SEMICONDUCTORS
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
applicationswhereminimalsensevoltageisrequired.
The very low offset voltage enables a typical accuracy
of 3% for sense voltages of only 10mV, giving better
tolerances for small sense resistors necessary at
higher currents.
The wide input voltage range of 20V down to as low as
2.5Vmakeitsuitableforarangeofapplications.Witha
minimum operating current of just 25µA, combined
with its SOT23-5 package make it suitable for portable
battery equipment too.
FEATURES
•Accurate high-side current sensing
•Output voltage scaling
•2.5V – 20V supply range
•25␮A quiescent current
•1% typical accuracy
•SOT23-5 package
PARTMARK
1021
APPLICATIONS
•Battery Chargers
•Smart Battery Packs
•DC Motor control
•Over current monitor
•Power Management
•Level translating
•Programmable current source
ZXCT1021
ISSUE 2 - MARCH 2004
LOW OFFSET HIGH-SIDE CURRENT MONITOR
1
TYPICAL CIRCUIT APPLICATION
DEVICE REEL
SIZE TAPE
WIDTH QUANTITY PER
REEL
ZXCT1021E5TA 7” 8mm 3,000 units
ORDERING INFORMATION
Absolute Maximum Ratings
Voltage on any pin -0.6V to 20V
Vsense -0.6V to Vin +0.5V
Operating Temperature -40 to 85°C
Storage Temperature -55 to 150°C
Package Power Dissipation (TA= 25°C)
SOT23 450mW
ZXCT1021
SEMICONDUCTORS
ISSUE 2 - MARCH 2004
2
SYMBOL PARAMETER CONDITIONS LIMITS UNIT
Min Typ Max
Vin VCC range 2.5 20 V
Vout Output voltage
(ZXCT1021) Vsense = 30mV
Vsense = 100mV
Vsense = 150mV
291
0.98
1.47
300
1.00
1.50
309
1.02
1.53
mV
V
V
Rout Output resistance 10 15 20 K⍀
TcOutput temperature
coefficient 50 300 ppm
IqGround pin current Vsense =0V 25 35 ␮A
Vsense(2) Sense voltage 0 1.5 V
Isense Load pin
input current 100 nA
Acc Accuracy Vsense = 100mV -2 2 %
Gain Vout /V
sense Vsense = 100mV 98 100 102 mV
BW Bandwidth Vsense = 10mV
Vsense = 100mV 300
2kHz
MHz
ELECTRICAL CHARACTERISTICS Test Conditions TA= 25°C, Vin = 15V
NOTES
(2) Vsense= Vin -V
load
ZXCT1021
SEMICONDUCTORS
ISSUE 2 - MARCH 2004
3
TYPICAL CHARACTERISTICS
TYPICAL CHARACTERISTICS
ZXCT1021
SEMICONDUCTORS
ISSUE 2 - MARCH 2004
4
BLOCK DIAGRAM
Application Information
The devices have fixed dc voltage gains of 10, no external scaling resistors are required for the output. Output
voltage is simply defined as:
Where Vsense = Vin - VLoad
PCB trace shunt resistor for low cost solution
The figure below 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 150mΩusing 1 oz copper. Smaller resistances can be used if required.
Total circuit solution: 1 component. Shows area of 150mΩsense resistor
compared to SOT23 package.
Practical tolerance of the PCB resistor will be around 5% depending on
manufacturing methods.
ZXCT1021
SEMICONDUCTORS
ISSUE 2 - MARCH 2004
5
Vout = 10 x Vsense (V)
GND Load
N/C
GND
Vout Vin
Load
4
1
2
3
5
Top view
PINOUT PIN NAME PIN FUNCTION
N/C Not internally connected
GND Ground
Vout Voltage output referenced to GND. Intended to
drive high impedance loads
Load High impedance negative sense voltage input
Vin Supply and positive sense voltage input
ZXCT1021
SEMICONDUCTORS
6
ISSUE 2 - MARCH 2004
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 Hwy
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 Headquaters
Zetex plc
Fields New Road, Chadderton
Oldham, OL9 8NP
United Kingdom
Telephone (44) 161 622 4444
Fax: (44) 161 622 4446
hq@zetex.com
These offices are supported by agents and distributors in major countries world-wide.
Thispublicationisissued toprovide outlineinformation onlywhich (unlessagreed bythe Companyin writing)may notbe used,applied orreproduced
for any purpose or form part of any order or contract 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.
For the latest product information, log on to www.zetex.com
© Zetex plc 2004
DIM Millimetres Inches
MIN MAX MIN MAX
A 0.90 1.45 0.035 0.057
A1 0.00 0.15 0.00 0.006
A2 0.90 1.3 0.035 0.051
b 0.35 0.50 0.014 0.020
C 0.09 0.20 0.0035 0.008
D 2.80 3.00 0.110 0.118
E 2.60 3.00 0.102 0.118
E1 1.50 1.75 0.059 0.069
e 0.95 REF 0.037 REF
e1 1.90 REF 0.075 REF
L 0.10 0.60 0.004 0.024
PACKAGE DIMENSIONSPACKAGE DIMENSIONS SOT23-5