ZXCT1011 ZETEX | Alldatasheet
Document overview
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Technical content
Features
■ Accurate high-side current sensing ■ 2.5V to 20V supply range ■ 4 µA quiescent current ■ 1% typical accuracy ■ Package SOT23-5 ■ Temperature range -40 to 125°C
Applications
■ Automotive current measurement ■ Battery management ■ DC motor and solenoid control ■ Over current monitor ■ Power management Typical application circuit Pin connections
Ordering information
V Rsense ZXCT1011 Vsense+ Iout GND Vsense- Rshunt 120Ω 5 4 Rout N/C Iout Rshunt Vsense+ Vsense- Order code Pack Part mark Reel Size inches (mm) Tape width Quantity Per reel ZXCT1011E5TA SOT23-5 1011 7 (180) 8mm 3,000
Issue 1- July 2005 2 www.zetex.com © Zetex Semiconductors plc 2005 Absolute maximum ratings Vsense+ 20 V Voltage on any pin 0.6V and V sense+ +0.5V Vsense+ to Vsense- 2.5V Operating temperature -40 to 125°C Storage temperature -55 to 150°C Maximum junction temperature 150°C Package power dissipation 300mW at T A = 25°C (De-rate to zero at 150°C) Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability.
Electrical characteristics
Test conditions TA = 25°C, Vin = 5V, Rshunt = 120/H9024. Vsense=100mV. Unless otherwise stated. Symbol Parameter Conditions Min Typ. Max Units Vin NOTES: *V sense+ relative to Iout. Supply range - 2.5 - 20 V Iout Output current V sense = 0V =10mV =30mV =100mV =200mV =500mV 273 0.97 1.95 4.85 116 320 1.00 2.00 5.00 124 330 1.03 2.05 5.15 µA µA µA mA mA mA V sense Sense voltage† †V sense = (Vsense+) - (Vsense-). - 0 - 500 mV Isense - Vsense- input current - - - 100 nA Acc Accuracy Rsense = 0.1/H9024 Vsense = 100mV -3 - 3 % gm Transconductance Iout/Vsense Rshunt = 120/H9024 -1 0- m A / V Tc Temperature coefficient‡ ‡ Temperature dependent measurements are extracted from characterization and simulation results. - - 30 150 ppm/ ° C BW Where CL is the capacitance across Rout. Bandwidth V sense = 10mV CL = 5pF, Rout = 1k/H9024 Vsense = 100mV CL = 5pF, Rout = 1k/H9024 -4 0 0 1.5 -k H z MHz PSSR Supply rejection Vsense = 200mV, Rout=1k/H9024-6 8- d B
Issue 1- July 2005 3 www.zetex.com © Zetex Semiconductors plc 2005 Typical characteristics TA=25°C, Rshunt = 120 unless otherwise stated.
Issue 1- July 2005 4 www.zetex.com © Zetex Semiconductors plc 2005 Typical characteristics TA=25°C, Rshunt = 120 unless otherwise stated.
Issue 1- July 2005 5 www.zetex.com © Zetex Semiconductors plc 2005 Pin description
Application information
The following lines describe how to scale a load current to an output voltage. Vsense = (Vsense+) - (Vsense-) = Iload x Rsense Defining then I out = Iq + Vsense x gm since g m= 1.2 / Rshunt Iout = Iq + [ (V sense x 1.2) / Rshunt ] = Iq + [ (1.2 x I load x Rsense / Rshunt) ] Note: Iq is embedded into the specification of the ZXCT1011 and therefore appears an offset error. ∴ Vout = (Rout x Ioffset) + [(1.2 x Rout x Iload x Rsense) / Rshunt] The output current of the ZXCT1011 is directly related to the size of the trimming resistor used. It is important to ensure the tolerance of R shunt is considered. A 1% change in R shunt will cause a 1% change in output. Consider the following: - Pin no. Pin name Pin function
1 N/C No connection
2I out Output current - follows transconductance of sense voltage gm = 10mA/V for Rshunt=120/H9024 3R shunt Trimming resistor Input. - used to trim gain value 60/H9024 /H11349 Rshunt /H11349 240/H9024 4V sense- Low side current sense input. – connect to load/battery etc. Must be lower than Vsense+ for correct operation. Cannot be grounded without additional series resistor. 5V sense+ High side current sense input. – Connect to supply rail. Must be higher than Vsense+ for correct operation.
Issue 1- July 2005 6 www.zetex.com © Zetex Semiconductors plc 2005 A 1 ampere load current is to be measured into a battery. The output signal required to an over current controller needs to be 3.3V. What is a suitable value of R out and what will the error due to the supply current be? Vin = 5.0V - 9.0V Iload = 1.0A Output signal required: 3.3V Figure 1 ZXCT1011 to measure a 1.0 A load current To obtain the highest accuracy, choose the of Rsense to give 100mV: Rsense = 0.1/1.0 = 0.1/H9024 The transconductance using a 120/H9024 resistor will be 10mA/V. Choose Rout to give Vout = 3.3V, when Vsense = 100mV Rearranging equation 1 without the offset error gives: Rout = (Vout x Rshunt) / (1.2 x ILoad x Rsense) Rout = 3.3k/H9024 Now consider the offset error for this resistor: Offset due to supply current = Rout x 4x10-6µA = 13.2mV = 0.4% Vsense+ ZXCT 1011 sense-V Vin R sense Iload = 1A Iout 5 4 R Rshunt out Rload Rshunt 120R 3.3V = 5.0V - 9.0V
Issue 1- July 2005 7 www.zetex.com © Zetex Semiconductors plc 2005 Application information (cont.) Minimum operating voltage The minimum operating voltage of the ZXCT1011 is 2.5V and is defined as the difference between Vsense+ and the Iout pin. It must be ensured that sufficient headroom is given for the operation of the device when considering Rout. Figure 2 Considerations for supply rail Voltage across device 2.5V Vin - Vout 2.5V Where Vout = Iout x Rout At low supply voltages and high Vsense measurements, special care must be taken to ensure the correct operation. The circuit in figure 2.0 shows a ZXCT1011 ope rating from 10V supply rail. The minimum operating voltage of the ZXCT1011 is 2.5V. This allows a maximum output voltage of 7.5V to be set at V out. A 3k resistor on the output would draw a maximum 2.5mA from Iout. - See minimum usable supply voltage graph on page 4. Vsense+ ZXCT 1011 sense-V Vin Rsense loadTo Iout 5 4 3.3K Vout Rshunt R Rshunt 120R = 10V
Issue 1- July 2005 8 www.zetex.com © Zetex Semiconductors plc 2005 These offices are supported by agents and distributors in major countries world-wide. This publication is issued to provide outline information only wh ich (unless agreed by the company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contact or be regarded as a representation relating to the products or services concerned. The company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. Europe Zetex GmbH Streitfeldstraße 19 D-81673 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 Packaging details - SOT23-5