PAM2803FBAF095 [PAM]
3W High Power White LED Driver; 3W高功率白光LED驱动器
| 型号： | PAM2803FBAF095 |
| 厂家： | 
POWER ANALOG MICOELECTRONICS |
| 描述： | 3W High Power White LED Driver |
| 文件： | 总8页 (文件大小：207K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PAM2803
3W High Power White LED Driver
Features
General Description
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LED Power Efficiency: up to 90%
Current Accuracy: 5%(VIN=3.6V to 1.8V
@VF=3.7V)
The PAM2803 is a set-up DC-DC converter that
delivers a regulated output current. The device
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switches at
a 1.0MHz constant frequency,
allowing for the use of small value external
inductor and ceramic capacitors.
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Low Start-Up Voltage: 0.9V(ILED=270mA)
Low Hold Voltage:0.75V(ILED=200mA)
1MHz Switching Frequency
Uses small, Low Profile External Components
Low RDS(ON) : 100mΩ (TYP.)
Open LED Protection
Over Temperature Protection
Low Profile SOT-23-6 Package
Pb-Free Package
The PAM2803 is targeted to be used for driving
loads up to 1A from a two-cell alkaline battery. The
LED current can be programmed by the external
current sense resistor, Rs, connected between the
feedback pin (FB) and ground. A low 95mV
feedback voltage reduces the power loss in the Rs
for better efficiency. With its internal 2A, 100mꢀ
NMOS switch, the device can provide high
efficiency even at heavy load. During the
shutdown mode, the feedback resistor Rs and the
load are completely disconnected and the current
consumption is reduced to less than 1uA.
Applications
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White LED Torch (Flashlight)
White LED Camera Flash
DSC(Digital Still Camera)Flash
Cellular Camera Phone Flash
PDA Camera Flash
The PAM2803 is available in the 6-lead SOT-23-6
package.
Camcorder Torch(Flashlight) Lamp
Typical Application
Block Diagram
SW
VOUT VIN
Comparator
2.2uH
95mV
Reference
+
A1
-
-
1
PWM Logic
And Driver
A2
+
Rc
Cc
SW
5
3
6
VIN
VOUT
FB
+
-
CIN
3W
WLED
PAM2803
SHDN FB
Σ
10uF
VIN
CO
4
Ramp
Generator
OFF ON
10uF
RS
GND
2
SHDN
Shutdown
And
Soft-start
1.0MHz
Oscillator
GND
ILED=750mA, RS=0.127ꢀ
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
1
PAM2803
3W High Power White LED Driver
Pin Configuration& Marking Information
Top View
SOT-23-6
XX: Product Code
V: Voltage Code
Y: Year
6
5
4
W: Weekly
XX V Y W
1
2
3
Pin Number
Name
SW
Function
1
2
3
4
5
6
Switch
Ground
Feedback
Shut Down
Output
GND
FB
SHDN
VOUT
VIN
Input
Absolute Maximum Ratings
These are stress ratings only and functional operation is not implied. Exposure to absolute
maximum ratings for prolonged time periods may affect device reliability. All voltages are with
respect to ground.
Input Pin Voltage...............................–0.3V to 6V
SW Pin Voltage..................................–0.3V to 6V
SHDN, FB Pin Voltage.........................–0.3V to 6V
Operating Temperature Range .........-40°C to 85°C
Storage Temperature Range......... –65°C to 125°C
Lead Temperature (Soldering, 5 sec) ...........300°C
Recommended Operating Conditions
Junction Temperature...............-40°C to 125°C
Ambient Temperature..................-40°C to 85°C
Thermal Information
Parameter
Package
Symbol
Maximum
Unit
℃/W
mW
Thermal Resistance
(Junction to Case)
SOT-23-6
θJC
130
Thermal Resistance
(Junction to Ambient)
Internal Power Dissipation
SOT-23-6
SOT-23-6
θJA
PD
250
400
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
2
PAM2803
3W High Power White LED Driver
Electrical Characteristic
TA=25℃, VIN=2.4V, ILED=750mA, VSHDN = VIN, L=2.2uH, CΙΝ=10uF, CO=10uF, unless otherwise noted.
Parameter
Input Voltage Range
Feedback Voltage
Start-up Voltage
Symbol
VIN
Conditions
Min
0.9
90
Typ
Max
VF-0.2
(note 1)
100
Unit
V
VFB
95
mV
V
VIN: 0V→3V
LED=270mA
VIN: 3V→0V
LED:750mA→200mA
VSTART
0.9
I
Hold Voltage
VHOLD
0.75
1.0
V
I
Oscillator Frequency
SHDN Input High
FOSC
VSH
0.85
1.0
1.15
0.4
MHz
V
VIN=1.8V
VIN=1.8V
SHDN Input Low
VSL
V
Over Temperature Shutdown
Over Temperature Hysteresis
Maximum Output Current
Range
OTS
OTH
150
15
℃
℃
IO(MAX)
750
mA
mA
ILED=0mA, VO=3.4V,
Device Switching at 1MHz
Shutdown mode
VO=3.4V
Quiescent Current
IQ
1
3
1
Shutdown Current
Switch on Resistance
Current Limit
ISD
RDSON
ILIM
uA
Ω
0.1
90
VO=3.4V
2
A
Efficiency
η
ILED=750mA
%
Note1: VF - LED Forward Voltage
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
3
PAM2803
3W High Power White LED Driver
Typical Performance Characteristics
TA=25℃, L=2.2uH , CΙΝ=10uF, CΟ=10uF, unless otherwise noted.
1. LED Power Efficiency vs Input Voltage
100
2. LED Current vs Input Voltage
800
750
90
80
70
60
50
40
ILED=750mA@VF=3.7V
700
650
600
550
500
450
400
ILED=750mA@VF=3.7V
3.6 3.3
3
2.7 2.4 2.1 1.8 1.5 1.2
Input Voltage(V)
3.6 3.3
3
2.7 2.4 2.1 1.8 1.5 1.2
Input Voltage(V)
4. Feedback Voltage vs Input Voltage
(ILED=750mA@VF=3.7V)
3. DC Input Current vs Input Voltage
2300
2100
1900
1700
1500
1300
1100
900
100
95
90
85
80
75
70
65
60
55
50
ILED=750mA@VF=3.7V
700
500
3.6 3.3
3
2.7 2.4 2.1 1.8 1.5 1.2
Input Voltage(V)
3.6 3.3
3
2.7 2.4 2.1 1.8 1.5 1.2
Input Voltage(V)
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
4
PAM2803
3W High Power White LED Driver
Typical Performance Characteristics (continued)
6. Start-Up Waveform
5. Switching Waveform
SHDN
SW
VO
VO
AC
Coupling
IL
IL
7. Overvoltage Protection
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
5
PAM2803
3W High Power White LED Driver
Application Information
Inductor Selection
LED Current Setting
The PAM2803 can use small value inductors due
to its switching frequency of 1 MHz. The value of
inductor will focus in the range of 2.2uH to 4.7uH
for most PAM2803 applications. In typical high
c u r r e n t w h i t e L E D a p p l i c a t i o n s , i t i s
recommended to use a 4.7uH inductor. The
inductor should have low DCR (DC resistance) to
minimize the I2R power loss, and it requires a
current rating of 2A to handle the peak inductor
current without saturating.
The LED current is set by the single external Rs
resistor connected to the FB pin as shown in the
typical application circuit on page 1. The typical
FB reference is internally regulated to 95mV. The
LED current is 95mV/Rs. It's recommended to
use a 1% or better precision resistor for the
better LED current accuracy. The formula and
table 1 for Rs selection are shown as follows:
Rs=95mV/ILED
Capacitor Selection
Table 1. Rs Resistor Value Selection
An input capacitor is required to reduce the input
ripple and noise for proper operation of the
PAM2803. For good input decoupling, Low ESR
(equivalent series resistance) capacitors should
be used at the input. At least 2.2uF input
capacitor is recommended for most applications.
Standard Value(Ω)
ILED(mA)
528
0.18
0.15
0.12
0.10
633
792
950
A minimum output capacitor value of 6.8uF is
r e c o m m e n d e d u n d e r n o r m a l o p e r a t i n g
conditions, while a 10uF-22uF capacitor may be
required for higher power LED current. A
reasonable value of the output capacitor
depends on the LED current. The ESR of the
output capacitor is the important parameter to
determine the output voltage ripple of the
converter, so low ESR capacitors should be used
at the output to reduce the output voltage ripple.
The small size of ceramic capacitors is an
excellent choice for PAM2803 applications. The
X5R and X7R types are preferred because they
maintain capacitance over wide voltage and
temperature ranges.
PCB Layout Guidelines
As for all switching power supplies, the layout
and components placement of the PAM2803 is
an important step in the design; especially at
high peak currents and high switching
frequencies.
The input capacitor and output capacitor should
be placed respectively as close as possible to
the input pin and output pin of the IC; the inductor
and schottky diode should be placed as close as
possible to the switch pin by using wide and short
traces for the main current path; the current
sense resistor should be placed as close as
possible between the ground pin and feedback
pin.
Diode Selection
It's indispensable to use a Schottky diode rated
at 2A with the PAM2803. Using a Schottky diode
with a lower forward voltage drop is better to
improve the power LED efficiency, and its voltage
rating should be greater than the output voltage.
I n a p p l i c a t i o n , t h e O N S e m i c o n d u c t o r
MBRA210LT3G is recommended.
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
6
PAM2803
3W High Power White LED Driver
Ordering Information
PAM2803 X X X X
FB Voltage
Number of Pins
Package Type
Pin Configuration
Pin Configuration
A Type
Package Type
A: SOT-23-6
Number of Pins
FB Voltage
F: 6
095：95mV
1. SW
2. GND
3. FB
4. SHDN
5. VOUT
6. VIN
Part Number
Marking
CFAYW
Package Type
SOT-23-6
Standard Package
3,000Units/Tape&Reel
PAM2803AAF095
Please consult PAM sales office or authorized Rep./Distributor for detailed ordering information.
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
7
PAM2803
3W High Power White LED Driver
Outline Dimension
SOT-23-6
e
A
A
e1
SEE VVIIEEWWSS
b
WITH PLANTING
BASE MMEETTAALL
SECTION AA--AA
GAUGE PPLLAANNEE
SSEEAATTIINNGG PPLLAANNEE
L
L1
VIEW BB
Symbol
A
A1
A2
b
c
D
E
Spec 1.20 0.25 0.10 0.05 1.10 0.2 0.40 0.1 0.15 0.0.7 2.90 0.1 2.80 0.2
Symbol
Spec
E11
e
e 1
L
L1
θ
1.60 0.1 0.95BSC 1.90BSC 0.55 0.25 0.60REF
4° 4°
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
8
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