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PDF ZXSC300 Data sheet ( Hoja de datos )
| Número de pieza | ZXSC300 | |
| Descripción | SINGLE OR MULTI CELL LED DRIVER SOLUTION | |
| Fabricantes | Zetex Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ZXSC300 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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SINGLE OR MULTI CELL LED DRIVER SOLUTION
ZXSC300
DESCRIPTION
The ZXSC300 is a single or multi cell LED driver
designed for applications where step-up voltage
conversion from very low input voltages is required.
These applications mainly operate from single 1.5V or
1.2V battery cells. The circuit generates constant
current pulses that are ideal for driving single or
multiple LED’s over a wide range of operating
voltages.
The ZXSC300 is a PFM controller IC that drives an
external Zetex switching transistor with a very low
saturation resistance. These transistors are the best
switching devices available for this type of switching
conversion enabling high efficiency conversion with
input voltages below 1 volt. The drive output of the
ZXSC controller generates a dynamic drive signal for
the switching transistor.
The circuit can start up under full load and operates
down to an input voltage of 0.8 volts. The solution
configuration ensures optimum efficiency over a wide
range of load currents, several circuit configurations
are possible depending on battery life versus
brightness considerations.
The ZXSC300 is offered in the SOT23-5 package
which, when combined with a SOT23 switching
transistor, generates a high efficiency small size
circuit solution. The IC and discrete combination
offers the ultimate cost vs performance solution for
single cell LED driving applications.
FEATURES
• 94% efficiency
• Minimum operating input voltage 0.8V
• Fixed output current
• Low saturation voltage switching transistor
• SOT23-5 package
TYPICAL APPLICATION CIRCUIT
ORDERING INFORMATION
VBATT
L1
100µH
U1
Vcc
Vdrive
Isense
Gnd
ZXSC300
Q1
FMMT617
LED1
WHITE LED
DEVICE
ZXSC300E5
R1
0.33R
Package
SOT23-5
Partmarking
C300
ISSUE 1 - JUNE 2001
1
1 page  
ZXSC300
DEVICE DESCRIPTION
The ZXSC300 is PFM, controller IC which, when
combined with a high performance external
transistor, enables the production of a high efficiency
boost converter for use in single cell LED driving
applications. A block diagram is shown for the
ZXSC300 in Figure 1.
With every on pulse the switching transistor is kept on
until the voltage across the current-sense resistor
exceeds the threshold of the ISENSE input. The on-pulse
length, and therefore the switching frequency, is
determined by the programmed peak current, the
input voltage and the input to output voltage
differential. See applications section for details.
The Driver circuit supplies the external switching
transistor with a fixed drive current. To maximise
efficiency the external transistor switched quickly,
typically being forced off within 30ns.
Pin out Diagram
Figure 1
ZXSC300 Block Diagram
The on chip comparator forces the driver circuit and
therefore the external switching transistor off if the
voltage at ISENSE exceeds 19mV. This threshold is set
by an internal reference circuit and divider.
The Voltage at ISENSE is taken from a current sense
resistor connected in series with the emitter of the
switching transistor. A monostable following the
output of the comparator forces the turn-off time of the
output stage to be typically 1.7µs. This ensures that
there is sufficient time to discharge the inductor coil
before the next on period.
Pin Descriptions
VCC
GND
1
2
3
5 VDRIVE
4 ISENSE
Top View
Pin No.
1
2
3
4
5
Name
VCC
Gnd
N/C
ISENSE
VDRIVE
Description
Supply voltage, generally Alkaline, NiMH or NiCd single cell
Ground
Not connected
Inductor current sense input. Internal threshold voltage set to 19mV.
Connect external sense resistor
Drive output for external switching transistor. Connect to base of
external switching transistor.
ISSUE 1 - JUNE 2001
5
5 Page 
ZXSC300
Supplier Listing
Zetex
GERMANY
Zetex GmbH
Munich
ASIA
Zetex Asia
Hong Kong
USA
Zetex Inc
Long Island NY
AVX
Coilcraft
Nichia Corporation
(49) 894549490
(852) 2610 0611 (1) 631 543 7100
http://www.zetex.com
AVX Asia
Singapore
(65) 258 2833
AVX USA
(1) 843 448 9411
http://www.avxcorp.com
Coilcraft Inc
(1) 847 639 6400
http://www.coilcraft.com
Nichia Europe B.V. Nichia Corporation Nichia America
Amsterdam
Tokyo Sales Office Corporation
The Netherlands Tokyo, Japan
Head Office
(31) 20 5060900 (81) 3 3456 3784 (1) 717 285 2323
San Jose
(1) 408 573 0933
http://www.nichia.co.jp
UK
Zetex PLC
Chadderton,
Oldham
(44) 161 622 4444
AVX UK
(44) 1252 770000
Coilcraft Europe
(44) 1236 730595
ISSUE 1 - JUNE 2001
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ZXSC300.PDF ] | |
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