Datasheet AD7705, AD7706 (Analog Devices) - 7

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AD7705/AD7706 Parameter B Version1 Unit Conditions/Comments
POWER REQUIREMENTS VDD Voltage 2.7 to 3.3 V min to V max For specified performance Power Supply Currents17 Digital I/Ps = 0 V or VDD, external MCLK IN and CLKDIS = 1 0.32 mA max BUF bit = 0, fCLKIN = 1 MHz, gains of 1 to 128 0.6 mA max BUF bit = 1, fCLKIN = 1 MHz, gains of 1 to 128 0.4 mA max BUF bit = 0, fCLKIN = 2.4576 MHz, gains of 1 to 4 0.6 mA max BUF bit = 0, fCLKIN = 2.4576 MHz, gains of 8 to 128 0.7 mA max BUF bit = 1, fCLKIN = 2.4576 MHz, gains of 1 to 4 1.1 mA max BUF bit = 1, fCLKIN = 2.4576 MHz, gains of 8 to 128 VDD Voltage 4.75 to 5.25 V min to V max For specified performance Power Supply Currents17 Digital I/Ps = 0 V or VDD, external MCLK IN and CLKDIS = 1 0.45 mA max BUF bit = 0, fCLKIN = 1 MHz, gains of 1 to 128 0.7 mA max BUF bit = 1, fCLKIN = 1 MHz, gains of 1 to 128 0.6 mA max BUF bit = 0, fCLKIN = 2.4576 MHz, gains of 1 to 4 0.85 mA max BUF bit = 0, fCLKIN = 2.4576 MHz, gains of 8 to 128 0.9 mA max BUF bit = 1, fCLKIN = 2.4576 MHz, gains of 1 to 4 1.3 mA max BUF bit = 1, fCLKIN = 2.4576 MHz, gains of 8 to 128 Standby (Power-Down) Current18 16 μA max External MCLK IN = 0 V or VDD, VDD = 5 V, see Figure 12 8 μA max External MCLK IN = 0 V or VDD, VDD = 3 V Power Supply Rejection19, 20 dB typ 1 Temperature range is −40°C to +85°C. 2 These numbers are established from characterization or design data at initial product release. 3 A calibration is effectively a conversion; therefore, these errors are of the order of the conversion noise shown in Table 5 and Table 7. This applies after calibration at the temperature of interest. 4 Recalibration at any temperature removes these drift errors. 5 Positive full-scale error includes zero-scale errors (unipolar offset error or bipolar zero error) and applies to both unipolar and bipolar input ranges. 6 Full-scale drift includes zero-scale drift (unipolar offset drift or bipolar zero drift) and applies to both unipolar and bipolar input ranges. 7 Gain error does not include zero-scale errors. It is calculated as (full-scale error – unipolar offset error) for unipolar ranges and (full-scale error - bipolar zero error) for bipolar ranges. 8 Gain drift does not include unipolar offset drift or bipolar zero drift. It is effectively the drift of the part if only zero-scale calibrations are performed. 9 This common-mode voltage range is allowed, provided that the input voltage on analog inputs is not more positive than VDD + 30 mV or more negative than GND − 100 mV. Parts are functional with voltages down to GND − 200 mV, but with increased leakage at high temperatures. 10 The AD7705/AD7706 can tolerate absolute analog input voltages down to GND − 200 mV, but the leakage current increases. 11 The analog input voltage range on AIN(+) is given with respect to the voltage on AIN(−) on the AD7705, and with respect to the voltage of the COMMON input on the AD7706. The absolute voltage on the analog inputs should not be more positive than VDD + 30 mV, or more negative than GND − 100 mV for specified performance. Input voltages of GND − 200 mV can be accommodated, but with increased leakage at high temperatures. 12 VREF = REFIN(+) − REFIN(−). 13 These logic output levels apply to the MCLK OUT only when it is loaded with one CMOS load. 14 Sample tested at 25°C to ensure compliance. 15 After calibration, if the analog input exceeds positive full scale, the converter outputs all 1s. If the analog input is less than negative full scale, the device outputs all 0s. 16 These calibration and span limits apply, provided that the absolute voltage on the analog inputs does not exceed VDD + 30 mV or go more negative than GND − 100 mV. The offset calibration limit applies to both the unipolar zero point and the bipolar zero point. 17 When using a crystal or ceramic resonator across the MCLK pins as the clock source for the device, the VDD current and power dissipation varies depending on the crystal or resonator type (see Clocking and Oscillator Circuit section). 18 If the external master clock continues to run in standby mode, the standby current increases to 150 μA typical at 5 V and 75 μA at 3 V. When using a crystal or ceramic resonator across the MCLK pins as the clock source for the device, the internal oscillator continues to run in standby mode, and the power dissipation depends on the crystal or resonator type (see Standby Mode section). 19 Measured at dc and applies in the selected pass band. PSRR at 50 Hz exceeds 120 dB, with filter notches of 25 Hz or 50 Hz. PSRR at 60 Hz exceeds 120 dB, with filter notches of 20 Hz or 60 Hz. 20 PSRR depends on both gain and VDD, as follows:
Gain 1 2 4 8 to 128
VDD = 3 V 86 78 85 93 VDD = 5 V 90 78 84 91 Rev. C | Page 7 of 44 Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM REVISION HISTORY PRODUCT HIGHLIGHTS SPECIFICATIONS TIMING CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS OUTPUT NOISE (5 V OPERATION) OUTPUT NOISE (3 V OPERATION) TYPICAL PERFORMANCE CHARACTERISTICS ON-CHIP REGISTERS COMMUNICATION REGISTER (RS2, RS1, RS0 = 0, 0, 0) SETUP REGISTER (RS2, RS1, RS0 = 0, 0, 1); POWER-ON/RESET STATUS: 01 HEXADECIMAL CLOCK REGISTER (RS2, RS1, RS0 = 0, 1, 0); POWER-ON/RESET STATUS: 05 HEXADECIMAL DATA REGISTER (RS2, RS1, RS0 = 0, 1, 1) TEST REGISTER (RS2, RS1, RS0 = 1, 0, 0); POWER-ON/RESET STATUS: 00 HEXADECIMAL ZERO-SCALE CALIBRATION REGISTER (RS2, RS1, RS0 = 1, 1, 0); POWER-ON/RESET STATUS: 1F4000 HEXADECIMAL FULL-SCALE CALIBRATION REGISTER (RS2, RS1, RS0 = 1, 1, 1); POWER-ON/RESET STATUS: 5761AB HEXADECIMAL Calibration Sequences CIRCUIT DESCRIPTION ANALOG INPUT Ranges Sample Rate BIPOLAR/UNIPOLAR INPUT REFERENCE INPUT DIGITAL FILTERING Filter Characteristics Postfiltering ANALOG FILTERING CALIBRATION Self-Calibration System Calibration Span and Offset Limits Power-Up and Calibration THEORY OF OPERATION CLOCKING AND OSCILLATOR CIRCUIT SYSTEM SYNCHRONIZATION RESET INPUT STANDBY MODE ACCURACY DRIFT CONSIDERATIONS POWER SUPPLIES SUPPLY CURRENT GROUNDING AND LAYOUT EVALUATING THE PERFORMANCE DIGITAL INTERFACE CONFIGURING THE AD7705/AD7706 MICROCOMPUTER/MICROPROCESSOR INTERFACING AD7705/AD7706-to-68HC11 Interface AD7705/AD7706-to-8051 Interface AD7705/AD7706-to-ADSP-2103/ADSP-2105 Interface CODE FOR SETTING UP THE AD7705/AD7706 C Code for Interfacing AD7705 to 68HC11 APPLICATIONS PRESSURE MEASUREMENT TEMPERATURE MEASUREMENT SMART TRANSMITTERS BATTERY MONITORING OUTLINE DIMENSIONS ORDERING GUIDE