Datasheet LTC2355-12, LTC2355-14 (Analog Devices) - 10

LTC2355-12/LTC2355-14
APPLICATIONS INFORMATION DRIVING THE ANALOG INPUT
detailed information is available in the Linear Technology The differential analog inputs of the LTC2355-12/LTC2355-14 Databooks and on the LinearView™ CD-ROM.) may be driven differentially or as a single-ended input (i.e.,
LTC1566-1:
Low Noise 2.3MHz Continuous Time Low- the A – IN input is grounded). Both differential analog in- Pass Filter. puts, A + – IN and AIN , are sampled at the same instant. Any
LT®1630:
Dual 30MHz Rail-to-Rail Voltage FB Amplifier. unwanted signal that is common to both inputs of each 2.7V to ±15V supplies. Very high A input pair will be reduced by the common mode rejection VOL, 500µV offset and 520ns settling to 0.5LSB for a 4V swing. THD and noise of the sample-and-hold circuit. The inputs draw only one are –93dB to 40kHz and below 1LSB to 320kHz (A small current spike while charging the sample-and-hold V = 1, 2V capacitors at the end of conversion. During conversion, P-P into 1kΩ, VS = 5V), making the part excellent for AC applications (to 1/3 Nyquist) where rail-to-rail performance the analog inputs draw only a small leakage current. If the is desired. Quad version is available as LT1631. source impedance of the driving circuit is low, then the LTC2355-12/LTC2355-14 inputs can be driven directly. As
LT1632:
Dual 45MHz Rail-to-Rail Voltage FB Amplifier. source impedance increases, so will acquisition time. For 2.7V to ±15V supplies. Very high AVOL, 1.5mV offset and minimum acquisition time with high source impedance, 400ns settling to 0.5LSB for a 4V swing. It is suitable for a buffer amplifier must be used. The main requirement is applications with a single 5V supply. THD and noise are that the amplifier driving the analog input(s) must settle –93dB to 40kHz and below 1LSB to 800kHz (AV = 1, after the small current spike before the next conversion 2VP-P into 1kΩ, VS = 5V), making the part excellent for starts (settling time must be 39ns for full throughput rate). AC applications where rail-to-rail performance is desired. Also keep in mind while choosing an input amplifier the Quad version is available as LT1633. amount of noise and harmonic distortion added by the
LT1813:
Dual 100MHz 750V/µs 3mA Voltage Feedback amplifier. Amplifier. 5V to ±5V supplies. Distortion is –86dB to 100kHz and –77dB to 1MHz with ±5V supplies (2VP-P into 500Ω).
CHOOSING AN INPUT AMPLIFIER
Excellent part for fast AC applications with ±5V supplies. Choosing an input amplifier is easy if a few requirements
LT1801:
80MHz GBWP, –75dBc at 500kHz, 2mA/Amplifier, are taken into consideration. First, to limit the magnitude of 8.5nV/√Hz. the voltage spike seen by the amplifier from charging the
LT1806/LT1807:
325MHz GBWP, –80dBc Distortion at 5MHz, Uni- sampling capacitor, choose an amplifier that has a low output ty-Gain Stable, R-R In and Out, 10mA/Amplifier, 3.5nV/√Hz. impedance (<100Ω) at the closed-loop bandwidth frequency. For example, if an amplifier is used in a gain of 1 and has a
LT1810:
180MHz GBWP, –90dBc Distortion at 5MHz, unity-gain bandwidth of 50MHz, then the output impedance at Unity-Gain Stable, R-R In and Out, 15mA/Amplifier, 16nV/√Hz. 50MHz must be less than 100Ω. The second requirement is
LT1818/LT1819:
400MHz, 2500V/µs,9mA, Single/Dual that the closed-loop bandwidth must be greater than 40MHz Voltage Mode Operational Amplifier. to ensure adequate small-signal settling for full throughput rate. If slower op amps are used, more time for settling can
LT6200:
165MHz GBWP, –85dBc Distortion at 1MHz, be provided by increasing the time between conversions. Unity-Gain Stable, R-R In and Out, 15mA/Amplifier, The best choice for an op amp to drive the LTC2355-12/ 0.95nV/√Hz. LTC2355-14 will depend on the application. Generally, ap-
LT6203:
100MHz GBWP, –80dBc Distortion at 1MHz, plications fall into two categories: AC applications where Unity-Gain Stable, R-R In and Out, 3mA/Amplifier, dynamic specifications are most critical and time domain 1.9nV/√Hz. applications where DC accuracy and settling time are most critical. The following list is a summary of the op amps that
LT6600-10:
Amplifier/Filter Differential In/Out with 10MHz are suitable for driving the LTC2355-12/LTC2355-14. (More Cutoff. LinearView is a trademark of Linear Technology Corporation. 2355fb 10 For more information www.linear.com/LTC2355-12 Document Outline Features Description Applications Block Diagram Absolute Maximum Ratings Pin Configuration Order Information Converter Characteristics Analog Input Dynamic Accuracy Internal Reference Characteristics Digital Inputs and Digital Outputs Power Requirements Timing Characteristics Typical Performance Characteristics Pin Functions Block Diagram Timing Diagram Applications Information Package Description Revision History Typical Application Related Parts