AD7357 Analog Devices, AD7357 Datasheet
AD7357
Specifications of AD7357
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AD7357 Summary of contents
Page 1
... The analog input range for the part is the differential common mode ±V /2. The AD7357 has an on-chip 2.048 V reference REF that can be overdriven when an external reference is preferred. The AD7357 is available in a 16-lead thin shrink small outline package (TSSOP). 1 Protected by U.S. Patent No. 6,681,332. Rev. B Information furnished by Analog Devices is believed to be accurate and reliable ...
Page 2
... Changes to Midscale Error Match Parameter, Table 2 ................ 3 Changes to Figure 21 and Figure 22............................................. 14 Added Voltage Reference Section ........................................................14 2/11—Rev Rev. A Changes to Features and Applications Sections ........................... 1 Changes to Table 2............................................................................ 3 Added AD7357WY Temperature Range to Endnote 1 in Table 3 ...5 Changes to SDATA , SDATA Pin Description............................ Changes to Figure 20 and Figure 22 ...
Page 3
... LSB V ± common-mode voltage; V REF IN+ remain within GND and V 1.6 V The voltage around which V and V IN+ IN− ±0.5 ±5 μ When in track mode 8 pF When in hold mode AD7357 1 , unless = 100 kHz NOISE and V must IN− DD are centered ...
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... Normal Mode (Operational) Normal Mode (Static) Partial Power-Down Mode Full Power-Down Mode 1 Temperature ranges are as follows: AD7357Y: −40°C to +125°C, AD7357B: −40°C to +85°C, AD7357WY: −40°C to +125°C. 2 See the Terminology section. 3 The interface is functional with V voltages down to 1 this condition, the SCLK speed may need to be slowed down. See the access and hold times in the DRIVE Timing Specifications section ...
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... Latency 1 conversion latency 1 Temperature ranges are as follows: AD7357Y: −40°C to +125°C, AD7357B: −40°C to +85°C, AD7357WY: −40°C to +125°C. 2 Specified with a load capacitance SDATA 3 The time required for the output to cross 0 2 MAX Unit ...
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... Digital Input Voltages to DGND 3 Digital Output Voltages to DGND 4 Input Current to Any Pin Except Supplies Operating Temperature Range AD7357Y AD7357B AD7357WY Storage Temperature Range Junction Temperature TSSOP Package θ Thermal Impedance JA θ Thermal Impedance JC Lead Temperature, Soldering Reflow Temperature (10 sec to 30 sec) ...
Page 7
... ADC follows on the SDATA pins. This allows data from a simultaneous conversion on both ADCs to be gathered in serial format on either SDATA or SDATA 15 SCLK Serial Clock. Logic input. A serial clock input provides the SCLK for accessing the data from the AD7357. This clock is also used as the clock source for the conversion process Logic Power Supply Input ...
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... AD7357 TYPICAL PERFORMANCE CHARACTERISTICS 0 –20 –40 –60 –80 –100 –120 –140 0 250 500 750 1000 1250 1500 FREQUENCY (kHz) Figure 3. Typical FFT 1.0 0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 –1.0 0 4000 8000 CODE Figure 4. Typical DNL 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 0 4000 8000 CODE Figure 5. Typical INL ...
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... EXTERNAL V (V) REF Figure 11. Linearity Error vs. External 1.8 2500 3000 1 2.40 2.45 2.50 REF Rev Page AD7357 +125°C +85°C +25°C –40°C 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 V (V) DRIVE Figure 12. Access Time vs. V DRIVE +125°C +85°C +25°C –40°C 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 V (V) DRIVE Figure 13 ...
Page 10
... Thus, for a 12-bit converter, SINAD and for a 14-bit REF converter, SINAD is 86 dB. Total Harmonic Distortion (THD) THD is the ratio of the rms sum of harmonics to the funda- mental. For the AD7357 defined THD dB where the rms amplitude of the fundamental. ...
Page 11
... The AD7357 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 frequency from the original sine waves, while the third-order terms are usually at a frequency close to the input frequencies ...
Page 12
... IN– ANALOG INPUT STRUCTURE Figure 16 shows the equivalent circuit of the analog input struc- ture of the AD7357. The four diodes provide ESD protection for CM the analog inputs. Care must be taken to ensure that the analog input signals never exceed the supply rails by more than 300 mV. ...
Page 13
... Differential Amplifier An ideal method of applying differential drive to the AD7357 is to use a differential amplifier such as the AD8138. This part can be used as a single-ended-to-differential amplifier differential-to-differential amplifier. The AD8138 also provides common-mode level shifting ...
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... Figure 20. Using the AD8138 as a Single-Ended-to-Differential Amplifier Op Amp Pair An op amp pair can be used to directly couple a differential signal to one of the analog input pairs of the AD7357. The circuit configurations shown in Figure 21 and Figure 22 show how an op amp pair can be used to convert a single-ended signal into a differential signal for a bipolar and unipolar input signal, respectively ...
Page 15
... This avoids accidental power- up due to glitches on the CS line. Although the device may section). begin to power up on the falling edge powers down again on the rising edge the AD7357 is already in partial power-down mode and CS is brought high between the second and 10 full power-down mode. ...
Page 16
... Note that it is not necessary to complete the 16 SCLKs once CS has been brought high to enter a power-down mode. To exit full power-down mode and power up the AD7357, perform a dummy conversion, such as powering up from partial power- down. On the falling edge the device begins to power up, as long held low until after the falling edge of the 10 SCLK ...
Page 17
... CS When power supplies are first applied to the AD7357, the ADC can power up in either of the power-down modes or in normal mode. Because of this best to allow a dummy cycle to elapse to ensure that the part is fully powered up before attempting a valid conversion ...
Page 18
... A minimum of 16 serial clock cycles are required to perform the conversion process and to access data from one conversion on either data line of the AD7357. Note that the data that is accessed on SDATA conversion. CS going low provides the leading zero to be read in by the microcontroller or DSP ...
Page 19
... The analog ground planes should be allowed to run under the AD7357 to avoid noise coupling. The power supply lines to the AD7357 should use as large a trace as poss- ible to provide low impedance paths and reduce the effects of glitches on the power supply line. ...
Page 20
... W = Qualified for Automotive Applications 3 The EVAL-AD7357EDZ can be used as a standalone evaluation board or in conjunction with the EVAL-CED1Z board for evaluation/demonstration purposes. 4 The EVAL-CED1Z is a complete unit allowing control and communicate with all Analog Devices evaluation boards ending in the ED designator. ...