Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - AD converter (ADC) External , Internal SOIC 28

FEATURES

● 100kHz min SAMPLING RATE

● STANDARD ±10V INPUT RANGE

● 86dB min SINAD WITH 20kHz INPUT

●

±3.0 LSB max INL

● DNL: 16 Bits No Missing Codes

● SINGLE +5V SUPPLY OPERATION

● PIN-COMPATIBLE WITH 12-BIT ADS7804

● USES INTERNAL OR EXTERNAL

REFERENCE

● FULL PARALLEL DATA OUTPUT

● 100mW max POWER DISSIPATION

● 0.3" DIP-28 AND SO-28

DESCRIPTION

The ADS7805 is a complete 16-bit sampling, Analog-to-

Digital (A/D) converter using state-of-the-art CMOS struc-

tures. It contains a complete 16-bit, capacitor-based, Suc-

cessive Approximation Register (SAR) A/D converter with

Sample-and-Hold (S/H), reference, clock, interface for micro-

processor use, and 3-state output drivers.

The ADS7805 is specified at a 100kHz sampling rate and

ensured over the full temperature range. Laser-trimmed

scaling resistors provide an industry-standard ±10V input

range while the innovative design allows operation from a

single +5V supply, with power dissipation under 100mW.

The ADS7805 is available in a 0.3" DIP-28 and an SO-28

package. Both are fully specified for operation over the

industrial –25°C to +85°C range; however, they will function

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

16-Bit, 10µs Sampling, CMOS

ANALOG-to-DIGITAL CONVERTER

Successive Approximation Register and Control Logic

Clock

Output

Latches

and

3-State

Drivers

3-State

Parallel

Data

Bus

BUSY

Comparator

BYTE

R/C

CDAC

Internal

+2.5V Ref

Buffer

4kΩ

±10V Input

REF

CAP

20kΩ

4kΩ10kΩ

ADS7805

SBAS020D – JANUARY 1996 – REVISED OCTOBER 2006

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.

All trademarks are the property of their respective owners.

Summary of content (18 pages)

PAGE 1
ADS ADS 780 ADS7805 780 5 5 SBAS020D – JANUARY 1996 – REVISED OCTOBER 2006 16-Bit, 10µs Sampling, CMOS ANALOG-to-DIGITAL CONVERTER FEATURES DESCRIPTION ● ● ● ● The ADS7805 is a complete 16-bit sampling, Analog-toDigital (A/D) converter using state-of-the-art CMOS structures. It contains a complete 16-bit, capacitor-based, Successive Approximation Register (SAR) A/D converter with Sample-and-Hold (S/H), reference, clock, interface for microprocessor use, and 3-state output drivers.
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ELECTROSTATIC DISCHARGE SENSITIVITY ABSOLUTE MAXIMUM RATINGS(1) Analog Inputs: VIN ............................................................................. ±25V REF .................................................. +VANA + 0.3V to AGND2 – 0.3V CAP .................. Indifinite Short to AGND2 Momentary Short to VANA Ground Voltage Differences: DGND, AGND1, AGND2 ................... ±0.3V VANA .......................................................................................................
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ELECTRICAL CHARACTERISTICS (Cont.) TA = –25°C to +85°C, fS = 100kHz, VDIG = VANA = +5V, using internal reference, unless otherwise specified. ADS7805P, U PARAMETER CONDITIONS REFERENCE Internal Reference Voltage Int. Ref. Source Current (must use external buffer) Internal Reference Drift Ext. Ref. Voltage Range for Specified Linearity External Reference Current Drain Ext. 2.5000V Ref DIGITAL OUTPUTS Data Format Data Coding VOL VOH Leakage Current Output Capacitance TYP MAX MIN TYP MAX UNITS 2.
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PIN CONFIGURATION VIN 1 28 VDIG AGND1 2 27 VANA REF 3 26 BUSY CAP 4 25 CS AGND2 5 24 R/C D15 (MSB) 6 23 BYTE D14 7 22 D0 (LSB) ADS7805 DIGITAL I/O D13 8 21 D1 D12 9 20 D2 D11 10 19 D3 D10 11 18 D4 D9 12 17 D5 D8 13 16 D6 DGND 14 15 D7 PIN # NAME 1 VIN DESCRIPTION 2 AGND1 3 REF Reference Input/Output. 2.2µF tantalum capacitor to ground. Reference Buffer Capacitor. 2.2µF tantalum capacitor to ground. Analog Input. See Figure 7. Analog Ground.
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TYPICAL CHARACTERISTICS TA = +25°C, fS = 100kHz, VDIG = VANA = +5V, using internal reference and fixed resistors shown in Figure 6b, unless otherwise specified. FREQUENCY SPECTRUM (8192 Point FFT; fIN = 45kHz, 0dB) 0 0 –20 –20 –40 –40 Amplitude (dB) Amplitude (dB) FREQUENCY SPECTRUM (8192 Point FFT; fIN = 20kHz, 0dB) –60 –80 –100 –60 –80 –100 –120 –120 –140 –140 0.0 12.5 25.0 37.5 50.0 0.0 25.0 37.5 50.
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TYPICAL CHARACTERISTICS (Cont.) TA = +25°C, fS = 100kHz, VDIG = VANA = +5V, using internal reference and fixed resistors shown in Figure 6b, unless otherwise specified. CONVERSION TIME vs TEMPERATURE 8.0 2.515 7.9 2.510 7.8 Conversion Time (µs) Internal Reference (V) INTERNAL REFERENCE VOLTAGE vs TEMPERATURE 2.520 2.505 2.500 2.495 2.490 7.7 7.6 7.5 7.4 7.3 2.485 2.480 7.
PAGE 7
BASIC OPERATION Table II for a summary of CS, R/C, and BUSY states and Figures 3 through 5 for timing diagrams. Figure 1 shows a basic circuit to operate the ADS7805 with a full parallel data output. Taking R/C (pin 24) LOW for a minimum of 40ns (7µs max) will initiate a conversion. BUSY (pin 26) will go LOW and stay LOW until the conversion is completed and the output registers are updated. Data will be output in Binary Two’s Complement with the MSB on pin 6.
PAGE 8
READING DATA PARALLEL OUTPUT (During a Conversion) The ADS7805 outputs full or byte-reading parallel data in Binary Two’s Complement data output format. The parallel output will be active when R/C (pin 24) is HIGH and CS (pin 25) is LOW. Any other combination of CS and R/C will tristate the parallel output. Valid conversion data can be read in a full parallel, 16-bit word or two 8-bit bytes on pins 6-13 and pins 15-22. BYTE (pin 23) can be toggled to read both bytes within one conversion cycle.
PAGE 9
t1 R/C t13 t2 t4 BUSY t3 t6 MODE DATA BUS t5 Acquire Previous Data Valid Convert Acquire t7 t8 Previous Data Valid Hi-Z t9 Not Valid Convert Hi-Z Data Valid Data Valid t10 t11 FIGURE 3. Conversion Timing with Outputs Enabled after Conversion (CS Tied LOW). t12 t12 t12 t12 R/C t1 CS t3 t4 BUSY t6 MODE Convert Acquire Acquire t7 Hi-Z State DATA BUS Data Valid Hi-Z State t9 t14 FIGURE 4. Using CS to Control Conversion and Read Timing.
PAGE 10
INPUT RANGES SOFTWARE CALIBRATION The ADS7805 offers a standard ±10V input range. Figure 6 shows the necessary circuit connections for the ADS7805 with and without hardware trim. Offset and full-scale error(1) specifications are tested and specified with the fixed resistors shown in Figure 6b. Adjustments for offset and gain are described in the “Calibration” section of this data sheet. To calibrate the offset and gain of the ADS7805 in software, no external resistors are required.
PAGE 11
Digital Output 7FFF –10V –9.99983V –9.9998V –50mV 9.9997V –15mV 9.999815V +10V Analog Input Ideal Transfer Function With External Resistors Range of Transfer Function Without External Resistors 8000 FIGURE 7. Full-Scale Transfer Function. REFERENCE CAP The ADS7805 can operate with its internal 2.5V reference or an external reference. By applying an external reference to pin 5, the internal reference can be bypassed.
PAGE 12
LAYOUT SIGNAL CONDITIONING POWER For optimum performance, tie the analog and digital power pins to the same +5V power supply and tie the analog and digital grounds together. As noted in the electrical specifications, the ADS7805 uses 90% of its power for the analog circuitry. The ADS7805 should be considered as an analog component. The +5V power for the A/D converter should be separate from the +5V used for the system’s digital logic.
PAGE 13
Revision History DATE REVISION PAGE 10/06 D 3 8/06 C 2 SECTION Absolute Maximum Ratings DESCRIPTION CAP and REF were switched. Package/Ordering Information Corrected typos in ordering table. NOTE: Page numbers for previous revisions may differ from page numbers in the current version. ADS7805 SBAS020D www.ti.
PAGE 14
PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 11-Apr-2013 (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.