ZXCT1009EV1 ZXCT1009EV1 USER GUIDE DESCRIPTION The ZXCT1009EV1 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. The board also incorporates additional solder pads for a user defined sense resistor to cater for additional load currents which may require measuring. FEATURES • Supply Range 2.5 to 20V • Selectable current measurement range • 2.5V Output Voltage • 3 Pin SOT23 package APPLICATIONS • Battery Charging • Power Supplies • DC motor and solenoid control ORDERING INFORMATION TYPICAL APPLICATION CIRCUIT ORDER NUMBER ZXCT1009EV1 V in Please note evaluation boards are subject to availability and qualified leads. R sense 2 V sense+ PAD NAMES AND DEFINITIONS To load 3 V sense- ZXCT 1009 R load I out . NAME VIN VLOAD DESCRIPTION VOUT Output Voltage GND SL6,SL7 0V – Ground Solder Links 1 Vout Supply Voltage Connection to load/Battery Rout ZXCT1009EV1 ISSUE 3 – January 2006 1 ZXCT1009EV1 REFERENCE DESIGN The ZXCT1009EV1 is configured to the reference design below. The target applications are battery chargers, power supply units and automotive current monitoring. The input voltage range for the ZXCT1009EV1 is 20V down to a minimum of 2.5V, making in suitable for a wide range of applications. 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 Rsense (mΩ Ω) 200 50 40 VOUT (V) 2.5 2.5 2.5 SOLDER LINK CONFIGURATION Short SL7 Short SL6 Short SL7 and SL6 Configuration for different LOAD currents. The board can be configured to accommodate different load currents if necessary. If surface mount sense resistors are to be used, remove R2 an R3 and replace with a required value. RST can be used if a through hole sense resistor is used. It is important to ensure an appropriate value of Rsense is selected to obtain the desired accuracy for a given output current. NB Changing the sense resistor value will change the output current. It may therefore be necessary to change R5 to obtain the required output voltage. Example: Scaling for 1.5A load current and a 500mV output. Choose a value of sense resistor to accommodate the required accuracy on the output. Choosing 150mV would require a 100mΩ sense resistor. Vout = 0.01 x Vsense x Rout ZXCT1009EV1 ISSUE 3 – January 2006 2 ZXCT1009EV1 Therefore, the required output resistor for a 500mV output would be: -3 -3 Rout = 500x10 / (150x10 x 0.01) = 333.33Ω Nearest preferred value: 332Ω Accuracy 1 The ZXCT1009 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 ZXCT1009EV1 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 Vout R5 2.49k GND ZXCT1009EV1 ISSUE 3 – January 2006 3 ZXCT1009EV1 Materials List Ref Value Package Part Number Manufacturer Notes R2 R3 R4 R5 ZXCT 1206 1206 0805 0805 SOT23 LR1206 LR1206 Welwyn Welwyn SMD Sense Resistor 1% SMD Sense Resistor 1% Zero ohm link SMD ±25ppm 0.1% ZXCT1009F ZETEX 50mΩ 200mΩ 0Ω 2.49k ZXCT1009EV1 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 ZXCT1009EV1 VIN PSU VLOAD SL7 SL6 LOAD ZXCT VOUT GND DVM GND The ZXCT1009EV1 board can also be used to evaluate the following Zetex current monitors IC’s: • ZXCT1008 • ZXCT1011 ZXCT1009EV1 ISSUE 3 – January 2006 4 ZXCT1009EV1 Layout . CURRENT MONITOR EVALUATION BOARD RST VIN R3 SL7 R2 SL6 VLOAD ZXCT R4 GND R1 VOUT R5 GND Bare pc b: ZDB237R2 Copy rightZetex PLC 2005 Top Silk Top Copper Bottom Copper Drill File ZXCT1009EV1 ISSUE 3 – January 2006 5 ZXCT1009EV1 Zetex plc. Fields New Road, Chadderton, Oldham, OL9 8NP, United Kingdom Telephone: (44) 161 622 4422 (Sales), (44) 161 622 4444 (General Enquiries) Fax: (44) 161 622 442 Zetex GmbH Streitfieldstraβe 19 D-81673 Munchen Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 Zetex Inc. 47 Mall Drive, Unit 4 Commack NY 11725 USA Telephone: (631) 543-7100 Fax: (631) 864-7630 Zetex (Asia) Ltd. 3701-04 Metroplaza, Tower 1 Hing Fong Road, Kwai Fong, Hong Kong Telephone: (852) 26100 611 Fax: (852) 24250 494 These are supported by agents and distributoRS in major countries world-wide © Zetex plc 2000 http://www.zetex.com 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 contact 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. ZXCT1009EV1 ISSUE 3 – January 2006 6