ZXCT1022 Low offset high-side current monitor Description The ZXCT1022 is a precision high-side current sense monitor. Using this type of device eliminates the need to disrupt the ground plane when sensing a load current. giving better tolerances for small sense resistors necessary at higher currents. The wide input voltage range of 20V down to as low as 2.5V make it suitable for a range of applications. With a minimum operating current of just 25µA, combined with its SOT235 package make it suitable for portable battery equipment too. The ZXCT1022 provides a fixed gain of 100 for applications where minimal sense voltage is required. The very low offset voltage enables a typical accuracy of 3% for sense voltages of only 10mV, Features Applications • Accurate high-side current sensing • Battery chargers • Ground referred output • Smart battery packs • 2.5V – 20V supply range • DC motor control • 25A quiescent current • Over-current protection • SOT23-5 package • Power supply current measurement • Level translating Pinout information NC Typical application circuit VSENSE- GND VSENSE+ VOUT Pinout - top view Ordering information Order reference Package Device marking Status Reel size (inches) Quantity per reel Tape width (mm) ZXCT1022E5TA SOT23-5 1022 Active 7 3000 8 Issue 6 - March 2008 © Zetex Semiconductors plc 2008 1 www.zetex.com ZXCT1022 Absolute maximum ratings -0.6V to 20V Voltage on Vs+ (*) pin Voltage on Vs-(*) (†)VOUT (*)(†) pin -0.6V to VS+ +0.5V VSENSE (‡) -0.6V to +0.5V Operating temperature -40 to 85°C Storage temperature -55 to 150°C Package power dissipation (TA = 25°C) - SOT23-5 - 450mW NOTES: (*) with respect to GND pin (†) voltage not to exceed 20V (‡) VSENSE = VS+ - VS- Pinout information Pin name Pin function N/C Not internally connected GND Ground VOUT Voltage output referenced to GND. Intended to drive high impedance loads VS_ High impedance negative sense voltage input VS+ Supply and positive sense voltage input Issue 6 - March 2008 © Zetex Semiconductors plc 2008 2 www.zetex.com ZXCT1022 Electrical characteristics test conditions Tamb = 25°C, VIN = 15V Symbol Parameter Conditions Limits Min. VIN VCC range VOUT Output voltage Typ. 2.5 VSENSE = 0V Unit Max. 20 V 0 30 100 mV VSENSE = 10mV 0.97 1.0 1.03 V VSENSE = 30mV 2.91 3.0 3.09 V VSENSE = 100mV 9.7 10.0 10.3 V 10 15 20 k⍀ 50 300 ppm 25 35 A 180 (‡) mV 100 nA 3 % ROUT Output resistance TC (*) Output temperature coefficient IQ Ground pin current VSENSE = 0V VSENSE (†) Sense voltage VIN = 20V ISENSE Load pin current VSENSE = 0V Acc Accuracy VSENSE = 10mV -3 Gain VOUT / VSENSE VSENSE = 10mV 97 BW Bandwidth VSENSE = 10mV 300 kHz VSENSE = 100mV 2 MHz 0 100 103 V/V NOTES: (*) TC limits are determined by characterization (†) VSENSE = VIN - VLOAD (‡) For linear operation maximum VSENSE is limited by operating voltage and is approximately: ( V IN – 2 ) 100 VSENSE = ----------------------- Issue 6 - March 2008 © Zetex Semiconductors plc 2008 3 www.zetex.com ZXCT1022 Typical characteristics Issue 6 - March 2008 © Zetex Semiconductors plc 2008 4 www.zetex.com ZXCT1022 Typical characteristics Issue 6 - March 2008 © Zetex Semiconductors plc 2008 5 www.zetex.com ZXCT1022 Application information The ZXCT1022 has a fixed dc voltage gain of 100. No external scaling resistors are required for the output. Output voltage is simply defined as: VOUT = 100 x VSENSE (V) Where VSENSE = VIN - VLOAD PCB trace shunt resistor for low cost solution Figure 1 shows a PCB layout suggestion for a low cost solution where a PCB resistive trace in replacement for a conventional shunt resistor, can be used. The resistor section is 25mm x 0.25mm giving approximately 150m⍀ using 1 oz copper. Smaller resistances can be used if required. Total circuit solution: 1 component. Shows area of 150m⍀ sense resistor compared to SOT23 package. Practical tolerance of the PCB resistor will be around 5% depending on manufacturing methods. ZXCT1021/2 GND Load VOUT VIN Figure 1 PCB layout suggestion Issue 6 - March 2008 © Zetex Semiconductors plc 2008 6 www.zetex.com ZXCT1022 Package outline - SOT23-5 DIM A A1 A2 b C D E E1 e e1 L a° Millimeters Min. 0.90 0.00 0.90 0.20 0.09 2.70 2.20 1.30 Inches Max. 1.45 0.15 1.30 0.50 0.26 3.10 3.20 1.80 Min. 0.0354 0.00 0.0354 0.0078 0.0035 0.1062 0.0866 0.0511 0.95 REF 1.90 REF 0.10 0° Max. 0.0570 0.0059 0.0511 0.0196 0.0102 0.1220 0.1181 0.0708 0.0374 REF 0.0748 REF 0.60 30° 0.0039 0° 0.0236 30° Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches Issue 6 - March 2008 © Zetex Semiconductors plc 2008 7 www.zetex.com ZXCT1022 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. 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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” Future device intended for production at some point. Samples may be available “Active” Product status recommended for new designs “Last time buy (LTB)” Device will be discontinued and last time buy period and delivery is in effect “Not recommended for new designs” Device is still in production to support existing designs and production “Obsolete” 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. “Provisional version” 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. “Issue” This term denotes an issued datasheet containing finalized specifications. However, changes to specifications may occur, at any time and without notice. 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