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PDF ( 数据手册 , 数据表 ) OZ9939

零件编号 OZ9939
描述 Change Summary
制造商 O2Micro
LOGO O2Micro LOGO 


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OZ9939 数据手册, 描述, 功能
CHANGES
No. Applicable Section
1. Electrical Characteristics
OZ9939www.DataSheet4U.com
Change Summary
Description
Updated limits for Protection Release Threshold
Page(s)
3
REVISION HISTORY
Revision No.
0.6
0.65
1.0
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
Ordering Information: Add OZ9939G, IG, D & DN. Recommended
Operating Range: 1. Add ‘Dimming Range’; 2. Fill in ‘Thermal Impedance’.
Electrical Characteristics: 1. Update ‘Supply Current’ limits; 2. Update ‘Soft
Start’ limits; 3. Update ‘Under Voltage Lockout’ limits; 4. Update ‘Reference
Voltage’ limits; 5. Update ‘Driver Frequency’ limits; 6. Update ‘Timer &
Protection’ limits; 6. Update ‘Drivers’ parameter name & limits; 7. Update
‘PWM Dimming Control’ limits; 8. Delete ‘Analog Dimming Control’.
Function Description: Update formula in NO. 4 Ignition, No. 6 Normal
Operation & No. 9 Dimming Control. Package Information: Add DIP
package drawing. Throughout datasheet: Miscellaneous changes.
Release Date
5/12/2005
6/27/2005
9/21/2005
10/27/2005
OZ9939-DS-1.1
Copyright © 2005 by O2Micro
All Rights Reserved
Patent#6,559,606, #6,856,519 & #6,809,93800
Page 0
CONFIDENTIAL







OZ9939 pdf, 数据表
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 time is
calculated by the following equation.
Td [Sec] = 0.33 XCTIMER [uF]
To resume operation, toggle the PWM signal or
restart VDDA.
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:
f LOSC =
3102
RLCT [M]*CLCT[nF]
[Hz]
With negative PWM dimming polarity, the LPWM
duty cycle will be 100% when DIM pin voltage is
lower than 0.1V. LCD panel will have maximum
brightness. When DIM pin voltage is higher than
1.5V, the LPWM duty cycle will be 0%. LCD
panel will be totally dark.
OZ9939www.DataSheet4U.com
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).
.
CONFIDENTIAL
OZ9939-DS-1.1
Page 7














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