ZXCT1008EV1 ZXCT1008EV1 USER GUIDE DESCRIPTION The ZXCT1008EV1 is a current monitor evaluation board which measures 0.5A, 2.0A or a 2.5A load current. This current is then translated to a proportional output current which is scaled by an external resistor to give a 2.5V full scale output voltage. protection from 110V transients and includes and additional current limiting resistor. The board also incorporates additional solder pads for a user defined sense resistor to cater for additional load currents which may require measuring. The board has also been designed to incorporate FEATURES • Supply Range 8 to 20V • Selectable current measurement range • 2.5V Output Voltage • Transient Protected • 3 Pin SOT23 package APPLICATIONS • Battery Charging • Power Supplies • DC motor and solenoid control ORDERING INFORMATION ORDER NUMBER ZXCT1008EV1 TYPICAL APPLICATION CIRCUIT V in R sense Please note evaluation boards are subject to availability and qualified leads. 2 To load 3 Vsense+ V sense- ZXCT 1008 I out 1 R load Rlim R ZXCT1008EV1 ISSUE 3 – April 2007 1 Vout ZXCT1008EV1 REFERENCE DESIGN ZXCT1008EV1 is configured to the reference design below. The target applications are battery chargers, power supply units and automotive current monitoring. The input voltage is typically between 14 to 16V for the ZXCT1008EV1 with a minimum of 8V. This board takes into account 110V voltage transients which may be present. See scaling for transient protection below for further information. Rsense The board has been designed with three set selectable values of Rsense, to measure either a 0.5A, 2.0A or 2.5A range. The value of sense resistor can be chosen by using the solder links SL6 and SL7. To measure a 0.5A load current, the 200mΩ resistor (R3) should be selected by shorting SL7. To measure a 2.0A current, the 50mΩ resistor (R2) should be selected by shorting SL6. To measure a 2.5A current, short both SL6 and SL7. The 50mΩ in parallel with the 200mΩ will give a 40mΩ resistance. RST is also available if a user defined current load level is required to be measured. This allows the user to scale in a more appropriate value of sense resistor. If the value of sense resistor is changed, the maximum power dissipation of the resistor must be appropriate to the load current level. NB The board is set by default to measure 0.5A i.e. SL7 is shorted, utilizing the 200mΩ Ω resistor. For further information on choosing a value of sense resistor please refer to the ZXCT1008 datasheet or Applications note 39. VOUT If the preset selectable values of sense resistor are chosen, the device will output 2.5V at both the 0.5A and 2.0A current levels. The board has been designed for each of the sense resistors to develop 100mV across them at the three levels of current. If a RST is used at a different current level, the value of Vout will change. Configuration table for ZXCT1008EV1 LOAD CURRENT (A) 0.5 2.0 2.5 VOUT (V) 2.5 2.5 2.5 Rsense (mΩ Ω) 200 50 40 SOLDERLINK CONFIGURATION Short SL7 Short SL6 Short SL7 and SL6 Scaling for Transient Protection The ZXCT1008EV1 has a current limiting resistor R4 which will limit the current from Iout. This is of particular use where high voltage transients maybe present. Assuming the worst case condition of Vout = 0V, the minimum value of Rlim is given by : Rlim (min) = Assuming 110V transients present; = V pk − Vmax I pk 110 − 20 40 × 10 −3 = 2.25kΩ Vpk = Peak transient voltage to be withstood (V) Vmax = Maximum Working Volage = 20V Ipk = Peak Output Current = 40mA ZXCT1008EV1 ISSUE 3 – April 2007 2 ZXCT1008EV1 The maximum value of Rlim is set by Vin(min), Vout(max) and the dropout voltage. Rlim (max) = [ ] Rout Vin (min) − (Vdp + Vout (max)) Vout (max) 2.5 × 10 3 [8 − (1.5 + 2.5)] = 4kΩ 2.5 = Vin(min) = Minimum Supply Operating Voltage (V) Vdp = Dropout Voltage (V) Vout(max) = Maximum Operating Output (V) Accuracy 1 The ZXCT1008 current monitor IC is a 2.5% accurate device. The accuracy of the output voltage will be influenced by the tolerance of the external resistors used. The ZXCT1008EV1 uses a 1% accurate sense resistor and a 0.1% accurate output resistors. 1 Maximum error at 200mV Schematic Diagram RST SL7 R3 200m SL6 R2 VIN VLOAD 50m 2 3 Vsense+ Vsense- ZXCT 1009 Iout 1 R4 2.49k Vout R5 2.49k GND ZXCT1008EV1 ISSUE 3 – April 2007 3 ZXCT1008EV1 Materials List Ref Value Package Part Number Manufacturer R1 R2 R3 R4 R5 ZXCT 1206 1206 0805 0805 SOT23 LR1206 LR1206 Welwyn Welwyn ZXCT1008F ZETEX Not fitted 50mΩ 200mΩ 2.49K 2.49k Notes Not fitted SMD Sense Resistor 1% SMD Sense Resistor 1% SMD ±25ppm 0.1% SMD ±25ppm 0.1% ZXCT1008EV1 Set-up and Test The board is preset to measure 0.5A. SL7 is shorted to connect in the 200mΩ Ω sense resistor. To change the board to measure 2.0A, de-solder SL7 and short SL6. 0.5 Ampere load test 1. 2. 3. 4. 5. 6. Ensure SL7 is shorted. Connect a linear power supply of +10V between the VIN and GND terminals. Set a load current of 0.5A. Turn on the power supply Check with a DVM the supply voltage is +10V between the VIN and GND terminals. Measure VOUT with a DVM. The nominal output voltage should read 2.5V. The output current can be set by using either an external power resistor or an electronic load. The accuracy of the current set will have an influence on the output voltage. Connection Diagram ZXCT1008EV1 VLOAD VIN PSU ZXCT LOAD VOUT GND DVM GND The ZXCT1008EV1 board can also be used to evaluate the ZXCT1009 and ZXCT1011Zetex current monitor devices. ZXCT1008EV1 ISSUE 3 – April 2007 4 ZXCT1008EV1 Layout . CURRENT MONITOR EVALUATION BOARD CURRENT MONITOR EVALUATION BOARD RST VIN GND R3 R2 ZXCT R4 RST SL7 VLOAD VIN R3 R2 ZXCT R4 SL6 R1 VOUT R5 VLOAD SL7 SL6 R1 VOUT R5 GND GND Bare pcb: ZDB237R3 GND CopyrightZetex PLC 2006 Bare pcb: ZDB237R3 Copy rightZetex PLC 2006 Top Silk Top composite Top Copper Bottom Copper ZXCT1008EV1 ISSUE 3 – April 2007 5 ZXCT1008EV1 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 and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is assumed by Zetex with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Zetex does not assume any legal responsibility or will not be held legally liable (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 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 properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device 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 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. 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Product status key: “Preview” “Active” “Last time buy (LTB)” “Not recommended for new designs” “Obsolete” Future device intended for production at some point. Samples may be available Product status recommended for new designs Device will be discontinued and last time buy period and delivery is in effect Device is still in production to support existing designs and production Production has been discontinued Datasheet status key: “Draft version” This term denotes a very early datasheet version and contains highly provisional information, which may change in any manner without notice. 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. This term denotes an issued datasheet containing finalized specifications. However, changes to specifications may occur, at any time and without notice. “Provisional version” “Issue” Europe Americas Asia Pacific Corporate Headquarters Zetex GmbH Kustermann-park Balanstraße 59 D-81541 München Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 [email protected] Zetex Inc 700 Veterans Memorial Highway Hauppauge, NY 11788 USA Zetex (Asia Ltd) 3701-04 Metroplaza Tower 1 Hing Fong Road, Kwai Fong Hong Kong Zetex Semiconductors plc Zetex Technology Park, Chadderton Oldham, OL9 9LL United Kingdom 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] © 2006 Published by Zetex Semiconductors plc. ZXCT1008EV1 ISSUE 3 – April 2007 6