ADS1601IPFBT.B datasheet(15/31 Pages) TI2

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AINP+AINN

Modulator

Digital

Filter

Serial

Interface

VREFN

IOVDD

VREFP

REF

AINP

AINN

FSO

DOUT

SCLK

CLK

1.06

ADS1601

www.ti.com

SBAS322D

– DECEMBER 2004 – REVISED OCTOBER 2011

OVERVIEW

The ADS1601 is a high-performance delta-sigma

The ADS1601 supports a very wide range of input

ADC. The modulator uses an inherently stable 2-1-1

signals. For VREF = 3V, the full-scale input voltage is

multi-stage

architecture

incorporating

proprietary

±2.82V. Having such a wide input range makes

circuitry

that

allows

for

very

linear

high-speed

out-of-range

signals

unlikely.

However,

operation. The modulator samples the input signal at

out-of-range signal occurs, the digital output OTR

20MSPS (when fCLK = 20MHz). A low-ripple linear

goes high.

phase digital filter decimates the modulator output by

The analog inputs must be driven with a differential

16 to provide high resolution 16-bit output data.

signal to achieve optimum performance. For the input

Conceptually, the modulator and digital filter measure

signal:

the differential input signal, VIN = (AINP – AINN),

against

the

scaled

differential

reference,

VREF = (VREFP – VREFN), as shown in Figure 35.

The voltage reference can either be generated

the recommended common-mode voltage is 2.7V. In

internally or supplied externally. A three-wire serial

addition to the differential and common-mode input

interface, designed for direct connection to DSPs,

voltages, the absolute input voltage is also important.

outputs the data. A separate power supply for the I/O

This is the voltage on either input (AINP or AINN)

allows flexibility for interfacing to different logic

with respect to AGND. The range for this voltage is:

families. Out-of-range conditions are indicated with a

–0.1V < (AINN or AINP) < 4.6V

dedicated digital output pin. Analog power dissipation

is controlled using an external resistor. This control

If either input is taken below

–0.1V, ESD protection

allows reduced dissipation when operating at slower

diodes on the inputs will turn on. Exceeding 4.6V on

speeds. When not in use, power consumption can be

either input results in degradation in the linearity

dramatically reduced by setting the PD pin low to

performance. ESD protection diodes will also turn on

enter Power-Down mode.

if the inputs are taken above AVDD (+5V).

The recommended absolute input voltage is:

ANALOG INPUTS (AINP, AINN)

–0.1V < (AINN or AINP) < 4.2V

The

ADS1601

measures

the

differential

signal,

VIN = (AINP – AINN), against the differential

Keeping the inputs within this range provides for

reference, VREF = (VREFP – VREFN). The most

optimum performance.

positive measurable differential input is 0.94VREF,

which produces the most positive digital output code

of 7FFFh. Likewise, the most negative measurable

differential input is

–0.94VREF, which produces the

most negative digital output code of 8000h.

Figure 35. Conceptual Block Diagram

ADS1601IPFBT.B Datasheet(PDF) 15 Page - Texas Instruments

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