ZXSC380 ZETEX | Alldatasheet
Document overview
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Technical content
Features
- 80% efficiency User adjustable output current Single cell operation Low saturation voltage switching transistor Simple application circuit Low external component count SOT23 package Available also in die form
Applications
LED flashlights and torches LED backlights White LED driver Pin connections Typical application circuit VCC VOUT GND Top view Vcc Vout GND VIN GND LED1 ZXSC380
Issue 1 - March 2007 2 www.zetex.com © Zetex Semiconductors plc 2007 Absolute maximum ratings Supply voltage (VCC) -0.6V to 10V Output voltage (VOUT) -0.6V to 20V Supply current 20mA Output switch current 200mA Power dissipation SOT23-3 450mW Power dissipation die 1W Operating temperature range 0°C to +85°C Storage temperature range -55°C to +150°C
Electrical characteristics
Measured at Tamb = 25°C, L = 100/H9262H and VCC = 1.5V unless otherwise specified. Pin descriptions Pin descriptions
Ordering information
Parameter Conditions Limits Units Min. Typ. Max. Supply voltage operating range 0.8 6 V Minimum supply start-up voltage 0.9 1.0 V Switch current V OUT = 1.0V 65 80 95 mA Switch saturation voltage IV OUT = 50mA 0.3 0.5 V Mean LED current V LED = 3.5V 18 mA Efficiency V LED = 3.5V 75 % Operating frequency V LED = 3.5V 160 kHz Discharge pulse width 1.4 2.2 3.0 /H9262s Pin No. Name Description 1V CC Supply voltage, generally Alkaline, NiMH or NiCd single cell
2 GND Ground
3V OUT Switch output external inductor/LED Device Package Part Mark ZXSC380FH SOT23 380 VCC VOUT GND Top view
Issue 1 - March 2007 3 www.zetex.com © Zetex Semiconductors plc 2007 Typical characteristics LED Current vs Supply Voltage for L = 100uH 0 . 511 . 522 . 53 Supply Voltage Vvcc (V) LED Current, ILed (mA) Ivcc vs Supply Voltage for L = 100uH 100 0.5 1 1.5 2 2.5 3 Supply Voltage Vvcc (V) Ivcc (mA) Efficiency vs Supply Voltgae for L = 100uH 100 0.5 1 1.5 2 2.5 3 Supply Voltage Vvcc (V) Efficiency (%) Operating Waveforms Channel 1 (lower): LED current ILed. 50mA/div. Channel 2 (upper): Voltage at Vout pin. 1V/div
Issue 1 - March 2007 4 www.zetex.com © Zetex Semiconductors plc 2007 Typical characteristics LED Current vs Supply Voltage for L = 22, 47, 68 & 100uH Supply Voltage Vvcc (V) LED Current ILed (mA) L = 100uH L = 68uH L = 47uH L = 22uH LED Current vs Supply Voltage for L= 22, 47, 68 & 100uH 11 . 5 22 . 5 Supply Voltage Vvcc (V) LED Current ILed (mA) L = 100uH L = 68uH L = 47uH L=22uH Frequency vs Supply Voltage for L= 22, 47, 68 & 100uH 100 150 200 250 300 350 1 1.5 2 2.5 Supply Voltage Vcc (V) Frequency (kHz) L = 100uH L = 68uH L = 47uH L = 22uH Efficiency vs Supply Voltage for L= 22, 47, 68 & 100uH 100 120 11 . 522 . 5 Supply Voltage Vvcc (V) Efficiency (%) L = 100uH L = 68uH L = 47uH L = 22uH
Issue 1 - March 2007 5 www.zetex.com © Zetex Semiconductors plc 2007 Device description The ZXSC380 is non-synchronous PFM, DC-DC cont roller IC which, with a high performance internal transistor, for a high efficiency boost converter for use in single cell applications. A block diagram is shown in Figure 1. Figure 1 ZXSC380 Block diagram The on chip comparator forces the driver circuit and therefore the internal switching transistor to switch off when the voltage at ISENSE exceeds 20mV. 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. This resistor is chosen to give 20mV at I SENSE for an emitter current of 80mA. A monostable following the output of the comparator forces the turn-off time of the output stage to be typically 2.2/H9262s. This ensures that there is sufficient time to discharge a significant proportion of the energy stored in the inductor coil before the next On period. With every On pulse the switching transistor is kept on until the voltage across the current-sense resistor exceeds the threshold of the I SENSE 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 internal switching transistor with a fixed drive current. To maximize efficiency the internal transistor is switched quickly, typically being switched off within 30ns. RSENSE + VREF GND ISENSE RSENSE + VREF GND ISENSE VCCVCC V OUT V OUT
Issue 1 - March 2007 8 www.zetex.com © Zetex Semiconductors plc 2007 Intentionally left blank
Issue 1 - March 2007 9 www.zetex.com © Zetex Semiconductors plc 2007 Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches Dim. Millimeters Inches Dim. Millimeters Inches A - 1.12 - 0.044 e1 1.90 NOM 0.075 NOM e0 . 9 5 N O M 0 . 0 3 7 5 N O M ----- E e L D A c E1L1 b 3 leads
Issue 1 - March 2007 10 www.zetex.com © Zetex Semiconductors plc 2007 Zetex sales offices Europe Zetex GmbH Kustermann-park Balanstraße 59 D-81541 München Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 europe.sales@zetex.com Americas Zetex Inc
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Hauppauge, NY 11788 USA Telephone: (1) 631 360 2222 Fax: (1) 631 360 8222 usa.sales@zetex.com Asia Pacific Zetex (Asia Ltd) 3701-04 Metroplaza Tower 1 Hing Fong Road, Kwai Fong Hong Kong Telephone: (852) 26100 611 Fax: (852) 24250 494 asia.sales@zetex.com Corporate Headquarters Zetex Semiconductors plc Zetex Technology Park, Chadderton Oldham, OL9 9LL United Kingdom Telephone: (44) 161 622 4444 Fax: (44) 161 622 4446 hq@zetex.com © 2007 Published by Zetex Semiconductors plc 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 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 Zetex with respect to the accuracy or use of such in formation, or infringement of patents or other intellectual prop erty rights arising from such use or otherwise. Zetex does not assume any le gal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory duty, restricti on or otherwise) for any damages, loss of profit, business, con tract, opportunity or consequential loss in the use of these circuit applications, under any circumstances. Life support 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 Zetex Semiconductors plc. 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 Zetex’ terms and conditions of sale, and this disclaimer (save in the event of a conflict bet ween 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 Zetex sales office. Quality of product Zetex is an ISO 9001 and TS16949 certified semiconductor manufacturer. To ensure quality of service and products we strongly advise the purchase of parts dire ctly from Zetex Semiconductors or one of our regionally authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com/salesnetwork Zetex Semiconductors 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 Zetex Semiconductors is committed to envir onmental excellence in all aspects of its operations which includes meeting or exce eding regulatory requirements with respect to the use of hazardous s ubstances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Zetex components are compliant with the Ro HS directive, and through this it is supporting its customers in their compliance 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.