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ISSUE 10 - JULY 2007

SEMICONDUCTORS

ZXCT1010

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

Summary of content (9 pages)

PAGE 1
ZXCT1010 ENHANCED HIGH-SIDE CURRENT MONITOR 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. APPLICATIONS 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.
PAGE 2
ZXCT1010 ABSOLUTE MAXIMUM RATINGS Voltage on any pin Continuous output current, IOUT, Continuous sense voltage, VSENSE2, Operating temperature, TA, Storage temperature Package power dissipation SOT23-5 -0.6V to 20V (relative to GND) 25mA -0.5V to +5V -40 to 85°C -55 to 150°C (TA = 25°C) 300mW Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for extended periods, may reduce device reliability.
PAGE 3
ZXCT1010 TYPICAL CHARACTERISTICS ISSUE 10 - JULY 2007 3 SEMICONDUCTORS
PAGE 4
ZXCT1010 PIN DESCRIPTION Pin Name Pin Function V sense + Supply voltage V sense - Connection to load/battery I out Output current, proportional to V in -V load GND Ground CONNECTION DIAGRAM SOT23-5 Package Suffix – E5 Top View SCHEMATIC DIAGRAM ISSUE 10 - JULY 2007 4 SEMICONDUCTORS
PAGE 5
ZXCT1010 POWER DISSIPATION APPLICATIONS INFORMATION 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: The following lines describe how to scale a load current to an output voltage. Vsense = Vin - Vload Vout = 0.01 x Vsense x Rout1 Pmax = (Tjmax – Tamb) / θja E.g.
PAGE 6
ZXCT1010 Bi-Directional Current Sensing APPLICATIONS INFORMATION (Continued) FZT789A 140µH Charger Input BC81725 The ZXCT1010 can be used to measure current bi-directionally, if two devices are connected as shown below. To Battery + 0.2Ω ZHCS1000 1kΩ Vin Load 100Ω BAS16 10µH + - 5V bq2954 MOD pin ZXCT1010 FMMT451 220Ω Iout SNS pin 100Ω support components omitted for clarity Li-Ion Charger Circuit The above figure shows the ZXCT1010 supporting the Benchmarq bq2954 Charge Management IC.
PAGE 7
ZXCT1010 APPLICATIONS INFORMATION (Continued) 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.
PAGE 8
ZXCT1010 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.
PAGE 9
ZXCT1010 PAD LAYOUT DETAILS PACKAGE DIMENSIONS Controlling dimensions are in millimeters. Approximate conversions are given in inches PACKAGE DIMENSIONS DIM Millimeters Inches MIN MAX MIN MAX A 0.90 1.45 0.035 0.057 A1 0.00 0.15 0.00 A2 0.90 1.3 b 0.35 C D DIM Millimeters Inches MIN MAX MIN MAX E 2.60 3.00 0.102 0.118 0.006 E1 1.50 1.75 0.059 0.069 0.035 0.051 e 0.95 REF 0.037 REF 0.50 0.014 0.020 e1 1.90 REF 0.075 REF 0.09 0.20 0.0035 0.008 L 0.