ZXCT1020 ZETEX | Alldatasheet
Document overview
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Technical content
Features
- Accurate high-side current sensing Versatile current output scaling 2.5V - 20V operating range 25µA quiescent current 1% typical accuracy SOT23-5 package
Applications
Battery chargers Over-current monitor Motherboard power supply current measurement Level translating Programmable current source Pinout information Typical application circuit Order reference Package Device marking Status Reel size (inches) Quantity per reel Tape width (mm) ZXCT1020E5TA SOT23-5 1020 Preview 7 3000 8 GND OUT VB Top view (LOAD)VB IL RSH RS GND VOUT ZXCT102023 RG
Issue 1 - August 2007 2 www.zetex.com © Zetex Semiconductors plc 2007 Absolute maximum ratings NOTES: (a) Subject to VSENSE+ never going 6V below VB. (b) Subject to absolute maximum VSENSE not being exceeded. (c) VSENSE is defined as the voltage difference across the se nse resistor. and is the voltage across resistor R SH plus the voltage between S+ and S-. (d) VSENSE might need to be reduced when used with smaller values of RSH and at larger rails due to increased power dissipation. Pin out information Recommended operating conditions Recommended resistor gain setting combinations Voltage on VB with respect to GND pin -0.5V to 20V Voltage on S+(a), S-(b), OUT with respect to GND pin -0.5V to VB+0.5V VSENSE(c) -0.5V to +2.5V(d) Junction temperature -40°C to125°C Storage temperature -55°C to 150°C Package power dissipation (T amb = 25°C) SOT23-5 300mW Pin Name Pin function 1 S+ Positive sense input. Should be tied to positive side of sense resistor via resistance (RSH) of the order of 150/H9024 to 1.5k/H9024. 2 GND Ground and substrate connection of device. 3 OUT Current output. A gain setting resistor (R G) referenced to GND should be connected to this pin to set overall voltage gain of: Gain = RG/RSH The resistance, RG, placed on out will set the ZXCT1020 output impedance equal to RG. When driving low impedance loads both RG and RSH should be reduced. 4V B Input voltage pin. Provides bias to current monitor and should be tied to the rail whose current is being monitored.
5 S- High impedance negative sense voltage input
Parameter Min. Max. Units VSENSE+ Common-mode sense input range 2.5 20 V VB Bias pin input voltage range (*) NOTES: (*) For best performance VB and VSENSE+ should be referred to the rail whose current is being measured. 2.5 20 V VSENSE Differential sense Input voltage range 0 1.5 V VOUT Output voltage range 0 V SENSE- - 1 V RSH Shunt resistor value 120 2000 /H9024 TA Ambient temperature range -40 85 °C Gain R SHUNT RGAIN 10 1.5k /H9024 15k/H9024 20 750 /H9024 15k/H9024 50 300 /H9024 15k/H9024 100 150 /H9024 15k/H9024
Issue 1 - August 2007 3 www.zetex.com © Zetex Semiconductors plc 2007
Electrical characteristics
Tamb = 25°C, VSENSE+ = VB = 15V, VSENSE = 100mV, RG = 15k/H9024, RSH = 1.5k/H9024 unless otherwise stated. Symbol Parameter Conditions Limits Unit Min. Typ. Max. VOUT Output voltage V SENSE = 0mV 3 15 mV VSENSE = 30mV 291 300 309 mV VSENSE = 100mV 0.98 1 1.02 V VSENSE = 150mV 1.47 1.5 1.53 V TC[1] Output voltage temperature coefficient 50 300 ppm IQ Ground pin current V SENSE = 0V 25 35 /H9262A IS- S- input current V SENSE = 0V 20 100 nA IS+ S+ input current V SENSE = 0V 100 nA Acc Accuracy V SENSE = 100mV -2 2 % Gain V OUT /VSENSE VSENSE = 100mV 10 V/V ROUT Output resistance R G not connected 370 M /H9024 BW Bandwidth V SENSE (DC) = 10mV 300 kHz VSENSE (DC) = 100mV 2 MHz PSRR Power supply rejection ratio V SENSE+ = VB = 2.5 to 20V 70 80 dB
Issue 1 - August 2007 4 www.zetex.com © Zetex Semiconductors plc 2007 Typical characteristics Test conditions unless otherwise stated: TA = 25°C, VB = VSENSE+ (via RSH) =15V, VSENSE = 100mV RSH = 1.5k/H9024, RG = 15k/H9024. Supply current v Temperature
Issue 1 - August 2007 5 www.zetex.com © Zetex Semiconductors plc 2007 Test conditions unless otherwise stated: TA = 25°C, VB = VSENSE+ (via RSH) =15V, VSENSE = 100mV Gain = 10, RG = 15k/H9024.
Issue 1 - August 2007 6 www.zetex.com © Zetex Semiconductors plc 2007 Test conditions unless otherwise stated: TA = 25°C, VB = VSENSE+ (via RSH) =15V, VSENSE = 100mV Gain = 20, RG = 15k/H9024.
Issue 1 - August 2007 7 www.zetex.com © Zetex Semiconductors plc 2007 Test conditions unless otherwise stated: TA = 25°C, VB = VSENSE+ (via RSH) =15V, VSENSE = 100mV RG = 15k/H9024. ° ° VSENSE = 10mV Gain = 100
Issue 1 - August 2007 8 www.zetex.com © Zetex Semiconductors plc 2007 Typical AC characteristics Test conditions unless otherwise stated: TA = 25°C, VB = VSENSE+ (via RSH) =15V, VSENSE = 100mV, RG = 15k/H9024. Gain = 10 Gain = 50
Issue 1 - August 2007 9 www.zetex.com © Zetex Semiconductors plc 2007 Test conditions unless otherwise stated: TA = 25°C, RG=15k, VB = VSENSE+ (via RSH) =15V, VSENSE = 100mV unless otherwise stated. Various gains with constant RG
Issue 1 - August 2007 10 www.zetex.com © Zetex Semiconductors plc 2007 Test conditions unless otherwise stated: TA = 25°C, G=100, RG = 15k, VB = VSENSE+ (via RSH), VSENSE = 100mV.
Issue 1 - August 2007 11 www.zetex.com © Zetex Semiconductors plc 2007
Application information
The ZXCT1020 has a VB pin that is used to provide power to the current monitor. The maximum voltage applied to the ZXCT1020 must be applied to this pin. The S+ and S- pins are used to measure the current flowing to the load through th e sense resistor. In normal use, the S+ is tied to VB via a shunt resistor, RH making the ZXCT1020 essentially line powered. The ZXCT1020 has a programmable gain set by the ratio of two external resistors R G and RSH. RSH sets the transconductance whereas R G set the gain and results in an output voltage defined as: Where VSENSE = RSENSE x IL The ZXCT1020 has been tested to the same conditions as the ZXCT1021 giving an overall voltage gain of 10. The gain of the ZXCT1020 can be adjusted simply by varying RG. So to achieve a gain of 50 RG is increased from 15k/H9024 to 75k/H9024. An alternative is to decrease RSH from 1.5k/H9024 to 300/H9024. Decreasing RSH increases the transconductance and, if for any given gain, reducing the R SH will reduce the overall output impedance. To achieve a gain of 100, for example, the following resistor values could be used: RSH = 150 RG = 15k (LOAD)VB IL RSH RS GND VOUT ZXCT102023 RG VOUT RG RSH
Issue 1 - August 2007 12 www.zetex.com © Zetex Semiconductors plc 2007 Intentionally left blank
Issue 1 - August 2007 13 www.zetex.com © Zetex Semiconductors plc 2007 Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches Dim. Millimeters Inches Min. Max. Min. Max. A 0.90 1.45 0.0354 0.0570 A1 0.00 0.15 0.00 0.0059 A2 0.90 1.30 0.0354 0.0511 b 0.20 0.50 0.0078 0.0196 C 0.09 0.26 0.0035 0.0102 D 2.70 3.10 0.1062 0.1220 E 2.20 3.20 0.0866 0.1181 E1 1.30 1.80 0.0511 0.0708 e 0.95 REF 0.0374 REF e1 1.90 REF 0.0748 REF L 0.10 0.60 0.0039 0.0236 a° 0° 30° 0° 30°
Issue 1 - August 2007 14 www.zetex.com © Zetex Semiconductors plc 2007 Zetex sales offices Europe Zetex GmbH Kustermannpark 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 © 2007 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.