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PDF EL7630 Data sheet ( Hoja de datos )
| Número de pieza | EL7630 | |
| Descripción | White LED Boost Regulator | |
| Fabricantes | Intersil Corporation | |
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®
Data Sheet
February 22, 2006
EL7630
FN7371.1
White LED Boost Regulator
The EL7630 represents a high efficiency, constant frequency
PWM regulator for use in white LED driving applications.
With efficiencies up to 86%, the EL7630 operates at 1.35MHz
switching frequency while operating from an input voltage of
between 2.7V and 5.5V. The maximum output voltage of 27V
enables the EL7630 to drive up to 6 LEDs in series. It is also
possible to use the EL7630 to drive LEDs in series/parallel
combination for applications requiring up to 15 LEDs.
Available in the 6 Ld SC-70 and the 5 Ld TSOT packages, the
EL7630 features the same pinout as competitive products
but offers higher efficiency, constant frequency operation. It
is specified for operation over the -40°C to +85°C ambient
temperature range.
Pinouts
EL7630
(6 LD SC-70)
TOP VIEW
www.DataSheet4U.com
LX 1
GND 2
FB 3
6 VIN
5 PGND
4 ENAB
EL7630
(5 LD TSOT)
TOP VIEW
LX 1
GND 2
FB 3
5 VIN
4 ENAB
Features
• Up to 6 LEDs in series
• 27V maximum output
• 2.7V to 5.5V input
• Up to 86% efficient
• 1.35MHz constant frequency
• Enable/PWM dimming control
• Pb-free plus anneal available (RoHS compliant)
Applications
• LED backlighting
• Cell phones
• PDAs
• Handheld devices
Ordering Information
PART NUMBER PART TAPE & PACKAGE PKG.
(See Note) MARKING REEL (Pb-free) DWG. #
EL7630ICZ-T7 BCA
7” 6 Ld SC-70 P6.049
(3K pcs)
EL7630ICZ-T7A BCA
7” 6 Ld SC-70 P6.049
(250 pcs)
EL7630IWTZ-T7 BAAC
7” 5 Ld TSOT MDP0049
(3K pcs)
EL7630IWTZ-T7A BAAC
7” 5 Ld TSOT MDP0049
(250 pcs)
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations. Intersil
Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2006. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
1 page  
EL7630
Detailed Description
EL7630 uses a constant frequency, current mode control
scheme to provide excellent line and load regulation. It
can drive up to 6 LEDs in series or 15 LEDs in
parallel/series configuration, with efficiencies of up 86%.
EL7630 operates from an input voltage of 2.7V to 5.5V and
can boost up to 27V.
Steady-State Operation
EL7630 operates with constant frequency PWM. The
switching frequency is around 1.2MHz. Depending on the
input voltage, inductance, number of LEDs and the LED
current, the converter operates in either continuous
conduction mode or discontinuous conduction mode. Both
are normal. The forward current of the LED is set using the
RSET resistor. In steady state mode, this current is given by
the equation:
ILED = R---V--S--F--E--B--T-
(EQ. 1)
Shut-Down
The ENAB pin, when taken low places EL7630 into power
down mode. When in power down, the supply current
reduced to less than 1µA.
Dimming Control
The ENAB pin also doubles as a brightness control. There
are two different types of dimming control methods. The first
dimming control is controlled through the duty-cycle of the
ENAB input PWM waveform, which can operate at
frequencies of 400Hz to 1kHz. The LEDs operate at either
zero or full current. This is called PWM dimming control
method. The relationship between the average LED current
and the duty-cycle (D) of the ENAB pin’s waveform is as
follows:
average ILED = R---V--S--F--E-B---T- ⋅ D
(EQ. 2)
The magnitude of the PWM signal should be higher than the
minimum ENAB voltage high. The bench PWM dimming test
results are shown in Figure 8. In the test, two PWM
frequencies 400Hz and 1kHz are chosen to compare the
linear dimming range. It is clear that for lower PWM
frequency, the linear dimming range is wider than one for
higher PWM frequency. In the PWM dimming test, the output
capacitor is 0.22µF.
25
20
15 1kHz
10
400Hz
5
0
0 10 20 30 40 50 60 70 80 90 10
DUTY-CYCLE (%)
FIGURE 8. PWM DIMMING LINEAR RANGE (FOR 400Hz AND
1kHz PWM FREQUENCIES CONDITION,
COUT = 0.22µF)
The second dimming control is to apply a variable DC
voltage to adjust the LED current. This is called analog
dimming control. The dimming control using a DC voltage is
shown in Figure 9. As the DC dimming signal voltage
increases, the voltages drop on R1 and R2 increases and
the voltage drop on RSET decreases. Thus, the LED current
decreases. The DC dimming signal voltage can be a variable
DC voltage or a DC voltage generated from a PWM control
signal. For some application areas, the PWM control signal
is a high frequency signal. To make dimming controllable
with these high frequency PWM signals, the high frequency
components of the PWM control signal should be filtered to
get the equivalent DC voltage. The equivalent DC voltage is
then used as the variable DC voltage for dimming LED
current.
ILED = R---V--S--F--E--B--T- ⋅ -R----1--R--+---2--R-----2- – R-V----SD----E-i-m--T----⋅-⋅--R-R----12-
(EQ. 3)
VDim
=
RR-----21-
⋅
VFB
⋅
1
+
RR-----12-
–
F
(EQ. 4)
where F is the brightness with respect to the undimmed
value.
5 FN7371.1
February 22, 2006
5 Page | ||
| Páginas | Total 7 Páginas | |
| PDF Descargar | [ Datasheet EL7630.PDF ] | |
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