ZXSC440EV1 ZXSC440EV1 USER GUIDE DESCRIPTION The ZXSC440EV1 is a dedicated photoflash charger, charging an 80F photoflash capacitor to 300V in 3.5 seconds from a 5V supply. The Charge pin enables the circuit to be initiated from the camera's microprocessor, using negligible current when flash is not being used. The flyback conversion efficiency is typically 75%, much higher than the commonly used discrete charging circuits. The Ready pin signals the microprocessor when the flash is charged and ready to be fired. FEATURES • Charges a 80F photoflash capacitor to 300V in 3.5 seconds from 5V • Charges various value photoflash capacitors • Over 75% flyback efficiency • Charge and Ready pins • Consumes only 4.5A when not charging • Small MSOP8 Low profile package APPLICATIONS • Digital camera flash unit • Film camera flash unit TYPICAL APPLICATION CIRCUIT • Camera-phone flash unit ORDER NUMBER ZXSC440EV1 Please note evaluation boards are subject to availability and qualified leads. ISSUE 1 - OCTOBER 2004 1 SEMICONDUCTORS ZXSC440EV1 REFERENCE DESIGN ZXSC440EV1 is configured to the reference design below. The target application is a photoflash charger for a Xenon strobe typically used in SLR, DSC and Camera-phone flash units. For other reference designs or further applications information please refer to the ZXSC440 datasheet. The input voltage is typically 5V for the ZXSC440EV1 with a minimum of 4V and a maximum of 8V. SCHEMATIC DIAGRAM MATERIALS LIST REF VALUE U1 Q1 PACKAGE PART NUMBER MANUFACTURER MSOP8 ZXSC440X8 Zetex NOTES SOT-23 ZXMN6A07F Zetex 60V N-channel MOSFET D1 (1) 200V/200mA SOT23 BAS21 Philips 200V fast rectifier diodes connected in series D2 (1) 200V/200mA SOT23 BAS21 Philips 200V fast rectifier diodes connected in series T-16-024A Tokyo Coil Eng Various Tx1 R1 22m⍀ 0805 Generic R2 10M⍀/2kV 2010 HVC201010MFI Welwyn 10⍀W/2kV 1% tolerance R3 9.1k⍀ 1206 Generic Various 1% tolerance R4 100k⍀ 0603 Generic Various 5% tolerance C1 100F/6V3 2220 GRM43SR60J10 7ME20L Murata X5R dielectric, ceramic capacitor C2 10pF/500V 1206 Generic Various Output voltage seen across capacitor C3 10nF/6V3 1206 Generic Various Y5V dielectric, ceramic capacitor C4 80F/330V Radial FW Series Rubycon Photoflash capacitor (1) Two 200V BAS21 fast rectifier diodes are connected in series for improved switching and higher efficiency. ISSUE 1 - OCTOBER 2004 SEMICONDUCTORS 2 ZXSC440EV1 PERFORMANCE GRAPHS ISSUE 1 - OCTOBER 2004 3 SEMICONDUCTORS ZXSC440EV1 WAVEFORMS ISSUE 1 - OCTOBER 2004 SEMICONDUCTORS 4 ZXSC440EV1 ZXSC440EV1 OPERATION Connection Diagram ZXSC440EV1 Set-up and test 1. Connect VIN and GND to positive and zero volts of the power supply respectively. 2. Connect CHG pin to positive of power supply. If CHG pin is left floating start up cannot be guaranteed. 3. Connect DVM to COUT positive and GND terminals. 4. Connect discharge resistor (2) to DVM ensuring that the discharge resistor, SW1, is in the open position. 5. Set the power supply to 5V. 6. Turn on power supply. 7. The output voltage should charge up to 300V ±15V - THIS IS A FUNCTIONAL EVAL BOARD. 8. Turn PSU off. 9. Switch the discharge resistor to the close position. 10. The output voltage should read 0V. CAUTION: HIGH VOLTAGES ARE PRESENT DO NOT TOUCH AND/OR SHORT CIRCUIT COUT LEADS WHEN PSU IS ON AND COUT IS CHARGED i.e. DISCHARGE RESISTOR SET TO OPEN POSITION AND/OR IS DISCONNECTED. Discharge Resistor and SW1. (2) The discharge resistor should be rated at 1⍀ / 10Watts / 500V and placed in series with a Single Pole Single Throw Switch (SPST) of similar rating. Attach insulated leads with 4mm plugs for connection to DVM. (2) If connecting directly to a Xenon tube with discharge circuit the discharge resistor is not needed. Please ensure all exposed areas of this test set-up are fully insulated from the person testing, as potentially lethal voltages are present. ISSUE 1 - OCTOBER 2004 5 SEMICONDUCTORS ZXSC440EV1 Low voltage operation For operation at lower input voltages, say a Lithium-Ion battery, rated at 4.2V to 3.3V, it is possible to split the inputs so that the power line of the primary winding can be connected to VIN with the low power line Vcc of the ZXSC440 connected to a separate 5V supply. To implement this cut the bottom track from Vcc to the transformer primary winding. Connect the low voltage input directly to the transformer primary winding and the low power 5V supply to the Vcc input of the ZXSC440EV1. Connect low power 5V supply Cut track on underside of PCB Connect low voltage supply ISSUE 1 - OCTOBER 2004 SEMICONDUCTORS 6 ZXSC440EV1 Layout considerations PCB tracks should be kept as short as possible to minimise ground bounce, and the ground pin of the device should be soldered directly to the ground plane. It is particularly important to mount the coil and the input/output capacitors close to the device to minimise parasitic resistance and inductance, which will degrade efficiency. The FB pin is a high impedance input, so PCB track lengths to this should also be kept as short as possible to reduce noise pickup. Excess capacitance from the FB pin to ground should be avoided. Below is the recommended layout of the ZXSC440EV1. ISSUE 1 - OCTOBER 2004 7 SEMICONDUCTORS ZXSC440EV1 © Zetex Semiconductors plc 2004 Europe Americas Asia Pacific Corporate Headquarters Zetex GmbH Streitfeldstraße 19 D-81673 München Germany Zetex Inc 700 Veterans Memorial Hwy Hauppauge, NY 11788 USA Zetex (Asia) Ltd 3701-04 Metroplaza Tower 1 Hing Fong Road, Kwai Fong Hong Kong Zetex Semiconductors plc Lansdowne Road, Chadderton Oldham, OL9 9TY United Kingdom Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 [email protected] Telephone: (1) 631 360 2222 Fax: (1) 631 360 8222 [email protected] Telephone: (852) 26100 611 Fax: (852) 24250 494 [email protected] Telephone (44) 161 622 4444 Fax: (44) 161 622 4446 [email protected] These offices are supported by agents and distributors in major countries world-wide. This publication is issued 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. The Company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. For the latest product information, log on to www.zetex.com ISSUE 1 - OCTOBER 2004 SEMICONDUCTORS 8