Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - AD converter (ADC) External SSOP 20

16-Bit, 8-Channel Serial Output Sampling

ANALOG-TO-DIGITAL CONVERTER

FEATURES

● BIPOLAR INPUT RANGE

● PIN-FOR-PIN COMPATIBLE WITH THE

ADS7844 AND ADS8344

● SINGLE SUPPLY: 2.7V to 5V

● 8-CHANNEL SINGLE-ENDED OR

4-CHANNEL DIFFERENTIAL INPUT

● UP TO 100kHz CONVERSION RATE

● 85dB SINAD

● SERIAL INTERFACE

● QSOP-20 AND SSOP-20 PACKAGES

DESCRIPTION

The ADS8345 is an 8-channel, 16-bit, sampling

Analog-to-Digital (A/D) converter with a synchronous serial

interface. Typical power dissipation is 8mW at a 100kHz

throughput rate and a +5V supply. The reference voltage

REF

) can be varied between 500mV and V

/2, providing a

corresponding input voltage range of ±V

REF

. The device

includes a shutdown mode which reduces power dissipation

to under 15µW. The ADS8345 is ensured down to 2.7V

operation.

Low-power, high-speed, and an onboard multiplexer make

the ADS8345 ideal for battery-operated systems such as

personal digital assistants, portable multi-channel data log-

gers, and measurement equipment. The serial interface also

provides low-cost isolation for remote data acquisition. The

ADS8345 is available in a QSOP-20 or SSOP-20 package

and is ensured over the –40°C to +85°C temperature range.

CDAC

SAR

Comparator

8-Channel

Multiplexer

Serial

Interface

and

Control

CH4

CH5

CH6

CH7

COM

REF

SHDN

OUT

BUSY

DCLK

CH0

CH1

CH2

CH3

ADS8345

SBAS177C – FEBRUARY 2001 – REVISED APRIL 2003

www.ti.com

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

APPLICATIONS

● DATA ACQUISITION

● TEST AND MEASUREMENT EQUIPMENT

● INDUSTRIAL PROCESS CONTROL

● PERSONAL DIGITAL ASSISTANTS

● BATTERY-POWERED SYSTEMS

Summary of content (24 pages)

PAGE 1
ADS8345 ADS 834 5 ADS 834 5 ® ® SBAS177C – FEBRUARY 2001 – REVISED APRIL 2003 16-Bit, 8-Channel Serial Output Sampling ANALOG-TO-DIGITAL CONVERTER FEATURES DESCRIPTION ● BIPOLAR INPUT RANGE The ADS8345 is an 8-channel, 16-bit, sampling Analog-to-Digital (A/D) converter with a synchronous serial interface. Typical power dissipation is 8mW at a 100kHz throughput rate and a +5V supply.
PAGE 2
ABSOLUTE MAXIMUM RATINGS(1) ELECTROSTATIC DISCHARGE SENSITIVITY +VCC to GND ........................................................................ –0.3V to +6V Analog Inputs to GND .......................................... –0.3V to (+VCC) + 0.3V Digital Inputs to GND ........................................................... –0.3V to +6V Power Dissipation .......................................................................... 250mW Maximum Junction Temperature ......................................
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ELECTRICAL CHARACTERISTICS: +5V At TA = –40°C to +85°C, +VCC = +5V, VREF = +2.5V, fSAMPLE = 100kHz, and fCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted. ADS8345E, N PARAMETER CONDITIONS MIN RESOLUTION ANALOG INPUT Full-Scale Input Span Absolute Input Range Positive Input-Negative Input +IN –IN 1.0 20 3 POWER-SUPPLY REQUIREMENTS +VCC Quiescent Current ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ 100 VIN VIN VIN VIN = = = = 5Vp-p 5Vp-p 5Vp-p 5Vp-p at at at at ✻ ✻ ✻ ✻ 500 30 100 2.4 0.
PAGE 4
ELECTRICAL CHARACTERISTICS: +2.7V At TA = –40°C to +85°C, +VCC = +2.7V, VREF = +1.25V, fSAMPLE = 100kHz, and fCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted.
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TYPICAL CHARACTERISTICS: +5V At TA = +25°C, +VCC = +5V, VREF = +2.5V, fSAMPLE = 100kHz, and fDCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted. FREQUENCY SPECTRUM (4096 Point FFT; fIN = 9.985kHz, –0.
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TYPICAL CHARACTERISTICS: +5V (Cont.) At TA = +25°C, +VCC = +5V, VREF = +2.5V, fSAMPLE = 100kHz, and fDCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted. DIFFERENTIAL LINEARITY ERROR vs CODE 3 2 2 1 1 DLE (LSB) ILE (LSB) INTEGRAL LINEARITY ERROR vs CODE 3 0 0 –1 –1 –2 –2 –3 8000H 0000H C000H 4000H –3 8000H 7FFFH C000H 7FFFH Output Code SUPPLY CURRENT vs TEMPERATURE CHANGE IN BPZ vs TEMPERATURE 1.7 4 3 Delta from 25°C (LSBs) 1.6 Supply Current (mA) 4000H 0000H Output Code 1.
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TYPICAL CHARACTERISTICS: +5V (Cont.) At TA = +25°C, +VCC = +2.5V, VREF = +2.5V, fSAMPLE = 100kHz, and fDCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted. WORST-CASE CHANNEL-TO-CHANNEL GAIN MATCH vs TEMPERATURE COMMON-MODE REJECTION vs FREQUENCY 0.5 100 90 CMRR (dB) Gain Match (LSBs) 0.4 0.3 80 70 0.2 60 VCM = 2Vp-p Sinewave Centered Around VREF 0.1 50 –50 –25 0 25 50 75 100 0.1 1 Temperature (°C) 10 100 Frequency (kHz) TYPICAL CHARACTERISTICS: +2.7V At TA = +25°C, +VCC = +2.
PAGE 8
TYPICAL CHARACTERISTICS: +2.7V (Cont.) At TA = +25°C, +VCC = +2.7V, VREF = +1.25V, fSAMPLE = 100kHz, and fDCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted. EFFECTIVE NUMBER OF BITS vs INPUT FREQUENCY CHANGE IN SIGNAL-TO-(NOISE + DISTORTION) vs TEMPERATURE 0.4 14.0 fIN = 4.956kHz, –0.2dB 0.2 13.0 Delta from +25°C (dB) Effective Number of Bits 13.5 12.5 12.0 11.5 11.0 10.5 10.0 0 –0.2 –0.4 –0.6 –0.8 9.5 –1.0 9.
PAGE 9
TYPICAL CHARACTERISTICS: +2.7V (Cont.) At TA = +25°C, +VCC = +2.7V, VREF = +1.25V, fSAMPLE = 100kHz, and fDCLK = 24 • fSAMPLE = 2.4MHz, unless otherwise noted. WORST-CASE CHANNEL-TO-CHANNEL BPZ MATCH vs TEMPERATURE CHANGE IN GAIN vs TEMPERATURE 1.0 0.9 BPZ Match (LSBs) Delta from 25°C (LSBs) 1.0 0.5 0 0.8 0.7 0.6 0.5 –0.5 –50 –25 0 25 50 75 –50 100 –25 0 Temperature (°C) WORST-CASE CHANNEL-TO-CHANNEL GAIN MATCH vs TEMPERATURE 50 75 100 COMMON-MODE REJECTION vs FREQUENCY 0.
PAGE 10
THEORY OF OPERATION determines the range over which the common voltage may vary (see Figure 3). The ADS8345 is a classic Successive Approximation Register (SAR) A/D converter. The architecture is based on capacitive redistribution which inherently includes a sampleand-hold function. The converter is fabricated on a 0.6µm CMOS process. When the input is differential, the amplitude of the input is the difference between the CHX and COM input (see Figure 4).
PAGE 11
REFERENCE INPUT The external reference sets the analog input range. The ADS8345 will operate with a reference in the range of 500mV to +VCC/2. Keep in mind that the analog input is the differ- ence between the CHX input and the COM input, as shown in Figure 4. For example, in the single-ended mode, a 1.25V reference with the COM pin at VCC/2, the selected input channel (CH0-CH7) will properly digitize a signal in the range of (VCC/2 – 1.25V) to (VCC/2 + 1.25V).
PAGE 12
There are several critical items concerning the reference input and its wide-voltage range. As the reference voltage is reduced, the analog voltage weight of each digital output code is also reduced. This is often referred to as the LSB (Least Significant Bit) size and is equal to the reference voltage divided by 65536. Any offset or gain error inherent in the A/D converter will appear to increase, in terms of LSB size, as the reference voltage is reduced.
PAGE 13
The SGL/DIF -bit controls the multiplexer input mode: either in single-ended mode, where the selected input channel is referenced to the COM pin, or in differential mode, where the two selected inputs provide a differential input. See Tables III and IV and Figure 4 for more information. The last two bits (PD1-PD0) select the Power-Down mode and Clock mode, as shown in Table V. If both PD1 and PD0 are HIGH, the device is always powered up.
PAGE 14
Since one clock cycle of the serial clock is consumed with BUSY going HIGH (while the MSB decision is being made), 16 additional clocks must be given to clock out all 16 bits of data; thus, one conversion takes a minimum of 25 clock cycles to fully read the data. Since most microprocessors communicate in 8-bit transfers, this means that an additional transfer must be made to capture the LSB.
PAGE 15
SYMBOL DESCRIPTION MIN tACQ tDS tDH tDO tDV tTR tCSS tCSH tCH tCL tBD tBDV tBTR Acquisition Time DIN Valid Prior to DCLK Rising DIN Hold After DCLK HIGH DCLK Falling to DOUT Valid CS Falling to DOUT Enabled CS Rising to DOUT Disabled CS Falling to First DCLK Rising CS Rising to DCLK Ignored DCLK HIGH DCLK LOW DCLK Falling to BUSY Rising CS Falling to BUSY Enabled CS Rising to BUSY Disabled 1.
PAGE 16
output of the analog comparator. Thus, during any single conversion for an n-bit SAR converter, there are n “windows” in which large external transient voltages can easily affect the conversion result. Such glitches might originate from switching power supplies, nearby digital logic, and highpower devices. The degree of error in the digital output depends on the reference voltage, layout, and the exact timing of the external event.
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PACKAGE OPTION ADDENDUM www.ti.
PAGE 18
PACKAGE OPTION ADDENDUM www.ti.com 11-Apr-2013 Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
PAGE 19
PACKAGE MATERIALS INFORMATION www.ti.com 24-Jul-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant ADS8345E/2K5 SSOP DBQ 20 2500 330.0 16.4 6.5 9.0 2.1 8.0 16.0 Q1 ADS8345N/1K SSOP DB 20 1000 330.0 16.4 8.2 7.5 2.5 12.0 16.
PAGE 20
PACKAGE MATERIALS INFORMATION www.ti.com 24-Jul-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS8345E/2K5 SSOP DBQ 20 2500 367.0 367.0 38.0 ADS8345N/1K SSOP DB 20 1000 367.0 367.0 38.
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MECHANICAL DATA MSSO002E – JANUARY 1995 – REVISED DECEMBER 2001 DB (R-PDSO-G**) PLASTIC SMALL-OUTLINE 28 PINS SHOWN 0,38 0,22 0,65 28 0,15 M 15 0,25 0,09 8,20 7,40 5,60 5,00 Gage Plane 1 14 0,25 A 0°–ā8° 0,95 0,55 Seating Plane 2,00 MAX 0,10 0,05 MIN PINS ** 14 16 20 24 28 30 38 A MAX 6,50 6,50 7,50 8,50 10,50 10,50 12,90 A MIN 5,90 5,90 6,90 7,90 9,90 9,90 12,30 DIM 4040065 /E 12/01 NOTES: A. B. C. D. All linear dimensions are in millimeters.
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