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PDF KIA3802F Data sheet ( Hoja de datos )
| Número de pieza | KIA3802F | |
| Descripción | LCD BACKLIGHT INVERTER CONTROLLER | |
| Fabricantes | KEC | |
| Logotipo |  |
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SEMICONDUCTOR
TECHNICAL DATA
KIA3802F
www.DataSheet4U.com
BIPOLAR LINEAR INTEGRATED CIRCUIT
LCD BACKLIGHT INVERTER CONTROLLER
FEATURES
Input voltage range of 7V to 20V
Low cost, push-pull inverter topology
Internal open lamp protection and over voltage detecting
Built-in stand-by function
Integrated with burst mode control, wide dimming range
Soft-Start
Timer function
Reduces the number of componerts
Supports multiple CCFLs
APPLICATION
LCD Monitor
Notebook Computer
DP
A
16 9
18
L
DIM MILLIMETERS
A 9.88+_ 0.2
B1 3.94 +_0.2
B2 6.00+_ 0.3
D 0.4+_ 0.1
G 0.15+0.1/-0.05
H 1.63+_ 0.2
L 0.65+_ 0.2
P 1.27
T 0.20+0.1/-0.05
FLP-16
BLOCK DIAGRAM
EN 1
CMP 2
SST 3
CT 4
RT 5
LCT 6
VDIM 7
LPWM 8
OSC
CT
RT
LCT
VDIM
LPWM
Burst
Mode
Err Amp
OUT
3V
Open
VCC
2.5V
Vref
Reference
TIMER
OUT
Over Voltage
-Q
2V
VCC
OUT
PWM Comparator
CLK + Q
Push Pull Controller
VCC
16 IN -
15 TIMER
14 VREF
13 OVP
12 VCC
11 OUT2
10 GND
9 OUT1
2005. 12. 6
Revision No : 0
KIA3802F
1/5
1 page  
KIA3802F
www.DataSheet4U.com
Functional Description
1) Main Frequency (Lamp Operation Frequency)
A resistor RT and a capacitor CT determine the main frequency of
IC. The main frequency can be calculated as below equation:
6.8 102
Main f [kHz] =
CT[nF] RT[kΩ]
2) Open Lamp Protection
Open lamp protection in the ignition time is provided through both
OVP and TIMER pin to ensure a rated voltage is achieved and a
required timing is satisfied.
If time that TIMER capacitor charges to 3V is long than the CCFL
ignition time, it can prevent over-operating by protection circuit.
3) Error Amplifier
The CCFL current is regulated through the error amplifier. Error
amplifier output (CMP) voltage and ramp wave (CT) make the
PWM pulses. The non-inverting reference is at 2.5V nominal.
4) OVP
When the output voltage reaches the threshold, it commands the
PWM controller to maintain the current driving level. This ensures
that output gets sufficient striking voltage while operating the power
transformer safely. The OVP threshold is set at 2V nominal.
5) On/Off Function
The Enable pin provides the function to turn on and off the output
without shut down the supply voltage. The threshold of the Enable is
set at 2.0V.
6) Soft-start
The soft-start function is provided with a capacitor connected to SST
pin. It provides a rate of rise for the pulse width where switches are
turned on. A 2.2 capacitor connected on the SST pin can set a 0.4
second period for striking the lamp.
7) Burst-mode Dimming
The burst-mode frequency is determined by a capacitor connected to
LCT pin.
The frequency can be calculated by:
f [Hz] =
1 106
LCT[nF] RT[k Ω]
To compare the input of VDIM pin with the ramp wave(LCT) makes
the PWM pulses for Burst-mode Dimming. The LPWM pin is pulled
to VREF to make the dark portion of the CCFL output burst and the
floating state to make the bright portion. A less than 0.6V input on
VDIM pin will obtain 100% brightness.
Transformer Design
1. Transformer Turns Ratio
Calculation of the required turns ratio involves the estimation of two
critical factors.
1). Estimating Minimum Primary Voltage.
The minimum primary voltage is obtained from the value of the low
supply voltage.
2). Estimating Maximum Secondary Voltage.
The secondary is composed of a ballast capacitor, a voltage divide
capacitor and the lamp parasitic capacitor.
The voltage across the ballast capacitor can be calculated as below
equation:
VBallast C = X Ballast ILamp
The maximum secondary voltage can be calculated as below
equation:
Vsecondary =
VLamp2 +
VBallast
2
C
Transformer turns ratio is:
Vsecondary
N = Vprimary
2. Required Number of Secondary Turns
From the core constant provided by the core manufacturer, you will
need the effective core cross sectional area(Ae).
From the Faraday's law, the required number of secondary turns
would be:
Nsecondary =
Vsecondary tmax 108
B Ae
3. Required Number of Primary Turns
From the turns ratio and number of secondary turns
Nsecondary
Nprimary =
N
4. Determination of Wire Gauge
Wire gauge can be done by an acceptable current density.
From the assumed current density (500cmil) and the current that
flows through wires, the required Circular Mils is:
Cmils = CDLim IRMS
From the AWG table, pick a wire-gauge that would fit limit.
Using the selected wire diameter and bobbin information, determine
if this wire gauge will fit in the space allotted. (when the space
factor[SF] is accounted for)
2005.12.6
Revision No : 0
5/5
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