AD7887AR Analog Devices Inc, AD7887AR Datasheet
AD7887AR
Specifications of AD7887AR
Available stocks
Related parts for AD7887AR
AD7887AR Summary of contents
Page 1
FEATURES Specified for Flexible power/throughput rate management Shutdown mode: 1 μA max One or two single-ended inputs Serial interface: SPI®/QSPI™/MICROWIRE™/DSP compatible 8-lead narrow SOIC and MSOP packages APPLICATIONS Battery-powered systems (personal digital ...
Page 2
AD7887 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Product Highlights ........................................................................... 1 Revision History ............................................................................... 2 Specifications ..................................................................................... 3 Timing Specifications .................................................................. 5 Absolute Maximum Ratings ............................................................ 6 ESD ...
Page 3
SPECIFICATIONS 2.5 V, external/internal reference unless otherwise noted REF Table 1. Parameter DYNAMIC PERFORMANCE 2, 3 Signal to Noise + Distortion Ratio (SNR) 2 Total Harmonic Distortion (THD) Peak ...
Page 4
AD7887 Parameter CONVERSION RATE Throughput Time Track/Hold Acquisition Time 2 Conversion Time POWER REQUIREMENTS Normal Mode (Mode 2) Static Operational (f = 125 kSPS) SAMPLE Using Standby Mode (Mode 4) Using Shutdown Mode (Modes 1, ...
Page 5
TIMING SPECIFICATIONS Table 2. Limit at T (A, B Versions) Parameter 4. 5. SCLK t 14.5 × t CONVERT SCLK t 1.5 × t ACQ SCLK ...
Page 6
AD7887 ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise noted. A Table 3. Parameter V to AGND DD Analog Input Voltage to AGND Digital Input Voltage to AGND Digital Output Voltage to AGND REF /REF to AGND IN OUT Input ...
Page 7
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS CS 1 AD7887 GND 3 TOP VIEW (Not to Scale) AIN1/V 4 REF Figure 3. SOIC_N Pin Configuration Table 4. Pin Function Descriptions Pin No. Mnemonic Description 1 CS Chip Select. Active ...
Page 8
AD7887 TYPICAL PERFORMANCE CHARACTERISTICS 0 –10 –30 –50 –70 –90 –110 Figure 5. Dynamic Performance 73 EXT REFERENCE 72.5 72.0 71.5 71.0 0.15 10.89 21.14 INPUT FREQUENCY (kHz) Figure 6. SNR vs. Input Frequency 4096 POINT FFT SAMPLING ...
Page 9
TERMINOLOGY Integral Nonlinearity This is the maximum deviation from a straight line passing through the endpoints of the ADC transfer function. The end- points of the transfer function are zero scale, a point ½ LSB below the first code transition, ...
Page 10
AD7887 CONTROL REGISTER The control register on the AD7887 is an 8-bit, write-only register. Data is loaded from the DIN pin of the AD7887 on the rising edge of SCLK. The data is transferred on the DIN line at the ...
Page 11
THEORY OF OPERATION CIRCUIT INFORMATION The AD7887 is a fast, low power, 12-bit, single-supply, single- channel/dual-channel ADC. The part can be operated from (2 3.6 V) supply or from (4. ...
Page 12
AD7887 ANALOG INPUT Figure 12 shows an equivalent circuit of the analog input structure of the AD7887. The two diodes, D1 and D2, provide ESD protection for the analog inputs. Care must be taken to ensure that the analog input ...
Page 13
POWER-DOWN OPTIONS The AD7887 provides flexible power management to allow the user to achieve the best power performance for a given throughput rate. The power management options are selected by programming the power management bits (that is, PM1 and PM0) ...
Page 14
AD7887 second conversion can put the part back into Mode 1, and the part goes into power-down mode when CS returns high. Mode 2 (PM1 = 0, PM0 = 1) In this mode of operation, the AD7887 remains fully powered ...
Page 15
THE PART POWERS FALLING EDGE AS PM1 AND PM0 = SCLK FOUR LEADING ZEROS + CONVERSION RESULT DOUT DIN DATA IN CONTROL REGISTER DATA IS LOADED ON THE FIRST EIGHT CLOCKS. PM1 AND PM0 ...
Page 16
AD7887 THE PART ENTERS SHUTDOWN AT THE END OF CONVERSION AS PM1 = 1 AND PM0 = SCLK FOUR LEADING ZEROS + CONVERSION RESULT DOUT DATA IN DIN CONTROL REGISTER DATA IS LOADED ON THE FIRST EIGHT ...
Page 17
SERIAL INTERFACE Figure 21 shows the detailed timing diagrams for serial interfacing to the AD7887. The serial clock provides the conversion clock and also controls the transfer of information to and from the AD7887 during conversion. CS initiates the data ...
Page 18
AD7887 MICROPROCESSOR INTERFACING The serial interface on the AD7887 allows the part to be directly connected to a range of many different microprocessors. This section explains how to interface the AD7887 with some of the more common microcontroller and DSP ...
Page 19
AD7887 to MC68HC11 The serial peripheral interface (SPI) on the MC68HC11 is configured for master mode (MSTR = 1) when the clock polarity bit (CPOL and the clock phase bit (CPHA The SPI is configured by ...
Page 20
AD7887 APPLICATION HINTS Grounding and Layout The AD7887 has very good immunity to noise on the power supplies, as can be seen in Figure 7. However, care should still be taken with regard to grounding and layout. The printed circuit ...
Page 21
... AD7887ARZ-REEL7 2 ±2 LSB −40°C to +125°C AD7887ARM ±2 LSB −40°C to +125°C AD7887ARM-REEL ±2 LSB −40°C to +125°C AD7887ARM-REEL7 ±2 LSB −40°C to +125°C 2 AD7887ARMZ ±2 LSB −40°C to +125°C AD7887ARMZ-REEL 2 ±2 LSB −40°C to +125°C ...
Page 22
AD7887 NOTES Rev Page ...
Page 23
NOTES Rev Page AD7887 ...
Page 24
AD7887 NOTES ©2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06191-0-2/09(D) Rev Page ...