AD7457 Analog Devices, AD7457 Datasheet
AD7457
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AD7457 Summary of contents
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... V power supply and features throughput rates 100 kSPS. The part contains a low noise, wide bandwidth, differential track-and-hold (T/H) amplifier that can handle input frequen- cies in excess of 1 MHz. The reference voltage for the AD7457 is applied externally to the V pin and can range from 100 mV to REF V , depending on what suits the application ...
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... AD7457 TABLE OF CONTENTS Specifications..................................................................................... 3 Timing Specifications....................................................................... 5 Absolute Maximum Ratings............................................................ 6 ESD Caution.................................................................................. 6 Pin Configuration and Function Descriptions............................. 7 Typical Performance Characteristics ............................................. 8 Terminology .................................................................................... 10 Theory of Operation ...................................................................... 11 Circuit Information.................................................................... 11 Converter Operation.................................................................. 11 ADC Transfer Function............................................................. 11 Typical Connection Diagram ................................................... 11 REVISION HISTORY 2/05—Rev Rev. A Changes to Table 3............................................................................ 6 Changes to Ordering Guide .......................................................... 17 10/03— ...
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... 200 µA 2.8 2.4 0.4 ±1 10 Straight natural binary 16 1 100 AD7457 Unit dB min dB min dB max dB max dB typ dB typ ns typ ps typ MHz typ MHz typ Bits LSB max LSB max LSB max LSB max µA max ...
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... Analog inputs with slew rates exceeding 27 V/µs (full-scale input sine wave > 3.5 MHz) within the acquisition time may cause an incorrect result to be returned by the converter input is applied provide a pseudo ground for V IN– 5 The AD7457 is functional with a reference input range of 100 Guaranteed by characterization. 7 See the Power Consumption section. ...
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... DB11 DB10 DB2 4 LEADING ZEROS Figure 2. AD7457 Serial Interface Timing Diagram Rev Page unless otherwise noted. MAX ) and timed from a voltage level and the time required for the output to DD Figure 3. The measured number is then extrapolated ...
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... AD7457 ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise noted. A Table 3. Parameter V to GND GND IN GND IN– Digital Input Voltage to GND Digital Output Voltage to GND V to GND REF Input Current to Any Pin Except Supplies Operating Temperature Range Commercial (B Version) Storage Temperature Range Junction Temperature θ ...
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... Serial Data. Logic output. The conversion result from the AD7457 is provided on this output as a serial data stream. The bits are clocked out on the falling edge of the SCLK input. The data stream of the AD7457 consists of four leading zeros followed by the 12 bits of conversion data that are provided MSB first. The output coding is straight (natural) binary ...
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... CODE Figure 8. Typical DNL for the AD7457 for V 1.0 0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 –1.0 0 1024 2048 3072 CODE Figure 9. Typical INL for the AD7457 for V 9949 CODES 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 27 CODES 24 CODES 0 2046 2047 2048 ...
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... POSITIVE INL 0 NEGATIVE INL – 1 – 0.5 1.0 1.5 2.0 2.5 V (V) REF Figure 12. Change in INL vs. V for V REF 3.0 3 3.0 3 Rev Page AD7457 0.5 1.0 1.5 2.0 2.5 3.0 V (V) REF Figure 13. ENOB vs. V for and 5 V REF DD 3.5 ...
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... The AD7457 is tested using the CCIF standard, where two input frequencies near the top end of the input bandwidth are used. In this case, the second order terms are usually distanced in fre- quency from the original sine waves, while the third order terms are usually at a frequency close to the input frequencies ...
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... THEORY OF OPERATION CIRCUIT INFORMATION The AD7457 is a 12-bit, low power, single supply, successive approximation analog-to-digital converter (ADC) with a pseudo differential analog input. It operates with a single 2 5.25 V power supply and is capable of throughput rates up to 100 kSPS. It requires an external reference to be applied to the V pin ...
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... SUPPLY 10µF Figure 19 shows the equivalent circuit of the analog input SERIAL structure of the AD7457. The four diodes provide ESD protec- INTERFACE tion for the analog inputs. Care must be taken to ensure that the SCLK analog input signals never exceed the supply rails by more than µ ...
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... The falling edge of CS powers up the AD7457 and also puts the track-and-hold into track. Power-up time is 1 µs minimum and, in this time, the device also acquires the analog input signal. CS must remain low for the duration of power-up. The rising edge of CS initiates the conversion process, puts the track-and-hold into hold mode, and takes the serial data bus out of three-state ...
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... The ADSP-218x family of DSPs can be interfaced directly to the vs. SCLK DD AD7457 without any glue logic. The serial clock for the ADC is provided by the DSP. SDATA from the ADC is connected to the data receive (DR) input of the serial port and CS can be con- trolled by a flag (FL0). The connection diagram is shown 25° ...
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... Not used SPORT0 is configured by setting the bits in its control register, as listed in Table 5. The flag to generate the CS signal is generated by SPORT1 connected to both the ADC and the RFS input of SPORT0 to provide the frame sync signal for the DSP. Rev Page AD7457 ...
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... The analog ground plane should be allowed to run under the AD7457 to avoid noise coupling. The power supply lines to the AD7457 should use as large a trace as possible to provide low impedance paths and reduce the effects of glitches on the power supply line. Fast switching signals, ...
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... COMPLIANT TO JEDEC STANDARDS MO-178BA Figure 26. 8-Lead Small Outline Transistor Package [SOT-23] (RT-8) Dimensions shown in millimeters 1 Linearity Error (LSB) ±1 ±1 ±1 Rev Page 0.60 8° 0.45 4° 0.30 0° Package Description Package Option 8-Lead SOT-23 RT-8 8-Lead SOT-23 RT-8 8-Lead SOT-23 RT-8 AD7457 Branding COJ COJ COD ...
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... AD7457 NOTES Rev Page ...
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... NOTES Rev Page AD7457 ...
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... AD7457 NOTES © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03157–0–2/05(A) Rev Page ...