ZXCT1021 EV1 ZXCT1021EV1 EVALUATION BOARD USER GUIDE DESCRIPTION The ZXCT1021EV1 is intended for the evaluation of the ZXCT1021 device. The ZXCT1021 is a high side current monitor providing a fixed voltage gain of 10. There is a second (50mΩ) resistor that can be selected by means of a solder link and provides an output of 1.5V for a load current of 3A. The device produces a voltage output proportional to the current sampled by a small inline sensing resistor, Rsense. The voltage output is scaled by the choice of Rsense. Additionally provision is made for a wire ended sampling resistor of the users choice. An open collector flag output indicates the direction of current flow. As delivered the board is set up to provide an output of 1.5V from a current of 300mA using a 500 mΩ sampling resistor. FEATURES • Supply Range 4.2 to 20V for 1.5V output. • Selectable current measurement range • 5 Pin SOT23-5 package Zdb341R2. 27-Feb-07 The printed circuit board is common to other devices in the ZXCT family. For the ZXCT1021, neither the FLAG pin nor the Vcc pin are used. APPLICATIONS • Battery Charging • Power Supplies • Over Current Monitoring 1/6 ZXCT1021 EV1 User Guide Rev2 ZXCT1021 EV1 ORDERING INFORMATION ORDER NUMBER ZXCT1021EV1 Please note evaluation boards are subject to availability and qualified leads. PAD NAMES AND DEFINITIONS . NAME DESCRIPTION V1 Supply Voltage V2 Connection to Load VOUT Output Voltage FLAG Not used GND 0V / Ground SL1,SL2 Solder Links Vcc Not used The ZXCT1021EV1 is configured as shown in figure 1; SL1 is shorted to output 1.5V for a 300mA current flow. The target applications are battery chargers, power supply units and other applications where current measurement is a requirement. The input voltage range for the ZXCT1021EV1 is 20V down to a minimum of (2.7V +Vout). E.g. if the required full scale output voltage is 1.5 V the input range is 4.2V to 20V. Zdb341R2. 27-Feb-07 2/6 ZXCT1021 EV1 User Guide Rev2 ZXCT1021 EV1 ZXCT1021EV1 Schematic Sense resistor The board has been designed with two selectable values of sense resistor. chosen by using the solder links SL1 and SL2. The value of the sense resistor can be The board is also tracked for a user defined through hole resistor (R3). The 500mΩ resistor (R1) is selected by shorting SL1 and opening SL2. This results in an output of 1.5V for a load current of 300mA (assuming that R3 is not fitted). The 50mΩ resistor (R2) is selected by shorting SL2 and opening SL1, resulting in an output of 1.5V for a load current of 3A (assuming that R3 is not fitted). If both links are shorted the effective resistance is 45.45mΩ giving an output of 1.5V for a current of 330mA (assuming that R3 is not fitted). If both links are open only the optional leaded resistor R3 (if fitted) is in circuit. The maximum power dissipation rating of the resistor must be appropriate to the load current level. N.B. The board is set by default with SL1 shorted and SL2 open, using the 500mΩ Ω resistor. For further information on choosing a value of sense resistor please refer to the ZXCT1021 datasheet . Vout If the preset selectable values of sense resistor are chosen, the device will produce 1.5V for a 300mA load current or 1.5V for a 3.0A load current, depending on which link is closed. The output is directly proportional to the differential voltage across the sense pins of the device. Zdb341R2. 27-Feb-07 3/6 ZXCT1021 EV1 User Guide Rev2 ZXCT1021 EV1 Configuration table for ZXCT1021EV1 LOAD CURRENT (A) Rsense (mΩ Ω) VOUT (V) SOLDER LINK CONFIGURATION 0.3 500 1.5 Short SL1 3.0 50 1.5 Short SL2 0.33 45.45 1.5 Short SL1 & SL2 Configuration for different LOAD currents. The board can be configured for different load currents by changing the smd resistors or fitting a suitable wire ended resistor and opening both solder links. It is important to ensure an appropriate value of Rsense is selected to obtain the desired accuracy for a given output current. The value of Vout is 10 times the voltage dropped across the sensing resistor, (providing that the voltage on V1 is more than 2.7V higher than the Vout.) Choosing a larger value for Rsense gives a higher output voltage for a given current resulting in better resolution but at the expense of increased voltage drop and higher dissipation in Rsense. It also reduces the minimum voltage at which the device will be linear as Vout +2.7V is the minimum input voltage for accurate results. The ZXCT1021 is optimized for values of Vsense between 0 and 150mV but may be used up to 800mV. Example: Scaling for 1.5A load current and a 500mV output. The ZXCT1021 has a fixed gain of 10. Vout = 10 x Vsense To obtain a 500mV output, 50mV is required between Vsense+ and Vsense-. The value for Rsense is thus 50mV /1.5A = 33mΩ. Accuracy 1 The ZXCT1021 current monitor IC is a 2% accurate device. The accuracy of the output voltage will be influenced by the tolerance of the external sense used. The ZXCT1021EV1 utilizes 1% accurate sense resistors. 1 Total error at +100mV sense voltage COMPONENTS LIST Ref Value Package Part Number R1 500mΩ 1206 R2 50mΩ 2512 LRF2512-R050FW Welwyn Welwyn SOT235 ZXCT1021E5 ZETEX ZXCT Zdb341R2. 27-Feb-07 LR1206-R50FI Manufacturer 4/6 Notes SMD Sense Resistor 1% SMD Sense Resistor 1% ZXCT1021 EV1 User Guide Rev2 ZXCT1021 EV1 SET-UP AND TEST The board is preset to give an output Voltage of 1.5V for a load current of 300mA (SL1 is shorted to connect in the 500mΩ Ω (R1) sense resistor). To change the board to give an output Voltage of 1.5V for a current of 3.0A, de-solder SL1 and short SL2. This connects the 50mΩ Ω (R2) sense resistor. 300mA load test 1. 2. 3. 4. 5. Ensure SL1 is shorted. Connect a linear power supply of +10V between the V1 and GND terminals. Set a load current of 300mA between the V2 and GND terminals using a suitable load. The load must be rated for at least 5W . Check with a DVM the supply voltage is +10V between the V1 and GND terminals. Measure VOUT with a DVM. The nominal output voltage should read 1.5V. The device may also be evaluated with lower power loads and lower currents by increasing the value of Rsense. As the device reacts only to the voltage across this resistor such tests are equally valid. CONNECTION DIAGRAM EVALUATION BOARD CURRENT MONITOR EVALUATION BOARD www.zetex.com Vcc FLAG ZXCT R4 C1 R5 V1 R7 R8 Vout R6 R1 SL1 R2 SL2 V2 R3 SL3 GND GND Refer to 'User Guide' for details. Bare board: ZDB341R2 Copyright Zetex PLC 2006 Top Silk Zdb341R2. 27-Feb-07 Top Copper 5/6 ZXCT1021 EV1 User Guide Rev2 ZXCT1021 EV1 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. 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 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 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 directly 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 malfunction to degradation of function or performance in use over time. Devices suspected of being affected should be replaced. Green compliance 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 hazardous substances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with WEEE and ELV directives. Product status key: “Preview” “Active” “Last time buy (LTB)” “Not recommended for new designs” “Obsolete” Datasheet status key: “Draft version” 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 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. Zdb341R2. 27-Feb-07 6/6 ZXCT1021 EV1 User Guide Rev2