Datasheet

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LTC6240/LTC6241/LTC6242

624012fe

Single/Dual/Quad 18MHz,

Low Noise, Rail-to-Rail Output,

CMOS Op Amps

The LTC

6240/6241/LTC6242 are single, dual and quad

low noise, low offset, rail-to-rail output, unity gain stable

CMOS op amps that feature 1pA of input bias current. Input

bias current is guaranteed to be 1pA max on the single

LTC6240. The 0.1Hz to 10Hz noise of only 550nV

P-P

, along

with an offset of just 125µV are signiﬁ cant improvements

over traditional CMOS op amps. Additionally, noise is

guaranteed to be less than 10nV/√Hz at 1kHz. An 18MHz

gain bandwidth, and 10V/µs slew rate, along with the wide

supply range and low input capacitance, make them perfect

for use as fast signal processing ampliﬁ ers.

These op amps have an output stage that swings within

30mV of either supply rail to maximize the signal dynamic

range in low supply applications. The input common mode

range extends to the negative supply. They are fully speci-

ﬁ ed on 3V and 5V, and an HV version guarantees operation

on supplies up to ±5V.

The LTC6240 is available in the 8-pin SO and the 5-pin SOT-

23 packages. The LTC6241 is available in the 8-pin SO, and

for compact designs it is packaged in a tiny dual ﬁ ne pitch

leadless (DFN) package. The LTC6242 is available in the

16-pin SSOP as well as the 5mm × 3mm DFN package.

Photo Diode Ampliﬁ ers

Charge Coupled Ampliﬁ ers

Low Noise Signal Processing

Medical Instrumentation

High Impedance Transducer Ampliﬁ er

0.1Hz to 10Hz Noise: 550nV

P-P

Input Bias Current:

0.2pA (Typ at 25°C)

1pA Max (LTC6240)

Low Offset Voltage: 125μV Max

Low Offset Drift: 2.5µV/°C Max

Gain Bandwidth Product: 18MHz

Output Swings Rail-to-Rail

Supply Operation:

2.8V to 6V LTC6240/LTC6241/LTC6242

2.8V to ±5.5V LTC6240HV/LTC6241HV/LTC6242HV

Low Input Capacitance

H-Grade Temperature Range: –40°C to 125°C

Single LTC6240 in 5-Pin Low Proﬁ le (1mm)

ThinSOT™ Package and 8-Pin SO for PCB Guard Ring

Dual LTC6241 in 8-Pin SO and Tiny DFN Packages

Quad LTC6242 in 16-Pin SSOP and 5mm × 3mm

DFN Packages

Low Noise Single-Ended Input to Differential Output Ampliﬁ er Noise Voltage vs Frequency

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

DESCRIPTION

FEATURES

APPLICATIONS

–

200k

10pF

+2.5V

–2.5V

6241 TA01a

4.99k

200k

OUT

–

1/2

LTC6241

–

1/2

LTC6241

10pF

4.99k

10pF

FREQUENCY (Hz)

NOISE VOLTAGE (nV/√Hz)

1 100 1k 100k

6241 TA01b

10k

= 25°C

= ±2.5V

= 0V

Summary of content (32 pages)

PAGE 1
LTC6240/LTC6241/LTC6242 Single/Dual/Quad 18MHz, Low Noise, Rail-to-Rail Output, CMOS Op Amps DESCRIPTION FEATURES n n n n n n n n n n n n 0.1Hz to 10Hz Noise: 550nVP-P Input Bias Current: 0.2pA (Typ at 25°C) 1pA Max (LTC6240) Low Offset Voltage: 125μV Max Low Offset Drift: 2.5μV/°C Max Gain Bandwidth Product: 18MHz Output Swings Rail-to-Rail Supply Operation: 2.8V to 6V LTC6240/LTC6241/LTC6242 2.8V to ±5.
PAGE 2
LTC6240/LTC6241/LTC6242 ABSOLUTE MAXIMUM RATINGS (Note 1) Total Supply Voltage (V+ to V–) LTC6240/LTC6241/LTC6242 ...................................7V LTC6240HV/LTC6241HV/LTC6242HV....................12V Input Voltage.......................... (V+ + 0.3V) to (V– – 0.3V) Input Current........................................................ ±10mA Output Short-Circuit Duration (Note 2) ............ Indeﬁnite Operating Temperature Range LTC6240C/LTC6241C/LTC6242C ..........
PAGE 3
LTC6240/LTC6241/LTC6242 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LTC6240CS5#PBF LTC6240CS5#TRPBF LTCRR 5-Lead Plastic TSOT-23 0°C to 70°C LTC6240HVCS5#PBF LTC6240HVCS5#TRPBF LTCRS 5-Lead Plastic TSOT-23 0°C to 70°C LTC6240IS5#PBF LTC6240IS5#TRPBF LTCRR 5-Lead Plastic TSOT-23 –40°C to 85°C LTC6240HVIS5#PBF LTC6240HVIS5 #TRPBF LTCRS 5-Lead Plastic TSOT-23 –40°C to 85°C LTC6240HS5#PBF LTC6240HS5#TRPBF LTCRR 5-Lead
PAGE 4
LTC6240/LTC6241/LTC6242 AVAILABLE OPTIONS PART NUMBER LTC6240CS5 LTC6240CS8 LTC6240HVCS5 LTC6240HVCS8 LTC6240IS5 LTC6240IS8 LTC6240HVIS5 LTC6240HVIS8 LTC6240HS5 LTC6240HS8 LTC6240HVHS5 LTC6240HVHS8 LTC6241CS8 LTC6241CDD LTC6241HVCS8 LTC6241HVCDD LTC6241IS8 LTC6241IDD LTC6241HVIS8 LTC6241HVIDD LTC6241HS8 LTC6241HVHS8 LTC6242CGN LTC6242CDHC LTC6242HVCGN LTC6242HVCDHC LTC6242IGN LTC6242IDHC LTC6242HVIGN LTC6242HVIDHC LTC6242HGN LTC6242HVHGN AMPS/PACKAGE 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 4 4 4 4 4 4
PAGE 5
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240C/I, LTC6240HVC/I, LTC6241C/I, LTC6241HVC/I, LTC6242C/I, LTC6242HVC/I) The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VS = 5V, 0V, VCM = 2.5V unless otherwise noted.
PAGE 6
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240C/I, LTC6240HVC/I, LTC6241C/I, LTC6241HVC/I, LTC6242C/I, LTC6242HVC/I) The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VS = 5V, 0V, VCM = 2.5V unless otherwise noted. SYMBOL PARAMETER CONDITIONS AVOL Large Signal Voltage Gain VO = 1V to 4V RL = 10k to VS/2 0°C to 70°C –40°C to 85°C MIN TYP MAX UNITS l l 425 300 200 1600 V/mV V/mV V/mV VO = 1.5V to 3.
PAGE 7
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240C/I, LTC6240HVC/I, LTC6241C/I, LTC6241HVC/I, LTC6242C/I, LTC6242HVC/I) The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VS = 3V, 0V, VCM = 1.5V unless otherwise noted.
PAGE 8
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240C/I, LTC6240HVC/I, LTC6241C/I, LTC6241HVC/I, LTC6242C/I, LTC6242HVC/I) The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VS = 3V, 0V, VCM = 1.5V unless otherwise noted.
PAGE 9
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240HVC/I, LTC6241HVC/I, LTC6242HVC/I) The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. VS = ±5V, 0V, VCM = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS en Input Noise Voltage Density f = 1kHz in Input Noise Current Density (Note 8) 0.
PAGE 10
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240H/LTC6240HVH, LTC6241H/LTC6241HVH, LTC6242H/LTC6242HVH) The l denotes the speciﬁcations which apply from –40°C to 125°C, otherwise speciﬁcations are at TA = 25°C. VS = 5V, 0V, VCM = 2.5V unless otherwise noted.
PAGE 11
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240H/LTC6240HVH, LTC6241H/LTC6241HVH, LTC6242H/LTC6242HVH) The l denotes the speciﬁcations which apply from –40°C to 125°C, otherwise speciﬁcations are at TA = 25°C. VS = 3V, 0V, VCM = 1.5V unless otherwise noted.
PAGE 12
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS (LTC6240HVH/LTC6241HVH/LTC6242HVH) The l denotes the speciﬁcations which apply from –40°C to 125°C, otherwise speciﬁcations are at TA = 25°C. VS = ±5V, VCM = 0V unless otherwise noted.
PAGE 13
LTC6240/LTC6241/LTC6242 ELECTRICAL CHARACTERISTICS Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: A heat sink may be required to keep the junction temperature below the absolute maximum rating when the output is shorted indeﬁnitely.
PAGE 14
LTC6240/LTC6241/LTC6242 TYPICAL PERFORMANCE CHARACTERISTICS VOS Distribution LTC6241 VOS Temperature Coefﬁcient Distribution LTC6241 VOS Distribution LTC6241 90 120 VS = ±2.5V 80 SO-8 PACKAGE 16 VS = ±2.5V DD PACKAGE 14 100 60 50 40 30 NUMBER OF UNITS 12 NUMBER OF UNITS NUMBER OF UNITS 70 80 60 40 20 10 0 –50 –30 –10 10 30 50 INPUT OFFSET VOLTAGE (μV) 6 0 0 70 –350 –250 –150 –50 50 150 250 INPUT OFFSET VOLTAGE (μV) 6241 G01 –1.0 –0.6 –0.2 0.2 0.6 1.
PAGE 15
LTC6240/LTC6241/LTC6242 TYPICAL PERFORMANCE CHARACTERISTICS 100 VS = 10V VS = 5V 10 1 0.1 TA = 25°C 1 TA = 125°C 0.1 TA = –55°C 0.01 0.001 0.
PAGE 16
LTC6240/LTC6241/LTC6242 TYPICAL PERFORMANCE CHARACTERISTICS Power Supply Rejection Ratio vs Frequency Channel Separation vs Frequency 90 –20 POWER SUPPLY REJECTION RATIO (dB) TA = 25°C VS = ±2.5V AV = 1 –10 –40 –50 –60 –70 –80 –90 –100 –110 –120 10k TA = 25°C VS = ±2.
PAGE 17
LTC6240/LTC6241/LTC6242 TYPICAL PERFORMANCE CHARACTERISTICS Warm-Up Drift vs Time 20 50 NOISE VOLTAGE (nV/√Hz) VS = ±5V 15 VS = ±2.5V 5 VS = ±1.5V 0 40 30 20 10 0 –5 0 5 10 15 20 25 30 35 40 45 50 55 60 TIME AFTER POWER UP (s) 10 1 10k 100 1k FREQUENCY (Hz) 100k TIME (1s/DIV) 6241 G28 Series Output Resistance and Overshoot vs Capacitive Load 50 OVERSHOOT (%) NOISE CURRENT (fA/√Hz) 75pF 1k 100 10 Minimum Output Series Resistance vs Capacitive Load 1000 60 TA = 25°C VS = ±2.
PAGE 18
LTC6240/LTC6241/LTC6242 TYPICAL PERFORMANCE CHARACTERISTICS Maximum Undistorted Output Signal vs Frequency Distortion vs Frequency –30 8 AV = –1 7 –50 –50 AV = +2 6 5 4 VS = ±5V AV = 1 –40 V OUT = 2VP-P DISTORTION (dBc) 9 RL = 1k, 2ND –60 –70 RL = 1k, 3RD –80 –60 RL = 1k, 2ND –70 RL = 1k, 3RD –80 3 TA = 25°C 2 VS = ±5V HD2, HD3 < –40dBc 1 10k 100k 1M FREQUENCY (Hz) –90 10M –90 –100 10k 100k 1M FREQUENCY (Hz) 6241 G37 –100 10k –30 –50 –50 10M Small Signal Response VS = ±5V AV = 2
PAGE 19
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION Ampliﬁer Characteristics The ampliﬁer input bias current is the leakage current of these ESD diodes. This leakage is a function of the temperature and common mode voltage of the ampliﬁer, as shown in the Typical Performance Characteristics curves. Figure 1 is a simpliﬁed schematic of the ampliﬁer, which has a pair of low noise input transistors M1 and M2.
PAGE 20
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION Proprietary design techniques are used to obtain simultaneous low 1/f noise and low input capacitance. Low input capacitance is important when the ampliﬁer is used with high value source and feedback resistors. High frequency noise from the ampliﬁer tail current source, ITAIL in Figure 1, couples through the input capacitance and appears across these large source and feedback resistors.
PAGE 21
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION DIFFERENTIAL OUTPUT VOLTAGE DENSITY (nV/√Hz) The op amp’s good input offset voltage match and low input bias current means that the typical differential output offset voltage is less than 40μV. A noise spectrum plot of the differential output is shown in Figure 5. 140 VS = ±2.5V TA = 25°C 120 –3dB BW = 80kHz The guard ring should extend as far as necessary to shield the high impedance signal from any and all leakage paths.
PAGE 22
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION V+ R3 C1 R1 G2 G1 G0 7 6 5 0.1μF 8 V1 LTC6910-2 OUT AGND IN V– 2 3 4 1 + 1/2 LTC6241 – VOUT R2 100Ω R4 R7 C3 V2 C2 V+ R1 = R2 = R3 = R4 0.1μF R5 – 1/2 LTC6241 1000pF + R6 20k 1 LT6650 2 5 VREF 1μF 3 1k 4 Example Design: Design a programmable gain AC difference ampliﬁer, with a bandwidth of at least 10Hz to 100kHz, an input impedance equal to or greater than 100kΩ, and an output DC reference equal to 1V.
PAGE 23
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION to achieve an extraordinarily low noise and low DC drift. The performance of this circuit is suited for the demanding transducer signal conditioning situations such as high resolution scales and magnetic search coils. with the input chopper, proper amplitude and polarity information is presented to A2, the DC output ampliﬁer. This stage integrates the square wave into a DC voltage, providing the output.
PAGE 24
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION The noise measured over a 50 second interval, in Figure 10, is 40nV in a 0.1Hz to 10Hz bandwidth.This low noise is attributed to the input JFET’s die size and current density. 20nV/DIV 5s/DIV by the sensor is forced across the feedback capacitor by the op amp action. Because the feedback capacitor is 100 times smaller than the sensor, it will be forced to 100 times what would have been the sensor’s open circuit voltage. So the circuit gain is 100.
PAGE 25
LTC6240/LTC6241/LTC6242 APPLICATIONS INFORMATION 1M Transimpedance Ampliﬁer with 43nV/√Hz Output Noise By achieving an output swing of 50V before attenuation, the circuit provides an output swing to 5V after attenuation. The 10M resistor sets the gain of the TIA stage and has a noise density of 400nV/√Hz. After attenuation, the effective TIA gain drops to 1M while the noise ﬂoor drops to 40nV/√Hz, which clearly dominates the observed 43nV/√Hz.
PAGE 26
LTC6240/LTC6241/LTC6242 PACKAGE DESCRIPTION DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.70 p0.05 3.5 p0.05 1.65 p0.05 2.10 p0.05 (2 SIDES) PACKAGE OUTLINE 0.25 p 0.05 0.50 BSC 2.38 p0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 3.00 p0.10 (4 SIDES) R = 0.125 TYP 5 0.40 p 0.10 8 1.65 p 0.10 (2 SIDES) PIN 1 TOP MARK (NOTE 6) (DD8) DFN 0509 REV C 0.200 REF 0.75 p0.05 4 0.25 p 0.05 1 0.50 BSC 2.38 p0.10 0.00 – 0.
PAGE 27
LTC6240/LTC6241/LTC6242 PACKAGE DESCRIPTION DHC Package 16-Lead Plastic DFN (5mm × 3mm) (Reference LTC DWG # 05-08-1706) 0.65 ±0.05 3.50 ±0.05 1.65 ±0.05 2.20 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 4.40 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5.00 ±0.10 (2 SIDES) R = 0.20 TYP 3.00 ±0.10 (2 SIDES) 9 0.40 ± 0.10 16 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) PIN 1 NOTCH (DHC16) DFN 1103 8 0.200 REF 1 0.25 ± 0.05 0.50 BSC 0.75 ±0.05 4.40 ±0.
PAGE 28
LTC6240/LTC6241/LTC6242 PACKAGE DESCRIPTION GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .189 – .196* (4.801 – 4.978) .045 ±.005 16 15 14 13 12 11 10 9 .254 MIN .009 (0.229) REF .150 – .165 .229 – .244 (5.817 – 6.198) .0165 ± .0015 .150 – .157** (3.810 – 3.988) .0250 BSC RECOMMENDED SOLDER PAD LAYOUT 1 .015 ± .004 × 45° (0.38 ± 0.10) .007 – .0098 (0.178 – 0.249) .0532 – .0688 (1.35 – 1.75) 2 3 4 5 6 7 8 .004 – .0098 (0.102 – 0.249) 0° – 8° TYP .
PAGE 29
LTC6240/LTC6241/LTC6242 PACKAGE DESCRIPTION S5 Package 5-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1635 Rev B) 0.62 MAX 0.95 REF 2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3.
PAGE 30
LTC6240/LTC6241/LTC6242 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 .050 BSC 8 .245 MIN 7 6 5 .160 ±.005 .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP 1 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN .053 – .069 (1.346 – 1.752) .014 – .019 (0.
PAGE 31
LTC6240/LTC6241/LTC6242 REVISION HISTORY (Revision history begins at Rev E) REV DATE DESCRIPTION E 07/10 Update to Simpliﬁed Schematic (Figure 1) PAGE NUMBER 19 624012fe Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 32
LTC6240/LTC6241/LTC6242 TYPICAL APPLICATION 150kHz 3RD ORDER BUTTERWORTH FILTER 1MΩ TIA R1 866Ω + 1/2 LTC6241 – RF 1M R2 1.69k R3 2k C1 1500pF C2 1500pF C3 180pF +1.5V + 1/2 LTC6241 – SFH213FA OR EQUIVALENT (≤4pF) –1.5V 6241 TA02a CF 1pF –1.5V Figure 15. Ultralow Noise 1MΩ 150kHz Photodiode Ampliﬁer Competition Output Noise Spectrum. Op Amp Noise Dominates; Performance Compromised 30nV/√Hz PER DIV 30nV/√Hz PER DIV LTC6241 Output Noise Spectrum.