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PDF AP3019A Data sheet ( Hoja de datos )
| Número de pieza | AP3019A | |
| Descripción | WHITE LED STEP-UP CONVERTER | |
| Fabricantes | BCD Semiconductor | |
| Logotipo |  |
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Data Sheet
WHITE LED STEP-UP CONVERTER
AP3019A
General Description
The AP3019A is an inductor-based DC/DC converter
designed to drive up to eight white LEDs in series for
backlight. Only one feedback resistor is needed to
control the LED current and obtain required
brightness.
A constant frequency 1.2MHz PWM control scheme
is employed in this IC, which means tiny external
components can be used. Specifically, 1mm tall
inductor and 0.22µF output capacitor for a typical
application is sufficient. Additionally, the Schottky
diode in boost circuit is integrated on this chip.
AP3019A also provides a disable pin to ease its use
for different systems.
The output over-voltage protection is implemented in
AP3019A. When any LED is broken or in other
abnormal conditions, the output voltage will be
clamped.
The AP3019A is available in standard SOT-23-6 and
TSOT-23-6 packages.
Features
• Inherently Uniform LED Current
• High Efficiency up to 84%
• No Need for External Schottky Diode
• Output Over-voltage Protection (OVP)
• Fixed 1.2MHz Switching Frequency
• Uses Tiny 1mm Tall Inductor
• Requires Only 0.22µF Output Capacitor
Applications
• Cellular Phones
• Digital Cameras
• LCD modules
• GPS Receivers
• PDAs, Handheld Computers
SOT-23-6
TSOT-23-6
Figure 1. Package Types of AP3019A
May. 2010 Rev. 1.8
BCD Semiconductor Manufacturing Limited
1
1 page  
Data Sheet
WHITE LED STEP-UP CONVERTER
AP3019A
Electrical Characteristics
VIN =3V, VCTRL=3V, TA =25°C, unless otherwise specified.
Parameter
Minimum Operating Voltage
Maximum Operating Voltage
Feedback Voltage (Note 2)
FB Pin Bias Current
Quiescent Current
Shutdown Quiescent Current
Switching Frequency
Maximum Duty Cycle
Switch Current Limit (Note 3)
Switch VCE Saturation Voltage
Switch Leakage Current
CTRL Pin Voltage
CTRL Pin Bias Current
OVP Voltage
Schottky Forward Drop
Schottky Leakage Current
Soft Start Time
Thermal Resistance
(Junction to Case)
Symbol
Conditions
VIN (min)
VIN (max)
VFB
IFB
IOUT=20mA, 4 LEDs,
TA=-40oC to 85oC
IQ VFB=VIN, no switching
ISHDN
VCTRL=0V
f
DMAX
ILIMIT
D=40%
D=80%
VCESAT
VCTRL
ISW=250mA
VSW=5V
High
low
ICTRL
VOV
VDROP
t
ID=150mA
VR(reverse voltage)=23V
VR(reverse voltage)=27V
SOT-23-6
θJC
TSOT-23-6
Min
2.5
188
1.5
2.0
0.9
90
1.8
Typ
200
35
2.5
4.0
1.2
93
550
550
360
0.01
100
30
0.7
0.1
300
60
60
Max Unit
V
16
212 mV
100 nA
3.2 mA
6.0 µA
1.5 MHz
%
mA
mV
5 µA
V
0.5
µA
V
V
4
µA
150
µS
°C/W
Note 2: The bold type specifications of full temperature range are guaranteed by design (GBD).
Note 3: The switch current limit is related to duty cycle. Please refer to Figure 15 for detail.
May. 2010 Rev. 1.8
BCD Semiconductor Manufacturing Limited
5
5 Page 
Data Sheet
WHITE LED STEP-UP CONVERTER
AP3019A
Application Information (Continued)
(2) Changing the Effective Feedback Voltage
There are three methods to change the effective
feedback voltage.
First, adding a constant DC voltage through a resistor
divider to FB pin can control the dimming. Changing
the DC voltage or resistor between the FB Pin and the
DC voltage can get appropriate luminous intensity.
Comparing with all kinds of PWM signal control, this
method features a stable output voltage and LEDs
current. Please refer Figure 21.
Third, using a logic signal to change the feedback
voltage. For example, the FB pin is connected to the
GND through a MOSFET and a resistor. And this
MOSFET is controlled a logic signal. The luminous
intensity of LEDs will be changed when the
MOSFET turns on or off.
Figure 23. Dimming Control Using Logic Signal
Figure 21. Dimming Control Using DC Voltage
Second, using a filtered PWM signal can do it. The
filtered PWM signal can be considered as a varying
and adjustable DC voltage.
Figure 22. Dimming Control Using a Filtered PWM
Voltage
May. 2010 Rev. 1.8
BCD Semiconductor Manufacturing Limited
11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet AP3019A.PDF ] | |
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