Datasheet ZXCT1041 Datasheet (ZETEX)

ZXCT1041
Bidirectional precision high-side current monitor

Description

The ZXCT1041 is a bidirectional precision high­side current sense monitor. The output voltage
is proportional to the differential input voltage.
Direction of current flow is indicated by the
Flag pin.

The ZXCT1041 provides a fixed gain of 10 for
applications where minimal sense voltage is
required.

Features

• Bidirectional high side measurement

• Output voltage scaling x10

• 2.7V to 20V high side voltage

• 35µA quiescent current

• 1% typical accuracy

• SOT23-5 package

Pin connections

The very low offset voltage enables a typical
accuracy of 2% for sense voltages of only
10mV, giving better tolerances for small sense
resistors necessary at higher currents.

The wide input voltage range of 18V down to
as low as 2.7V make it suitable for a range of
applications.

A minimum operating current of just 40␮A,
combined with a SOT23-5 package makes this
part suitable for portable battery equipment.

Applications

• Battery management

• Over current monitor

• Battery gas gauging

• Motor control

Typical application circuit

R

V

+

IN

SENSE

VIN-

54

Flag

V

SENSE

V

-

SENSE

V

+

SENSE-

ZXCT1041

Flag

1

GND

V

OUT

3

V

OUT

V

OUT

V

SENSE

GND

+

2

Ordering information

Order code Package Partmark Reel size

(inches)

ZXCT1041E5TA SOT23-5 1041 7 8 3000

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Tape width

(mm)

Quantity

per reel

Absolute maximum ratings

ZXCT1041

Voltage on V

Voltage on all other pins -0.6V to (V

Vsense [(V

SENSE

Operating temperature, T

SENSE-

+) - (V

and V

SENSE

SENSE+

-)] +/-6V

A

-0.6 to 20V

-40 to 125°C

SENSE+

/ V

SENSE-

) +0.6V

Storage temperature -55 to 150°C

Maximum junction temperature, T

Package power dissipation 300mW at T

Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for
extended periods, may reduce device reliability.

150°C

J

= 25°C (De-rate to zero at 150°C)

A

Recommended operating conditions

Parameter Min. Max. Units

V

SENSE±

Flag Current direction flag output 0 V

V

SENSE

V

OUT

T

A

Common-mode sense input range 2.7 20 V

SENSE±

V

Differential sense input voltage range 0 ±0.8 V

Output voltage range 0 V

SENSE±

-1.5 V

Ambient temperature range -40 125 °C

Pin function table

Pin Name Description

1 Flag This is the current direction pin. It is open collector and allows the logic high

level to be set independent of V
greater than V

SENSE-

2 GND Ground pin

3 OUT Output voltage pin

4V

SENSE+

This is the positive input of the current monitor. It also acts as the supply
voltage pin providing current for internal circuitry. The current through this
pin varies with differential sense voltage

5V

SENSE-

This is the negative input of the current monitor. The current through this
pin varies with differential sense voltage

SENSE+

voltage. Low indicates V

SENSE+

is

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Electrical characteristics

ZXCT1041

Test conditions TA = 25°C, V

SENSE

+ = 10V, V

SENSE

= 100mV

Symbol Parameter Conditions Min. Typ. Max. Units

I

Q

I

SENSE

I

SENSE

V

OUT

Ground pin current 15 35 50 µA

+V

-V

Output voltage

+ input current V

SENSE

- input current V

SENSE

SENSE

SENSE

V

SENSE

= 0V 10 17 24 µA

= 0V 10 17 24 µA

= +150mV 1.55 1.5 1.45 V

[flag high]

= +100mV 1.02 1 0.98 V

SENSE

= +30mV 309 300 291 mV

SENSE

= 0V 0 15 mV

SENSE

= -30mV 285 300 315 mV

SENSE

= -100mV 0.95 1 1.05 V

SENSE

= -150mV 1.42 1.50 1.58 V

SENSE

= ±100mV 30 ppm/ºC

SENSE

V

OUT

[flag low] V

TC V

variation with

OUT

V

V

V

V

V

V

temperature

Gain V

OUT/VSENSE

10

Accuracy Total output error

V

= 100mV -2 2 %

SENSE

(Gain + offset)

Accuracy Total output error

V

SENSE

= -100mV -5 5 %

(Gain + offset)

BW Bandwidth V

CMRR V

SENSE+

common

SENSE(DC)

V

SENSE(AC)

VIN = 2.7 to 20V TBD 60 dB

= 100mV
= 63mV

300 kHz

PP

mode rejection ratio

Flag TP Flag trip point Referred to V

V

FL

Flag low output

I

= 100␮A60200mV

SINK

SENSE

-2.5 +2.5 mV

voltage

I

FH

Flag high leakage

VOH = 5V 1 ␮A

current

NOTES:

(a) - V
(b) Temperature dependent measurements are extracted from characterisation and simulation results.

SENSE

= "V

SENSE+

" - "V

SENSE-

"

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Typical characteristics

V

Y-axis X-axis Conditions

V

V

V

V

Error

Error

V

I

I

I

I

Diff gain V

V

Flag V

AC and transients

Small signal
bandwidth

CMRR Frequency TA = -40°C, 25°C, 85°C, 125°C. V

Large
signal

Small
signal

Flag Time V

SENSE

OUT

OUT

OUT

OUT

OUT

SENSE+

SENSE+

SENSE-

SENSE-

OUT

+ = 10V, V

V

SENSE

T

A

V

SENSE+

V

SENSE+

+ve V

-ve V

V

SENSE+

V

SENSE

V

SENSE+

V

SENSE

V

SENSE+

SENSE

I

OUT

SENSE

= 100mV, TA = 25°C unless otherwise stated

SENSE

TA = -40°C, 0°C, 25°C, 85°C, 125°C. V

V

= 10mV, 30mV, 100mV. V

SENSE

TA = -40°C, 0°C, 25°C, 85°C, 125°C. V

V

V

V

SENSETA

SENSETA

V

SENSE+

SENSE+

SENSE+

SENSE

swept from 0 to 20V

= 100mV and -100mV. TA = 0°C, 25°C and 85°C
zoomed in 2.6V to 4.2V

= -40°C, 0°C, 25°C, 85°C, 125°C

= -40°C, 0°C, 25°C, 85°C, 125°C

= ±10mV, ±0.1, ±0.2, ±0.4, ±0.5V. V

TA = -40°C, 25°C, 85°C, 125°C. V

TA = -40°C, 25°C, 85°C, 125°C. V

TA = -40°C, 25°C, 85°C, 125°C. V

TA = -40°C, 25°C, 85°C, 125°C. V

V

SENSE+

= 10V and 3.6V. TA = -40°C, 25°C, 85°C, 125°C

TA = -40°C, 0°C, 25°C, 85°C, 125°C. V

TA = -40°C, 25°C, 85°C, 125°C. V
V

swept over ±5mV

SENSE

Frequency TA = -40°C, 25°C, 85°C, 125°C. V

= 10mV and 100mV. V

= 10mV

= 0 to 200mV to 0

= 0 to -200mV to 0

= 200mV to -200mV to 200mV

= 0 to 20mV to 0

= 0 to -20mV to 0

= 20mV to -20mV to 20mV

= 200mV to -200mV to 200mV

= 20mV to -20mV to 20mV

time V

Time V

V

SENSE(DC)

V

SENSE+(AC)

SENSE

V

SENSE

V

SENSE

SENSE

V

SENSE

V

SENSE

SENSE

V

SENSE

PP. VSENSE(DC)

SENSE+

SENSE+

SENSE

SENSE+

SENSE

SENSE+

SENSE

SENSE+

SENSE+

SENSE+

SENSE(AC)

SENSE+(DC)

= 10V and 3.6V

= 10V and 3.6V

+ = 100mV and -100mV.

SENSE+

= 10V and 3.6V

= 0

= 10V and 3.6V

= 0

= 10V and 3.6V. V

= 10V and 3.6V

= 10V and 3.6V

= 10mV

= 10V and 3.6V.

= 10mV and 100mV

ZXCT1041

= 10V and 3.6V

= ±100mV

SENSE

PP

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ZXCT1041

Application information

The ZXCT1041 uses two current monitors in anti-parallel to provide bidirectional current
measurement. The integrated resistors while having a broad actual value variance provide very
good matching to one another; this provides very tight gain matching from forward current
measurement to reverse current management and removes the need to trim the resistor values.

The internal transconductance setting resistors have a nominal value of 1.5k⍀ thereby setting the
internal transconductance to 1mA/V of V
summed into an internal common gain-setting resistor of 15k⍀. This sets the overall gain to 10
which has a very small variance due to the very good matching of internal transistors.

To improve accuracy the offset of amplifier 1 is trimmed.

The direction of measured current flow is determined by comparing the voltages applied to the
bases of transconductance transistors (Q1 and Q2). For maximum versatility the flag output uses
an open collector; this allows the ZXCT1041 to monitor rails at a much higher potential than what
the flag output is interfacing to.

. The outputs of both current monitors (current) are

SENSE

A common application for micro-power current monitors is measuring the discharge current of a
rechargeable lithium ion/polymer battery. The ZXCT1041 enables measuring both the charge and
discharge current into the battery and with its wide operating voltage of 2.5 to 20V enables it to
measure the currents in to/ out of up to 4 cells connected in series.

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ZXCT1041

Load

Battery
charger

control

When choosing appropriate values for R

SENSE-

ZXCT1041

GND

a compromise must be reached between in-line

SENSE

SENSE+

Battery

Flag

OUT

signal loss (including potential power dissipation effects) and small signal accuracy.

Higher values for R

gives better accuracy at low load currents by reducing the inaccuracies

SENSE

due to internal offsets. For best operation the ZXCT1041 has been designed to operate with
VSENSE of the order of 50mV to 150mV.

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Packaging details - SOT23-5

ZXCT1041

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

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ZXCT1041

Definitions
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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
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approval of the Chief Executive Officer of Zetex Semiconductors plc. As used herein:
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1. are intended to implant into the body

or

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Devices suspected of being affected should be replaced.

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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
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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

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© 2006 Published by Zetex Semiconductors plc

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.

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