LT1469 datasheet(11/26 Pages) LINER

11 / 26 page

LTC2326-16

232616fa

For more information www.linear.com/LTC2326-16

applicaTions inForMaTion

OVERVIEw

The LTC2326-16 is a low noise, high speed 16-bit suc-

cessive approximation register (SAR) ADC with pseudo-

differential inputs. Operating from a single 5V supply, the

LTC2326-16hasa±10.24Vtruebipolarinputrange,making

it ideal for high voltage applications which require a wide

dynamic range. The LTC2326-16 achieves ±1.5LSB INL

maximum, no missing codes at 16-bits and 93.5dB SNR.

The LTC2326-16 has an onboard single-shot capable

reference buffer and low drift (20ppm/°C max) 2.048V

temperature-compensated reference. The LTC2326-16

also has a high speed SPI-compatible serial interface that

supports1.8V,2.5V,3.3Vand5Vlogicwhilealsofeaturing

a daisy-chain mode. The fast 250ksps throughput with

no cycle latency makes the LTC2326-16 ideally suited

for a wide variety of high speed applications. An internal

oscillator sets the conversion time, easing external timing

considerations. The LTC2326-16 dissipates only 28mW

and automatically naps between conversions, leading to

reduced power dissipation that scales with the sampling

rate. A sleep mode is also provided to reduce the power

consumption of the LTC2326-16 to 300μW for further

power savings during inactive periods.

CONVERTER OPERATION

The LTC2326-16 operates in two phases. During the

acquisition phase, the charge redistribution capacitor

D/A converter (CDAC) is connected to the outputs of

the resistor divider networks that pins IN+ and IN– drive

to sample an attenuated and level-shifted version of the

pseudo-differential analog input voltage as shown in Fig-

ure 3. A rising edge on the CNV pin initiates a conversion.

Duringtheconversionphase,the16-bitCDACissequenced

throughasuccessiveapproximationalgorithm,effectively

comparing the sampled input with binary-weighted frac-

tions of the reference voltage (e.g. VREFBUF/2, VREFBUF/4

… VREFBUF/65536) using the differential comparator. At

the end of conversion, the CDAC output approximates the

sampledanaloginput.TheADCcontrollogicthenprepares

the 16-bit digital output code for serial transfer.

Figure 2. LTC2326-16 Transfer Function

TRANSFER FUNCTION

The LTC2326-16 digitizes the full-scale voltage of ±2.5 •

REFBUF into 216 levels, resulting in an LSB size of 312.5µV

withREFBUF=4.096V.Theidealtransferfunctionisshown

in Figure 2. The output data is in 2’s complement format.

ANALOG INPUT

The analog inputs of the LTC2326-16 are pseudo-differen-

tial in order to reduce any unwanted signal that is common

to both inputs. The analog inputs can be modeled by the

equivalent circuit shown in Figure 3. The back-to-back

diodes at the inputs form clamps that provide ESD protec-

tion. Each input drives a resistor divider network that has

Figure 3. The Equivalent Circuit for the Differential

Analog Input of the LTC2326-16

RON

400

CIN

45pF

RON

0.63 • VREFBUF

CIN

45pF

IN+

IN–

BIAS

VOLTAGE

1.6k

400

0.63 • VREFBUF

232616 F03

INPUT VOLTAGE (V)

–1

LSB

232616 F02

011...111

011...110

000...001

000...000

100...000

100...001

111...110

LSB

BIPOLAR

ZERO

111...111

FSR/2 – 1LSB

–FSR/2

FSR = +FS – –FS

1LSB = FSR/65536

LT1469 датащи(PDF) 11 Page - Linear Technology

LT1469 датащи(HTML) 11 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

датащи скачать

ссылки URL