Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsLinear ICsLinear IC - Op-amp, differential amplifier Differential SO 8

LT1990

1990fb

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Battery Cell Voltage Monitoring

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High Voltage Current Sensing

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Signal Acquisition in Noisy Environments

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Input Protection

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Fault Protected Front Ends

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Level Sensing

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Isolation

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Pin Selectable Gain of 1 or 10

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High Common Mode Voltage Range:

85V Window (V

= 5V, 0V)

±250V (V

= ±15V)

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Common Mode Rejection Ratio: 70dB Min

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Input Protection to ±350V

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Gain Error: 0.28% Max

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PSRR: 82dB Min

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High Input Impedance: 2MΩ Differential,

500kΩ Common Mode

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Micropower: 120µA Max Supply Current

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Wide Supply Range: 2.7V to 36V

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–3dB Bandwidth: 100kHz

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Rail-to-Rail Output

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8-Pin SO Package

±250V Input Range

G = 1, 10, Micropower,

Difference Amplifier

The LT

1990 is a micropower precision difference ampli-

fier with a very high common mode input voltage range. It

has pin selectable gains of 1 or 10. The LT1990 operates

over a ±250V common mode voltage range on a ±15V

supply. The inputs are fault protected from common

mode voltage transients up to ±350V and differential

voltages up to ±500V. The LT1990 is ideally suited for both

high side and low side current or voltage monitoring.

On a single 5V supply, the LT1990 has an adjustable 85V

input range, 70dB min CMRR and draws less than 120µA

supply current. The rail-to-rail output maximizes the dy-

namic range, especially important for single supplies as

low as 2.7V.

The LT1990 is specified for single 3V, 5V and ±15V

supplies over both commercial and industrial temperature

ranges. The LT1990 is available in the 8-pin SO package.

Full-Bridge Load Current Monitor

SOURCE

–12V ≤ V

≤ 73V

OUT

= V

REF

± (10 • I

• R

)

–

40k

100k

900k

900k 10k

10k

OUT

LT1990

LT6650

GND

OUT

54.9k

20k

1nF

1µF

REF

= 1.5V

1990 TA01

–

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

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

All other trademarks are the property of their respective owners.

Summary of content (16 pages)

PAGE 1
LT1990 ±250V Input Range G = 1, 10, Micropower, Difference Amplifier DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Pin Selectable Gain of 1 or 10 High Common Mode Voltage Range: 85V Window (VS = 5V, 0V) ±250V (VS = ±15V) Common Mode Rejection Ratio: 70dB Min Input Protection to ±350V Gain Error: 0.28% Max PSRR: 82dB Min High Input Impedance: 2MΩ Differential, 500kΩ Common Mode Micropower: 120µA Max Supply Current Wide Supply Range: 2.
PAGE 2
LT1990 U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Notes 1, 2) Total Supply Voltage (V + to V –) ............................... 36V Input Voltage Range Continuous ...................................................... ±250V Transient (0.1s) ............................................... ±350V Differential ....................................................... ±500V Output Short-Circuit Duration (Note 3) ............ Indefinite Operating Temperature Range (Note 4) LT1990C ......
PAGE 3
LT1990 3V/5V ELECTRICAL CHARACTERISTICS VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6) SYMBOL PARAMETER CONDITIONS VOS Offset Voltage, RTI en MIN TYP MAX G = 1, 10 0.8 3 Input Noise Voltage, RTI fO = 0.1Hz to 10Hz 22 µVP-P Noise Voltage Density, RTI fO = 1kHz 1 µV/√Hz RIN Input Resistance Differential Common Mode PSRR Power Supply Rejection Ratio, RTI VS = 2.7V to 12.7V, VCM = VREF = 1.
PAGE 4
LT1990 3V/5V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of 0°C ≤ TA ≤ 70°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) LT1990C/LT1990I MIN TYP MAX SYMBOL PARAMETER CONDITIONS VOS Input Offset Voltage, RTI VS = 3V, 0V G = 1, 10 ● 4.1 mV VS = 5V, 0V G = 1, 10 ● 4.
PAGE 5
LT1990 3V/5V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 85°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) LT1990C/LT1990I MIN TYP MAX SYMBOL PARAMETER CONDITIONS UNITS VOS Input Offset Voltage, RTI VS = 3V, 0V G = 1, 10 ● 4.5 mV VS = 5V, 0V G = 1, 10 ● 4.
PAGE 6
LT1990 3V/5V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 125°C. VS = 3V, 0V; VS = 5V, 0V; RL = 10k, VCM = VREF = half supply, G = 1, 10, unless otherwise noted. (Notes 4, 6) SYMBOL PARAMETER CONDITIONS MIN VOS Input Offset Voltage, RTI VS = 3V, 0V G = 1, 10 ● VS = 5V, 0V G = 1, 10 ● LT1990H TYP MAX 5.2 mV 5.
PAGE 7
LT1990 ±15V ELECTRICAL CHARACTERISTICS VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, TA = 25°C, unless otherwise noted. (Note 6) SYMBOL PARAMETER CONDITIONS ISC Output Short-Circuit Current Short to V– BW Bandwidth SR Slew Rate G = 1, VOUT = ±10V Settling Time to 0.01% 10V Step, G = 1 Reference Gain to Output G=1 G = 10 AVREF Short to V+ MIN TYP 6 15 9 22 mA mA 105 7 kHz kHz 0.55 V/µs G=1 G = 10 0.3 MAX UNITS µs 60 1 ± 0.0007 1 ± 0.
PAGE 8
LT1990 ±15V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 85°C. VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, unless otherwise noted. (Notes 4, 6) LT1990C/LT1990I MIN TYP MAX UNITS ● ● ● 0.67 0.35 0.95 % % % VOUT = ±10V G=1 G = 10 ● ● 0.003 0.
PAGE 9
LT1990 ±15V ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 125°C. VS = ±15V, RL = 10k, VCM = VREF = 0V, G = 1, 10, unless otherwise noted. (Notes 4, 6) PARAMETER CONDITIONS VOSH Input Offset Voltage Hysteresis, RTI (Note 11) ● PSRR Power Supply Rejection Ratio, RTI VS = ±1.35V to ±18V ● Minimum Supply Voltage Guaranteed by PSRR ● ±1.
PAGE 10
LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Supply Current vs Supply Voltage 200 TA = 125°C 180 TA = 85°C 160 TA = 25°C 140 TA = –40°C 120 TA = –55°C 100 80 V + – 0.01 VS = 5V, 0V 60 130 120 110 100 90 80 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 60 –50 40 35 –25 0 25 50 75 TEMPERATURE (°C) 100 1990 G01 TA = 125°C –1 TA = 25°C TA = 25°C +1 SINKING (+IN = –2.5V) +0.1 TA = 125°C TA = –55°C TA = –55°C V + –0.01 VS = ±2.5V G = 10 –0.
PAGE 11
LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Common Mode Rejection Ratio vs Frequency Gain vs Frequency 50 VS = 5V, 0V 40 TA = 25°C VS = 5V, 0V TA = 25°C G = 1 OR 10 REFERRED TO INPUT 90 80 30 70 20 60 10 GAIN (dB) COMMON MODE REJECTION RATIO (dB) 100 50 40 0 G = 10 G=1 –10 –20 30 20 –30 10 –40 0 100 10k 1k FREQUENCY (Hz) –50 100 100k 200k 1k 10k 100k FREQUENCY (Hz) 1M 1990 G10 –3dB Bandwidth vs Supply Voltage, G = 1 120 8 1.
PAGE 12
LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Power Supply Rejection Ratio vs Frequency 70 G = 10 G=1 100 10 VS = 5V, 0V TA = 25°C 1 100 10k 1k FREQUENCY (Hz) 60 VS = 5V, 0V TA = 25°C G=1 50 40 30 G = 10 20 10 0 –10 –20 SETTLING TIME (µs) SETTLING TIME (µs) 0.01% OF STEP 0.01% OF STEP 0.1% OF STEP 0.01% OF STEP 260 0.01% OF STEP 240 220 200 0.1% OF STEP 180 0.1% OF STEP 160 8 140 –10 –8 –6 –4 –2 0 2 4 OUTPUT STEP (V) 10 VS = ±1.
PAGE 13
LT1990 U W TYPICAL PERFOR A CE CHARACTERISTICS Small Signal Transient Response 1.5V VS = 3V, 0V G = 1, –1 RL = 10k VREF = 1.
PAGE 14
LT1990 U W U U APPLICATIO S I FOR ATIO Primary Features VCM+ ≤ 27 • V+ – 26 • VREF – 23 – VGAIN The LT1990 is a complete gain-block solution for high input common mode voltage applications, incorporating a low power precision operational amplifier providing railto-rail output swing along with on-chip precision thin-film resistors for high accuracy. The Block Diagram shows the internal architecture of the part.
PAGE 15
LT1990 U W U U APPLICATIO S I FOR ATIO following relationship: While the LT1990 comes from the factory with an excellent CMRR, some precision applications with a large applied common mode voltage may require a method to trim out residual common mode error. This is easily accomplished by adding series resistance to each input, +IN and –IN, such that an adjustable resistance difference of ±1kΩ is provided.
PAGE 16
LT1990 U TYPICAL APPLICATIO Telecom Supply Current Monitor + LOAD IL Selectable Gain Amplifier Boosted Bidirectional Controlled Current Source +V 5V 48V +V – 3 7 + RS G2 LT1990 2 – 4 G1 VIN 5 6 + 8 7 + VIN– 2 – 4 G1 1 REF 1k G2 LT1990 VOUT 1 –77V ≤ VCM ≤ 8V VOUT = VREF – (10 • IL • RS) 3 REF VREF = 4V CZT751 5 6 VOUT 8 VCTL 3 + 6 LT1990 2 –V – + 10µF 4 RSENSE 1 2N7002 4 5 IN OUT LT6650 1 GND FB 2 7 REF ILOAD 1nF 174k 1k GAIN_SEL (HI = 10X, LO =