Diodes ZXCT1023 User Manual

MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

Description

The ZXCT1023 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 ZXCT1023 has a fixed internal gain of 50 and the only external component required is the external current sense resistor; this combined with its 1.2mm x 1.8mm TDFN package more than quarters the solution size of the ZXCT1010.

The wide input voltage range of 20V down to as low as

2.5V makes it suitable for a range of applications. The combination of operation down to 2.5V and just 3.5µA

quiescent current makes it ideal for single cell Li-Ion/polymer battery charge/discharge measurement applications.

Features

Pin Assignments

TDFN1218-4L

OUT

GND

1

2

Applications

ZXCT1023

Top View

4

S+

3

S-

• Accurate high-side current sensing

• Fixed gain of 50 output scaling

• 2.5V – 20V operating range

• 3.5µA quiescent current

• TDFN1218 package

Typical Application Circuit

V

S+

OUT

• Battery capacity measurement

• Battery chargers

• Over-current monitor

R

S

R

GT

S-

– +

R

G

GND

ZXCT1023

Document number: DS31997 Rev. 3 - 2

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ZXCT1023

Pin Descriptions

Pin Name Pin Number Description

1 OUT

2 GND Ground and substrate connection of device 3 S- High impedence negative sense voltage input 4 S+ Positive sense input. Also acts as power supply pin to ZXCT1023

Central Paddle Substrate. Connect to GND

Absolute Maximum Ratings

Description Rating Unit

Voltage on S+ (Note 1) -0.5 to 20 V Voltage on S- (Note 1, 2), OUT(Note 1) V Junction Temperature -40 to 125 °C Storage Temperature -55 to 150 °C Package Power Dissipation (TA = 25°C) TDFN1218

ESD Ratings

Human Body Model 2000 V Machine Model 150 V

These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure. Operation at the absolute maximum rating for extended periods may reduce device reliability. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices.

Notes: 1. Measured with respect to GND pin

2. Subject to absolute maximum V

3. V

4. The usable V

Recommended Operating Conditions (T

ZXCT1023

Document number: DS31997 Rev. 3 - 2

(Note 3)

SENSE

is defined as the voltage difference across the sense resistor, RS.

SENSE

range is limited by the output voltage range; and as such will be reduced at lower VS+ values.

SENSE

Symbol Parameter Min Max Unit

V

(Note 1)

S+

V

SENSE

V

OUT

TA

Common-Mode Sense Input Range 2.5 20 V Differential Sense Input Voltage Range 0 Output Voltage Range 0

Ambient Temperature Range -40 85 °C

MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

Voltage output. The output voltage is referenced to GND. The overall voltage gain is 50, i.e.,

= 50 x V

V

OUT

not being exceeded.

where V

SENSE

= 25°C)

A

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= VS+ - VS-

SENSE

S+

+0.5

-0.5 V

-0.5 to +2.5 V

mW

V

380

(Note 4)

VS- - 1

mV

V

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MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

Electrical Characteristics (T

= 25°C, VS+ = 3.6V, V

A

Symbol Parameter Conditions

V

= 0mV

SENSE

V

= 10mV

SENSE

V

OUT

TC

(Note 5)

IQ IS-

Output voltage

Output voltage temperature coefficient

Ground pin current SENSE- input current

Acc Accuracy

Gain

R

OUT

V

OUT/VSENSE

Output resistance 15 kΩ

V

BW Bandwidth

PSRR

(Note 6)

Notes 5. TC limits are determined by characterization.

Power supply rejection ratio

6. PSRR is defined as change in output voltage per change in S+ voltage, V

ZXCT1023

Document number: DS31997 Rev. 3 - 2

V

= 30mV

SENSE

V

= 50mV

SENSE

V

= 100mV, VS+ = 20V

SENSE

50 300 ppm/°C V

= 0V

SENSE

V

= 0V

SENSE

V

= 50mV

SENSE

= 50mV

SENSE

V

(DC) = 10mV

SENSE

V

(DC) = 50mV

SENSE

V

= 30mV, VS+ = 2.5 to 20V

SENSE

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= 50mV, unless otherwise stated)

SENSE

Limits

Min. Typ. Max.

0.3 50

425 500 575

1.41 1.5 1.59

2.425 2.5 2.575

4.85 5 5.15

3.5 8 μA 100 nA

-3 3 % 50 V/V

300 kHz 1 MHz

50 60 dB

.

S+

ZXCT1023

Unit

mV

V

June 2011

ZXCT1023

0

MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

Typical DC Characteristics

2.5

V

= 0V, VS+ = 3.6V

SENSE

2

1.5

(µA)

S+

I

1

0.5

0

2 4 6 8 10 12 14 16 18 20

T

A

= 85°C

TA = -40°C

T

= 0°C

A

VS+ (V)

S+ Input Current vs. Supply voltage Normalised Gain Error vs. Sense Voltage

70

)

60

SENSE

V

Δ

/

OUT

50

V

Δ

TA = 0°C

-40°C

25°C

85°C

VS+ = 3.6V

40

30

Differential Gain (

20

024681

V

SENSE

(mV)

Differential Gain vs. Sense Voltage Output Voltage vs. Sense Voltage

3

TA = 25°C

2.5

2

(V)

1.5

OUT

V

1

0.5

0

2 4 6 8 10 12 14 16 18 20

V

(V)

S+

V

SENSE

V

SENSE

= 50mV

= 30mV

= 10mV

Output Voltage vs. Input voltage Relative Output Voltage Change vs. Temperature

3%

2%

T

A

= -40°C

TA = 85°C

Vs+ = 3.6v

Relative to gain = 50

1%

TA = 25°C

0%

Differential Gain Error

-1%

TA = 0°C

-2% 0 1020304050

V

SENSE

(mV)

3.5 VS+ = 3.6V

3

2.5

(V)

2

OUT

V

1.5

1

0.5

0

0 102030405060

V

SENSE

(mV)

TA = 85°C

TA = 25°C

TA = 0°C

TA = -40°C

0.6%

0.4%

0.2%

%Error

0.0%

OUT

ΔV

-0.2%

-0.4%

-0.6%

10mV

30mV

50mV

-40 -15 10 35 60 85

VS+ =3.6V

w.r.t. V

V

OUT

= 10mV, 30mV, 50mV

SENSE

Temperature (°C)

at 25°C

50mV

30mV

ZXCT1023

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+

0

Typical AC Characteristics

40

30

VS+=3.6V

=25°C

T

A

20

10

Gain (dB)

0

-10

V

SENSE

ZXCT1023

MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

70

V

= 50mV

SENSE

= 10mV

60

50

40

30

PSRR (dB)

20

10

VS+ =

VS+ = 10V

V

SENSE

TA = 25°C

= 50mV

-20 10E+0 100E+0 1E+3 10E+3 100E+3 1E+6 10E

frequency (Hz)

Small Signal Frequency Response Power Supply Rejection Ratio

25

20

15

10

Input (mV)

5

0

-5

Input

0 50 100 150 200 250 300

VS+=3.6V, TA = 25°C V

= 20mV

SENSE

Time (µs)

Output

Large Signal Pulse Response 20mV Large Signal Pulse Response 50mV

56 55 54 53 52 51

Sense voltage (mV)

50 49

0 50 100 150 200

VS+=3.6V, TA =25°C

= 50mV(DC) + 5mV

V

SENSE

Input

time (µs)

Output

Small Signal Positive Pulse Response Small Signal Negative Pulse Response

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

2.80

2.75

2.70

2.65

2.60

2.55

2.50

2.45

0

0.01 0.1 1 10 100 100 Frequency (kHz)

60 50 40 30 20

Input (mV)

Output (V)

10

0

-10

Input

0 50 100 150 200

VS+=3.6V, TA = 25°C V

= 50mV

SENSE

Time (µs)

Output

VS+=3.6V, TA =25°C V

= 50mV(DC) - 5mV pulse

SENSE

Input

time (µs)

Output voltage (V)

51

50

49

48

(mV)

47

SENSE

V

46

45

44

0 25 50 75 100 125 150

Output

3.0

2.5

2.0

1.5

1.0

0.5

0.0

-0.5

2.55

2.50

2.45

2.40

2.35

2.30

2.25

2.20

Output (V)

(V)

OUT

V

ZXCT1023

Document number: DS31997 Rev. 3 - 2

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MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

Application Information

The ZXCT1023 is line powered (derives its power from the rail being sensed) this reduces the number of pins used and PCB trace routing. The fixed gain of 50 reduces the PCB area by reducing the number of external components. The only external component required is the sense resistor. This coupled with the

1.2mm x 1.8mm TDFN package makes the solution size very small.

ZXCT1023

The ZXCT1023 has its gain setting resistor, RG, set at 15kΩ which further reduces power consumption at larger V

Application Examples

Please refer to Zetex AN39 for sample applications.

SENSE

.

The fixed gain of 50 has been chosen to meet the normal requirements of most applications.

S

+

R

GT

R

S

-

S

– +

V

OUT

R

G

Ordering Information

Order Reference Package

ZXCT1023DFGTA TDFN1218 23 Active 7 3000 8

ZXCT1023

Document number: DS31997 Rev. 3 - 2

GND

Marking

Device

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Status

Reel Size

(inches)

Quantity Per Reel

Tape Width

(mm)

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MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

Package Outline Dimensions (All Dimensions in mm)

TDFN1218-4

ZXCT1023

Recommended PCB Land Pattern

ZXCT1023

Document number: DS31997 Rev. 3 - 2

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ZXCT1023

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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 instructi ons for us e provided in the labeling 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 .

Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives agai nst any damages arising out of the use of Diodes Incorporated products in such safety-critic al, l ife support devic es or syst ems .

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MICROPOWER FIXED GAIN OF 50 CURRENT MONITOR

IMPORTANT NOTICE

LIFE SUPPORT

ZXCT1023

Document number: DS31997 Rev. 3 - 2

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