ZXCT1041 EV1 ZXCT1041EV1 EVALUATION BOARD USER GUIDE DESCRIPTION The ZXCT1041EV1 is intended for the evaluation of the ZXCT1041 device. The ZXCT1041 is a high side bidirectional current monitor providing a fixed voltage gain of 10. 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. As delivered the board is set up to provide an out put of 1.5V from a current of 1.5A using a 100 mΩ sampling resistor. There is a second 25 mΩ resistor that can be selected by means of a solder link and provides an output of 1.5V for a load current of 6A. 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. The printed circuit board is common to other devices in the ZXCT family, for the ZXCT1041, the Vcc pin is not used. FEATURES • Supply Range 4.2 to 20V for 1.5V output. • Selectable current measurement range • 5 Pin SOT23-5 package Zdb341R2. 26-Feb-07 APPLICATIONS • Battery Charging • Power Supplies • Over Current Monitoring 1/8 ZXCT1041 EV1 User Guide Rev2 ZXCT1041 EV1 ORDERING INFORMATION ORDER NUMBER ZXCT1041EV1 Please note evaluation boards are subject to availability and qualified leads. PAD NAMES AND DEFINITIONS . NAME DESCRIPTION V1 Supply Voltage Or Connection to Load/Battery Supply Voltage Or Connection to Load/Battery V2 VOUT Output Voltage FLAG GND Flag Output Indicates direction of current flow 0V / Ground SL1,SL2 Solder Links Vcc Not used Figure 1: ZXLD1350EV2 evaluation board The ZXCT1041EV1 is configured as shown in figure 1; SL1 is shorted to output 1.5V for a 1.5A current flow. The target applications are battery chargers, power supply units and other applications where bi-directional current measurement is a requirement. The input voltage range for the ZXCT1041EV1 is 20V down to a minimum of (2.7V +Vout). Eg if the required full scale output voltage is 1.5 V the input range is 4.2V to 20V. Note that the Flag output requires a pull-up resistor. Zdb341R2. 26-Feb-07 2/8 ZXCT1041 EV1 User Guide Rev2 ZXCT1041 EV1 Figure 1 Schematic Diagram of ZXCT1041EV1 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 100mΩ resistor (R1) is selected by shorting SL1 and opening SL2. This results in an output of 1.5V for a load current of 1.5A (assuming that R3 is not fitted). The 25mΩ resistor (R2) is selected by shorting SL2 and opening SL1, resulting in an output of 1.5A for a load current of 6A (assuming that R3 is not fitted). If both links are shorted the effective resistance is20mΩ giving an output of 1.5V for a current of 7.5A (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 100mΩ Ω resistor. For further information on choosing a value of sense resistor please refer to the ZXCT1041 datasheet . Vout If the preset selectable values of sense resistor are chosen, the device will output 1.5V for a 1.5A load current and 1.25V for a 5.0A load current. The output is directly proportional to the differential voltage across the sense pins of the device. The ZXCT1041 will output the same voltage for current flow in either direction, but the level of the Flag output will change. Zdb341R2. 26-Feb-07 3/8 ZXCT1041 EV1 User Guide Rev2 ZXCT1041 EV1 Configuration table for ZXCT1041EV1 LOAD CURRENT (A) Rsense (mΩ Ω) VOUT (V) SOLDER LINK CONFIGURATION 1.5 100 1.5 Short SL1 6.0 25 1.5 Short SL2 7.5 20 1.5 Short SL1 & SL2 FLAG The direction of current flow can be determined from the flag output pin. The flag output of the device is an open collector output. On board the ZXCT1041EV1 is a 30kΩ resistor which is connected to V1, it may be connected to a lower voltage eg 3V3 if that is appropriate in the application. If current is flowing from V1 to V2, the FLAG pin will be High, at the same potential as V1 or the supply connected to the collector resistor on the Flag output. If current is flowing in the reverse direction, i.e. from V2 to V1, the FLAG pin will be Low, typically 60mV. 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 input Voltage 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 ZXCT1041 is optimized for values of Vsense of either polarity between 0 and 800mV. Example: Scaling for 1.5A load current and a 500mV output. The ZXCT1041 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 2 The ZXCT1041 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 ZXCT1041EV1 utilizes 1% accurate sense resistors. 2 Total error at +100mV sense voltage COMPONENTS LIST Ref Value Package Part Number R1 100mΩ 1206 LR1206-R10FI R2 25mΩ 2512 LRF2512-R025FW R3 30kΩ 0805 ZXCT SOT235 Zdb341R2. 26-Feb-07 ZXCT1041E5 4/8 Manufacturer Welwyn Welwyn Generic Notes SMD Sense Resistor 1% SMD Sense Resistor 1% SMD 1% 0.125W ZETEX ZXCT1041 EV1 User Guide Rev2 ZXCT1041 EV1 SET-UP AND TEST The board is preset to give an output |Voltage of 1.5V for a load current of 1.5A (SL1 is shorted to connect in the 100mΩ Ω (R1) sense resistor). To change the board to give an output Voltage of 1.5V for a current of 6.0A, de-solder SL1 and short SL2. This connects the 25mΩ Ω (R2) sense resistor. 1.0 Ampere load test 1. 2. 3. 4. 5. 6. Ensure SL1 is shorted. Connect a linear power supply of +15V between the V1 and GND terminals. Set a load current of 1.5A between the V2 and GND terminals using a suitable load. The load must be rated for at least 30W. Check with a DVM the supply voltage is +15V between the V1 and GND terminals. Measure VOUT with a DVM. The nominal output voltage should read 1.5V. Measure the FLAG pin with a DVM, it should be High, approximately V1 15Vin this case. 1.0 Ampere load test 1. 2. 3. 4. 5. 7. (forward current flow) (reverse current flow) Ensure SL1 is shorted. Connect a linear power supply of +15V between the V2 and GND terminals. Set a load current of 1.5A between the V1 and GND terminals using a suitable load. The load must be rated for at least 30W. Check with a DVM the supply voltage is +15V between the V2 and GND terminals. Measure VOUT with a DVM. The nominal output voltage should read 1.5V. Measure the FLAG pin with a DVM, it should be logic Low, less than 200mV 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. Zdb341R2. 26-Feb-07 5/8 ZXCT1041 EV1 User Guide Rev2 ZXCT1041 EV1 CONNECTION DIAGRAM Forward Current flow CURRENT MONITOR EVALUATION BOARD ZXCT1041EV1 FLAG VOUT V2 LOAD V1 PSU GND GND 10 Ω DVM DVM CONNECTION DIAGRAM……continued Reverse Current flow CURRENT MONITOR EVALUATION BOARD ZXCT1041EV1 FLAG 10 Ω LOAD VOUT Zdb341R2. 26-Feb-07 V1 V2 PSU GND DVM DVM GND 6/8 ZXCT1041 EV1 User Guide Rev2 ZXCT1041 EV1 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. 26-Feb-07 Top Copper 7/8 ZXCT1041 EV1 User Guide Rev2 ZXCT1041 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. 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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. 26-Feb-07 8/8 ZXCT1041 EV1 User Guide Rev2