OZ964
09/03/04
OZ964-DS-1.2
Page 1
Copyright
2004 by O2Micro
All Rights Reserved
U.S. Patent No. 6,259,615
CONFIDENTIAL
Phase-Shift PWM Controller
FEATURES
•
Controller for high-voltage DC/DC and
DC/AC converters
•
High efficiency, zero-voltage switching
•
Supports wide input voltage range
•
Constant operating frequency
•
Built-in PWM dimming control with wide
dimming range
•
Soft start function
•
Built-in intelligence for ignition and normal
operation of CCFLs
•
Built-in open-lamp protection and over-
voltage protection
•
Shutdown delay for input voltage brownout
condition
•
Built-in under-voltage lockout protection
•
Toggle pin to reset the IC after shutdown
•
Low stand-by power
ORDERING INFORMATION
Part
Number
Temp Range
Package
OZ964S
0
° C to 70° C
20-pin SSOP
OZ964SN
0
° C to 70° C
20-pin SSOP,
Leadfree
OZ964
IS
-40
° C to +85°C
20-pin SSOP
OZ964ISN
-40
° C to +85°C
20-pin SSOP,
Leadfree
OZ964G
0
° C to 70° C
20-pin SOIC
OZ964GN
0
° C to 70° C
20-pin SOIC,
Leadfree
OZ964IG
-40
° C to +85°C
20-pin SOIC
OZ964IGN
-40
° C to +85°C
20-pin SOIC,
Leadfree
OZ964D
0
° C to 70° C
20-pin PDIP
OZ964DN
0
° C to 70° C
20-pin PDIP,
Leadfree
GENERAL DESCRIPTION
OZ964 is a high efficiency, Pulse Width
Modulation (PWM) controller designed for both
DC/DC and DC/AC high-voltage applications.
The average current mode control is suitable for
DC/DC converters where both voltage and
current feedback are required, as well as for Cold
Cathode Fluorescent Lamp (CCFL)_ backlight
applications for small and large Liquid Crystal
Displays (LCD).
OZ964 operates in a zero-voltage switching
mode
that
minimizes
electromagnetic
interference (EMI). In addition, OZ964 achieves a
high power-conversion efficiency resulting in a
lower operating temperature and higher system
reliability.
OZ964 supports a wide input voltage range and
provides a constant, user-defined, operating
frequency, ensuring that the CCFLs operate at a
fixed frequency. This eliminates interference
among CCFLs and the LCD panel. Interference
causes
electromagnetic
compatibility
(EMC)
problems
and
may
create
visual
effects
(waterfall) on LCD panels. The controller
provides a phase-shift square wave output that is
able to drive a full bridge power train.
OZ964 utilizes a pulse width modulation (PWM)
dimming method to achieve a wide dimming
range. The IC performs the CCFL dimming
function with an analog or low frequency PWM
control. The PWM frequency is user-defined.
To avoid over-shoot and in-rush current to the
CCFLs during ignition, a soft start function is
provided for reliable CCFL operation.
The controller provides open-lamp protection and
over-voltage protection, while providing an
appropriate response for either open-lamp
ignition or removal of a CCFL during normal
operation. Intelligent open-lamp protection and
over voltage protection provides design flexibility
with various transformer characteristics. Open-
lamp protection time is user-defined.
In addition, OZ964 provides a shutdown delay
function that will keep the inverter module in
normal operation for a short period of time if the
input voltage suddenly drops and subsequently
resumes to a normal level. The shutdown delay
time is user-defined.
OZ964 provides under-voltage lockout protection
and will disable the IC if VDDA falls below a
threshold. OZ964 will resume normal operation
when VDDA exceeds the threshold.
To reset the IC, toggle the enable (ENA) pin.
OZ964 operates with a standby current of
approximately 200uA.
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