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PDF TD8203 Data sheet ( Hoja de datos )
| Número de pieza | TD8203 | |
| Descripción | White LED Step-up Converter | |
| Fabricantes | Techcode | |
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Techcode®
White LED Step-up Converter
DATASHEET
TD8203
General Description
Features
The TD8203 is a current-mode and fixed frequency boost
converter with an integrated N-FET to drive white LEDs.
The series connection allows the LED current to be
identical for uniform brightness. Its low on-resistance of
NFET and low feedback voltage reduce power loss and
achieve high efficiency. Fast switching frequency(1.5MHz
typical) allows using small-size inductor and both of input
and output capacitors. An over voltage protection
function,which monitors the output voltage via OVP pin,
stops switching of the IC if the OVP voltage exceeds the
over voltage threshold. An internal soft-start circuit
eliminates the inrush current during start-up.
The TD8203 also integrates under-voltage lockout,
overtemperature protection, and current limit circuits to
protect the IC in abnormal conditions. The TD8203 is
available in a SOT-23-6A
Wide Input Voltage from 2.7V to 6V
Fixed 1.5MHz Switching Frequency
Reference Voltage : 0.2V
PWM Brightness Control with Wide Frequency
Range of 100Hz to 100kHz
Build-In Power MOSFET : 0.2Ω
Open-LED Protection
Under-Voltage Lockout Protection
Over-Temperature Protection
<1mA Quiescent Current during Shutdown
SOT-23-6A
Halogen and Lead Free Available
RoHS Compliant
Applications
White LED Display Backlighting
Cell Phone and Smart Phone
PDA, PMP, MP3
Digital Camera
December, 20, 2011
Techcode Semiconductor Limited
1
www.techcodesemi.com
1 page  
Techcode®
White LED Step-up Converter
Electrical Characteristics
The following specifications apply for VIN =3.6V TA=25 oC, unless specified otherwise.
DATASHEET
TD8203
Symbol Parameter
VIN
IDD1
IDD2
ISD
VREF
Input Voltage
Input DC Bias Current
UVLO Threshold Voltage
UVLO Hysteresis Voltage
Regulated Feedback Voltage
IFB
FSW
RON
ILIM
DMAX
FB Input Current
Switching Frequency
Power Switch On Resistance
Power Switch Current Limit
LX Leakage Current
LX Maximum Duty Cycle
Over Voltage Threshold
TOTP
Over Voltage Hysteresis
OVP Leakage
Enable Voltage Threshold
Shutdown Voltage Threshold
EN Leakage Current
EN Minimum On Pluse Width
Over-Temperature Protection
Over-Temperature Protection
Test Conditions
VFB=0.4V,no switching
TD8203
Min. Typ.
2.5
- 300
VFB=0V, switching
EN=GND
VIN Rising
VIN Falling
VIN=2.7V~6V, TA = 25 oC
VIN=2.7V~6V, TA = -40 ~ 85 oC
-
-
2.0
50
0.185
0.18
-50
1.25
VEN = 0V, VLX = 0V or 6V, VIN = 6V
-1
92
VOUT Rising
TD8203A
TD8203B
22
14.5
VOVP Falling
-
VOVP =20V
-
VEN Rising
1
VEN Falling
-
VEN = 0 ~ 6V, VIN = 6V
-2
VEN = 0 ~ 6V, VIN = 6V, PWM-
DTJimRimsinimgg
FTrJeFqaulleinngcy=100Hz to 100kHz
2
-
2.2
100
0.2
1.5
0.2
2
95
24
16
3
50
-
-
-
800
150
40
Max.
6
-
5
1
2.4
150
0.215
0.22
50
1.75
1
98
27.5
20
-
-
-
0.4
2
-
Unit
V
uA
mA
µA
V
mV
V
nA
MHz
Ω
A
uA
%
V
V
nA
V
V
uA
ns
oC
oC
December, 20, 2011
Techcode Semiconductor Limited
5
www.techcodesemi.com
5 Page 
Techcode®
White LED Step-up Converter
DATASHEET
TD8203
Application Information
Input Capacitor Selection
The input capacitor (CIN) reduces the current peaks drawn from
the input supply and reduces noise injection into the IC. The
reflected ripple voltage will be smaller with larger CIN. For reliable
operation, it is recommended to select the capacitor voltage
rating at least 1.2 times higher than the maximum input voltage.
The capacitors should be placed close to the VIN and GND.
Inductor Selection
For high efficiencies, the inductor should have a low dc
resistance to minimize conduction losses. Especially at
high-switching frequencies the core material has a higher impact
on efficiency. When using small chip inductors, the efficiency is
reduced mainly due to higher inductor core losses. This needs to
be considered when selecting the appropriate inductor. The
inductor value determines the inductor ripple current. The larger
the inductor value, the smaller the inductor ripple current and the
lower the conduction losses of the converter. Conversely, larger
inductor values cause a slower load transient response. A
reasonable starting point for setting ripple current, IL,is 30% to
50% of the average inductor current. The recommended inductor
value can be calculated as below:
The peak inductor current is calculated as the following equation:
where
VIN = input voltage
VOUT = output voltage
FSW = switching frequency in MHz
IOUT = maximum output current in amp.
η = Efficiency
IL /IL(AVG) = inductor ripple current/average current (0.3 to 0.5
typical)
To avoid saturation of the inductor, the inductor should be rated
at least for the maximum input current of the converter plus the
inductor ripple current. The maximum input current is calculated
as below:
Output Capacitor Selection
The current-mode control scheme of the TD8203 allows the usage
of tiny ceramic capacitors. The higher capacitor value provides
good load transient response.Ceramic capacitors with low ESR
values have the lowest output voltage ripple and are
recommended. If required,tantalum capacitors may be used as
well. The output ripple is the sum of the voltages across the ESR
and the ideal output capacitor.
where IPEAK is the peak inductor current.
December, 20, 2011
Techcode Semiconductor Limited
11
www.techcodesemi.com
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet TD8203.PDF ] | |
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