O2Micro OZ960D, OZ960G, OZ960S Schematics

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

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

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-

OZ960

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

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.

10/23/01 OZ960-DS-1.6 Page 1
Copyright 2000 - 01 by O2Micro All Rights Reserved U.S. Patent #6,259,615

TYPICAL APPLICATION CIRCUIT

F1

FUSE 1A

J1

C4

100P

7

8

U1

Si5504

2

1

C1

10U

5.1K

R2

C3

4.7V

D1

R1

Vin

VIN

DIM

ENA

GND

5VDC

0.047u

20

U2

OZ960

1

C2

1.0u

22

Figure 1: An 8-22V Application Circuit of OZ960

J2

C7

C6

2.2U

6

QB

3

4 5

R3

D2

R4

52.3K

C5

220P

1817161514

CT

PDR_A

NDR_B

CTIMR

OVP

ENA

23456

1

RT

SST

22P

QA

10K

4.7V

RT

2

PGND

VDDA

C9

C8

C11

T1

0.47u

1.0u

0.033U

32:2200

8

1

C12

C10

LCT

DIM

GNDA

REF

7199

7

2

0.047u

6.8nF

138

LPWMRT1

RT

C13

QD

R5240K

12

PDR_C

FB

0.1u

CR1

BAV99L

6

QC

U3

3

4 5

11

NDR_D

CMP

10

C14

0.015u

OZ960

499

R9

CR2

Si5504

R6 33k

BAV99L

R7

1M

C15

0.1u

R8

51k

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-DS-1.6 Page 2

CTIMR

OVP

ENA

ACTIVE

"HIGH"

SST

OZ960

I=3uA

1

2V

+

2

3

4

OVP

-

hys.
COMP

+

ENA

-

hys.

1.5V

COMP

Protection

POFF

I=6uA

Soft

Start

NDR_B

PDR_A

HF

OSC

20

19

18

17

NDR_B

PDR_A

CT

RT

VDDA

GNDA

REF

RT1

FB

CMP

10

5

6

7

8

9

1.25V

Reference

2.75V

2.50V

Ignition

­EA

+

POFF

­OPLAMP

+

ZVS

Phase-Shift

Controller

PDR_C

NDR_D

Burst­Mode

Control

16

15

14

13

12

11

PGND

LCT

DIM

LPWM

PDR_C

NDR_D

Figure 2. Functional Block Diagram

OZ960-DS-1.6 Page 3

OZ960

PIN DESCRIPTION

Names Pin No. I/O Description

CTIMR 1 I Capacitor for CCFL ignition duration

OVP 2 I Output voltage sense Vth=2.0V

ENA 3 I Enable input; TTL signal is applicable
SST 4 I Soft-start capacitor

VDDA 5 I Voltage source for the IC

GNDA 6 I Analog signal ground ref erence

REF 7 O Reference voltage output; 2.5V typical

RT1 8 I Resistor for programming ignition frequency

FB 9 I CCFL current feedback signal

CMP 10 O Compensation output of the current error amplifier
NDR_D 11 O NMOSFET drive output
PDR_C 12 O PMOSFET drive output

LPWM 13 O Low-frequency PWM signal f or burst-mode dimmi ng control

DIM 14 I Input analog signal for burst-m ode di mming control
LCT 15 I Triangul ar wave for burst-mode dimming; frequency

PGND 16 I Power ground reference

RT 17 I Timing res i stor set operating frequency
CT 18 I Timing c apacitor set operating frequency

PDR_A 19 O P MOSFE T dri ve output

NDR_B 20 O NMOSFET drive output

ABSOLUTE MAXIMUM RATINGS WITH RESPECT TO INPUT POWER SOURCE RETURN REFERENCE

VDDA 7.0V
GNDA, PGND +/- 0.3V
Logic inputs -0.3V to VDD +0.3V

OZ960
Operating temp. 0oC to 70oC -40oC to 85oC

Operating junction temp.
Storage temp. -55 oC to 150 oC

150 oC

OZ960I

RECOMMENDED OPERATING RANGE

VDDA
Fosc 30 KHz to 150 KHz
Rosc 50 k to 150 k

(1)

Note

: The “Absolute Maximum Ratings” are those values beyond which the safety of the devic e cannot be guaranteed.
The device should not be operated at these limits. The “Functional Specifications” table w ill def ine the conditions for
actual device operation. Exposure to absolute maximum rated condit i ons for extended periods may affec t device
reliability.

4.7V ~ 5.5V

(1)

OZ960-DS-1.6 Page 4