ZXCT1080 High voltage high-side current monitor Description The ZXCT1080 is a high side current sense monitor with a gain of 10 and a voltage output. Using this device eliminates the need to disrupt the ground plane when sensing a load current. The wide input voltage range of 60V down to as low as 3V make it suitable for a range of applications; including systems operating from industrial 24-28V rails and -48V rails. The separate supply pin (VCC) allows the device to continue functioning under short circuit conditions, giving an end stop voltage at the output. The ZXCT1080 has an extended ambient operating temperature range of -40°C to 125°C enabling it to be used in a wide range of applications including automotive. Features Applications • 3V to 60V continuous high side voltage • Industrial applications current measurement • Accurate high-side current sensing • Battery management • -40 to 125°C temperature range • Over-current measurement • Output voltage scaling x10 • Power management • 4.5V to 12V VCC range • Automotive current measurement • Low quiescent current: • 80µA supply pin • • 27µA IS+ SOT23-5 package Pin connections Typical application circuit R SENSE V IN VCC 1 5 S4 GND 2 5 S- S+ OUT 3 4 V CC 1 S+ V cc ZXCT1080 OUT GND 3 2 V OUT Ordering information Device Package Part mark Reel size (inches) Tape width (mm) Quantity per reel ZXCT1080E5TA SOT23-5 1080 7 8 3000 Issue 3 - March 2008 © Zetex Semiconductors plc 2008 1 www.zetex.com ZXCT1080 Absolute maximum ratings Continuous voltage on S- and S+ -0.6 and 65V Voltage on all other pins -0.6V and +14V Differential sense voltage, VSENSE 800mV Operating temperature -40 to 125°C Storage temperature -55 to 150°C Maximum junction temperature 125°C Package power dissipation 300mW* at TA = 25°C Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability. VSENSE is defined as the differential voltage between S+ and S- pins. * Assumes ⍜JA = 420°C/W Recommended operating conditions Parameter Min. Max. Units 3 60 V 4.5 12 V VIN Common-mode sense+ input range VCC Supply voltage range VSENSE Differential sense input voltage range 0 0.15 V VOUT Output voltage range 0 1.5 (*) V TA Ambient temperature range -40 125 °C NOTES: (*) Based on 10x VSENSE Pin function table Pin Name Description 1 VCC This is the analogue supply and provides power to internal circuitry 2 GND Ground pin 3 OUT Output voltage pin. NMOS source follower with 20µA bias to ground 4 S+ This is the positive input of the current monitor and has an input range from 60V down to 3V. The current through this pin varies with differential sense voltage 5 S- This is the negative input of the current monitor and has an input range from 60V down to 3V Issue 3 - March 2008 © Zetex Semiconductors plc 2008 2 www.zetex.com ZXCT1080 Electrical characteristics Test conditions TA = 25°C, VIN = 12V, VCC = 5 V, VSENSE(a) = 100mV unless otherwise stated. Symbol Parameter Conditions TA Min(e). Typ. ICC VCC supply current VCC = 12V, 25°C 40 80 VSENSE(a) = 0V full range VSENSE(a) = 0V 25°C 27 25°C 15 40 Zero VSENSE(a) error(b) 25°C Output offset voltage(c) VSENSE(a) = 10mV S+ input current IS- S- input current VO(0) VO(10) full range Gain ⌬VOUT/⌬VSENSE(a) VSENSE(a) = 10mV to 150mV 120 µA 145 15 IS+ Max(e). Units 42 µA 60 80 nA 0 35 mV 25°C -25 +25 mV full range -55 +55 25°C 9.9 full range 9.8 10 10.1 V/V 10.2 VOUT TC VOUT variation with temperature Acc Total output error IOH Output source current ⌬VOUT = -30mV 1 mA IOL Output sink current ⌬VOUT = +30mV 20 µA PSRR VCC supply rejection ratio VCC = 4.5V to 12V 54 60 dB CMRR Common-mode sense rejection ratio VIN = 60V to 3V 68 80 dB BW -3dB small signal bandwidth VSENSE(a) (AC) = 10mVPP 500 kHz (d) 30 -3 ppm/°C 3 % NOTES: (a) VSENSE = "VS+" - "VS-" (b) The ZXCT1080 operates from a positive power rail and the internal voltage-current converter current flow is unidirectional; these result in the output offset voltage for VSENSE = 0V always being positive. (c) For VSENSE > 10mV, the internal voltage-current converter is fully linear. This enables a true offset to be defined and used. VO(10) is expressed as the variance about an output voltage of 100mV> (d) Temperature dependent measurements are extracted from characterization and simulation results. (e) All Min and Max specifications over full temperature range are guaranteed by design and characterisation Issue 3 - March 2008 © Zetex Semiconductors plc 2008 3 www.zetex.com ZXCT1080 Typical characteristics Test conditions unless otherwise stated: TA = 25°C, VCC = 5V, VSENSE+ =12V, VSENSE = 100mV Issue 3 - March 2008 © Zetex Semiconductors plc 2008 4 www.zetex.com ZXCT1080 Typical characteristics Test conditions unless otherwise stated: TA = 25°C, VCC = 5V, VSENSE+ =12V, VSENSE = 100mV Issue 3 - March 2008 © Zetex Semiconductors plc 2008 5 www.zetex.com ZXCT1080 Typical characteristics Test conditions unless otherwise stated: TA = 25°C, VCC = 5V, VSENSE+ =12V, VSENSE = 100mV Issue 3 - March 2008 © Zetex Semiconductors plc 2008 6 www.zetex.com ZXCT1080 Typical characteristics Test conditions unless otherwise stated: TA = 25°C, VCC = 5V, VSENSE+ =12V, VSENSE = 100mV Issue 3 - March 2008 © Zetex Semiconductors plc 2008 7 www.zetex.com ZXCT1080 Application information The ZXCT1080 has been designed to allow it to operate with 5V supply rails while sensing common mode signals up to 60V. This makes it well suited to a wide range of industrial and power supply monitoring applications that require the interface to 5V systems while sensing much higher voltages. To allow this its VCC pin can be used independently of S+. Figure 1 shows the basic configuration of the ZXCT1080. Input R SENSE S+ S- Load ZXCT1080 R GT V CC A1 M1 OUT A2+1 RG GND Figure 1 Typical configuration of ZXCT1080 Load current from the input is drawn through RSENSE developing a voltage VSENSE across the inputs of the ZXCT1080. The internal amplifier forces VSENSE across internal resistance RGT causing a current to flow through MOSFET M1. This current is then converted to a voltage by RG. A ratio of 10:1 between RG and RGT creates the fixed gain of 10. The output is then buffered by the unity gain buffer. The gain equation of the ZXCT1080 is: RG - × 1 = I L × R SENSE × 10 V OUT = I L R SENSE --------R GT The maximum recommended differential input voltage, VSENSE, is 150mV; it will however withstand voltages up to 800m⍀. This can be increased further by the inclusion of a resistor, RLIM, between S- pin and the load; typical value is of the order of 10k . Issue 3 - March 2008 © Zetex Semiconductors plc 2008 8 www.zetex.com ZXCT1080 R SENSE R LIM CD S- S+ ZXCT1080 Figure 2 Protection/error sources for ZXCT1080 Capacitor CD provides high frequency transient decoupling when used with RLIM; typical values are of the order 10pF For best performance RSENSE should be connected as close to the S+ (and SENSE ) pins; minimizing any series resistance with RSENSE. When choosing appropriate values for RSENSE a compromise must be reached between in-line signal loss (including potential power dissipation effects) and small signal accuracy. Higher values for RSENSE gives better accuracy at low load currents by reducing the inaccuracies due to internal offsets. For best operation the ZXCT1080 has been designed to operate with VSENSE of the order of 50mV to 150mV. Current monitors' basic configuration is that of a unipolar voltage to current to voltage converter powered from a single supply rail. The internal amplifier at the heart of the current monitor may well have a bipolar offset voltage but the output cannot go negative; this results in current monitors saturating at very low sense voltages. As a result of this phenomenon the ZXCT1080 has been specified to operate in a linear manner over a VSENSE range of 10mV to 150mV range, however it will still be monotonic down to VSENSE of 0V. It is for this very reason that Zetex has specified an input offset voltage (VO(10)) at 10mV. The output voltage for any VSENSE voltage from 10mV to 150mV can be calculated as follows: V OUT = ( V SENSE )xG + V O ( 10 ) Alternatively the load current can be expressed as: ( V OUT – V O ( 10 ) ) I L = -----------------------------------------GxR SENSE Issue 3 - March 2008 © Zetex Semiconductors plc 2008 9 www.zetex.com ZXCT1080 Package details - 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 3 - March 2008 © Zetex Semiconductors plc 2008 10 www.zetex.com ZXCT1080 Intentionally left blank Issue 3 - March 2008 © Zetex Semiconductors plc 2008 11 www.zetex.com ZXCT1080 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 labelling 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” 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. Zetex sales offices Europe Americas Asia Pacific Corporate Headquarters Zetex GmbH Kustermannpark 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] © 2007 Published by Zetex Semiconductors plc Issue 3 - March 2008 © Zetex Semiconductors plc 2008 12 www.zetex.com