ZXCT1051 ZETEX | Alldatasheet
Document overview
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Technical content
Features
Accurate down to end current sensing Output voltage scaling x10 0 to VCC-2V sense input range 2.7 to 20V supply range 50 µA quiescent current 1% typical accuracy SOT23-5 package Pin connections The ZXCT1051 provides a fixed gain of 10 thereby removing the need for an additional resistor.
Applications
DC motor and solenoid control Battery management Over current monitor Power management Short circuit detection Typical application circuit
Ordering information
(inches) Tape width (mm) Quantity per reel ZXCT1051E5TA SOT23-5 1051 3,000
www.zetex.com © Zetex Semiconductors plc 2006 Absolute maximum ratings VCC max. 20V Voltage on VSENSE- and VSENSE+ -0.6 to VCC Voltage on all other pins -0.6V and VCC +0.6V VSENSE "(VSENSE+) - (VSENSE-) 500 mV Operating temperature, TA -40 to 125°C Storage temperature -55 to 150°C Maximum junction temperature 150°C Package power dissipation 300mW at TA = 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. Recommended operating conditions Pin function table Parameter Min. Max. Units VSENSE+ Common-mode sense input range VCC-2 V VCC Supply voltage range 2.7 V VSENSE Differential sense input voltage range 0.3 V VOUT Output voltage range VCC - 2 V TA Ambient temperature range -40 125 PIN Name
Description
This is the analog supply and provides power to internal circuitry GND Ground pin OUT Output voltage pin. NMOS source follower with 20µA bias to ground VSENSE+ This is the positive input of the current monitor and has an input range from 0V up to VCC – 2V. The current through this pin varies with differential sense voltage VSENSE- This is the negative input of the current monitor and has an input range from 0V up to VCC – 2V
www.zetex.com © Zetex Semiconductors plc 2006
Electrical characteristics
Test conditions TA = 25°C, VSENSE+ = 10V, VCC = 12V, VSENSE = 100mV NOTES: (a) VSENSE = "VSENSE+" - "VSENSE-" (b)Temperature dependent measurements are extracted from characterization and simulation results. Symbol Parameter Conditions Min. Typ. Max. Units IQ VCC pin current VSENSE = 0V µA VOUT Output voltage VSENSE = 0V =30mV =100mV =150mV 291 0.98 1.45 300 1.00 1.50 309 1.02 1.55 mV mV V V ISENSE+ VSENSE+ input current VSENSE = 0V TBD TBD µA ISENSE- VSENSE- input current VSENSE = 0V 150 nA VOUT TC VOUT variation with temperature See note (b) 300 ppm/ºC ROUT Output resistance 2.5 3.75 k Gain VOUT/VSENSE Accuracy Total output error BW Bandwidth VSENSE(DC) = 10mV VSENSE(AC) = 10mVPP CL = 5pF, 300 kHz VSENSE(DC) = 100mV MHz PSRR Power supply rejection ratio VCC = 2.7V to 20V VSENSE+ = 0.7V TBD TBD dB CMRR Common mode rejection ratio VCC = 20V VSENSE+ = 0 to 18V TBD TBD dB
www.zetex.com © Zetex Semiconductors plc 2006 Typical characteristics Test conditions unless otherwise stated: TA = 25°C, VCC = 12V, VSENSE+ =10V, VSENSE = 100mV DC characteristics Y-axis X-axis Variables ICC VCC (0 to 20V) TA = -40, 25, 85, 125°C, VSENSE = 0V VSENSE+ = 0V VCC (2 to 20V) TA = -40, 25, 85, 125°C, VSENSE = 0V VSENSE+ = VCC - 2V ISENSE+ VSENSE+ (0 to 18V) TA=25°C, VSENSE = 0V, VCC = 20V ISENSE+ TA VSENSE = 0V, VSENSE+ = 18V VCC = 20V ISENSE- VSENSE+ (0 to 18V) TA=25°C, VSENSE = 0V, VCC = 20V VOUT VSENSE VOUT TA VSENSE = 10mV, 50mV, 100mV. VOH IOH source Output source current swept VOL IOL sink Differential gain VSENSE Differential sense voltage swept and differential gain calculated ∆VOUT VSENSE+ (0 to 18V) VSENSE = 10mV, 50mV, 100mV, 150mV ∆VOUT VCC (0 to 20V) VSENSE = 10mV, 50mV, 100mV, 150mV AC and transient characteristics Small signal bandwidth Frequency VSENSE(DC) = 10mV, VSENSE(AC) = 10mVPP VSENSE(DC) = 100mV, VSENSE(AC) = 10mVPP Large signal response Time VSENSE+ = 12V, VSENSE- = 0V to -0.2V to +0.2V to 0V Small signal response Time VSENSE+ = 12V, VSENSE- = 0V to -0.01V to +0.1V to 0V PSRR Frequency VCC(AC) = 10mVPP CMRR Frequency VSENSE+(AC) = 10mVPP
www.zetex.com © Zetex Semiconductors plc 2006
Application information
The ZXCT1051 is Zetex’ first current monitor with a separate power supply pin. All biasing for the internal amplifiers comes from its separate VCC input and is not ‘line powered’, unlike the ZXCT1021. This means that at very small sense voltages the ZXCT1051 draws very little current (<1µA) from the lines being sensed. The separate VCC pin enables the ZXCT1051 to be operated at sense line voltages down to 0V, where the ZXCT1021 would switch off. This feature enables the ZXCT1051 to be used to sense the currents flowing through lines that have been shorted to ground and is Zetex’ first current monitor to do this. Basic operation Load current from VIN is drawn through RSENSE developing a voltage VSENSE across the ZXCT1051. The internal amplifier forces VSENSE across internal resistance RSH causing a current to flow through transistor Q1. This current is then converted to a voltage by RG. A ratio of 10:1 between RSH and RG creates the fixed gain of 10 with an output impedance equal to RG (see electrical characteristics for output current-voltage characteristics). The gain equation of the ZXCT1051 is: The maximum differential input voltage, VSENSE, is 150mV (IL * RSENSE); however voltages up to 500mV will not damage it. This can be increased further by the inclusion of a resistor, RLIM, between VSENSE- pin and the load. For best performance RSENSE should be connected as close to the VSENSE+ and VSENSE- pins thus minimizing any series resistance with RSENSE. RSENSE VSENSE+ VSENSE- VOUT VCC VRAIL RG RSH GND GND Load VSENSE ILRSENSE RG RSH
www.zetex.com © Zetex Semiconductors plc 2006 The ZXCT1051 has been designed to allow it to operate from supplies (VCC) ranging from 2.7V to 20V while sensing common mode signals from 0V up to VCC -2V. 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 ZXCT1051 has been designed to operate with VSENSE of the order of 50mV to 150mV. Due to the very nature of current monitors they tend to saturate at very low sense voltages. This is due to them being operated from single supply and that the basic configuration is that of a unipolar voltage to current to voltage converter. The internal amplifiers at the heart of the current monitor may well have a bipolar offset voltage but the output cannot go negative. For this reason the ZXCT1051 has been designed 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. The device has a fixed DC voltage gain of 10; no external scaling resistors are required for the output. Output voltage is simply defined as: VOUT = gain x VSENSE (V)
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www.zetex.com © Zetex Semiconductors plc 2006 For international sales offices, agents and distributors please go to www.zetex.com/salesnetwork This publication is 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 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
700 Veterans Memorial Highway
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 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 0.00 0.15 0.00 0.0059 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 1.30 1.80 0.0511 0.0708 e
0.95 REF
0.0374 REF
1.90 REF
0.0748 REF
L 0.10 0.60 0.0039 0.0236 30° 30°