Diodes ZXCT1021 User Manual

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ZXCT1021 Low offset high-side current monitor

Description

The ZXCT1021 is a precision high-side current sense monitor. Using this type of device eliminates the need to disrupt the ground plane when sensing a load current.

The ZXCT1021 provides a fixed gain of 10 for applications where minimal sense voltage is required.

The very low offset voltage enables a typical accuracy of 3% for sense voltages of only 10mV,

Features

• Accurate high-side current sensing

• Output voltage scaling

• 2.5V – 20V supply range

•25␮A quiescent current

• 1% typical accuracy

• SOT23-5 package

giving better tolerances for small sense resistors necessary at higher currents.

The wide input voltage range of 20V down to as low as 2.5V make it suitable for a range of applications. With a minimum operating current of just 25µA, combined with its SOT235 package make it suitable for portable battery equipment too.

Applications

• Battery chargers

• Smart battery packs

• DC motor control

• Over current monitor

• Power management

• Level translating

• Programmable current source

Pinout information Typical application circuit

GND

OUT

Pinout - top view

SENSE

Ordering information

Order reference Package Device

marking

ZXCT1021E5TA SOT23-5 1021 Released 7 3000 8

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Status Reel size

(inches)

Quantity

per reel

Tape width

(mm)

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Absolute maximum ratings

ZXCT1021

Voltage on any pin

-0.6V to 20V

with respect to END pin

SENSE

-0.6V to VIN +0.5V

Operating temperature -40 to 85°C

Storage temperature -55 to 150°C

Package power dissipation (T

amb

= 25°C)

SOT23-5 300mW

Pinout information

Pin name Pin function

N/C Not internally connected

GND Ground

OUT

SENSE

SENSE+

Voltage output referenced to GND. Intended to drive high impedance loads

High impedance negative sense voltage input

Supply and positive sense voltage input

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ZXCT1021

NOTES:

Electrical characteristics test conditions T

= 25°C, VIN = 15V

amb

Symbol Parameter Conditions Limits Unit

Min. Typ. Max.

OUT

(*)

SENSE

LOAD

(†)

VCC range 2.5 20 V

Output voltage V

= 30mV 291 300 309 mV

SENSE

= 100mV 0.98 1.00 1.02 V

SENSE

= 150mV 1.47 1.50 1.53 V

SENSE

Output resistance 10 15 20 k⍀

Output voltage

50 300 ppm

temperature coefficient

Ground pin current V

Sense voltage VIN = 20V 0

SENSE-

load pin

= 0V 25 35 ␮A

SENSE

= 0V 100 nA

SENSE

1.5

(‡)

input current

Acc Accuracy V

Gain V

OUT

/ V

SENSE

BW Bandwidth V

= 100mV -2 2 %

SENSE

= 100mV 9.8 10 10.2 V/V

SENSE

= 10mV 300 kHz

SENSE

= 100mV 2 MHz

SENSE

(*) TC limits are determined by characterization

SENSE

= VIN - V

LOAD

voltages due to clipping of output voltage.

(†) V (‡) This will be reduced at lower V

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Typical characteristics

ZXCT1021

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Typical characteristics

ZXCT1021

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ZXCT1021

Application information

The ZXCT1021 has a fixed dc voltage gain of 100. No external scaling resistors are required for the output. Output voltage is simply defined as:

OUT

= 10 x V

SENSE

(V)

Where V

SENSE

= VIN - V

LOAD

PCB trace shunt resistor for low cost solution

Figure 1 shows a PCB layout suggestion for a low cost solution where a PCB resistive trace in replacement for a conventional shunt resistor, can be used. The resistor section is 25mm x

0.25mm giving approximately 150m⍀ using 1 oz copper. Smaller resistances can be used if required.

Total circuit solution: 1 component. Shows area of 150m⍀ sense resistor compared to SOT23 package.

Practical tolerance of the PCB resistor will be around 5% depending on manufacturing methods.

Figure 1 PCB layout suggestion

ZXCT1021/2

GND

OUT

Load

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Package outline - SOT23-5

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°

Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches

ZXCT1021

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ZXCT1021

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 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

2. support or sustain life and whose failure to perform when properly 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 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” “Obsolete” Production has been discontinued

Datasheet status key:

“Draft version” This term denotes a very early datasheet version and contains highly provisional information, which

“Provisional version” This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance.

“Issue” This term denotes an issued datasheet containing finalized specifications. However, changes to

Zetex sales offices

Europe

Zetex GmbH Kustermann-park Balanstraße 59 D-81541 München Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 europe.sales@zetex.com

Device is still in production to support existing designs and production

may change in any manner without notice.

However, changes to the test conditions and specifications may occur, at any time and without notice.

specifications may occur, at any time and without notice.

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

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