ZXCT1081E5TA

A Product Line of Diodes Incorporated ZXCT1081 HIGH VOLTAGE HIGH-SIDE CURRENT MONITOR Description Pin Assignments The ZXCT1081 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. VCC 1 GND 2 The wide input voltage range of 40V down to as low as 3V make it suitable for a range of applications; including systems operating from industrial 24-28V rails and power supplies. OUT 3 Features Applications • • • 3V to 40V continuous high side voltage Accurate high-side current sensing Output voltage scaling x10 • 4.5V to 12V VCC range • Low quiescent current: o 80 μA supply pin • • • • • • o • • 5 SENSE- 4 SENSE+ Automotive current measurement Industrial applications current measurement Battery management Over current monitor Power management Power adapters 30 μA ISENSE+ SOT23-5 package -40°C to 125°C ambient temperature range Typical Application Circuit VIN R SENSE 4 SENSE+ VCC 1 5 SENSE- ZXCT1081 Vcc GND 2 OUT 3 V OUT ZXCT1081 Document number: DS32102 Rev. 1 - 2 1 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Pin Description Pin Name Description 1 2 3 VCC GND OUT 4 SENSE+ 5 SENSE- This is the analogue supply and provides power to internal circuitry Ground pin Output voltage pin. NMOS source follower with 20μA bias to ground This is the positive input of the current monitor and has an input range from 40V (60V transient) down to 3V. The current through this pin varies with differential sense voltage This is the negative input of the current monitor and has an input range from 40V (60V transient) down to 3V Absolute Maximum Ratings Parameter Continuous Voltage on SENSE+ and SENSETransient Voltage on SENSE+ and SENSEVoltage On All Other Pins Differential Sense Voltage, VSENSE Operating Temperature Storage Temperature Maximum Junction Temperature Package Power Dissipation Rating -0.6 and 45 -0.6 and 65 -0.6 and 14 800 -40 to 125 -55 to 150 125 300 @ TA= 25°C Unit V V V mV °C °C °C (de-rate to zero at 125°C) mW 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 Symbol Parameter Min Max Units 3 40 V 4.5 12 V Differential Sense Input Voltage Range 0 0.15 V Output Voltage Range 0 1.5 V -40 125 °C VIN Common-Mode Sense+ Input Range VCC Supply Voltage Range VSENSE VOUT TJ Ambient Temperature Range ZXCT1081 Document number: DS32102 Rev. 1 - 2 2 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Electrical Characteristics (Test conditions: TA = 25°C, VIN = 12V, VCC = 5V, VSENSE(a) = 100mV unless otherwise stated) Symbol ICC ISENSE+ ISENSEVO(0) VO(10) Gain (d) VOUTTC ACC IOH IOL PSRR CMRR BW Notes: Parameter VCC Supply Current SENSE+ Input Current SENSE- Input Current (a) (b) Zero VSENSE error (c) Output Offset Voltage (a) ΔVOUT/ΔVSENSE VOUT Variation with Temperature Total Output Error Output Source Current Output Sink Current VCC Supply Rejection Ration Common-Mode Sense Rejection Ratio -3dB Small Signal Bandwidth Condition VCC = 12V (a) VSENSE = 0V (a) VSENSE = 10mV (a) VSENSE = 10mV to 150mV Min. 40 15 10 0 -30 9.95 Typ. 80 30 40 10 30 -3 VOUT = 30mV VOUT = +30mV VCC = 4.5V to 12V VIN + 40V to 3V (a) VSENSE (AC) = 10mVpp 54 60 Max. 120 60 80 35 +30 10.05 3 1 20 60 75 50 Unit µA µA nA mV mV ppm/°C % mA µA dB dB kHz (a) VSENSE = "VSENSE+" - "VSENSE-" (b) The ZXCT1081 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. ZXCT1081 Document number: DS32102 Rev. 1 - 2 3 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Typical Operating Conditions (Test conditions: TA = 25°C, VCC = 5V, VSENSE+ = 12V, VSENSE = 100mV) ZXCT1081 Document number: DS32102 Rev. 1 - 2 4 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Typical Operating Conditions (Cont.) ZXCT1081 Document number: DS32102 Rev. 1 - 2 5 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Typical Operating Conditions (Cont.) ZXCT1081 Document number: DS32102 Rev. 1 - 2 6 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Typical Operating Conditions (Cont.) ZXCT1081 Document number: DS32102 Rev. 1 - 2 7 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Application Information The ZXCT1081 has been designed to allow it to operate with 5V supply rails while sensing common mode signals up to 40V. 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 SENSE+. Figure 1 shows the basic configuration of the ZXCT1081. Input RSENSE SENSE+ Load SENSE- ZXCT1081 RSH VCC A1 M1 OUT A2 +1 RG GND Figure 1 Typical Configuration of ZXCT1081 Load current from the input is drawn through RSENSE developing a voltage VSENSE across the inputs of the ZXCT1081. The internal amplifier forces VSENSE across internal resistance RSH 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 RSH creates the fixed gain of 10. The output is then buffered by the unity gain buffer. The gain equation of the ZXCT1081 is: VOUT = IL RSENSE RG RSH x 1 = x RSENSE x 10 The maximum recommended differential input voltage, VSENSE, is 150mV; it will however withstand voltages up to 800mΩ. This can be increased further by the inclusion of a resistor, RLIM, between SENSE- pin and the load; typical value is of the order of 10k . ZXCT1081 Document number: DS32102 Rev. 1 - 2 8 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 RSENSE RLIM CD SENSE+ SENSE- ZXCT1081 Figure 2 Protection/Error Sources for ZXCT1081 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 SENSE+ (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 ZXCT1081 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 ZXCT1081 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: VOUT = (VSENSE) xG + VO(10) Alternatively the load current can be expressed as: IL = VOUT – VO(10) GxRSENSE ZXCT1081 Document number: DS32102 Rev. 1 - 2 9 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 Package Outline – 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 1.3 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 ZXCT1081 Document number: DS32102 Rev. 1 - 2 10 of 11 www.diodes.com March 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXCT1081 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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