ADAQ4003BBCZ datasheet(21/35 Pages) AD

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Data Sheet

ADAQ4003

Rev. 0 | Page 21 of 35

0.1µF

10kΩ

VCMO

10kΩ

33Ω

10µF

1nF

0.1µF

VS–

VCMO

MODE

GND

ADCIN+

ADCIN–

VDD = 1.8V

REF_OUT

REF = 5V

VS+ = 5.5V

2.2µF

VIO

SDI

SCK

SDO

CNV

OUT–

1kΩ

VCMO

1kΩ

1.1kΩ

1kΩ

IN–

IN+

OUT+

R1K–

R1K1–

R1K1+

R1K+

PD_AMP

PD_REF

ADC

+2.5V

EXAMPLE 3

–2.5V

–7V

+7V

–7V

+7V

+9.5V

EXAMPLE 2

G = 1

+4.5V

+7V

+0.5V

EXAMPLE 1

–4.5V

–2V

R1K+

R1K–

R1K+

R1K–

R1K+

R1K–

ADAQ4003

FDA

Figure 46. Differential Configuration with G = 1

0.1µF

10kΩ

VCMO

10kΩ

33Ω

10µF

1nF

0.1µF

VS–

VCMO

MODE

GND

ADCIN+

ADCIN–

VDD = 1.8V

REF_OUT

REF = 5V

VS+ = 5.5V

2.2µF

VIO

SDI

SCK

SDO

CNV

OUT–

1kΩ

VCMO

1kΩ

1.1kΩ

1kΩ

IN–

IN+

OUT+

R1K–

R1K1–

R1K1+

R1K+

ADC

+1.3V

EXAMPLE 3

–1.3V

–5V

+5V

–5V

+5V

+6.3V

EXAMPLE 2

G = 1.9

+3.7V

+5V

+0V

EXAMPLE 1

–2.6V

–1.3V

R1K+

R1K–

R1K+

R1K–

R1K+

R1K–

ADAQ4003

FDA

PD_AMP

PD_REF

Figure 47. Differential Configuration with G = 1.9

ANALOG INPUTS

High Frequency Input Signals

The ADAQ4003 ac performance over a wide input frequency

range using a 5 V reference voltage is shown in Figure 21 and

Figure 24. The ADAQ4003 maintains exceptional ac performance

for input frequencies up to the Nyquist frequency with minimal

performance degradation.

EASE OF DRIVE FEATURES

Input Span Compression

The ADAQ4003 includes a span compression feature that

increases the headroom and footroom available to the ADC driver

by reducing the input range by 10% from the top and bottom of

the range while still accessing all available ADC codes. The SNR

decreases by approximately 1.9 dB (20 × log(8/10)) for the

reduced input range when span compression is enabled. Span

compression is disabled by default but can be enabled by writing to

the relevant register bit (see the Digital Interface section).

ADC High-Z Mode

The ADAQ4003 incorporates ADC high-Z mode, which reduces

the nonlinear charge kickback when the capacitor DAC

switches back to the input at the start of the acquisition. The

ADC high-Z mode is disabled by default but can be enabled by

writing to the register (see Table 14). Disable high-Z mode for

input frequencies above 100 kHz or when multiplexing.

Driving the ADAQ4003 Using a High Impedance PGIA

The majority of instrumentation and programmable gain

instrumentation amplifiers (PGIAs) are single-ended output,

which cannot directly drive the fully differential data

acquisition signal chain. However, the LTC6373 PGIA offers

fully differential outputs, low noise, low distortion, and high

bandwidth. The LTC6373 is dc-coupled on the input and the

output with programmable gain settings (using the A2, A1, and

A0 pins). These features enable the LTC6373 to drive the

ADAQ4003 directly in many signal chain applications without

sacrificing precision performance.

ADAQ4003BBCZ Datasheet(PDF) 21 Page - Analog Devices

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