Diodes ZXCT1050 User Manual

ZXCT1050

SENSE-

SENSE+

V

CC

GND

OUT

1

2

3

5

4

Precision wide input range current monitor

Description

The ZXCT1050 is a wide input range current
monitor, which operates over a range of input
voltages from ground up to V

-2V. As a

CC

result the ZXCT1050 can be used on the high
or low side of the load.

The ZXCT1050 provides variable gain by
using two external resistors. The first of
which sets the transconductance and the
second setting the overall gain.

The very low offset voltage enables a typical
accuracy of 1% for sense voltages of only 30mV,
giving better tolerances for small sense
resistors necessary at higher currents.

Features

• Accurate down to end current sensing

• Output voltage scaling x10

•0 to V

• 2.7 to 20V supply range

• 50µA quiescent current

• SOT23-5 package

-2V sense input range

CC

Applications

• Power supply

• DC motor and solenoid control

• Battery management

• Over current monitor

• Power management

• Short circuit detection

Pin connections Typical application circuit

R

IN

V

CC

SENSE

R

SHUNT

SENSE+ SENSE-

ZXCT1050

OUT

OUT

R

GAIN

Load

Ordering information

Order code Pack Part mark Reel size

(inches)

ZXCT1050E5TA SOT23-5 1050 7 8 3000

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Tape width

(mm)

Quantity

per reel

Absolute maximum ratings

VCC max. 20V

ZXCT1050

Voltage on SENSE- and SENSE+ -0.6 to V

Voltage on all other pins -0.6V and V

V

SENSE

= ‘(V

SENSE

+) - (V

-)’ 500mV

SENSE

CC

CC

+0.6V

Operating temperature -40 to 125°C

Storage temperature -55 to 150°C

Maximum junction temperature 150°C

Package power dissipation 300mW

*

at TA = 25°C (De-rate to zero for TJ = 150°C)

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

Recommended operating conditions

Parameter Min. Max. Units

V

SENSE+

V

CC

V

SENSE

V

OUT

T

A

Common-mode sense input range 0 VCC-2

V

Supply voltage range 2.7 20 V

Differential sense input voltage range 10 300 mV

Output voltage range 0 VCC-2 V

Ambient temperature range -40 125 °C

Recommended resistor gain setting combinations

Gain R

SH

R

G

10 7.5k⍀ 3.75k⍀
20 7.5k⍀ 7.5k⍀
50 7.5k⍀ 18.7k⍀

100 7.5k⍀ 37.5k⍀

20 3.75k⍀ 3.75k⍀
50 1.5k⍀ 3.75k⍀

100 750⍀ 3.75k⍀

Pin function table

PIN Name Description

1V

CC

2 GND Ground pin.
3 OUT Output pin. A resistor, R

4 SENSE+ This is the positive input of the current monitor and has an input range from

5 SENSE- This is the negative input of the current monitor and has an input range from

This is the analog supply and provides power to internal circuitry.

, connected from this pin pin down to ground

GAIN

develops an output voltage.

0V up to VCC – 2V.

0V up to V
voltage. A resistor, R

– 2V. The current through this pin varies with differential sense

CC

, from this pin to the rail being sensed set the

SHUNT

transconductance of the current monitor.

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Electrical characteristics

NOTES:

ZXCT1050

Test conditions TA = 25°C, V

= 10V, VCC = 12V, V

SENSE+

= 100mV, RSH = 7.5k⍀, RG = 3.75k⍀.

SENSE

Symbol Parameter Conditions Min. Typ. Max. Units

I

Q

V

OUT

I

SENSE+

I

SENSE-

V

OUT

TC V

VCC pin current V

Output voltage V

V

SENSE+

V

SENSE-

OUT

input current V

input current V

variation with

= 0V 45 70 µA

SENSE

= 0V

SENSE

=30mV
=100mV
=150mV

= 0V 60 150 nA

SENSE

= 0V 15 150 nA

SENSE

See note

(*)

0

285

0.97

1.45

3

300

1.00

1.50

mV

15

315

1.03

1.55

mV
V
V

300 ppm/°C

temperature

Gain V

OUT/VSENSE

10

Accuracy Total output error -3 3 %

BW Bandwidth V

SENSE(DC)

= 10mV

V

SENSE(DC)

V

SENSE(AC)

= 10mV
CL = 5pF,

PP

300 kHz

0.8 MHz

= 100mV

PSRR Power supply

rejection ratio

CMRR Common mode

rejection ratio

(*) Temperature dependent measurements are extracted from characterisation and simulation results.

V

= 2.7V to 20V

CC

V

SENSE+

V

CC

V

SENSE+

= 0.7V

= 20V

= 0 to 18V

60 dB

70 dB

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Typical characteristics

Supply Current v Input Voltage

I

CC

Supply Current (A)

Supply Current v Supply Voltage

I

CC

Supply Current (A)

Sense- Current v Supply Voltage

I

S-

Sense Current

(A)

Sense- Current v Temperature

Percentage Change I

S-

(%)

Supply Current v Sense Voltage

I

CC

Supply Current (A)

Sense- Current v Sense Voltage

I

S-

Sense Current (A)

RG = 3.75k⍀, RSH = 7.5k⍀ unless otherwise stated.

ZXCT1050

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Typical characteristics

1E-3 0.01 0.1

10m

100m

1

-20 -15 -10 -5 0 5 10 15 20

900

950

1000

1050

1100

0 50m 100m 150m

9.9

10.0

10.1

0 2 4 6 8 101214161820

-8

-6

-4

-2

0

2

4

6

8

10

12

14

16

18

0 5 10 15 20

-12

-8

-4

0

4

8

12

-40 -20 0 20 40 60 80 100 120

-5

0

5

10

V

OUT

- Output Voltage (V)

V

OUT

v Load Current

V

OUT

- Output Voltage (mV)

μ

Incremental Gain v Sense Voltage

Incremental Gain

Common Mode Characteristic

Δ

V

OUT

- Output Voltage (mV)

Supply Characteristic

Δ

V

OUT

- Output Voltage (mV)

Temperature Characteristic

Δ

V

OUT

Output Voltage (mV)

RG = 3.75k⍀, RSH = 7.5k⍀ unless otherwise stated.

ZXCT1050

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Typical characteristics

RG = 3.75k⍀, RSH = 7.5k⍀ unless otherwise stated.

ZXCT1050

Referred
to 1V

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ZXCT1050

GAIN 20

R

G

R

SH

----------

×=

Applications information

The ZXCT1050 is a current output version of the ZXCT1051 and as such uses a separate power
supply pin. All biasing for the internal amplifiers comes from its separate V
powered’, unlike the ZXCT1021.

This means that at very small sense voltages the ZXCT1050 draws very little current (<1␮A) from
the lines being sensed.

input and is not ‘line

CC

The separate V

pin enables the ZXCT1050 to be operated at sense line voltages down to 0V,

CC

where the ZXCT1021 would switch off. This feature enables the ZXCT1050 to be used to sense the
currents flowing through lines that have been shorted to ground.

V

RAIL

SENSE+ (4)

V

CC

R

SENSE

R

SH

(5) SENSE-

I

L

(1)

Load

Q1

ZXCT1050

Out

(3)

R

G

GND (2)

GND

Basic operation

Load current, I
sense inputs of the ZXCT1050.

The internal amplifier forces V
causing a current to flow through transistor Q1 and out of the output pin, OUT. This current is then
converted to a voltage by a resistor, R

The overall gain of the ZXCT1050 is determined by the following expression:

, from V

L

is drawn through R

RAIL

across external resistance RSH (internal on the ZXCT1051)

SENSE

, between OUT and GND.

G

developing a voltage V

SENSE

SENSE

across the

A ratio of 1:2 between R

and RG creates the fixed gain of 10 with an output impedance equal to

SH

RG (see electrical characteristics for output current-voltage characteristics).

The ZXCT1050 has both R

and RSH external. This allows RG and RSH to be varied so that the

G

required gain can be achieved at the required output impedance.

For low power applications both R
R

and RSH can be decreased.

G

The maximum recommended value for R
RSH is 10k⍀. Large values of R
of R

can created load errors and reduce bandwidths.

G

The maximum differential input voltage, V
500mV will not damage it. This can be increased further by the inclusion of a resistor, R
between the SENSE+ pin and the rail being sensed, V

For best performance R

SENSE

minimizing any series resistance with R

and RSH can be increased whereas for driving low impedance

G

is 40k⍀ and the maximum recommended value for

start increasing the effective input offset error, while large values

SH

G

, is 150mV (IL * R

SENSE

RAIL

); however voltages up to

SENSE

LIM

.

should be connected as close to the SENSE+ and SENSE- pins thus

.

SENSE

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,

ZXCT1050

Intentionally left blank

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Package outline - SOT23-5

DIM Millimeters Inches

Min. Max. Min. Max.

A - 1.00 - 0.0393
A1 0.01 0.10 0.0003 0.0039
A2 0.84 0.90 0.0330 0.0354

b 0.30 0.45 0.0118 0.0177
c 0.12 0.20 0.0047 0.0078

D 2.90 BSC 0.114 BSC

E 2.80 BSC 0.110 BSC

E1 1.60 BSC 0.062 BSC

e 0.95 BSC 0.0374 BSC

e1 1.90 BSC 0.0748 BSC

L 0.30 0.50 0.0118 0.0196

L2 0.25 BSC 0.010 BSC

a° 4° 12° 4° 12°

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

ZXCT1050

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ZXCT1050

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.

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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
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.

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To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our
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Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels.
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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.

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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
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

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Europe

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Telefon: [phone]
Fax: [phone]
[e-mail]

© 2007 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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USA

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