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ZXLD1350EV2
ZXLD1350EV2 EVALUATION BOARD USER GUIDE
DESCRIPTION
The ZXLD1350EV2, Figure 1, is an evaluation board for evaluating the ZXLD1350 350mA LED driver with internal
switch. The evaluation board can be used to drive 1, 2 or 3 one-watt LEDs, or an external choice of LEDs. The
number of external connected LEDs depends on the forward voltage of the LEDs connected. A connector, J1, is
provided, which is compatible with the modular evaluation system used by Future Electronics Ltd.
Summary of the content on the page No. 2
ZXLD1350EV2 ZXLD1350 DEVICE DESCRIPTION The ZXLD1350 is a continuous mode inductive driver in a TSOT23-5 package, for driving one or more series connected LEDs efficiently from a voltage source higher than the LED voltage. The device includes the output switch and a current sense circuit, which requires an external sense resistor to set the nominal current up to 350mA. ZXLD1350 DEVICE FEATURES DEVICE APPLICATIONS • Drives one or more series-connected 1W white • LED flashlights. LED
Summary of the content on the page No. 3
ZXLD1350EV2 ZXLD1350EV2 EVALUATION BOARD REFERENCE DESIGN The ZXLD1350EV2 is configured to the reference design in Figure 2. The target application is a driver for one or more series-connected 1W white LEDs for torches and other high powered LED driving applications. The operating voltage is a nominal 24V. For three 1W series-connected LEDs, the voltage can be from 12V minimum to 30V maximum. The nominal current is set at 300mA with a 0.33Ω sense resistor, Rs. For three series -
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ZXLD1350EV2 ZXLD1350EV2 Evaluation Board. Ref Value Package Part Number Manufacturer Notes R 0.33R 0805 NCST10FR330FTRF NIC S 1%,200ppm components R1,R2 Not fitted 0805 Not fitted 50V, 1206 X7R C1,C2 1uF, 50V 1206 NIC NMC1206X7R105K50F components C3 Not fitted 0805 Not fitted L1 100uH NPIS53D101MTRF NIC 100uH/0.5A rms components Inductor SD1 40V, 1.16A SOT23 ZLLS1000 Zetex Schottky diode U1 ZXLD1350 TSOT23-5 ZXLD1350E5TA Zetex DC-DC converter D1, D2, D3 1W LED
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ZXLD1350EV2 ZXLD1350EV2 EVALUATION BOARD k D1 LED k a JP1 JP2 J1 C2 k +VIN R2 L1 U1 C3 D2 SD1 C1 GND R1 RS a JP3 ADJ k In partnership with: LED a D3 a Bare board: ZDB308R3 Copyright Zetex Plc 2006 Figure 4: Top View Figure 5: Bottom View ZXLD1350EV2 Connection Point Definition Name Description +VIN Positive supply voltage. Connect a +24V positive supply to this pin. GND Supply Ground (0V). Connect supply ground to this pin. ADJ Internal volt
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ZXLD1350EV2 OTHER FEATURES Dimming The ZXLD1350 provides three dimming options: DC, high-frequency PWM, and low-frequency PWM dimming. DC Voltage Dimming 1. Switch off the power supply. 2. Solder a link across R1 pads. 3. Fit a 10nF capacitor at C3 to decouple the pin. 4. Drive the ADJ pin on the board with a DC voltage in the range 0.3V to 1.25V. 5. Do not exceed 1.25V, as this represents 100% of the LED current set by Rs. The current will increase in proportion to
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ZXLD1350EV2 Low Frequency PWM Dimming 1. Switch off the power supply. 2. Solder a link across R1 pads. 3. Make sure C3 is not fitted. 4. Connect a PWM signal to the ADJ pin via an open collector NPN transistor or an open drain N-channel MOSFET. 5. Alternatively, drive the ADJ pin directly with a PWM signal. However, make sure the PWM signal voltage levels do not violate the ADJ pin voltage rating. Driving the ADJ pin above 1.25V will exceed the maximum set current for the valu
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ZXLD1350EV2 PERFORMANCE The system efficiency depends on the sense resistor, supply voltage, switching inductor and the number of 1W LEDs connected in series. The graph below shows the efficiency with a 0.33Ω sense resistor R and a 100uH inductor, for 1 to 3 series S, connected 1W LEDs. With a 24V supply, the switching frequency is typically 545kHz for three series-connected 1-watt LEDs and 300kHz for a single 1-watt LED. With a 12V supply, the switching frequency is typi
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ZXLD1350EV2 Definitions Product change Zetex Semiconductors reserves the right to alter, without notice, specifications, design, price or conditions of supply of any product or service. Customers are solely responsible for obtaining the latest relevant information before placing orders. Applications disclaimer The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for the user’s application a
