PAM2801VOUTAF095 [PAM]
1W High Power White LED Driver; 1W大功率白光LED驱动器
| 型号： | PAM2801VOUTAF095 |
| 厂家： | 
POWER ANALOG MICOELECTRONICS |
| 描述： | 1W High Power White LED Driver |
| 文件： | 总9页 (文件大小：266K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PAM2801
1W High Power White LED Driver
Features
General Description
n
LED Power Efficiency: up to 90%
LED Current Accuracy: 3%(VIN=3.2V to 1.1V
@VF=3.4V)
The PAM2801 is a step-up DC-DC converter that
delivers a regulated output current. The device
n
switches at
a 1.0MHz constant frequency,
allowing for the use of small value external
inductor and ceramic capacitors.
n
n
n
n
n
n
n
n
n
n
Low Start-Up Voltage: 0.9V(ILED=243mA)
Low Hold Voltage:0.65V(ILED=95mA)
Internal 2A MOSFET Switch
1.0MHz Switching Frequency
Uses Small,Low Profile External Components
Low RDS(ON): 100mΩ (TYP.)
The PAM2801 is targeted to be used for driving
1W white LED from a 0.9V to 3.2V input. 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.
Open LED Protection
Over Temperature Protection
Low Profile SOT-23 Package
Pb-Free Package
Applications
LED dimming can be done by using a DC voltage
applied to the FB pin and a pulse width modulation
(PWM) signal applied to the FB pin or SHDN pin.
During the shutdown mode, the feedback resistor
Rs and the load are completely disconnected and
the current consumption is reduced to less than
1uA.
n
n
n
n
n
n
White LED Torch (Flashlight)
White LED Camera Flash
DSC(Digital Still Camera)Flash
Cellular Camera Phone Flash
PDA Camera Flash
Camcorder Torch(Flashlight) Lamp
The PAM2801 is available in the 6-lead SOT-23-6
package.
Block Diagram
Typical Application
SW
VOUT VIN
2.2uH
Comparator
95mV
Reference
+
A1
1
-
-
PWM Logic
And Driver
A2
+
Rc
Cc
SW
5
3
6
VIN
VOUT
FB
CIN
1W
WLED
+
-
PAM2801
SHDN FB
10uF
Σ
VIN
CO
OFF ON
4
10uF
Ramp
Generator
RS
GND
2
SHDN
Shutdown
And
Soft-start
1.0MHz
Oscillator
GND
ILED=350mA,RS=0.27ꢀ
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
1
PAM2801
1W 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
PAM2801
1W High Power White LED Driver
Electrical Characteristic
TA=25℃, VIN=2.4V, ILED=350mA, 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
ILED=243mA（RS=0.39Ω）,
VIN: 0V→2.4V
VSTART
0.9
ILED=95mA（RS=1Ω）,
VIN: 2.4V→0V
Hold Voltage
VHOLD
0.65
1.0
V
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)
350
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=350mA
%
Note1: VF - LED Forward Voltage
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
3
PAM2801
1W High Power White LED Driver
Typical Performance Characteristics
TA=25℃, L=2.2uH , CΙΝ=10uF, CΟ=10uF, unless otherwise noted.
DC Input Current vs Input Voltage
LED Power Efficiency vs Input Voltage
2100
1900
1700
1500
1300
1100
900
95
90
85
80
75
70
65
60
55
50
ILED=185mA @VF=3.2V
ILED=350mA @VF=3.4V
ILED=350mA@VF=3.4V
700
500
300
ILED=185 mA@VF=3.2V
100
3.3
3
2.7 2.4 2.1 1.8 1.5 1.2 0.9
Input Voltage(V)
3.3
3
2.7 2.4 2.1 1.8 1.5 1.2 0.9
Input Voltage(V)
LED Current vs Input Voltage
LED Power Efficiency vs LED Current
95
90
85
80
75
70
65
60
400
350
300
250
200
150
100
VIN=3V
ILED=350mA@VF=3.4V
VIN=2.4V
VIN=1.8V
ILED=185mA@VF=3.2V
3.3
3
2.7 2.4 2.1 1.8 1.5 1.2 0.9
Input Voltage(V)
100
150
200
250
300
350
400
LED Current(mA)
Feedback Voltage vs Temperature
(ILED=350mA)
Feedback Voltage vs Input Voltage
(ILED=350mA)
100
95
90
85
80
75
70
100
95
90
85
80
75
70
TA=+25℃
VIN=1.8V
VIN=3V
VIN=2.4V
TA=+85℃
25
50
75
100
125
3.3
3
2.7 2.4 2.1 1.8 1.5 1.2 0.9
Input Voltage(V)
Temperature(℃)
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
4
PAM2801
1W High Power White LED Driver
Typical Performance Characteristics (continued)
Switching Waveform
Start-Up Waveform
EN
SW
VOUT
VOUT
AC
Coupling
IL
IL
Overvoltage Protection
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
5
PAM2801
1W High Power White LED Driver
Application Information
Inductor Selection
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:
The PAM2801 can use a small value inductor
due to its switching frequency of 1MHz. The
value of inductor focuses in the range of 1.5uH to
4.7uH for most PAM2801 applications. In typical
high current white LED applications, it is
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.
Rs=95mV/ILED
Table 1. Rs Resistor Value Selection
Standard Value(Ω)
ILED(mA)
95
1
0.47
0.39
0.33
0.27
0.24
202
Capacitor Selection
243
288
An input capacitor is required to reduce the input
ripple and noise for proper operation of the
PAM2801. 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.
352
396
LED Dimming Control
A minimum output capacitor value of 4.7uF 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 PAM2801 applications. The
X5R and X7R types are preferred because they
maintain capacitance over wide voltage and
temperature ranges.
Dimming Control Using a DC Voltage to FB Pin
One method for dimming the LEDs is to apply a
variable DC voltage through a resistor to the FB
pin of the PAM2801. The dimming control with a
DC voltage is shown in the Figure1. The DC
voltage artificially raises the FB pin voltage, with
the DC voltage increasing, the voltage across R2
increases and the voltage across Rs decreases,
which therefore lowers the LED current. The
values of resistor R1 and R2 should be large
enough to make the current from the DC source
much smaller than the LED current while much
larger than the FB leakage current. When VDC
ranges from 0V to 2V, the resistors in the Figure
will set the LED current from 0mA to 350mA.
Diode Selection
It's indispensable to use a Schottky diode rated
at 2A with the PAM2801. 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.
PAM2801
1 W
WLED
FB
R1
R2
VDC
22KΩ
1KΩ
RS
0.27Ω
LED Current Setting
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
Figure 1. Dimming Control Using a DC Voltage to
FB Pin
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
6
PAM2801
1W High Power White LED Driver
Application Information(continued)
Dimming Control Using a PWM Signal to FB
Pin
SHDN
FB
By using the PWM signal to FB pin as shown in
the Figure 2, the LED turns on or off and its
current operates at either 0mA or the set
maximum current. The PWM signal can be
considered as an adjustable DC voltage. As the
PWM duty cycle increases, the LED current
decreases. Typically, the PWM frequency ranges
from 5KHz to 40KHz.
ILED
PAM2801
FB
1 W
WLED
（3a）100Hz
10KΩ
0.1uF
R2
R1
SHDN
FB
PWM
22kΩ
1KΩ
RS
0.27Ω
Figure 2. Dimming Control Using a PWM Signal
to FB Pin
ILED
（3b）1 KHz
Figure 3. Dimming Control Using a PWM Signal
to SHDN Pin
Dimming Control Using a PWM Signal to
SHDN Pin
With the PWM signal applied to the SHDN pin of
the PAM2801, the LED turns on or off. When the
SHDN pin is high, the LED turn on and its current
is at the set maximum current; when the SHDN
pin is low, the LED turn off and its current turns to
0mA. The average LED current increase
proportionally with the PWM duty cycle. A 0%
duty cycle produces 0mA of LED current; a 100%
duty cycle corresponds to the set maximum
current. The magnitude of the PWM signal
should be higher than the SHDN input high (VSH).
The typical frequency of the PWM signal ranges
from 100Hz to 1KHz. Figure 3 shows the LED
current with the PWM duty cycle set to 50% and
the PWM frequency set respectively to 100Hz
and 1KHz. Figure 4 shows the LED current
versus the PWM duty cycle, setting the PWM
frequency to 100Hz.
LED Current vs Duty Cycle
400
350
300
250
200
150
100
50
0
0
20
40
60
80
100
Duty Cycle(%)
Figure 4. LED Current vs Duty Cycle
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
7
PAM2801
1W High Power White LED Driver
Application Information(continued)
PCB Layout Guidelines
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.
As for all switching power supplies, the layout
and components placement of the PAM2801 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
Ordering Information
PAM2801 X X X X
FB Voltage
Number of Pins
Package Type
Pin Configuration
Pin Configuration
A Type
Package Type
Number of Pins
FB Voltage
A: SOT-23-6
F: 6
095：95mV
1. SW
2. GND
3. FB
4. SHDN
5. VOUT
6. VIN
Part Number
Marking
CDAYW
Package Type
SOT-23-6
Standard Package
3,000Units/Tape&Reel
PAM2801AAF095
Please consult PAM sales office or authorized Rep./Distributor for detailed ordering information.
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2007
8
PAM2801
1W 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
9
相关型号：
©2020 ICPDF网 联系我们和版权申明