ZXCT1012 ZETEX | Alldatasheet
Document overview
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Technical content
Features
- 2.5V to 20V supply range 3.5µA quiescent current Current output - user set gain Thin package - TSOT23-5 and TDFN3x3-5 Temperature range -40 to 85°C
Applications
Battery fuel gauge Battery chargers Overcurrent monitor Power management Pin connections Applications circuit SENSE- TSOT23-5 Pinout - top view SENSE+OUT OUT GND NC SENSE+ SENSE- TDFN3x3-5 Pinout - bottom view OUT OUT OUT SENSE+ SENSE- LOAD ZXCT1012 IN SENSE Device Package Status Device marking Reel size (inches) Tape width (mm) Quantity per reel ZXCT1012DAATA TDFN-5 (3mm x 3mm) Active 1012 7 8 3000 ZXCT1012ET5TA TSOT23-5 Active 1012 7 8 3000
Issue 1 - December 2006 2 www.zetex.com © Zetex Semiconductors plc 2006 Pin information Absolute maximum ratings Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability. NOTES: (‡) VSENSE is defined as the differential voltage between the SENSE+ and SENSE- pins. VSENSE = VSENSE+ - VSENSE- (†) Exposed lead not connected to thermal plane Pin Name Description TDFN5 TSOT23-5 3 1 N/C No connection 2 2 GND Ground connection 1 3 OUT Output current pin. Current generated due to a difference voltage between V SENSE+ and VSENSE- flows out of this pin. A suitable value resistor connected to ground creates an output voltage. The maximum voltage out of this pin will be VSENSE- - 1.5V. 5 4 SENSE+ This pin should be connected to the rail whose current is being measured and also provides power to internal circuitry. It is the positive input of the current monitor and has an input range from 20V down to 2.5V. The current through this pin varies with differential sense voltage. 4 5 SENSE- This is the negative input of the current monitor and has an input range from 20V down to 2.5V. V SENSE+ max. 20V Voltage on any pin (relative to GND pin) -0.6 and V SENSE+ +0.5V VSENSE (‡) -0.15V to +3V Ambient operating temperature range -40 to 85°C Storage temperature -55 to 150°C Maximimum junction temperature 150°C Package power dissipation 300mW at T amb= 25°C (De-rate to zero at 150°C) Package R /H9052JA PDISS at 25°C TSOT23-5 (*) NOTES: (*) Mounted on 30mm x 16mm x1.1mm FR4 board with 1oz copper. 250°C/W 500mW TDFN3x3 5 pin(*) (†) 232°C/W 540mW
Issue 1 - December 2006 3 www.zetex.com © Zetex Semiconductors plc 2006 Recommended operating conditions
Electrical characteristics
Test conditions Tamb = 25°C, VIN = VSENSE+ = 5V, unless otherwise stated Symbol Recommended parameter Limits Min. Max. Units VIN Sense+ range 2.5 20 V TA Ambient temperature range differential -40 85 °C VSENSE Sense voltage 10 2500 mV VOUT Output voltage swing 0 V SENSE- -1.5 V Symbol Parameter Conditions Limits Unit Min. Typ. Max. IOUT Output current V SENSE = 0V 0 0.3 15 /H9262A VSENSE = 10mV 85 100 115 /H9262A VSENSE = 40mV 380 400 420 /H9262A VSENSE = 100mV 0.975 1.00 1.025 mA VSENSE = 200mV 1.95 2.00 2.05 mA IQ Ground pin current V SENSE = 0V 3.5 8 /H9262A ISENSE- SENSE- pin input current 100 nA Acc Accuracy R SENSE = 0.1V VSENSE = 200mV -2.5 2.5 % Gm Transconductance, IOUT/VSENSE (*) 10 mA/V Tc Temperature coefficient VSENSE = 200mV Tamb = 0 to 50°C (*) NOTES: (*) Temperature dependent measurements are extracted from characterisation and simulation results. (‡) With the ZXCT1012 using SENSE+ as its power supply pin, common mode rejection cannot be distinguished from power supply rejection. 500 ppm/ BW Bandwidth C L = 5pF, ROUT = 1k/H9024 VSENSE = 10mV VSENSE = 100mV 300 kHz MHz CMRR(‡) Common mode rejection ratio V SENSE = 100mV, ROUT = 1k/H9024 VIN = 2.5V to 20V 80 dB
Issue 1 - December 2006 4 www.zetex.com © Zetex Semiconductors plc 2006 Typical characteristics -2% -4% -6%
Issue 1 - December 2006 5 www.zetex.com © Zetex Semiconductors plc 2006 Applications information The ZXCT1012 current monitor works by converting the voltage developed across a small sense resistor into a current on the out pin. In realit y it is a voltage to current converter. This output current can be converted into a voltage simply by passing it through a resistor (ROUT) to ground. The current monitor has a transconductance of 10mA/V. But the overall amplifying conversion is affected by both the RSENSE and ROUT. The gain equation of the ZXCT1012 is: For best performance R SENSE should be connected as close to the SENSE+ (and SENSE-) pins; which minimizes any series resistance with RSENSE and potential for interference pickup. When choosing appropriate values for R SENSE 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 ZXCT1012 has been designed to provide best performance with V SENSE of the order of 40mV to 200mV. Current monitors are single supply devices which means they tend to saturate at very low sense voltages. However it does mean the output can never go negative. Also the output can never change direction (monotonic). This is important if the current monitor is used in a control loop. As the sense voltage is reduced the output will tend to saturate as the input offset voltage starts to have greater effect. It is recommended to have a minimum sense voltage of 10mV to minimize linearity errors. Zetex has specified the output voltage at V SENSE of 10mV, 40mV, 100mV and 200mV; which is the recommended sense voltage range. The maximum differential input voltage, V SENSE, is 2.5V; however this will cause large output currents to flow increasing power dissipation in the chip. The sense voltage can be increased further, without damaging the ZXCT1012, by the inclusion of a resistor, RLIM, between SENSE- pin and the load. Typical values around 10k/H9024. See figure below. If large reverse currents are expected then the resistor, R LIM, will provide protection from exceeding absolute maximum ratings. A suitable value for RLIM can be determined from: Where VSENSE(REV) is the maximum expected reverse sense voltage generated. VOUT IL RSENSE× ROUT ZXCT1012 SENSE RLIM CC RLIM VSENSE REF()
Issue 1 - December 2006 6 www.zetex.com © Zetex Semiconductors plc 2006 The following lines describe how to scale a load current to an output voltage. VSENSE = RSENSE * ILOAD equation (1) IOUT = 10mA/V x VSENSE equation (2) VOUT = IOUT x ROUT equation (3) Design example In the circuit below a 1A current is to be represented by a 100mV output voltage (VOUT): A) To be within recommended values choose the value of R SENSE to give: 50mV > VSENSE > 200mV at full load. For example set VSENSE = 100mV at 1.0A. From equation (1) R SENSE = 0.1V/1.0A = 0.1 /H9024 B) Now choose R OUT to give: VOUT = 100mV, when VSENSE = 100mV. From equation (2) IOUT = 10mA/V x 0.1 = 1mA Rearranging equation (3) for ROUT gives: ROUT = VOUT/IOUT = 0.1/0.001 = 100 /H9024 Typical circuit application Where RLOAD represents any load including DC motors, a charging battery or further circuitry that requires monitoring, Rsense can be selected on specific requirements of accuracy, size and power rating. OUT OUT OUTGND SENSE+ SENSE- LOAD ZXCT1012 IN SENSE
Issue 1 - December 2006 7 www.zetex.com © Zetex Semiconductors plc 2006 Power dissipation The maximum allowable power dissipation of the device for normal operation (P MAX), is a function of the package junction to ambient thermal resistance ( /H9052JA), maximum junction temperature (TJMAX), and ambient temperature (Tamb), according to the expression: PMAX = (TJMAX – Tamb) / /H9052JA The device power dissipation, PD is given by the expression: PD=IOUT.(VIN-VOUT) watts Care must be taken when using this device at large input voltages and large sense voltages to prevent too much power dissipation. VIN = 20V V SENSE = 2.5V ROUT = 100/H9024 IOUT = 2.5 x 0.01 = 25mA VOUT = IOUT x ROUT = 25mA x 100/H9024 = 2.5V = 438mW Power Dissipation 100 200 300 400 500 600 0 2 55 07 5 1 0 0 1 2 5 1 5 0 TA - Ambient tempera ture (°C) PD - Power Dissipation (mW) TDFN3x3-5 TSOT23-5
Issue 1 - December 2006 8 www.zetex.com © Zetex Semiconductors plc 2006 Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches DIM Millimeters Inches Min. Max. Min. Max. A - 1.00 - 0.0393 A1 0.01 0.10 0.0003 0.0039 A2 0.84 0.90 0.0330 0.0354 b 0.30 0.45 0.0118 0.0177 c 0.12 0.20 0.0047 0.0078 D 2.90 BSC 0.114 BSC E 2.80 BSC 0.110 BSC E1 1.60 BSC 0.062 BSC e 0.95 BSC 0.0374 BSC e1 1.90 BSC 0.0748 BSC L 0.30 0.50 0.0118 0.0196 L2 0.25 BSC 0.010 BSC a° 4° 12° 4° 12°
Issue 1 - December 2006 9 www.zetex.com © Zetex Semiconductors plc 2006 DAA package outline - TDFN3x3-5 Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches Dim. Millimeters Inches Dim. Millimeters Inches D 3.00BSC 0.1181BSC K 0.20 - 0.0079 - D2 1.85 2.10 0.0728 0.0827 - - - - - E D A b E2/2L K D2/2 ee
Issue 1 - December 2006 10 www.zetex.com © Zetex Semiconductors plc 2006 Zetex sales offices Europe Zetex GmbH Kustermann-park Balanstraße 59 D-81541 München Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 europe.sales@zetex.com Americas Zetex Inc
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Hauppauge, NY 11788 USA Telephone: (1) 631 360 2222 Fax: (1) 631 360 8222 usa.sales@zetex.com Asia Pacific Zetex (Asia Ltd) 3701-04 Metroplaza Tower 1 Hing Fong Road, Kwai Fong Hong Kong Telephone: (852) 26100 611 Fax: (852) 24250 494 asia.sales@zetex.com Corporate Headquarters Zetex Semiconductors plc Zetex Technology Park, Chadderton Oldham, OL9 9LL United Kingdom Telephone: (44) 161 622 4444 Fax: (44) 161 622 4446 hq@zetex.com © 2006 Published by Zetex Semiconductors plc 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 desi gn ideas. It is the responsibility of the user to ensure that t he circuit is fit for the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoev er is assumed by Zetex with respect to the accuracy or use of such in formation, or infringement of patents or other intellectual prop erty rights arising from such use or otherwise. Zetex does not assume any le gal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory duty, restricti on or otherwise) for any damages, loss of profit, business, con tract, 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 proper ly 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 devi ce 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 issu ed 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. 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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 ha s been discontinued Datasheet status key: “Draft version” This term denotes a very early datasheet ver sion 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 cont aining finalized specifications. However, changes to specifications may occur, at any time and without notice.