LT1994 Linear Technology, LT1994 Datasheet

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LT1994

Manufacturer Part Number
LT1994
Description
Low Noise - Low Distortion Fully Differential Input/Output Amplifier/Driver
Manufacturer
Linear Technology
Datasheet

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ALTERA
0
APPLICATIO S
FEATURES
TYPICAL APPLICATIO
2V
Fully Differential Input and Output
Wide Supply Range: 2.375V to 12.6V
Rail-to-Rail Output Swing
Low Noise: 3nV/√Hz
Low Distortion, 2V
Adjustable Output Common Mode Voltage
Unity Gain Stable
Gain-Bandwidth: 70MHz
Slew Rate: 65V/μs
Large Output Current: 85mA
DC Voltage Offset <2mV MAX
Open-Loop Gain: 100V/mV
Low Power Shutdown
8-Pin MSOP or 3mm × 3mm DFN Package
Differential Input A/D Converter Driver
Single-Ended to Differential Conversion
Differential Amplifi cation with Common Mode
Translation
Rail-to-Rail Differential Line Driver/Receiver
Low Voltage, Low Noise, Differential Signal
Processing
A/D Preamplifi er: Single-Ended Input to Differential Output with Common
V
P-P
IN
0.1µF
499Ω
499Ω
3V
V
+
U
OCM
499Ω
+
499Ω
P-P
LT1994
0.1µF
, 1MHz: –94dBc
Mode Level Shifting
V
24.9Ω
24.9Ω
OCM
U
= 1.5V
47pF
A
LTC1403A-1
A
IN
IN
+
GND
V
3V
DD
CONV
V
SD0
SCK
REF
10µF
10µF
DESCRIPTIO
The LT
tion, fully differential input/output amplifi er optimized for
3V, single supply operation. The LT1994’s output common
mode voltage is independent of the input common mode
voltage, and is adjustable by applying a voltage on the
V
path provides accurate output phase balancing and reduced
even-order harmonics. This makes the LT1994 ideal for
level shifting ground referenced signals for driving dif-
ferential input, single supply ADCs.
The LT1994 output can swing rail-to-rail and is capable
of sourcing and sinking up to 85mA. In addition to the
low distortion characteristics, the LT1994 has a low input
referred voltage noise of 3nV/√Hz. This part maintains
its performance for supply voltages as low as 2.375V. It
draws only 13.3mA of supply current and has a hardware
shutdown feature that reduces current consumption to
225µA.
The LT1994 is available in an 8-pin MSOP or 8-pin DFN
package.
All other trademarks are the property of their respective owners.
50.4MHz
OCM
1994 TA01
, LTC and LT are registered trademarks of Linear Technology Corporation.
Low Noise, Low Distortion
pin. A separate internal common mode feedback
®
Output Amplifi er/Driver
1994 is a high precision, very low noise, low distor-
Fully Differential Input/
–100
–110
–120
–10
–20
–30
–40
–50
–60
–70
–80
–90
U
0
LT1994 Driving an LTC1403A-1 1MHz
0
F
F
INPUT = 2V
SINGLE ENDED
SFDR = 93dB
Sine Wave, 8192 Point FFT Plot
SAMPLE
IN
= 1.001MHz
0.35
= 2.8Msps
P-P
FREQUENCY
,
www.DataSheet4U.com
0.70
(MHz)
1.05
LT1994
1994 TA01b
1.40
1994fa
1

Related parts for LT1994

LT1994 Summary of contents

Page 1

... The LT1994 is available in an 8-pin MSOP or 8-pin DFN package. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. ...

Page 2

... SHDN – – OUT 5 – ORDER PART NUMBER LBQM LT1994CMS8 LBQM LT1994IMS8 The denotes the specifi cations which apply over the full operating ● + – = 25° – )/ defi ned OUTDIFF ...

Page 3

... R = 800Ω 3V 100Ω ±5V, No Load ±5V 800Ω ±5V 100Ω LT1994 www.DataSheet4U.com = mid-supply OPEN, ⎯ S ⎯ H ⎯ D ⎯ OCM ICM + – is defi ned (V – OUTCM + – + – defi ned as (V ...

Page 4

... Note 4: The LT1994C/LT1994I are guaranteed functional over the operating temperature range –40°C to 85°C. Note 5: The LT1994C is guaranteed to meet specifi ed performance from 0°C to 70°C. The LT1994C is designed, characterized, and expected to meet specifi ed performance from –40°C to 85°C but is not tested or QA sampled at these temperatures. The LT1994I is guaranteed to meet specifi ...

Page 5

... ± –1 –2 100 0 FREQUENCY (MHz) LT1994 www.DataSheet4U.com pin to the change in differential input OCM – OUTCM OCM Input Bias Current and Input Offset Current vs Temperature –10 = ± – – ...

Page 6

... LT1994 W U TYPICAL PERFOR A CE CHARACTERISTICS Output Impedance vs Frequency 100 499Ω 0.1 0 FREQUENCY (MHz) 1994 G07 Input Common Mode Rejection vs Frequency 100 ∆V ICM ∆V OSDIFF 90 = ± 10k 100k 1M 10M 100M ...

Page 7

... Large Signal Step Response 499Ω – OUT – OUT SINGLE ENDED IN P-P 100ns/DIV LT1994 www.DataSheet4U.com 2V Step Response Settling +0.1% ERROR V OUT 499Ω 100 25ns/DIV 1994 G16 Output with Large Input Overdrive 499Ω ...

Page 8

... LT1994 W U TYPICAL PERFOR A CE CHARACTERISTICS Supply Current vs Supply Voltage 20 + SHDN PIN VOLTAGE = 85° –40° 0° 25° 70° 5.0 7.5 10.0 2.5 SUPPLY VOLTAGE (V) 1994 G21 ⎯ S ⎯ H ⎯ D ⎯ N Pin Current vs ⎯ S ⎯ H ⎯ D ⎯ N ...

Page 9

... Pin 7 is directly tied to V operating mode. When Pin 7 is pulled a minimum of 2.1V + below V , the LT1994 enters into a low power shutdown state. Refer to the ⎯ S ⎯ H ⎯ D ⎯ N pin section under Applications Information for description of the LT1994 output imped- ance in the shutdown state. ...

Page 10

... V differential signals in preparation for driving low voltage, single-supply, differential input ADCs. Unlike traditional op amps which have a single output, the LT1994 has two outputs to process signals differentially. This allows for two times the signal swing in low voltage systems when compared to single-ended output amplifi ...

Page 11

... OUT OUT and output common mode voltages, or the voltage at the common mode pin. This makes the LT1994 ideally suited pre-amplifi cation, level shifting, and conversion of single ended signals to differential output signals in preparation for driving differential input ADCs. ...

Page 12

... A direct OCM = OCM Input Common Mode Voltage Range The LT1994’s input common mode voltage (V as the average of the two input voltages input INP INM It extends from V INP input common mode range depends on the circuit con- fi guration (gain), V ...

Page 13

... Noise Considerations The LT1994’s input referred voltage noise is on the order – OUT L of 3nV/√ ...

Page 14

... (kΩ Figure 6. LT1994 Output Spot Noise vs Spot Noise Contributed by Feedback Network Alone Figure 6 shows the noise voltage that will appear differ- entially between the outputs. The common mode output noise voltage does not add to this differential noise. For optimum noise and distortion performance, use a dif- ferential output confi ...

Page 15

... LOAD 540 ) Layout Considerations Because the LT1994 is a high speed amplifi er sensitive to both stray capacitance and stray inductance. Compo- nents connected to the LT1994 should be connected with as short and direct connections as possible. A low noise, low impedance ground plane is critical for the highest performance. In single supply applications, high quality surface mount 1μ ...

Page 16

... RF (2pF to 5pF). Always keep in mind the differential nature of the LT1994, and that it is critical that the output impedances seen by both outputs (stray or intended) should be as bal- anced and symmetric as possible. This will help preserve ...

Page 17

... C11 = 400pF abs = 1000kHz, C11 = 390pF and Gain = 4, R21 ) 2.5MHz 3dB and –28dB at 5 • f 3dB R21 C21 R11 R31 + V 0.1µ – C11 LT1994 0.1µ – R12 R32 C22 R22 3dB + V OUT – V OUT 1994 TA04 1994fa 17 ...

Page 18

... R11 = R21 = 549Ω, R21 = R22 = 549Ω and R31 = R32 = 15.4Ω. Note 1: The equations for R1, R2, R3 are ideal and do not account for the fi nite gain bandwidth product (GBW) of the LT1994 (70MHz). The maximum gain is set MHz ≤ ...

Page 19

... MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) DETAIL “A” 0.254 (.010) 0° – 6° TYP GAUGE PLANE 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.18 (.007) SEATING LT1994 www.DataSheet4U.com R = 0.115 TYP 5 1.65 ± 0.10 3.00 ±0.10 (4 SIDES) (2 SIDES) 4 0.25 ± 0.05 0.75 ±0.05 2.38 ±0.10 (2 SIDES) 0.00 – ...

Page 20

... LT1994 Q 2 OUT 8 0.1µ 0.056µF 140Ω 402Ω 82pF 1994 TA02 LT 0306 REV A • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2005 ...

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