Zetex ZXLD1321EV2 Uesr Manual
ZXLD1321EV2 USER GUIDE
DESCRIPTION
The ZXLD1321 is an inductive DC-DC converter,
with an internal switch, designed for driving single or
multiple LEDs in series up to a total of 1A output
current.
Applications cover commercial environments with
input voltages ranging from 1.2V to 12V.
The device employs a variable ‘on’ and ‘off’ time
control scheme with adjustable peak switch current
limiting and supports step-up (Boost) mode and selfpowering Bootstrap operating modes, offering higher
power efficiency and lower system cost than
conventional PFM circuitry.
The device includes the DC-DC converter, a
high-side current monitor and an NPN switching
transistor to provide an integrated solution offering
small PCB size, competitive cost/performance, high
power efficiency of DC-DC conversion and maximum
LED brightness/reliability. More importantly, it retains
design flexibility to add customer specific features
FEATURES
•
1.2V to 12V Input Voltage Range
•
Up to 1A output current
•
Typical efficiency (*) : >85%
•
Bootstrap operation enables input voltage down to
1V
•
User-defined thermal control of LED output current
using external thermistor
•
12µA typical standby current
•
Adjustable Soft-Start
•
Drives up to 5 white LEDs in series
ORDERING INFORMATION
ORDER NUMBER
ZXLD1321EV2
Please note evaluation boards
are subject to availability and
qualified leads.
The feedback control circuitry inside the
ZXLD1321 provides excellent load and current
regulation, resulting in very stable LED current over the
useful life of the battery and over the full operating
temperature range.
The LED current can be adjusted from 100% down to
10% of the set value by applying a dc voltage to the
ADJ pin and down to 1% by applying a PWM signal to
the ADJ pin. An on-chip LED protection circuit also
allows output current to be reduced linearly above a
predetermined threshold temperature using an external
thermistor at the TADJ pin.
External resistors set nominal average LED
current and coil peak current independently.
The device can be shut down by applying a continuous
low level dc voltage to the ADJ pin.
APPLICATIONS
• High power LED flashlights
• LED back-up lighting
• General LED lighting
TYPICAL APPLICATION CIRCUIT
Issue 2 - April 2008 www.zetex.com
© Zetex Semiconductors plc, 2008
ZXLD1321EV2
REFERENCE DESIGN
ZXLD1321EV2 evaluation board is designed with LED output connector which is compatible with the FLS Emitter
Board connection standard. The target application is 700mA/1000mA high current LED driver for single or
multiple LEDs with wide input voltage range.
If the ZXLD1321EV2 is connected to 1 off-board LED, the supply voltage is: VIN=2V ~ 3.4V.
The ZXLD1321EV2 boards are initially set at LED current of around 700mA with150mΩ (R3) current sensing
resistor. In order to boost the LED current to 1000mA, on-board 300mΩ (R3A) could made parallel to R3 by
means of soldering jumper pad JP1.
For other reference designs or further applications information please refer to the ZXLD1321 datasheet.
SCHEMATIC DIAGRAM
Materials List
Ref Value Package Part Number Manufacturer Contact Details
U1 LED Driver DFN14 ZXLD1321DCA Zetex www.zetex.com
D1 Schottky Diode SOT23-6 ZHCS2000 Zetex www.zetex.com
MSS7341-103ML
NPIS64D100MTRF
L1 10uH 2A
C1 10nF 10V 0603 Generic Generic
C2 2.2uF 25V 1206 GRM31MR71E225K Murata www.murata.com
C3 4.7uF 50V 1206 GRM31CR71H475K Murata www.murata.com
R1 430Ω 0805 Generic Generic
R2 25mΩ 0603 Generic Generic
R3 150mΩ 0805 Generic Generic
R3A 300mΩ 0805 Generic Generic
R4 5.1KΩ 0603 Generic Generic
Z1 18V 3W Zener DO-214AC BZG03C18 Vishay www.vishay.com
744-777910
Coilcraft
NIC Comps.
Wurth
www.coilcraft.com
www.niccomp.com
www.we-online.com
Issue 2 – April 2008 www.zetex.com
© Zetex Semiconductors plc, 2008
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