LTC2361HS6 データシートの表示（PDF） - Linear Technology

部品番号

コンポーネント説明

メーカー

LTC2361HS6

100ksps/250ksps/500ksps, 12-Bit Serial ADCs in TSOT-23

Linear Technology 

LTC2360/LTC2361/LTC2362

APPLICATIONS INFORMATION

CONV

SCK

SDO

ACQUIRE

INPUT

tACQ

EXECUTE CONVERSION

DATA TRANSFER

EXECUTING A DUMMY CONVERSION AND

PUT THE DEVICE INTO SLEEP MODE

tCONV

tDATA

tCONV

SLEEP MODE

RECOMMENDED HIGH OR LOW

12 34

B11 B10 B9

9 10 11 12

B3 B2 B1 B0

RECOMMENDED HIGH OR LOW

Hi-Z STATE

tTHROUGHPUT = tACQ + 2 • tCONV + tDATA + tSLEEPMODE

236012 F13

Figure 13. Minimize the Time When the Device Draws Power, While the Conversion Results are Available Right After Conversion

SINGLE-ENDED ANALOG INPUT

Driving the Analog Input

The analog input of the LTC2360/LTC2361/LTC2362 is

easy to drive. The input draws only one small current

spike while charging the sample-and-hold capacitor with

the ADC going into track mode. During the conversion,

the analog input draws only a small leakage current. If

the source impedance of the driving circuit is low, then

the input of the LTC2360/LTC2361/LTC2362 can be driven

directly. As source impedance increases, so will acquisi-

tion time. For minimum acquisition time with high source

impedance, a buffer amplifier should be used. The main

requirement is that the amplifier driving the analog input

must settle after the small current spike before the next

conversion starts (settling time must be less than tACQ

for full throughput rate). While choosing an input ampli-

fier, also keep in mind the amount of noise and harmonic

distortion the amplifier contributes.

Choosing an Input Amplifier

Choosing an input amplifier is easy if a few requirements

are taken into consideration. First, to limit the magnitude

of the voltage spike seen by the amplifier from charging

the sampling capacitor, choose an amplifier that has a low

output impedance (<100Ω) at the closed-loop bandwidth

frequency. For example, if an amplifier is used in a gain

of 1 and has a unity-gain bandwidth of 10MHz, then the

output impedance at 10MHz must be less than 100Ω. The

second requirement is that the closed-loop bandwidth must

be greater than 8MHz to ensure adequate small-signal

settling for full throughput rate. If slower op amps are

used, more time for settling can be provided by increasing

the time between conversions. The best choice for an op

amp to drive the LTC2360/LTC2361/LTC2362 will depend

on the application. Generally, applications fall into two

categories: AC applications where dynamic specifications

are most critical and time domain applications where DC

accuracy and settling time are most critical. The follow-

ing list is a summary of the op amps that are suitable for

driving the LTC2360/LTC2361/LTC2362. (More detailed

information is available on the Linear Technology website at

www.linear.com.)

LTC1566-1: Low Noise 2.3MHz Continuous Time Low-

pass Filter.

LT®1630: Dual 30MHz Rail-to-Rail Voltage FB Amplifier.

2.7V to ±15V supplies. Very high AVOL, 500μV offset and

520ns settling to 0.5LSB for a 4V swing. THD and noise

are –93dB to 40kHz and below 1LSB to 320kHz (AV =

1, 2VP-P into 1k, VS = 5V), making the part excellent for

AC applications (to 1/3 Nyquist) where rail-to-rail perfor-

mance is desired. Quad version is available as LT1631.

LTC6241: Dual 18MHz, Low Noise, Rail-to-Rail, CMOS

Voltage FB Amplifier. 2.8V to 6V supplies. Very high AVOL

and 125μV offset. It is suitable for applications with a single

5V supply. Quad version is available as LTC6242.

LT1797: Unity-Gain Stable 10MHz, Rail-to-Rail Voltage

Feedback Amplifier.

LT1801: 180MHz GBWP, –75dBc at 500kHz, 2mA/Ampli-

fier, 8.5nV/√Hz.

LT6203: 100MHz GBWP, –80dBc Distortion at 1MHz, Unity-

Gain Stable, R-R In and Out, 3mA/Amplifier, 1.9nV/√Hz.

16

236012fa

Share Link: