ZXCT1010 DIODES | Alldatasheet

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Technical content

DESCRIPTION

The ZXCT1010 is a high side current sense monitor. Using this device eliminates the need to disrupt the ground plane when sensing a load current. It is an enhanced version of the ZXCT1009 offering reduced typical output offset and improved accuracy at low sense voltage. The wide input voltage range of 20V down to as low as 2.5V make it suitable for a range of applications. A minimum operating current of just 4µA, combined with its SOT23-5 package make suitable for portable battery equipment.

FEATURES

  • Low cost, accurate high-side current sensing
  • Output voltage scaling
  • Up to 2.5V sense voltage
  • 2.5V – 20V supply range
  • 300nA typical offset current
  • 3.5µA quiescent current
  • 1% typical accuracy
  • SOT23 -5 package

APPLICATIONS

  • Battery chargers
  • Smart battery packs
  • DC motor control
  • Over current monitor
  • Power management
  • Programmable current source ENHANCED HIGH-SIDE CURRENT MONITOR APPLICATION CIRCUIT DEVICE REEL SIZE TAPE WIDTH QUANTITY PER REEL ZXCT1010E5TA 7” 8mm 3,000 units PARTMARK 101 PACKAGE SOT23-5

ORDERING INFORMATION

Voltage on any pin -0.6V to 20V (relative to GND) Continuous output current, IOUT, 25mA Continuous sense voltage, VSENSE 2, -0.5V to +5V Operating temperature, TA, -40 to 85°C Storage temperature -55 to 150 °C Package power dissipation (T A = 25°C) SOT23-5 300mW 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, Rout = 100Ω. SYMBOL PARAMETER CONDITIONS LIMITS UNIT Min Typ Max Vin VCC Range 2.5 20 V Iout 1 Output current V sense =0 V Vsense = 10mV Vsense =1 0 0 m V Vsense = 200mV Vsense =1 V 0.975 1.95 9.7 0.3 100 1.00 2.00 10.0 115 1.025 2.05 10.3 µA µA mA mA mA I q Ground pin current Vsense =0 V 3 . 5 8 µ A Vsense 2 Sense Voltage 0 2500 mV Isense -V sense - input current 100 nA Acc Accuracy Rsense =0 . 1Ω Vsense =2 0 0 m V -2.5 2.5 % Gm Transconducta nce, Iout /V sense 10000 µA/V BW Bandwidth V SENSE(DC) = 10mV, Pin = -40dBm ‡ VSENSE(DC) = 100mV, Pin = -20dBm ‡ 300 kHz MHz

1 Includes input offset voltage contribution

2 VSENSE is defined as the differential voltage between VSENSE+ and VSENSE-. VSENSE = VSENSE+ - VSENSE- = VIN - VLOAD = ILOAD x RSENSE 3 -20dBm=63mVp-p into 50Ω ISSUE 10 - JULY 2007

Vsense - Connection to load/battery Iout Output current, proportional to V in-Vload GND Ground SOT23-5 Package Suffix – E5 Top View CONNECTION DIAGRAM SCHEMATIC DIAGRAM

The following lines describe how to scale a load current to an output voltage. Vsense = Vin -V load Vout = 0.01 x Vsense x Rout1 E.g. A 1A current is to be represented by a 100mV output voltage: 1)Choose the value of Rsense to give 50mV > Vsense > 500mV at full load. For example Vsense = 100mV at 1.0A. Rsense = 0.1/1.0 => 0.1 ohms. 2)Choose Rout to give Vout = 100mV, when V sense = 100mV. Rearranging 1 for Rout gives: Rout =V out /(Vsense x 0.01) Rout = 0.1 / (0.1 x 0.01) = 100 Ω TYPICAL CIRCUIT APPLICATION POWER DISSIPATION The maximum allowable power dissipation of the device for normal operation (Pmax), is a function of the package junction to ambient thermal resistance (θja), maximum junction temperature (Tjmax), and ambient temperature (Tamb), according to the expression: P max = (Tjmax – Tamb) / θja The device power dissipation, P D is given by the expression: PD=Iout.(Vin-Vout) Watts Where Rload represents any load including DC motors, a charging battery or further circuitry that requires monitoring, R sense c a nb es e l e c t e do ns p e c i f i c requirements of accuracy, size and power rating. APPLICATIONS INFORMATION

The above figure shows the ZXCT1010 supporting the Benchmarq bq2954 Charge Management IC. Most of the support components for the bq2954 are omitted for clarity. This design also uses the Zetex FZT789A high current Super-/H9252PNP as the switching transistor in the DC-DC step down converter and the FMMT451 as the drive NPN for the FZT789A. The circuit can be configured to charge up to four Li-Ion cells at a charge current of 1.25A. Charge can be terminated on maximum voltage, selectable minimum current, or maximum time out. Switching frequency of the PWM loop is approximately 120kHz. 100Ω 0.2Ω 100Ω FZT789A BC81725 1kΩ BAS16 10µH FMMT451 140µH ZHCS1000 220Ω SNS pin MOD pin Charger Input To Battery + bq2954 ZXCT1010 support components omitted for clarity + - Vin Load Iout APPLICATIONS INFORMATION (Continued) Bi-Directional Current Sensing The ZXCT1010 can be used to measure current bi-directionally, if two devices are connected as shown below. If the voltage V1 is positive with respect to the voltage V2 the lower device will be active, delivering a proportional output current to Rout. Due to the polarity of the voltage across Rsense, the upper device will be inactive and will not contribute to the current delivered to Rout. When V2 is more positive than V1, current will be flowing in the opposite direction, causing the upper device to be active instead. Non-linearity will be apparent at small values of Vsense due to offset current contribution. Devices can use separate output resistors if the current direction is to be monitored independently. Bi-directional Transfer Function -400 -200 0 200 400 Output Current (mA) Sense Voltage (mV) Output Current v Sense Voltage

PCB trace shunt resistor for low cost solution The figure below shows output characteristics of the device when using a PCB resistive trace for a low cost solution in replacement for a conventional shunt resistor. The graph shows the linear rise in voltage across the resistor due to the PTC of the material and demonstrates how this rise in resistance value over temperature compensates for the NTC of the device. The figure opposite shows a PCB layout suggestion. The resistor section is 25mm x 0.25mm giving approximately 150mΩ using 1oz copper. The data for the normalised graph was obtained using a 1A load current and a 100 Ω output resistor. An electronic version of the PCB layout is available at www.zetex.com/isense APPLICATIONS INFORMATION (Continued) Layout shows area of shunt resistor compared to SOT23-5 package. Not actual size Actual Size

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 design ideas. It is the responsibility of the user to ensure that the circuit is fit for the user's application and meets with the user's requirements. No representation or warranty is given and no liability whatsoever is assumed by Zetex with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Zetex does not assume any legal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract, 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 properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device 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 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 contract or be regarded as a representation relating to the products or services concerned. Terms and Conditions All products are sold subjects to Zetex' terms and conditions of sale, and this disclaimer (save in the event of a conflict between the two when the terms of the contract shall prevail) according to region, supplied at the time of order acknowledgement. For the latest information on technology, delivery terms and conditions and prices, please contact your nearest Zetex sales office. Quality of product Zetex is an ISO 9001 and TS16949 certified semiconductor manufacturer. To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our regionally authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com/salesnetwork Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels. ESD (Electrostatic discharge) Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices. The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time. Devices suspected of being affected should be replaced. Green compliance Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding regulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with WEEE and ELV directives. Product status key: "Preview"Future device intended for production at some point. 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 has been discontinued Datasheet status key: "Draft version"This term denotes a very early datasheet version 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

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