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PDF HV9903 Data sheet ( Hoja de datos )
| Número de pieza | HV9903 | |
| Descripción | White LED Driver | |
| Fabricantes | Supertex Inc | |
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HV9903
Initial Release
White LED Driver
Features
❑ Power efficiency of up to 85%
❑ Drives up to 6 White LEDs
❑ 2.6V to 4.6V Supply
power stage can operate at 1.8V (see page 8)
❑ Built-in Soft Start
❑ DC and PWM Dimming Control
❑ Built-in Open LED protection
❑ Open LED indicator (via RSET)
❑ 1.2MHz Fixed Switching Frequency
❑ 500nA max leakage current when disabled
❑ No leakage current path through LEDs when
disabled
❑ Resistor-programmable LED Current
❑ Small 6-lead MLP (3mm x 3mm) package
(similar to 6-pin SOT-23)
Applications
❑ Color LCD Backlighting
❑ Cell phones, smart phones
❑ PDAs, pocket PCs
❑ Organizers
❑ Digital Cameras
❑ MP3 Players
Description
The Supertex HV9903 is a fixed frequency DC-DC
boost converter designed for driving Light Emitting
Diodes (LEDs) with constant current where the light
intensity is proportional to the current through them.
The input supply voltage range into the device (VDD)
is 2.6 to 4.6V. Operation of the driver at lower
voltages is possible as long as a 2.6–4.6V low-
current supply is available for the HV9903. The
device uses a single inductor and a minimum
number of passive components. The device can be
enabled/disabled via the SHDN pin.
The HV9903 has an internal oscillator. The oscillator
frequency is at fixed frequency of 1.2MHz that allows
use of small value inductors. The LED current can
be adjusted from 5 to 40mA by an external resistor
connected between the RSET and the GND pins. The
amount of current though the LED can also be
adjusted via DC voltage or a pulse width modulated
(PWM) signal to the RSET pin.
Soft-start is implemented on-chip, minimizing inrush
current to only 30% over steady state current.
An open LED circuit detects an open LED condition,
disables the driver, and sets the RSET pin high. The
driver is re-enabled by asserting SHDN low, then
high. If the open LED condition persists, the driver
will again latch off.
Typical Application
Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products
liability indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be
defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product
specifications, refer to the Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer
page on the Supertex website.
1 page  
HHVV99990033
fairly low frequency so that the 1ms soft-start interval
does not introduce much error. The RSET input is
better for PWM dimming, as it does not include soft-
start. (See below for PWM dimming techniques.)
Soft Start
SHDN
IIN
50mA/div
ILED
10mA/div
inductor rating. Choosing an inductor with lower
resistance results in more efficient operation.
Inductor Value for 2.7V Operation
100 H
10 H
1H
5V
Select the next lower standard value,
taking inductor tolerance into account.
ILED
5mA
10V 15V 20V
VVLELDED-S-STRTRININGG++(IL(EILDE·D5-?5)Ω+)V+DVD
25V
10mA
15mA
20mA
25mA
30mA
35mA
40mA
Open LED Protection
Open LED protection is integrated into the HV9903.
Without open LED protection, output voltage would
climb to destructive levels as the driver attempts to
correct for the open LED condition.
Should the voltage at the SW pin exceed 33V, the
driver latches off and the RSET pin is pulled to VDD,
indicating a fault condition. To reset the latch, assert
SHDN low for at least 200ns. When SHDN is again
brought high, the driver will be re-enabled, including
soft-start. If the open LED condition persists, the
HV9903 will again latch off.
Inductor Selection
The HV9903 is designed for discontinuous mode
operation. Control loop stability may be compromised
if the converter is allowed to operate in continuous
mode. To assure discontinuous mode operation, the
inductor must not exceed a certain value depending
on supply voltage, output current, and output voltage.
The following graphs show the maximum permissible
inductor value and inductor current rating for a lithium-
ion battery application (2.7V minimum battery
voltage). When calculating LED string voltage drop,
use maximum LED voltage. If using paralleled LED
strings with current balancing resistors, include the
resistor voltage drop in VLED-STRING. VD is the diode’s
forward voltage drop. Always select the next lower
standard value inductor and be conservative on
Inductor Rating for 2.7V Operation
1A
Exceeds max recommended SW current
100mA
40mA
35mA
30mA
25mA
20mA
15mA
10mA
5mA
ILED
Apply correction factor and select an
inductor with an equal or higher rating.
10mA
5V
10V 15V 20V
VLED-STRING + (ILED · 5? ) + VD
VLED-STRING + (ILED -5Ω) +VD
25V
When selecting the next lower standard value
inductor, the current rating must be adjusted
according to the following equation.
ICORRECTED
IGRAPH
LGRAPH
LSELECTED
As an example, 4 LEDs with 4V max drop are to be
driven at 20mA. LED string drop is 16V plus 0.6V for
the diode plus 0.1V for LED pin voltage, for a total of
16.7 volts. From the graphs, inductor value at 16.7V
and 20mA is 3.7µH and rating is 320mA. The next
5
5 Page 
Typical Performance
HHVV99990033
COUT=Murata GRM32RR71H105KA01L, LEDs = Nichia NSPW500BS, D = Zetex ZHCS400 or ZHCS500
DL
COUT
CIN
HV9903
1 SW
VDD 6
2 GND SHDN 5
3 LED
RSET 4
2.6–4.6V
Shutdown
Fault
RSET
VIN
VDD
CDD
VDD = VIN
3.3V
CIN
L
RSET
COUT
10.0µF
4.7µH, Murata
LQH32CN4R7M11
1.5KΩ
1.0µF,
50V
LEDs
4
6
IIN
78.5mA
111.2mA
VOUT
13.1V
19.4V
ILED
15.5mA
Other Examples
COUT=Murata CRM32RR71H105KA01L, LEDs = Nichia NSPW500BS, D = Zetex ZHCS400 or ZHCS500
VDD = VIN
CIN
L
RSET
COUT
LEDs
IIN
VOUT
ILED
3.3V
10.0µF
4.7µH, Murata
LQH32CN4R7M11
1.0KΩ
1.0µF,
50V
4
6
111.3mA
166.9mA
13.6V
19.9V
22.8mA
VDD
3.0V
VIN
1.8V
6.0V
9.0V
6.0V
9.0V
CIN
L
RSET
COUT
10.0µF
4.7µH, Murata
LQH32CN4R7M1
1
1.5KΩ
1.0µF,
50V
LEDs
4
6
IIN
154.8
40.2mA
26.1mA
63.4mA
41.3mA
VOUT
13.0V
19.4V
ILED
16.5mA
16.5mA
VDD = VIN
3.3V
CIN
10.0µF
L
10µH, Murata
LQH2MC100K02
RSET
1.5KΩ
COUT
1.0µF,
50V
LEDs
4
IIN
77.9mA
VOUT
ILED
12.92V 16.8mA
10/7/03
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet HV9903.PDF ] | |
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