Linear Technology LT1787HV, LT1787 Datasheet

FEATURES

■

Input Offset Voltage: 75µV (Max)

■

60V Supply Operation (LT1787HV)

■

12-Bit Dynamic Range

■

Operating Current: 60µA

■

User-Selectable External Sense Resistor

■

Bidirectional High Side Current Sensing

■

Unidirectional or Bidirectional Output

■

Input Noise Filtering

■

Available in 8-Lead SO and MSOP Packages

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APPLICATIO S

■

Battery Monitoring

■

Power Monitoring

■

Portable Phones

■

Cellular Phones

■

Portable Test/Measurement Systems

■

Battery-Operated Systems

LT1787/LT1787HV

Precision, High Side

Current Sense Amplifiers

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DESCRIPTIO

The LT®1787 is a complete micropower precision high
side current sense amplifier. The LT1787 monitors bidi­rectional currents via the voltage across an external sense
resistor. A current or voltage output depicts the direction
and magnitude of the sense current. The LT1787 delivers
greater than a 12-bit dynamic range with ultralow 40µV
input offset voltage compared to a typical 250mV full­scale input voltage. A fixed gain of 8 is set by onboard
precision resistors. Input signal filtering is easily imple­mented with a capacitor between the FIL– and FIL+ pins.
The LT1787HV operates from 2.5V to 60V total supply
voltage and the LT1787 operates from 2.5V to 36V total
supply voltage. Both versions have a PSRR in excess of
120dB. The LT1787/LT1787HV draw only 60µA and are
available in 8-lead SO and MSOP packages.

, LTC and LT are registered trademarks of Linear Technology Corporation.

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TYPICAL APPLICATIO

12-Bit Dynamic Resolution Unidirectional Output into LTC®1286 ADC

R

SENSE

FIL
V

S

DNC

V

EE

LOAD

–

LT1787HV

–

• R

0.0016Ω

SENSE

V

R
20k

V

)

FIL

V

BIAS

OUT

OUT

S

+

+

0.1µF

2.5V TO 60V

R1
15k

V

REFVCC

+IN

–IN

C2

LT1634-1.25

LTC1286

GND

1µF

D

C1

CS

CLK

OUT

LOAD

V

OUT

TO

= V

I = 100A

18

27

36

45

+ (8 • I

BIAS

TO µP

1787 TA01

Input Offset Voltage vs Supply Voltage

50
40
30
20

5V

10

0
–10
–20
–30

INPUT OFFSET VOLTAGE (µV)

–40
–50

10

0

20

TOTAL SUPPLY VOLTAGE (V)

30 40

50

1787 TA01b

60

1

LT1787/LT1787HV

1
2
3
4

8
7
6
5

TOP VIEW

MS8 PACKAGE

8-LEAD PLASTIC MSOP

FIL

+

V

S

+

V

BIAS

V

OUT

FIL

–

V

S

–

DNC*

V

EE

WW

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ABSOLUTE MAXIMUM RATINGS

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(Notes 1, 2)

Differential Sense Voltage...................................... ±10V

Total Supply Voltage (LT1787) ................................ 40V

Total Supply Voltage (LT1787HV) ........................... 65V

Output Voltage..................... (VEE – 0.3V) to (VEE + 35V)

Output Bias Voltage .............(VEE – 0.3V) to (VEE + 35V)

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PACKAGE/ORDER INFORMATION

ORDER PART NUMBER

LT1787CMS8
LT1787IMS8
LT1787HVCMS8
LT1787HVIMS8

* DO NOT CONNECT

T

= 150°C, θJA = 250°C/W

JMAX

MS8 PART MARKING

LTGM
LTGN
LTKJ
LTKK

Operating Temperature Range ................ –40°C to 85°C

Specified Temperature Range (Note 3)... – 40°C to 85°C

Storage Temperature Range ..................–65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................300°C

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FIL

V

DNC*

V

–

1

–

2

S

3

4

EE

T

JMAX

8-LEAD PLASTIC SO

* DO NOT CONNECT

TOP VIEW

8

7

6

5

S8 PACKAGE

= 150°C, θJA = 190°C/W

FIL
V
V
V

S

BIAS

OUT

ORDER PART NUMBER

+

+

LT1787CS8
LT1787IS8
LT1787HVCS8
LT1787HVIS8

S8 PART MARKING

1787
1787I
1787HV
787HVI

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
Total supply = (V

–

– VEE) = 2.5V to 36V (LT1787), 2.5V to 60V (LT1787HV) unless otherwise specified.

S

(Note 4)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

–

+

V

, V

S

V

SENSE

V

OS

Sense Amplifier Supply Voltage Single Supply Operation (LT1787) ● 2.5 36 V

S

Input Sense Voltage Full Scale V
Input Offset Voltage (S8) I

Input Offset Voltage (MS8) I

Single Supply Operation (LT1787HV)

+

= V

SENSE

= 0, VS Supply = 5V –75 ±40 75 µV

OUT

≤ 70°C ● –135 135 µV

0°C ≤ T

A

–40°C ≤ T
I

= 0 (LT1787) –100 100 µV

OUT

≤ 70°C ● –160 160 µV

0°C ≤ T

A

–40°C ≤ T
I

= 0 (LT1787HV) –100 100 µV

OUT

≤ 70°C ● –160 160 µV

0°C ≤ T

A

–40°C ≤ T

= 0, VS Supply = 5V –125 ±40 125 µV

OUT

≤ 70°C ● –230 230 µV

0°C ≤ T

A

–40°C ≤ T
I

= 0 (LT1787) –150 150 µV

OUT

0°C ≤ T

≤ 70°C ● –250 250 µV

A

–40°C ≤ T
I

= 0 (LT1787HV) –150 150 µV

OUT

≤ 70°C ● –250 250 µV

0°C ≤ T

A

–40°C ≤ T

–

– V

, VS = 10V, V

S

S

≤ 85°C ● –200 200 µV

A

≤ 85°C ● –225 225 µV

A

≤ 85°C ● –225 225 µV

A

≤ 85°C ● –250 250 µV

A

≤ 85°C ● –280 280 µV

A

≤ 85°C ● –280 280 µV

A

= 5V, AV = 8 ±10% ● 500 mV

BIAS

● 2.5 60 V

2

LT1787/LT1787HV

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
Total supply = (V

–

– VEE) = 2.5V to 36V (LT1787), 2.5V to 60V (LT1787HV) unless otherwise specified.

S

(Note 4)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VOS TC Temperature Coefficient of VOSVS Supply = 5V (Note 5) 0.5 2 µV/°C
I

OUT(O)

V

OUT(O)

g

m

A

V

No-Load Output Current Error V
No-Load Output Voltage Error V

SENSE

SENSE

(S8) 0°C ≤ T

–40°C ≤ T

No-Load Output Voltage Error V

SENSE

(MS8) 0°C ≤ T

–40°C ≤ T

Tranconductance, I

Gain, V

OUT/VSENSE

OUT/VSENSE±VSENSE

V

Supply = Total Supply + |V

S

±V

SENSE

= 0V 4 nA
= 0V, VS Supply = 5V –600 600 µV

≤ 70°C ● –1080 1080 µV

A

≤ 85°C ● –1600 1600 µV

A

= 0V, VS Supply = 5V –1000 1000 µV

≤ 70°C ● –1840 1840 µV

A

≤ 85°C ● –2000 2000 µV

A

= 10mV, 50mV, 100mV, 150mV, 250mV, 400 µA/V

|

SENSE

= 100mV, VS Supply = 5V ● 7.6 8 8.4 V/V

Output Voltage Gain Error ● –5 2 5 %

VS PSRR VS Supply Rejection Ratio V

VEE PSRR Negative Supply Rejection Ratio V

∆V
∆V

I

S+(O)

I

S–(O)

I

EE(O)

I

OUT

V

OUT

OS

BIAS

Change in Input Offset Voltage V
with Change in V

Voltage V

BIAS

Positive Input Sense Current V
Negative Input Sense Current V
Negative Supply Current V
Output Current V
Output Voltage V
Ripple Rejection V

V

OMIN

Minimum Output Voltage V

Unipolar Output V
Saturation Voltage V

V

OMAX

R

G1A, RG2A

R

OUT

Maximum Output Voltage V
Input Gain-Setting Resistor Pin 1 to Pin 2, Pin 7 to Pin 8 1.25 kΩ
Output Resistor Pin 5 to Pin 6 20 kΩ

= 0V, VS Supply = 2.5V to 36V (LT1787) ● 120 135 dB

SENSE

= 0V, VS Supply = 2.5V to 60V (LT1787HV) ● 120 135 dB

V

SENSE

= 0V, VS Supply = 15V, V

SENSE

= –1V to –15V (LT1787)

V

EE

V

= 0V, VS Supply = 40V, V

SENSE

= –1V to –15V (LT1787HV)

V

EE

= 0V, VS Supply = 36V, V

SENSE

= 0V, VS Supply = 60V, V

SENSE

= 0V ● 10 20 µA

SENSE

= 0V ● 50 100 µA

SENSE

= 0V ● 60 120 µA

SENSE

= ±128mV ±50 µA

SENSE

SENSE

S

SENSE

V

SENSE

SENSE
SENSE

V

SENSE

V

SENSE

+

= V

= ±128mV, V

–

= 20V, ∆VS Supply = 1V, f = 1kHz ● 80 88 dB

S

= 0V, V

+

= V

– V

S

= 2mV, V
= 4mV, V
= 5mV, V
= 6mV, V

+

≥ 3.3V V

S

= 0V ● 30 45 mV

BIAS

–

= –128mV, V

S

= 0V ● 32 50 mV

BIAS

= 0V ● 38 55 mV

BIAS

= 0V ● 43 60 mV

BIAS

= 0V ● 49 65 mV

BIAS

= 0V, ● 100 130 dB

BIAS

= 0V, ● 100 130 dB

BIAS

= 0.5V to 25V (LT1787) ● 100 130 dB

BIAS

= 0.5V to 25V (LT1787HV) ● 100 130 dB

BIAS

±1.024 V

BIAS

= 0V 10 mV

BIAS

+

– 0.75 V

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Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: ESD (Electrostatic Discharge) sensitive devices. Extensive use of
ESD protection devices are used internal to the LT1787/LT1787HV,
however, high electrostatic discharge can damage or degrade the device.
Use proper ESD handling precautions.

Note 3: The LT1787C/LT1787HVC are guaranteed to meet specified
performance from 0°C to 70° and are designed, characterized and

expected to meet these extended temperature limits, but are not tested at
–40°C and 85°C. The LT1787I/LT1787HVI are guaranteed to meet the
extended temperature limits.

Note 4: Testing done at V

= 1.25V, VEE = 0V unless otherwise

BIAS

specified.
Note 5: This parameter is not 100% tested.

3

LT1787/LT1787HV

SENSE VOLTAGE (V

S

+

– V

S

–

) (mV)

–250

OUTPUT VOLTAGE (V)

2.5

2.0

1.5

1.0

0.5

V

BIAS

–0.5
–1.0
–1.5
–2.0
–2.5

150

1787 G06

–150

–50

50

250

VS = 5.5V TO 60V
V

BIAS

= 2.5V

V

EE

= 0V

W

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TYPICAL PERFORMANCE CHARACTERISTICS

Input Offset Voltage vs
Supply Voltage

50

+

–

V

= V

S

V

BIAS

V

EE

S

= 0V

= –1.25V

40
30
20
10

0
–10
–20
–30

INPUT OFFSET VOLTAGE (µV)

–40
–50

0

10

20

TOTAL SUPPLY VOLTAGE (V)

Input Offset Voltage vs
Negative Supply Voltage

30

+

–

V

= V

= 2.5V

S

S

= 1V

V

BIAS

20

10

0

–10

INPUT OFFSET VOLTAGE (µV)

–20

–30

0

–5 –10 –15 –20 –25

NEGATIVE SUPPLY VOLTAGE (V)

T

T

T

A

T

= 25°C

A

T

= –40°C

A

A

= 85°C

A

= 25°C

= –40°C

30 40

T

A

= 85°C

No Load Output Voltage
vs Supply Voltage

400

+

–

V

= V

S

S

V

BIAS

V

EE

= 0V

= –1.25V

T

= 85°C

A

300

200

100

0

T

= 25°C

A

–100

OUTPUT VOLTAGE (µV)

–200

–300

50

60

–400

010

= –40°C

T

A

20 4030

50

60

TOTAL SUPPLY VOLTAGE (V)

1787 G01

1787 G02

Input Offset Voltage vs
Temperature

50

+

–

V

= V

S

V

BIAS

V

EE

S

= 0V

= –1.25V

40
30

No Load Output Current vs
Supply Voltage

10

T

= –40°C

A

8
6

T

= 25°C

A

4
2

0
–2
–4

OUTPUT CURRENT (nA)

–6

V

= 1V

BIAS

= 0V

V

EE

–8

+

= V

V

S

–10

S

0

10

= 85°C

T

A

–

30 40

20

TOTAL SUPPLY VOLTAGE (V)

Output Voltage vs Sense Voltage
(Bidirectional Mode)

50

60

1787 G03

20
10

0
–10
–20

INPUT OFFSET VOLTAGE (µV)

–30
–40

–30

1787 G04

–50

–20 0 20 40 60

–40

TEMPERATURE (°C)

80

1787 G05

85

1.4

1.2

1.0

0.8

0.6

OUPUT VOLTAGE (V)

0.4

0.2

4

Output Voltage vs Sense Voltage
(Unidirectional Mode)

VS = 2.5V TO 60V
T

= –40°C TO 85°C

A

= V

V

BIAS

EE

0

30 60 90 150

0

SENSE VOLTAGE (V

+

– V

S

S

120

–

) (mV)

1787 G07

8.195

8.185

8.175

8.165

GAIN (V/V)

8.155

8.145

8.135

V

= (2.5V + |V

S

–40

–20 0 20 40 60

TEMPERATURE (°C)

Gain vs FrequencyGain vs Temperature

|)TO 60V

SENSE

+

–

V

> V

S

S

+

–

V

< V

S

S

80

85

1787 G08

30

20

10

0

–10

GAIN (dB)

–20

–30

–40

–50

0.1k 1k

10k 1M100k

FREQUENCY (Hz)

V

SENSE

= 10mV

10M

1787 G09

100M