ZXLD383 ZETEX | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 10
Technical content
Features
- 85% efficiency U s e r adjustable output current Single cell operation Low saturation voltage TSOT23-5 package Available also in die form Simple application circuit
Applications
Garden lights Door/pathway illumination LED flashlight and torches LED backlights White LED driver Gated boost supply generator ZXLD383 4NC GND VOUT
5 VCC
1.2V LED ENA
Issue 1 - September 2008 2 www.zetex.com © Diodes Incorporated www.diodes.com Absolute maximum ratings Supply Voltage (Vcc) -0.6V to 6V Output Voltage (Vout) -0.6V to 20V Enable Voltage (Vena) -1V to 3.5V Supply Current 20mA Output Switch Current 800mA Power Dissipation (TSOT23-5) 450mW Power Dissipation Die 1W Operating Temperature Range -20°C to +85°C Storage Temperature Range -55°C to +150°C
Electrical Characteristics
AMB = 25°C, L = 6.8uH, IENA = 0 and VCC = 1.5V unless otherwise specified. Parameter Conditions Limits Units Min Typ Max Supply Voltage Operating Range L = 10uH 0.9 3.3 V Minimum Supply Start-up Voltage L = 10uH 0.8 0.9 V Supply Current Quiescent 248 m A Supply Current Shutdown VENA = VCC – 0.8V 17 30 uA Supply Current Under-Voltage VCC = 0.6V 20 uA Switch Current At turn-off 250 320 400 mA Switch Saturation Voltage IOUT = 200mA 100 300 mV Switch Leakage Current VOUT = 20V, VENA = 0V 10 uA Mean LED Current V LED = 3.5V 40 50 65 mA Efficiency V LED = 3.5V 85 % Operating Frequency VLED = 3.5V 330 kHz Discharge Pulse Width 0.7 1.5 2.5 us Enable Input Threshold VCC - 0.8 VCC - 0.6 VCC - 0.2 V Enable Input Current VENA = 0.2V 0 -11 -20 uA Enable Input Voltage IENA = -20mA 0 -90 -250 mV
Issue 1 - September 2008 3 www.zetex.com © Diodes Incorporated www.diodes.com Typical characteristics Note VLED = 3.5V for all graphs ZXLD383 I O U T(AV E R AG E ) vs V CC V CC (V) IOUT (mA) 4.7uH 6.8uH 10uH 22uH 47uH ZXLD383 Efficiency vs V CC 100 V CC (V) Efficiency (%) 4.7uH 6.8uH 10uH 22uH 47uH ZXLD383 I IN vs V CC 100 150 200 250 V CC (V) IIN (mA) 4.7uH 6.8uH 10uH 22uH 47uH ZXLD383 Peak_I IN vs V CC 100 150 200 250 300 350 400 450 500 V CC (V) IIN (mA) 4.7uH 6.8uH 10uH 22uH 47uH ZXLD383 V( ENA ) vs I ENA For V CC = 0.8, 1.0, 1.2 and 1.4V 100 150 200 250 300 350 400 450 01 0 2 0 3 0 4 0 5 0 IV ENA (m A) V ENA (mV) 0.8V 1.0V 1.2V 1.4V ZXLD383 Operating Waveforms for L = 6.8uH, V CC = 1.5V Channel -1 (Upper): I LED @ 100mA/cm Channel -2 (Lower): VOUT @ 1V/cm Timebase: 500ns/cm
Issue 1 - September 2008 4 www.zetex.com © Diodes Incorporated www.diodes.com Device description The ZXLD383 is a simple PFM, DC-DC controlle r combined with a high performance internal switching transistor, enabling the production of a high efficiency boost converter for use in single cell applications. It includes a dual function Enable input which serves both as an operation inhibit control and an ultra-low voltage drop isolation diode for battery charging purposes in Garden Light applications. A block diagram is shown for the ZXLD383 in Figure 1. Figure 1 - ZXLD383 block diagram With power applied and the enable pin held at V CC, an oscillator within the pulse control block forces the internal switching tran sistor to switch on to start an energy charge cycle. The low saturation voltage switch pulls the V OUT pin close to ground which forces the supply voltage across the external inductor L1. This causes a current to build up, storing energy in the inductor. During this phase, switch current and supply voltage are monitored and used by the pulse control circuit to determine the optimum drive conditions and on-time. At the end of the energy charge cycle, the internal switch is turned off rapi dly, interrupting the current flow through L1 which causes the voltage on V OUT to rise dramatically. When the voltage on VOUT reaches the load LED’s forward (on) voltage, the inductor current is transferred from the internal switch to the LED, starting the energy discharge cycle. With the voltage across the inductor reversed, the current flowing through it (and the LED) now falls. When the inductor current reaches zero, the voltage on the V OUT pin falls back towards V CC. This action is sensed by the pulse control circuit and is combined with the output of an off-period timer to initiate the next energy charge cycle. Except for low level losses, all the energy stored in th e inductor during a charge cycle is channelled to the load LED during the following discharge cycle. The current fed into the load LED has a sawtooth waveform, the average (DC) value of which is kept constant by the pulse control circuit fo r varying supply voltage and temperature. It is possible to change the output current given by the ZXLD383 by changing the value of inductor L1. The larger the inductance of L1, the lower the output current. A table/graph showing the relationship between inductance and output current is given later in this datasheet. Since the ZXLD383 GND VOUT VCC NIMH 1.2V LED CoffCon Pulse Control Rsense Dch ENA Diode Array
Issue 1 - September 2008 5 www.zetex.com © Diodes Incorporated www.diodes.com output current of the ZXLD383 is a sawtooth waveform, its peak value is substantially larger than the DC/average value. The table also provides this data. The internal switching transistor has a minimum collector-emitter breakdown voltage of 20V and this sets the maximum load voltage allowable. The minimum value is set by a feature of the pulse control circuit that requires the load voltage to be at least 0.5V greater than V CC. (The device will function with load voltages smaller than this but output current regulation will be impaired.) Higher than nominal load voltages will lower the average (DC) output current generated for a given inductor value. The Enable pin inhibi ts the operation of the output switch if held at a potential of Vcc-0.8V or lower. It also includes a diode to ground which allows the input to be wired directly to a photocell array that will then both enable operation of the converter when in darkness and charge the IC’s power source in daylight conditions. The diode f unction is performed by an active circuit that gives an ultra low forward voltage drop (typically less than 0.1V at 20mA). This allows the use of a lower output voltage photocell array (lower cost) without degrading performance. Application Examples Apart from the Garden Light appl ication circuit shown on the front page of this datasheet, the ZXLD383 may be used in many other ways. The following circuits and notes show some other possibilities and give typical performance details. Standard operating mode The following circuit demonstrates how few com ponents are required to produce a light source using the ZXLD383. Operating from a single cell, this simple circui t is suited for use in car key fobs, novelty products etc. where small size and low cost are critical aspects. By directly wiring the Ena pin to Vcc, the part is permanently enabled once a power supply is provided. The ZXLD383 is highly tolerant of su pply ripple so no decoupling of Vcc should be needed in a compactly constructed circuit. Also, the part’s capability of operating with a Vcc below 0.9V means that this simple circuit will make the best use of available battery capacity. The attached table shows the average LED currents that can be obtained using a range of inductor values. Also shown are the peak currents required to achieve the given currents. Note VLED = 3.5V L I LED (peak) ILED (avg) (uH) (mA) (mA) 47 45 8.5 22 100 17.3 10 210 34 6.8 330 50 4.7 415 63 ZX LD383 ENA GND VOUT 1.5V LED NC
Issue 1 - September 2008 6 www.zetex.com © Diodes Incorporated www.diodes.com Low ripple LED current mode It is possible that the peak LED current required to achieve a given average current is either too high for the LED of choice or it leads to some loss of efficiency (due to LED resistance losses). In these cases, just two extra low cost components can be added to provide a low ripple current supply for the LED. The Schottky diode D1 and capacitor C1 rectifies and smoothes the output of the ZXLD383 giving a low ripple current supply to the load LED. Of course, this circuit could also be used to power loads other than LEDs. Note: VLED =3.5V, D1=ZHCS1000, C1 = 1uF (low ESR) Buck-boost mode Simple boost converters can run into problems when the input supply voltage is similar to or exceeds the intended load voltage as there is usually a direct current path from the power source through to the load via the boost inductor. This path does not require switching action and so is uncontrolled. When using the ZXLD383, this problem can be avoided by wiring the cathode of the load LED to Vcc rather than ground. Without swit ching action, the LED is reverse-biased and so no current can flow. When switching, the anode of the LED is driven to Vcc + Vf(led). The higher than normal output voltage reduces the available output current as described earlier and this is shown in the typical data provided. Note: VLED =3.5V L I LED (uH) (mA) 47 7.5 22 15.5 10 31 6.8 46 4.7 58 LED ZXLD383 ENA GND VOUT 1.5V NC L ILED (uH) (mA) 47 5.5 22 10.3 10 23.2 6.8 36.7 4.7 46.2 ZX LD383 ENA GND VOUT
Issue 1 - September 2008 7 www.zetex.com © Diodes Incorporated www.diodes.com Low ripple buck-boost mode The output of the Buck-Boost converter can be rectified and smoothed as with the standard circuit to give a low ripple output to improve LED efficiency or to give a DC output for other loads. Note: VLED =3.5V, D1=ZHCS1000, C1 = 1uF (low ESR) L I LED (uH) (mA) 47 5 22 9.7 10 21.7 6.8 34 4.7 43 LED ZXLD383 ENA GND VOUT
Issue 1 - September 2008 8 www.zetex.com © Diodes Incorporated www.diodes.com Pin descriptions Pinout diagram
Ordering information
Pin No. Name Description
1 ENA Enable / Photodiode array battery charge input
2 GND Ground
3 NC Not connected (internally open circuit)
4 VOUT Switch output external inductor/LED
5 VCC Supply voltage, generally Alkaline, NiMH or NiCd single cell
(inches) Reel width (mm) Quantity per reel Device mark ZXLD383ET5TA 7” 8 3,000 383 ENA TSOT23-5 Top view GND NC VCC VOUT ZXLD383
Issue 1 - September 2008 9 www.zetex.com © Diodes Incorporated www.diodes.com Packaging information - TSOT23-5 Dim. Millimeters Inches Dim. Millimeters Inches A - 1.00 - 0.0393 E1 1.60 BSC 0.062 BSC D 2.90 BSC 0.114 BSC Q 4o 12o 4o 12o E 2.80 BSC 0.110 BSC
Issue 1 - September 2008 10 www.zetex.com © Diodes Incorporated 2008 www.diodes.com Sales offices The Americas 3050 E. Hillcrest Drive Westlake Village, CA 91362-3154 Tel: (+1) 805 446 4800 Fax: (+1) 805 446 4850 Europe Kustermann-Park Balanstraße 59, D-81541 München Germany Tel: (+49) 894 549 490 Fax: (+49) 894 549 4949 Taiwan 7F, No. 50, Min Chuan Road Hsin-Tien Taipei, Taiwan Tel: (+886) 289 146 000 Fax: (+886) 289 146 639 Shanghai Rm. 606, No.1158 Changning Road Shanghai, China Tel: (+86) 215 241 4882 Fax (+86) 215 241 4891 Shenzhen ANLIAN Plaza, #4018 Jintian Road Futian CBD, Shenzhen, China Tel: (+86) 755 882 849 88 Fax: (+86) 755 882 849 99 Korea
6 Floor, Changhwa B/D,
1005-5 Yeongtong-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do, Korea 443- 813 Tel: (+82) 312 731 884 Fax: (+82) 312 731 885 Definitions Product change Diodes Incorporated reserves the right to alter, without notice, specifications, desi gn, price or conditions of supply of any p roduct 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 desi gn ideas. It is the responsibility of the user to ensure that t he circuit is fit for the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoev er is assumed by Diodes Inc. with respect to the accuracy or use of such information, or infringement of patents or other intellectua l property rights arising from such use or otherwise. Diodes Inc. does not assume any legal responsibility or will not be held legally lia ble (whether in contract, tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract, opportunity or consequential loss in the use of these circuit applications, under any circumstances. Life support Diodes Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body or 2. support or sustain life and whose failure to perform when proper ly used in accordance with instructions for use provided in the labelling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support devi ce or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Reproduction The product specifications contained in this publication are issu ed to provide outline information only which (unless agreed by the company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. Terms and Conditions All products are sold subjects to Diodes Inc. terms and conditio ns of sale, and this disclaimer (save in the event of a conflic t between the two when the terms of the contract shall prevail) according to region, supplied at the time of order acknowledgement. For the latest information on technology, delivery terms and conditions and prices, please contact your nearest Diodes sales office. Quality of product Diodes Zetex Semiconductors Limited is an ISO 9001 and TS16949 certified semiconductor manufacturer. To ensure quality of service and products we strongly advise the purchase of parts directly from Diodes Incorporated or one of our Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels. ESD (Electrostatic discharge) Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices. The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent of damage can vary from immediate functional or parametric malfunc tion to degradation of function or performance in use over ti me. Devices suspected of being affected should be replaced. Green compliance Diodes Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding regulatory requirements with respect to the use of haza rdous substances. Numerous successful programs have been imple - mented to reduce the use of hazardous substances and/or emissions. All Diodes Zetex components are co mpliant with the RoHS directive, and through this it is supporting its customers in their com pliance with WEEE and ELV directives. Product status key: “Preview” Future device intended for production at some point. Samples may be available “Active” Product status recommended for new designs “Last time buy (LTB)” Device will be discontinued and last time buy period and delivery is in effect “Not recommended for new designs” Device is still in production to support existing designs and production “Obsolete” Production ha s been discontinued Datasheet status key: “Draft version” This term denotes a very early datasheet ver sion and contains highly provisional information, which may change in any manner without notice. “Provisional version” This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance. However, changes to the test conditions and specifications may occur, at any time and without notice. “Issue” This term denotes an issued datasheet cont aining finalized specifications. However, changes to specifications may occur, at any time and without notice.