AD7616BSTZ datasheet(25/51 Pages) AD

25 / 51 page

AD7616

Data Sheet

Rev. 0 | Page 24 of 50

ing resistor on the VxAGND or VxBGND channel, an offset

error occurs on that channel. Use the input overvoltage clamp

protection circuitry to protect the AD7616 against transient

overvoltage events. It is not recommended to leave the AD7616

in a condition where the clamp protection circuitry is active in

normal or power-down conditions for extended periods.

Figure 43. Input Resistance Matching on the Analog Input

Analog Input Antialiasing Filter

An analog antialiasing filter (a first-order Butterworth) is also

provided on the AD7616. Figure 44 and Figure 45 show the

frequency and phase response, respectively, of the analog

antialiasing filter. The typical corner frequency in the ±10 V

range is 39 kHz, and 33 kHz in the ±5 V range.

Figure 44. Analog Antialiasing Filter Frequency Response

Figure 45. Analog Antialiasing Filter Phase Response

ADC TRANSFER FUNCTION

The output coding of the AD7616 is twos complement. The

designed code transitions occur midway between successive

integer LSB values, that is, 1/2 LSB and 3/2 LSB. The LSB size is

full-scale range ÷ 65,536 for the AD7616. The ideal transfer

characteristics for the AD7616 are shown in Figure 46. The LSB

size is dependent on the analog input range selected.

Figure 46. Transfer Characteristics

INTERNAL/EXTERNAL REFERENCE

The AD7616 can operate with either an internal or external

reference. The device contains an on-chip 2.5 V band gap refer-

ence. The REFINOUT pin allows access to the 2.5 V reference

that generates the on-chip 4.096 V reference internally, or it

allows an external reference of 2.5 V to be applied to the AD7616.

An externally applied reference of 2.5 V is also amplified to 4.096 V

using the internal buffer. This 4.096 V buffered reference is the

reference used by the SAR ADC.

The REFSEL pin is a logic input pin that allows the user to select

between the internal reference and an external reference. If this

pin is set to logic high, the internal reference is selected and

enabled. If this pin is set to logic low, the internal reference is

disabled and an external reference voltage must be applied

to the REFINOUT pin.

The internal reference buffer is always enabled. After a full reset,

the AD7616 operates in the reference mode selected by the

REFSEL pin. Decoupling is required on the REFINOUT pin for

both the internal and external reference options. A 100 nF, X8R

ceramic capacitor is required on the REFINOUT pin to

REFINOUTGND.

The AD7616 contains a reference buffer configured to amplify

the reference voltage to ~4.096 V. A 10 μF, X5R ceramic capacitor

is required between REFCAP and REFGND. The reference voltage

available at the REFINOUT pin is 2.5 V. When the AD7616 is

configured in external reference mode, the REFINOUT pin is a

high input impedance pin.

1MΩ

CLAMP

Vxx

1MΩ

CLAMP

VxxGND

RFB

ANALOG

INPUT

SIGNAL

AD7616

–30

–25

–20

–15

–10

–5

100

10k

100k

INPUT FREQUENCY (Hz)

±10V RANGE

±5V RANGE

±2.5V RANGE

100

10k

100k

INPUT FREQUENCY (Hz)

±10V RANGE

±5V RANGE

±2.5V RANGE

011...111

011...110

000...001

000...000

111...111

100...010

100...001

100...000

–FS + 1/2LSB 0V – 1/2LSB +FS – 3/2LSB

ANALOG INPUT

+FS

MIDSCALE

–FS

LSB

±10V RANGE +10V

–10V

305µV

±5V RANGE

+5V

–5V

152µV

±2.5V RANGE

+FS – (–FS)

2N*

*WHERE N IS THE NUMBER OF BITS OF THE CONVERTER

LSB =

VIN

2.5V

REFINOUT

±5VCODE=

× 32,768 ×

VIN

2.5V

REFINOUT

±2.5VCODE=

× 32,768 ×

VIN

10V

2.5V

REFINOUT

±10V CODE =

× 32,768 ×

+2.5V

–2.5V

76µV

AD7616BSTZ датащи(PDF) 25 Page - Analog Devices

AD7616BSTZ датащи(HTML) 25 Page - Analog Devices

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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

датащи скачать

ссылки URL