Datasheet

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LT2078/LT2079

20789fa

Micropower, Dual and

Quad, Single Supply,

Precision Op Amps

FEATURES

■

Supply Current per Amplifier: 50µA Max

■

Offset Voltage: 70µV Max

■

Offset Current: 250pA Max

■

Voltage Noise: 0.6µV

P-P

, 0.1Hz to 10Hz

■

Current Noise: 3pA

P-P

, 0.1Hz to 10Hz

■

Offset Voltage Drift: 0.4µV/°C

■

Gain Bandwidth Product: 200kHz

■

Slew Rate: 0.07V/µs

■

Single Supply Operation

Input Voltage Range Includes Ground

Output Swings to Ground while Sinking Current

No Pull-Down Resistors Needed

■

Output Sources and Sinks 5mA Load Current

■

SO Package with Standard Pinout

DESCRIPTION

The LT

2078 is a micropower dual op amp in 8-pin small

outline, standard surface mount package, and LT2079 is

a micropower quad op amp offered in the standard 14-pin

surface mount package. Both devices are optimized for

single supply operation at 5V. ±15V specifications are also

provided.

Micropower performance of competing devices is achieved

at the expense of seriously degrading precision, noise,

speed and output drive specifications. The design effort of

the LT2078/LT2079 was concentrated on reducing sup-

ply current without sacrificing other parameters. The

offset voltage achieved is the lowest on any dual or quad

nonchopper stabilized op amp––micropower or other-

wise. Offset current, voltage and current noise, slew rate

and gain bandwidth product are all two to ten times better

than on previous micropower op amps.

Both the LT2078/LT2079 can be operated from a single

supply (as low as one lithium cell or two NiCd batteries).

The input range goes below ground. The all NPN output

stage swings to within a few millivolts of ground while

sinking current––no power consuming pull-down resis-

tors are needed. For applications requiring DIP packages

refer to the LT1078/LT1079.

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

■

Battery or Solar-Powered Systems

Portable Instrumentation

Remote Sensor Amplifier

Satellite Circuitry

■

Micropower Sample-and-Hold

■

Thermocouple Amplifier

■

Micropower Filters

TYPICAL APPLICATION

Single Battery, Micropower, Gain = 100, Instrumentation Amplifier Distribution of Input Offset Voltage

INPUT OFFSET VOLTAGE (µV)

–120

NUMBER OF OP AMPS

2078/79 • TA02

–80 –40 40

800

700

600

500

400

300

200

100

120

= 5V, 0V

5000 OP AMPS

–

INVERTING

–INPUT

1/2 LT2078

10.1k

NONINVERTING

+INPUT

1/2 LT2078

(Li-Ion)

OUT

TYPICAL PERFORMANCE

INPUT OFFSET VOLTAGE = 40µV

INPUT OFFSET CURRENT = 0.2nA

TOTAL POWER DISSIPATION = 240µW

COMMON MODE REJECTION = 110dB (AMPLIFIER LIMITED)

GAIN BANDWIDTH PRODUCT = 200kHz

OUTPUT NOISE = 85µV

P-P

0.1Hz TO 10Hz

= 300µV

RMS

OVER FULL BANDWIDTH

INPUT RANGE = 0.03V TO 1.8V

OUTPUT RANGE = 0.03V TO 2.3V

(0.3mV ≤ V

– V

–

≤ 23mV)

OUTPUTS SINK CURRENT—NO PULL-DOWN RESISTORS

LT2078/79 • TA01

APPLICATIONS

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

Summary of content (16 pages)

PAGE 1
LT 2078/LT 2079 Micropower, Dual and Quad, Single Supply, Precision Op Amps U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO DESCRIPTION Supply Current per Amplifier: 50µA Max Offset Voltage: 70µV Max Offset Current: 250pA Max Voltage Noise: 0.6µVP-P, 0.1Hz to 10Hz Current Noise: 3pAP-P, 0.1Hz to 10Hz Offset Voltage Drift: 0.4µV/°C Gain Bandwidth Product: 200kHz Slew Rate: 0.
PAGE 2
LT2078/LT 2079 W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage ...................................................... ±22V Differential Input Voltage ....................................... ±30V Input Voltage ............... Equal to Positive Supply Voltage ............5V Below Negative Supply Voltage Output Short-Circuit Duration .......................... Indefinite Specified Temperature Range Commercial ............................................. 0°C to 70°C Industrial ...................
PAGE 3
LT 2078/LT 2079 ELECTRICAL CHARACTERISTICS CONDITIONS (NOTE 1) LT2078AC/LT2078AI LT2079AC/LT2079AI MIN TYP MAX LT2078C/LT2078I LT2079C/LT2079I MIN TYP MAX Large-Signal Voltage Gain VO = 0.03V to 4V, No Load VO = 0.03V to 3.5V, RL = 50k 200 150 1000 600 150 120 1000 600 Maximum Output Voltage Swing Output Low, No Load Output Low, 2k to GND Output Low, ISINK = 100µA Output High, No Load Output High, 2k to GND 4.2 3.5 3.5 0.55 95 4.4 3.9 4.2 3.5 3.5 0.55 95 4.4 3.9 0.04 0.07 0.04 0.
PAGE 4
LT2078/LT 2079 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 5V, 0V, VCM = 0.1V, VO = 1.4V, 0°C ≤ TA ≤ 70°C, unless otherwise noted. SYMBOL PARAMETER AVOL IS CONDITIONS Large-Signal Voltage Gain VO = 0.05V to 4V, No Load VO = 0.05V to 3.
PAGE 5
LT 2078/LT 2079 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = ±15V, 0°C ≤ TA ≤ 70°C, unless otherwise noted (Note 7). SYMBOL PARAMETER CONDITIONS LT2078AC/LT2079AC MIN TYP MAX LT2078C/LT2079C MIN TYP MAX UNITS VOS Input Offset Voltage LT2078 LT2079 ● ● 70 80 330 410 90 100 460 540 µV µV ∆VOS ∆T Input Offset Voltage Drift (Note 6) LT2078 LT2079 ● ● 0.5 0.6 1.8 3.0 0.6 0.
PAGE 6
LT2078/LT 2079 U W TYPICAL PERFORMANCE CHARACTERISTICS 0.01Hz to 10Hz Noise 0.1Hz to 10Hz Noise Noise Spectrum 1000 CHANNEL B VOLTAGE NOISE DENSITY (nV/√Hz) CURRENT NOISE DENSITY (fA/√Hz) TA = 25°C VS = ±2.5V CHANNEL A NOISE VOLTAGE (0.4µV/DIV) NOISE VOLTAGE (0.4µV/DIV) TA = 25°C VS = ±2.5V CHANNEL A 0.4µV 300 CURRENT NOISE 100 VOLTAGE NOISE 30 1/f CORNER 0.
PAGE 7
LT 2078/LT 2079 U W TYPICAL PERFORMANCE CHARACTERISTICS Gain, Phase vs Frequency 10M 5V, 0V 120 100 140 PHASE MARGIN 46° 10 160 5V, 0V 180 ±15V 200 0 PHASE SHIFT (DEG) ±15V 120 VS = ±15V VS = 5V, 0V TA = 25°C VS = ±15V 80 VS = 5V, 0V 60 25°C 125°C VOLTAGE GAIN (V/V) 20 100 VOLTAGE GAIN (dB) PHASE MARGIN 58° VOLTAGE GAIN (dB) Voltage Gain vs Load Resistance Voltage Gain vs Frequency 140 30 40 –55°C –55°C 1M 25°C 125°C 20 0 –20 0.01 0.
PAGE 8
LT2078/LT 2079 U W TYPICAL PERFORMANCE CHARACTERISTICS Common Mode Range vs Temperature 50 V+ – 1 VS = ±15V 45 40 VS = 5V, 0V 35 30 Closed-Loop Output Impedance V + = 2.5V TO 18V V – = 0V TO –18V 1k OUTPUT IMPEDANCE (Ω) 55 V+ COMMON MODE RANGE (V) V+ – 2 V– + 1 V– AV = 100 100 AV = 10 10 AV = 1 1 0.
PAGE 9
LT 2078/LT 2079 W W SI PLIFIED SCHEMATIC 1/2 LT2078, 1/4 LT2079 V+ 10k 10k 2.2k 5.6k 11.5k 5k 3.6k 1.3k Q54 1 Q16 Q6 Q5 Q14 Q15 Q53 2 1 Q32 Q52 Q47 Q4 Q46 Q37 Q29 Q3 Q30 Q24 1 V– 3 Q12 8.6k 4 Q11 C1 50pF Q40 3k Q25 Q35 V 1 2.9k 30Ω Q44 C5 2.5pF Q27 IN + 600Ω 600Ω Q41 + Q26 C4 4pF OUT IN – 12.5k Q1 Q21 150k Q18 Q28 Q2 Q22 V+ Q31 C3 40pF J1 Q36 Q33 Q48 Q19 Q50 Q42 Q49 Q39 Q9 Q23 Q10 Q17 C2 175pF Q7 Q8 V+ Q34 6.2k 6.2k 9.
PAGE 10
LT2078/LT 2079 U W U U APPLICATIONS INFORMATION The LT2078/LT2079 devices are fully specified with V + = 5V, V – = 0V, VCM = 0.1V. This set of operating conditions appears to be the most representative for battery powered micropower circuits. Offset voltage is internally trimmed to a minimum value at these supply voltages. When 9V or 3V batteries or ±2.5V dual supplies are used, bias and offset current changes will be minimal.
PAGE 11
LT 2078/LT 2079 U W U U APPLICATIONS INFORMATION 1. When the input is more than a diode drop below ground, unlimited current will flow from the substrate (V – terminal) to the input. This can destroy the unit. On the LT2078/LT2079, resistors in series with the input protect the devices even when the input is 5V below ground. 2. When the input is more than 400mV below ground (at 25°C), the input stage saturates and phase reversal occurs at the output. This can cause lockup in servo systems.
PAGE 12
LT2078/LT 2079 U U W U APPLICATIONS INFORMATION the individual characteristics of the two devices, the two and three op amp instrumentation amplifier configurations shown in this data sheet are examples. Matching characteristics are not 100% tested on the LT2078/LT2079. Some specifications are guaranteed by definition. For example, 70µV maximum offset voltage implies that mismatch cannot be more than 140µV. 95dB (= 17.5µV/V) CMRR means that worst-case CMRR match is 89dB (= 35µV/V).
PAGE 13
LT 2078/LT 2079 U TYPICAL APPLICATIONS Picoampere Input Current, Triple Op Amp Instrumentation Amplifier with Bias Current Cancellation 3 –IN + 2 R2 1M 1 1/4 LT2079 1M 9V R1 1M – 2R 20M 9 7 1/4 LT2079 5 +IN R 10M 12 2R 20M 10 + + – 2 10M 3 OUTPUT 4mV TO 8.2V + + ( 4 5 7 OUTPUT 8V TO –9V + LT2078/79 • TA06 ) Absolute Value Circuit (Full-Wave Rectifier) 200k 200k – INPUT 2 OUTPUT 1/2 LT2078 5V 3.5V 8 0V – 1/2 LT2078 + 3 3.
PAGE 14
LT2078/LT 2079 U TYPICAL APPLICATIONS Single Supply, Micropower, Second Order Lowpass Filter with 60Hz Notch 0.02µF 27.6k 0.1% 27.6k 0.1% 3 IN + 0.01µF 6 5V 8 1 1/2 LT2078 2 – 2.64M 0.1% 2.64M 0.1% – 5 OUTPUT TYPICAL OFFSET ≈ 600µV 7 1/2 LT2078 + 2000pF 0.5% 4 5.1M 1% 120k 5% 1.35M 0.1% 100pF 1000pF 0.5% 1000pF 0.5% fC = 40Hz Q = 30 LT2078/79 • TA10 Micropower Multiplier/Divider 505k 0.1% – 220pF 4 30k 5% + 30k 5% 11 14 Q1,Q2, Q3, Q4 = MAT-04 TYPICAL LINEARITY = 0.
PAGE 15
LT 2078/LT 2079 U TYPICAL APPLICATIONS Lead-Acid Low-Battery Detector with System Shutdown BATTERY OUTPUT 2M 1% 2M 1% 910k 5% 3 12V + 1 1/2 LT2078 2 LO = BATTERY LOW (IF VS < 10.90V) – 5 8 + 1/2 LT2078 255k 1% 6 280k 1% – LO = SYSTEM SHUTDOWN (IF VS < 10.05V) 7 4 LT1004-1.2 LT2078/79 • TA13 TOTAL SUPPLY CURRENT = 105µA U PACKAGE DESCRIPTION S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .
PAGE 16
LT2078/LT 2079 U PACKAGE DESCRIPTION S Package 14-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .337 – .344 (8.560 – 8.738) NOTE 3 .045 ±.005 .050 BSC 12 11 10 9 8 N .245 MIN .160 ±.005 .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) 1 .030 ±.005 TYP 13 14 N 2 3 N/2 N/2 RECOMMENDED SOLDER PAD LAYOUT 1 .010 – .020 × 45° (0.254 – 0.508) 3 2 5 4 6 .053 – .069 (1.346 – 1.752) .008 – .010 (0.203 – 0.254) .004 – .010 (0.101 – 0.