDED LEAD TIPS ARE PREFERRED TO EASE INSERTION. 5. DISTANCE BETWEEN LEADS INCLUDING DAM BAR PROTRUSIONS TO BE .005 INCH MINIMUM. 6. DATUM PLANE H COINCIDENT WITH THE BOTTOM OF LEAD, WHERE LEAD EXITS BODY.

OZ960-DS-1.6

eB

E

Page 11

OZ960
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. O2Micro warrants performance of its products to the specifications applicable at the time of sale in accordance with O2Micro's 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. Copyright 2002, O2Micro International Limited

OZ960-DS-1.6

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