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Número de pieza | PAM2800 | |
Descripción | High Power White LED Driver | |
Fabricantes | Power Analog Micoelectronics | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de PAM2800 (archivo pdf) en la parte inferior de esta página. Total 7 Páginas | ||
No Preview Available ! Features
n High Efficiency 92%
n Up to 350mA Constant Source Current
n Low Quiescent Current: Typ. 65 μA
n 0.5μA Shutdown Current
n Short Circuit Protection
n Open Load LED Protection
n Thermal Protection
n Space Saving Package SOT23-5
n Pb-Free Package
Applications
n High Power White LED Driver
Typical Application Circuit
PAM2800
High Power White LED Driver
General Description
The PAM2800 is a high power white LED driver
with 350mA constant rated source current. It
features high efficiency and low quiescent current,
making it ideal for battery powered applications.
Efficiency vs Supply Voltage
IN
VIN PAM2800VOUT
EN GND FB
R1
100
95
90
85
CO 80
CIN 1W 2.2μF
1μF
R2 WLED
75
www.DataSheet4U.com
70
RS 65
60
4.8
4.5 4.2 3.9 3.6
Supply Voltage(V)
Figure 1
3.3
Power Analog Microelectronics,Inc
www.poweranalog.com
1
09/2008 Rev 1.1
1 page PAM2800
High Power White LED Driver
Application Information
In the typical application (see Figure 1), the LED
current will come to constant current level little by
little after the device is powered. A 62ΚΩ resistor
is recommended for R1, and the value for R2
should be adjusted around 33ΚΩ due to LED
forward voltage variation from lot-to-lot or brand-
to-brand.
Power Dissipation and Thermal Consideration
Thermal protection limits power dissipation in the
PAM2800. When the operation junction
temperature exceeds 150°C, the OTP (Over
Temperature Protection) starts the thermal
shutdown and turns the pass transistor off. The
pass transistor resumes operation after the
junction temperature drops below 120°C.
For continuous operation, the junction
temperature should be maintained below 125°C.
The power dissipation is defined as:
PD= (V -IN V )OUT *IO+VIN*IGND
The maximum power dissipation depends on the
thermal resistance of IC package, PCB layout, the
rate of surrounding airflow and temperature
difference between junction and ambient. The
maximum power dissipation can be calculated by
the following formula:
PD(MAX) = (TJ(MAX)-TA)/θJA
Where TJ(MAX) is the maximum operation junction
temperature 125°C.TA is the ambient
temperature, and θJA is the thermal resistance
from the junction to the ambient.
For example, as θJA is 250°C/W for SOT-23,
based on the standard JEDEC 51-3 for a single-
layer thermal test board, the maximum power
dissipation for SOT-23 package at TA=25°C can
be calculated by following formula:
P =D(MAX) (125°C-25°C)/250=0.4W
To calculate the junction temperature of the
PAM2800 SOT-23 package, if we use input
voltage VIN=4V at an output current IO=300mA
and the case temperature TA=40°C measured by
the thermal couple while operating, the power
dissipation is defined as:
PD=(4V-2.8V)*300mA+4V*70μA≈360mW
www.DataSheet4U.com
Power Analog Microelectronics,Inc
www.poweranalog.com
5
09/2008 Rev 1.1
5 Page |
Páginas | Total 7 Páginas | |
PDF Descargar | [ Datasheet PAM2800.PDF ] |
Número de pieza | Descripción | Fabricantes |
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