1.25 MSPS, 16 mW Internal REF and CLK, 12-Bit Parallel ADC AD7492 FUNCTIONAL BLOCK DIAGRAM Specified for VDD of 2.7 V to 5.25 V Throughput rate of 1 MSPS (AD7492) Throughput rate of 1.25 MSPS (AD7492-5) Throughput rate of 400 kSPS (AD7492-4) Low power 4 mW typ at 1 MSPS with 3 V supplies 11 mW typ at 1 MSPS with 5 V supplies Wide input bandwidth 70 dB typ SNR at 100 kHz input frequency 2.5 V internal reference On-chip CLK oscillator Flexible power/throughput rate management No pipeline delays High speed parallel interface Sleep mode: 50 nA typ 24-lead SOIC and TSSOP packages AVDD DVDD REF OUT 4 20 5 2.5V REF T/H 21 CLOCK OSCILLATOR BUF VIN 6 VDRIVE CONTROL LOGIC CONVST 10 DB11 OUTPUT DRIVERS 12-BIT SAR ADC DB0 11 PS/FS 8 CS 9 RD AD7492 12 7 19 AGND DGND BUSY 01128-001 FEATURES Figure 1. GENERAL DESCRIPTION The AD7492, AD7492-4, and AD7492-5 are 12-bit high speed, low power, successive approximation ADCs. The parts operate from a single 2.7 V to 5.25 V power supply and feature throughput rates up to 1.25 MSPS. They contain a low noise, wide bandwidth track/hold amplifier that can handle bandwidths up to 10 MHz. The conversion process and data acquisition are controlled using standard control inputs allowing for easy interface to microprocessors or DSPs. The input signal is sampled on the falling edge of CONVST and conversion is also initiated at this point. The BUSY pin goes high at the start of conversion and goes low 880 ns (AD7492/AD7492-4) or 680 ns (AD7492-5) later to indicate that the conversion is complete. There are no pipeline delays associated with the part. The conversion result is accessed via standard CS and RD signals over a high speed parallel interface. The AD7492 uses advanced design techniques to achieve very low power dissipation at high throughput rates. With 5 V supplies and 1.25 MSPS, the average current consumption AD7492-5 is typically 2.75 mA. The part also offers flexible power/throughput rate management. It is also possible to operate the part in a full sleep mode and a partial sleep mode, where the part wakes up to do a conversion and automatically enters a sleep mode at the end of conversion. The type of sleep mode is hardware selected by the PS/FS pin. Using these sleep modes allows very low power dissipation numbers at lower throughput rates. The analog input range for the part is 0 V to REFIN. The 2.5 V reference is supplied internally and is available for external referencing. The conversion rate is determined by the internal clock. PRODUCT HIGHLIGHTS 1. High Throughput with Low Power Consumption. The AD7492-5 offers 1.25 MSPS throughput with 16 mW power consumption. 2. Flexible Power/Throughput Rate Management. The conversion time is determined by an internal clock. The part also features two sleep modes, partial and full, to maximize power efficiency at lower throughput rates. 3. No Pipeline Delay. The part features a standard successive approximation ADC with accurate control of the sampling instant via a CONVST input and once-off conversion control. 4. Flexible Digital Interface. The VDRIVE feature controls the voltage levels on the I/O digital pins. 5. Fewer Peripheral Components. The AD7492 optimizes PCB space by using an internal reference and internal CLK. Rev. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved. AD7492 TABLE OF CONTENTS Features .............................................................................................. 1 Converter Operation.................................................................. 13 Functional Block Diagram .............................................................. 1 Typical Connection Diagram ................................................... 13 General Description ......................................................................... 1 ADC Transfer Function............................................................. 13 Product Highlights ....................................................................... 1 AC Acquisition Time ................................................................. 14 Revision History ........................................................................... 2 DC Acquisition Time................................................................. 14 Specifications..................................................................................... 3 Analog Input ............................................................................... 14 AD7492-5 ...................................................................................... 3 Parallel Interface......................................................................... 14 AD7492/AD7492-4 ...................................................................... 4 Operating Modes........................................................................ 14 Timing Specifications .................................................................. 6 Power-Up..................................................................................... 16 Absolute Maximum Ratings............................................................ 7 Grounding and Layout .............................................................. 18 ESD Caution.................................................................................. 7 Power Supplies ............................................................................ 18 Pin Configuration and Function Descriptions............................. 8 Microprocessor Interfacing....................................................... 18 Typical Peformance Characteristics ............................................. 10 Outline Dimensions ....................................................................... 21 Terminology .................................................................................... 12 Ordering Guide .......................................................................... 21 Circuit Description......................................................................... 13 REVISION HISTORY 5/06—Rev. 0 to Rev. A Added AD7492-4................................................................Universal Changes to Table 4............................................................................ 8 Updated Outline Dimensions ....................................................... 22 Changes to Ordering Guide .......................................................... 22 1/01—Revision 0: Initial Version Rev. A | Page 2 of 24 AD7492 SPECIFICATIONS AD7492-5 VDD = 4.75 V to 5.25 V, TA = TMIN to TMAX, unless otherwise noted. Table 1. Parameter DYNAMIC PERFORMANCE Signal-to-Noise and Distortion (SINAD) Signal-to-Noise Ratio (SNR) Total Harmonic Distortion (THD) Peak Harmonic or Spurious-Free Dynamic Noise (SFDR) Intermodulation Distortion (IMD) Second Order Terms Third Order Terms Aperture Delay Aperture Jitter Full Power Bandwidth DC ACCURACY Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Gain Error ANALOG INPUT Input Voltage Ranges DC Leakage Current Input Capacitance REFERENCE OUTPUT REF OUT Output Voltage Range LOGIC INPUTS Input High Voltage, VINH 2 Input Low Voltage, VINL2 Input Current, IIN Input Capacitance, CIN 3 LOGIC OUTPUTS Output High Voltage, VOH Output Low Voltage, VOL Floating-State Leakage Current Floating-State Output Capacitance Output Coding A Version 1 B Version1 Unit 69 68 70 68 −83 −87 −75 −83 69 68 70 68 −83 −87 −75 −83 dB typ dB min dB typ dB min dB typ dB typ dB max dB typ Test Conditions/Comments fS = 1.25 MSPS fIN = 500 kHz sine wave fIN = 100 kHz sine wave fIN = 500 kHz sine wave fIN = 100 kHz sine wave fIN = 500 kHz sine wave fIN = 100 kHz sine wave fIN = 100 kHz sine wave fIN = 500 kHz sine wave −90 −76 −90 −76 dB typ dB max fIN = 100 kHz sine wave fIN = 100 kHz sine wave −82 −90 −71 −88 5 15 10 −82 −90 −71 −88 5 15 10 dB typ dB typ dB typ dB typ ns typ ps typ MHz typ fIN = 500 kHz sine wave fIN = 100 kHz sine wave fIN = 500 kHz sine wave fIN = 100 kHz sine wave 12 ±1.5 +1.5/–0.9 12 ±1.25 +1.5/−0.9 Bits LSB max LSB max ±9 ±2.5 ±9 ±2.5 LSB max LSB max 0 to 2.5 ±1 33 0 to 2.5 ±1 33 V μA max pF typ 2.5 2.5 V ±1.5% for specified performance VDRIVE × 0.7 VDRIVE × 0.3 ±1 10 VDRIVE × 0.7 VDRIVE × 0.3 ±1 10 V min V max μA max pF max VDD = 5 V ± 5% VDD = 5 V ± 5% Typically 10 nA, VIN = 0 V or VDD VDRIVE − 0.2 0.4 ±10 10 Straight (natural) binary VDRIVE − 0.2 0.4 ±10 10 Straight (natural) binary V min V max μA max pF max ISOURCE = 200 μA ISINK = 200 μA fS = 1.25 MSPS Rev. A | Page 3 of 24 Guaranteed no missed codes to 12 bits (A and B versions) AD7492 Parameter CONVERSION RATE Conversion Time Track/Hold Acquisition Time Throughput Rate POWER REQUIREMENTS VDD IDD Normal Mode Quiescent Current Partial Sleep Mode Full Sleep Mode Power Dissipation 4 Normal Mode Partial Sleep Mode Full Sleep Mode A Version 1 B Version1 Unit 680 120 1.25 680 120 1.25 ns max ns min MSPS max 4.75/5.25 4.75/5.25 V min/max 3.3 1.8 250 1 3.3 1.8 250 1 mA max mA max μA max μA max 16.5 1.25 5 16.5 1.25 5 mW max mW max μW max Test Conditions/Comments Conversion time + acquisition time Digital I/Ps = 0 V or DVDD fS = 1.25 MSPS, typ 2.75 mA Static, typ 190 μA Static, typ 200 nA Digital I/Ps = 0 V or DVDD 1 Temperature ranges as follows: A and B Versions: −40°C to +85°C. VINH and VINL trigger levels are set by the VDRIVE voltage. The logic interface circuitry is powered by VDRIVE. Sample tested @ 25°C to ensure compliance. 4 See the Power vs. Throughput section. 2 3 AD7492/AD7492-4 VDD = 2.7 V to 5.25 V, TA = TMIN to TMAX, unless otherwise noted. 1 Table 2. Parameter DYNAMIC PERFORMANCE Signal-to-Noise and Distortion (SINAD) Signal-to-Noise Ratio (SNR) Total Harmonic Distortion (THD) Peak Harmonic or Spurious-Free Dynamic Noise (SFDR) Intermodulation Distortion (IMD) Second Order Terms Third Order Terms Aperture Delay Aperture Jitter Full Power Bandwidth A Version 2 B Version2 Unit 69 68 70 68 −85 −87 −75 −86 69 68 70 68 −85 −87 −75 −86 dB typ dB min dB typ dB min dB typ dB typ dB max dB typ Test Conditions/Comments fS = 1 MSPS for AD7492 fS = 400 kSPS for AD7492-4 fIN = 500 kHz sine wave 3 fIN = 100 kHz sine wave fIN = 500 kHz sine wave3 fIN = 100 kHz sine wave fIN = 500 kHz sine wave3 fIN = 100 kHz sine wave fIN = 100 kHz sine wave fIN = 500 kHz sine wave3 −90 −76 −90 −76 dB typ dB max fIN = 100 kHz sine wave fIN = 100 kHz sine wave −77 −90 −69 −88 5 15 10 −77 −90 −69 −88 5 15 10 dB typ dB typ dB typ dB typ ns typ ps typ MHz typ fIN = 500 kHz sine wave3 fIN = 100 kHz sine wave fIN = 500 kHz sine wave3 fIN = 100 kHz sine wave Rev. A | Page 4 of 24 AD7492 Parameter DC ACCURACY Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Gain Error ANALOG INPUT Input Voltage Ranges DC Leakage Current Input Capacitance REFERENCE OUTPUT REF OUT Output Voltage Range LOGIC INPUTS Input High Voltage, VINH 4 Input Low Voltage, VINL4 Input Current, IIN Input Capacitance, CIN3, 5 LOGIC OUTPUTS Output High Voltage, VOH Output Low Voltage, VOL Floating-State Leakage Current Floating-State Output Capacitance Output Coding CONVERSION RATE Conversion Time Track/Hold Acquisition Time Throughput Rate A Version 2 B Version2 Unit 12 ±1.5 12 +1.5/−0.9 ±0.6 ±1 +1.5/−0.9 Bits LSB max LSB typ LSB max LSB max ±9 ±2.5 ±9 ±2.5 LSB max LSB max 0 to 2.5 ±1 33 0 to 2.5 ±1 33 V μA max pF typ 2.5 2.5 V ±1.5% for specified performance VDRIVE × 0.7 VDRIVE × 0.3 ±1 10 VDRIVE × 0.7 VDRIVE × 0.3 ±1 10 V min V max μA max pF max VDD = 5 V ± 5% VDD = 5 V ± 5% Typically 10 nA, VIN = 0 V or VDD VDRIVE − 0.2 0.4 ±10 10 Straight (Natural) Binary VDRIVE − 0.2 0.4 ±10 10 Straight (Natural) Binary V min V max μA max pF max ISOURCE = 200 μA ISINK = 200 μA 880 120 1 880 120 1 ns max ns min MSPS max kSPS max 400 POWER REQUIREMENTS VDD IDD Normal Mode Quiescent Current Partial Sleep Mode Full Sleep Mode Power Dissipation4, 6 Normal Mode Partial Sleep Mode Full Sleep Mode 2.7/5.25 2.7/5.25 V min/max 3 3 mA max 1.8 250 1 1.8 250 1 mA max μA max μA max 15 1.25 5 15 1.25 5 mW max mW max μW max 1 Only A version specification applies to the AD7492-4. Temperature ranges as follows: A and B versions: −40°C to +85°C. 3 500 kHz sine wave specifications do not apply for the AD7492-4. 4 VINH and VINL trigger levels are set by the VDRIVE voltage. The logic interface circuitry is powered by VDRIVE. 5 Sample tested @ 25°C to ensure compliance. 6 See the Power vs. Throughput section. 2 Rev. A | Page 5 of 24 Test Conditions/Comments fS = 1 MSPS for AD7492 fS = 400 kSPS for AD7492-4 VDD = 5 V VDD = 3 V Guaranteed no missed codes to 12 bits (A and B versions) Conversion time + acquisition time for AD7492 Conversion time + acquisition time for AD7492-4 Digital I/Ps = 0 V or DVDD. fS = 1 MSPS, typ 2.2 mA fS = 400 kSPS, Typ 2.2 mA (AD7492-4) Static, typ 190 μA Static, typ 200 nA Digital I/Ps = 0 V or DVDD VDD = 5 V VDD = 5 V VDD = 5 V AD7492 TIMING SPECIFICATIONS VDD = 2.7 V to 5.25 V, TA = TMIN to TMAX, unless otherwise noted. 1 Table 3. Parameter tCONVERT tWAKEUP t1 t2 t3 t4 4 t5 t64 t7 5 t8 t9 t10 Limit at TMIN, TMAX AD7492/AD7492-4 AD7492-5 2 880 680 20 3 203 500 500 10 10 10 10 40 N/A 0 0 0 0 20 20 15 15 8 8 0 0 120 120 100 100 Unit ns max μs max μs max ns min ns max ns max ns max ns max ns min ns min ns max ns max ns min ns min Description Partial Sleep Wake-Up Time Full Sleep Wake-Up Time CONVST Pulse Width CONVST to BUSY Delay, VDD = 5 V CONVST to BUSY Delay, VDD = 3 V BUSY to CS Setup Time CS to RD Setup Time RD Pulse Width Data Access Time after Falling Edge of RD Bus Relinquish Time after Rising Edge of RD CS to RD Hold Time Acquisition Time Quiet Time 1 Sample tested @ 25°C to ensure compliance. All input signals are specified with tR = tF = 5 ns (10% to 90% of VDD) and timed from a voltage level of 1.6 V (see Figure 2). The AD7492-5 is specified with VDD = 4.75 V to 5.25 V. This is the time needed for the part to settle within 0.5 LSB of its stable value. Conversion can be initiated earlier than 20 μs, but there is no guarantee that the part samples within 0.5 LSB of the true analog input value. Therefore, the user should not start conversion until after the specified time. 4 Measured with the load circuit of Figure 2 and defined as the time required for the output to cross 0.8 V or 2.0 V 5 t7 is derived from the measured time taken by the data outputs to change 0.5 V when loaded with the circuit of Figure 2. The measured number is then extrapolated back to remove the effects of charging or discharging the 50 pF capacitor. This means that the time, t7, quoted in the timing characteristics is the true bus relinquish time of the part and is independent of the bus loading. 2 3 200µA 1.6V CL 50pF 200µA IOH 01128-002 TO OUTPUT PIN IOL Figure 2. Load Circuit for Digital Output Timing Specifications Rev. A | Page 6 of 24 AD7492 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 4. Parameter AVDD to AGND/DGND DVDD to AGND/DGND VDRIVE to AGND/DGND AVDD to DVDD VDRIVE to DVDD AGND to DGND Analog Input Voltage to AGND Digital Input Voltage to DGND Input Current to Any Pin Except Supplies1 Operating Temperature Range Commercial (A and B Versions) Storage Temperature Range Junction Temperature SOIC, TSSOP Package Dissipation θJA Thermal Impedance θJC Thermal Impedance Lead Temperature, Soldering Vapor Phase (60 sec) Infrared (15 sec) 1 Ratings −0.3 V to +7 V −0.3 V to +7 V −0.3 V to +7 V −0.3 V to +0.3 V −0.3 V to DVDD + 0.3 V −0.3 V to +0.3 V −0.3 V to AVDD + 0.3 V −0.3 V to DVDD + 0.3 V ±10 mA Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. −40°C to +85°C −65°C to +150°C 150°C 450 mW 75°C/W (SOIC) 115°C/W (TSSOP) 25°C/W (SOIC) 35°C/W (TSSOP) 215°C 220°C Transient currents of up to 100 mA do not cause SCR latch-up. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. A | Page 7 of 24 AD7492 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS DB9 1 24 DB8 DB10 2 23 DB7 (MSB) DB11 3 22 DB6 AVDD 4 21 V DRIVE REF OUT 5 VIN 6 AGND 7 CS 8 17 DB4 RD 9 16 DB3 CONVST 10 15 DB2 PS/FS 11 14 DB1 BUSY 12 13 DB0 (LSB) AD7492 20 DV DD 01128-003 TOP VIEW 19 DGND (Not to Scale) 18 DB5 Figure 3. Pin Configuration Table 5. Pin Function Descriptions Pin 1 to 3, 13 to 18, 22 to 24 4 Mnemonic DB11 to DB0 5 6 REF OUT VIN 7 AGND 8 CS 9 RD 10 CONVST 11 PS/FS 12 BUSY 19 DGND AVDD Function Data Bit 11 to Data Bit 0. Parallel digital outputs that provide the conversion result for the part. These are three-state outputs that are controlled by CS and RD. The output high voltage level for these outputs is determined by the VDRIVE input. Analog Supply Voltage, 2.7 V to 5.25 V. This is the only supply voltage for all analog circuitry on the AD7492. The AVDD and DVDD voltages should ideally be at the same potential and must not be more than 0.3 V apart, even on a transient basis. This supply should be decoupled to AGND. Reference Out. The output voltage from this pin is 2.5 V ± 1%. Analog Input. Single-ended analog input channel. The input range is 0 V to REFIN. The analog input presents a high dc input impedance. Analog Ground. Ground reference point for all analog circuitry on the AD7492. All analog input signals should be referred to this AGND voltage. The AGND and DGND voltages should ideally be at the same potential and must not be more than 0.3 V apart, even on a transient basis. Chip Select. Active low logic input used in conjunction with RD to access the conversion result. The conversion result is placed on the data bus following the falling edge of both CS and RD. CS and RD are both connected to the same AND gate on the input so the signals are interchangeable. CS can be hardwired permanently low. Read Input. Logic input used in conjunction with CS to access the conversion result. The conversion result is placed on the data bus following the falling edge of both CS and RD. CS and RD are both connected to the same AND gate on the input so the signals are interchangeable. CS and RD can be hardwired permanently low, in which case the data bus is always active and the result of the new conversion is clocked out slightly before to the BUSY line going low. Conversion Start Input. Logic input used to initiate conversion. The input track/hold amplifier goes from track mode to hold mode on the falling edge of CONVST and the conversion process is initiated at this point. The conversion input can be as narrow as 10 ns. If the CONVST input is kept low for the duration of conversion and is still low at the end of conversion, the part automatically enters a sleep mode. The type of sleep mode is determined by the PS/FS pin. If the part enters a sleep mode, the next rising edge of CONVST wakes up the part. Wake-up time depends on the type of sleep mode. Partial Sleep/Full Sleep Mode. This pin determines the type of sleep mode the part enters if the CONVST pin is kept low for the duration of the conversion and is still low at the end of conversion. In partial sleep mode the internal reference circuit and oscillator circuit are not powered down and draws 250 μA maximum. In full sleep mode all of the analog circuitry are powered down and the current drawn is negligible. This pin is hardwired either high (DVDD) or low (GND). BUSY Output. Logic output indicating the status of the conversion process. The BUSY signal goes high after the falling edge of CONVST and stays high for the duration of the conversion. Once the conversion is complete and the conversion result is in the output register, the BUSY line returns low. The track/hold returns to track mode just prior to the falling edge of BUSY and the acquisition time for the part begins when BUSY goes low. If the CONVST input is still low when BUSY goes low, the part automatically enters its sleep mode on the falling edge of BUSY. Digital Ground. This is the ground reference point for all digital circuitry on the AD7492. The DGND and AGND voltages should ideally be at the same potential and must not be more than 0.3 V apart, even on a transient basis. Rev. A | Page 8 of 24 AD7492 Pin 20 Mnemonic DVDD 21 VDRIVE Function Digital Supply Voltage, 2.7 V to 5.25 V. This is the supply voltage for all digital circuitry on the AD7492 apart from the output drivers and input circuitry. The DVDD and AVDD voltages should ideally be at the same potential and must not be more than 0.3 V apart even on a transient basis. This supply should be decoupled to DGND. Supply Voltage for the Output Drivers and Digital Input Circuitry, 2.7 V to 5.25 V. This voltage determines the output high voltage for the data output pins and the trigger levels for the digital inputs. It allows the AVDD and DVDD to operate at 5 V (and maximize the dynamic performance of the ADC) while the digital input and output pins can interface to 3 V logic. Rev. A | Page 9 of 24 AD7492 TYPICAL PEFORMANCE CHARACTERISTICS 71 0 70 –20 69 5V –40 67 66 (dB) SNR+D (dB) 68 3V 65 64 –60 –80 63 62 –100 61 500 1000 1500 2000 2500 INPUT FREQUENCY (kHz) –120 0 100000 Figure 4. Typical SNR + D vs. Input Tone 500000 600000 Figure 7. Typical SNR @ 500 kHz Input Tone 95 0 90 –0.5 85 5V 5V –1.0 80 –1.5 75 (dB) THD (dB) 200000 300000 400000 FREQUENCY (Hz) 01128-007 0 01128-004 60 3V 70 –2.0 65 –2.5 60 –3.0 55 200 350 500 1000 2000 –3.5 INPUT FREQUENCY (kHz) 1 10 100 1000 10000 01128-008 100 01128-005 50 100000 FREQUENCY (Hz) Figure 5. Typical THD vs. Input Tone Figure 8. Typical Bandwidth 70.60 0 70.4 –40°C –20 VCC = 5V 100mV p-p SINEWAVE ON VCC fSAMPLE = 1MHz, fIN = 100kHz 70.2 –40 –55°C PSSR (dB) 69.8 +25°C +125°C 69.6 –60 –80 +85°C 69.4 –100 69.2 3.0 3.5 4.0 4.5 SUPPLY (Volts) 5.0 5.5 Figure 6. Typical SNR vs. Supply –120 0 5 10 16 20 26 31 36 41 46 51 57 61 67 72 77 82 88 92 97 3 8 13 18 23 28 34 39 44 49 54 59 64 69 74 80 84 89 94 100 VCC RIPPLE FREQUENCY (kHz) Figure 9. Typical Power Supply Rejection Ratio (PSRR) Rev. A | Page 10 of 24 01128-009 69.0 2.50 01128-006 SNR (dB) 70.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 0 –0.2 –0.2 –0.4 –0.4 –0.6 –0.6 –0.8 –0.8 –1.0 0 512 1023 1534 2045 2556 3067 CODE 3578 4089 Figure 10. Typical INL for 2.75 V @ 25°C –1.0 0 512 1023 1534 2045 2556 3067 CODE Figure 11. Typical DNL for 2.75 V @ 25°C Rev. A | Page 11 of 24 3578 4089 01128-011 (DNL) 1.0 01128-010 (INL) AD7492 AD7492 TERMINOLOGY Integral Nonlinearity This is the maximum deviation from a straight line passing through the endpoints of the ADC transfer function. The endpoints of the transfer function are zero scale, a point 1/2 LSB below the first code transition, and full scale, a point 1/2 LSB above the last code transition. Differential Nonlinearity This is the difference between the measured and the ideal 1 LSB change between any two adjacent codes in the ADC. Offset Error This is the deviation of the first code transition (00 . . . 000) to (00 . . . 001) from the ideal, that is, AGND + 1 LSB. Gain Error The last transition should occur at the analog value 1 1/2 LSB below the nominal full scale. The first transition is a 1/2 LSB above the low end of the scale (zero in the case of AD7492). The gain error is the deviation of the actual difference between the first and last code transitions from the ideal difference between the first and last code transitions with offset errors removed. Track/Hold Acquisition Time The track/hold amplifier returns into track mode after the end of the conversion. Track/Hold acquisition time is the time required for the output of the track/hold amplifier to reach its final value, within ±0.5 LSB, after the end of conversion. Signal-to-Noise and Distortion Ratio This is the measured ratio of signal-to-noise and distortion at the output of the A/D converter. The signal is the rms amplitude of the fundamental. Noise is the sum of all nonfundamental signals up to half the sampling frequency (fS/2), excluding dc. The ratio is dependent on the number of quantization levels in the digitization process; the more levels, the smaller the quantization noise. The theoretical signal to (noise + distortion) ratio for an ideal N-bit converter with a sine wave input is given by: Signal-to-Noise and Distortion = (6.02 N + 1.76) dB Thus for a 12-bit converter, this is 74 dB and for a 10-bit converter is 62 dB. Total Harmonic Distortion Total harmonic distortion (THD) is the ratio of the rms sum of harmonics to the fundamental. For the AD7492 it is defined as: THD (dB) = 20 log (V22 + V32 + V4 2 + V52 + V62 ) where: V1 is the rms amplitude of the fundamental. V2, V3, V4, V5, and V6 are the rms amplitudes of the second through the sixth harmonics. Peak Harmonic or Spurious Noise Peak harmonic or spurious noise is defined as the ratio of the rms value of the next largest component in the ADC output spectrum (up to fS/2 and excluding dc) to the rms value of the fundamental. Normally, the value of this specification is determined by the largest harmonic in the spectrum, but for ADCs where the harmonics are buried in the noise floor, it is a noise peak. Intermodulation Distortion With inputs consisting of sine waves at two frequencies, fa and fb, any active device with nonlinearities creates distortion products at sum and difference frequencies of mfa ± nfb where m, n = 0, 1, 2, 3, etc. Intermodulation distortion terms are those for which neither m nor n is equal to zero. For example, the second order terms include (fa + fb) and (fa − fb), while the third order terms include (2fa + fb), (2fa − fb), (fa + 2fb), and (fa − 2fb). The AD7492 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. As a result, the second and third order terms are specified separately. The calculation of the intermodulation distortion is as per the THD specification where it is the ratio of the rms sum of the individual distortion products to the rms amplitude of the sum of the fundamentals expressed in dBs. Aperture Delay In a sample/hold, the time required after the hold command for the switch to open fully is the aperture delay. The sample is, in effect, delayed by this interval, and the hold command would have to be advanced by this amount for precise timing. Aperture Jitter Aperture jitter is the range of variation in the aperture delay. In other words, it is the uncertainty about when the sample is taken. Jitter is the result of noise that modulates the phase of the hold command. This specification establishes the ultimate timing error, hence the maximum sampling frequency for a given resolution. This error increases as the input dV/dt increases. V1 Rev. A | Page 12 of 24 AD7492 CIRCUIT DESCRIPTION CONVERTER OPERATION TYPICAL CONNECTION DIAGRAM The AD7492 is a 12-bit successive approximation analog-todigital converter based around a capacitive DAC. The AD7492 can convert analog input signals in the range 0 V to VREF. Figure 12 shows a very simplified schematic of the ADC. The control logic, SAR register, and capacitive DAC are used to add and subtract fixed amounts of charge from the sampling capacitor to bring the comparator back into a balanced condition. Figure 15 shows a typical connection diagram for the AD7492. Conversion is initiated by a falling edge on CONVST. Once CONVST goes low the BUSY signal goes high, and at the end of the conversion, the falling edge of BUSY is used to activate an interrupt service routine. The CS and RD lines are then activated in parallel to read the 12 data bits. The internal band gap reference voltage is 2.5 V, providing an analog input range of 0 V to 2.5 V, making the AD7492 a unipolar A/D. A capacitor with a minimum capacitance of 100 nF is needed at the output of the REF OUT pin as it stabilizes the internal reference value. It is recommended to perform a dummy conversion after power-up as the first conversion result could be incorrect. This also ensures that the part is in the correct mode of operation. The CONVST pin should not be floating when power is applied, as a rising edge on CONVST might not wake up the part. CAPACITIVE DAC VREF SWITCHES VIN CONTROL INPUTS CONTROL LOGIC OUTPUT DATA 12-BIT PARALLEL 01128-012 SAR Figure 12. Simplified Block Diagram of AD7492 Figure 13 shows the ADC during its acquisition phase. SW2 is closed and SW1 is in Position A. The comparator is held in a balanced condition and the sampling capacitor acquires the signal on VIN. In Figure 15 the VDRIVE pin is tied to DVDD, which results in logic output voltage values being either 0 V or DVDD. The voltage applied to VDRIVE controls the voltage value of the output logic signals and the input logic signals. For example, if DVDD is supplied by a 5 V supply and VDRIVE by a 3 V supply, the logic output voltage levels would be either 0 V or 3 V. This feature allows the AD7492 to interface to 3 V parts while still enabling the A/D to process signals at 5 V supply. 10µF CAPACITIVE DAC 1nF VIN 2kΩ A SW1 B CONTROL LOGIC 01128-013 SW2 COMPARATOR AGND µC/µP Figure 14 shows the ADC during conversion. When conversion starts, SW2 opens and SW1 moves to Position B, causing the comparator to become unbalanced. The ADC then runs through its successive approximation routine and brings the comparator back into a balanced condition. When the comparator is rebalanced, the conversion result is available in the SAR register. CAPACITIVE DAC 2kΩ A SW1 B AGND COMPARATOR AD7492 100nF VIN 0V TO 2.5V DB0 TO DB9 (DB11) PS/FS Figure 15. Typical Connection Diagram ADC TRANSFER FUNCTION The output coding of the AD7492 is straight binary. The designed code transitions occur at successive integer LSB values (that is, 1 LSB, 2 LSB, etc.). The LSB size equals 2.5/4096 for the AD7492. The ideal transfer characteristic for the AD7492 is shown in Figure 16. CONTROL LOGIC SW2 47µF ANALOG SUPPLY 2.7V TO 5.25V VDRIVE AVDD DVDD CS CONVST RD BUSY 01128-014 VIN 0.1µF + REF OUT 2.5V PARALLELED INTERFACE Figure 13. ADC Acquisition Phase + 01128-015 COMPARATOR Figure 14. ADC Conversion Phase Rev. A | Page 13 of 24 AD7492 ANALOG INPUT 111...000 Figure 18 shows the equivalent circuit of the analog input structure of the AD7492. The two diodes, D1 and D2, provide ESD protection for the analog inputs. The Capacitor C3 is typically about 4 pF and can be primarily attributed to pin capacitance. The Resistor R1 is an internal switch resistance. This resistor is typically about 125 Ω. The Capacitor C1 is the sampling capacitor while R2 is used for bandwidth control. 1LSB = VREF /4096 011...111 01128-016 000...010 000...001 000...000 +VREF –1LSB 0V 1/2LSB ANALOG INPUT VDD Figure 16. Transfer Characteristic for 12 Bits D1 VIN AC ACQUISITION TIME In ac applications, it is recommended to always buffer analog input signals. The source impedance of the drive circuitry must be kept as low as possible to minimize the acquisition time of the ADC. Large values of impedance at the VIN pin of the ADC cause the THD to degrade at high input frequencies. Table 6. Dynamic Performance Specifications Input Buffers AD9631 AD797 SNR 500 kHz 69.5 69.6 THD 500 kHz 80 81.6 Typical Amplifier Current Consumption 17 mA 8.2 mA DC ACQUISITION TIME The ADC starts a new acquisition phase at the end of a conversion and ends it on the falling edge of the CONVST signal. At the end of the conversion, there is a settling time associated with the sampling circuit. This settling time lasts 120 ns. The analog signal on VIN is also acquired during this settling time; therefore, the minimum acquisition time needed is 120 ns. Figure 17 shows the equivalent charging circuit for the sampling capacitor when the ADC is in its acquisition phase. R3 represents the source impedance of a buffer amplifier or resistive network, R1 is an internal switch resistance, R2 is for bandwidth control, and C1 is the sampling capacitor. C2 is back-plate capacitance and switch parasitic capacitance. During the acquisition phase the sampling capacitor must be charged to within 0.5 LSB of its final value. VIN R1 125Ω C2 8pF C1 22pF R2 636Ω Figure 17. Equivalent Analog Input Circuit 01128-017 R3 C3 4pF D2 R1 125Ω C1 22pF R2 636Ω C2 8pF 01128-018 ADC CODE 111...111 111...110 Figure 18. Equivalent Analog Input Circuit PARALLEL INTERFACE The parallel interface of the AD7492 is 12 bits wide. The output data buffers are activated when both CS and RD are logic low. At this point the contents of the data register are placed onto the data bus. Figure 19 shows the timing diagram for the parallel port. Figure 20 shows the timing diagram for the parallel port when CS and RD are tied permanently low. In this setup, once the BUSY line goes from high to low, the conversion process is completed. The data is available on the output bus slightly before the falling edge of BUSY. Note that the data bus cannot change state while the A/D is doing a conversion, as this would have a detrimental effect on the conversion in progress. The data out lines go three-state again when either the RD or CS line goes high. Thus the CS can be tied low permanently, leaving the RD line to control conversion result access. Please reference the VDRIVE section for output voltage levels. OPERATING MODES The AD7492 has two possible modes of operation depending on the state of the CONVST pulse at the end of a conversion, Mode 1 and Mode 2. Mode 1 (High-Speed Sampling) In this mode of operation the CONVST pulse is brought high before the end of conversion, that is, before BUSY goes low (see Figure 20). If the CONVST pin is brought from high-to-low while BUSY is high, the conversion is restarted. When operating in this mode a new conversion should not be initiated until 140 ns after BUSY goes low. This acquisition time allows the track/hold circuit to accurately acquire the input signal. As mentioned earlier, a read should not be done during a conversion. This mode facilitates the fastest throughput times for the AD7492. Rev. A | Page 14 of 24 AD7492 tCONVERT CONVST t9 t2 t10 BUSY t3 CS t8 t4 RD t6 t7 DBx 01128-019 t5 Figure 19. Parallel Port Timing tCONVERT CONVST t9 t2 DBx DATA N DATA N+1 01128-020 BUSY Figure 20. Parallel Port Timing with CS and RD Tied Low Mode 2 (Partial or Full Sleep Mode) Figure 21 shows the AD7492 in Mode 2 operation where the ADC goes into either partial or full sleep mode after conversion. The CONVST line is brought low to initiate a conversion and remains low until after the end of the conversion. If CONVST goes high and low again while BUSY is high, the conversion is restarted. Once the BUSY line goes from high-to-low, the CONVST line has its status checked and, if low, the part enters a sleep mode. The type of sleep mode the AD7492 enters depends on what way the PS/FS pin is hardwired. If the PS/FS pin is tied high, the AD7492 enters partial sleep mode. If the PS/FS pin is tied low, the AD7492 enters full sleep mode. The device wakes up again on the rising edge of the CONVST signal. From partial sleep the AD7492 is capable of starting conversions typically 1 μs after the rising edge of CONVST. The CONVST line can go from high-to-low during the wake-up time, but the conversion is still not initiated until after 1 μs. It is recommended that the conversion should not be initiated until at least 20 μs of the wake-up time has elapsed. This ensures that the AD7492 has stabilized to within 0.5 LSB of the analog input value. After 1 μs, the AD7492 has only stabilized to within approximately 3 LSB of the input value. From full sleep, this wake-up time is typically 500 μs. In all cases the BUSY line only goes high once CONVST goes low. Superior power performance can be achieved in these modes of operation by waking up the AD7492 only to carry out a conversion. The optimum power performance is obtained when using full sleep mode as the ADC comparator, reference buffer, and reference circuit are powered down. While in partial sleep mode, only the ADC comparator is powered down and the reference buffer is put into a low power mode. The 100 nF capacitor on the REF OUT pin is kept charged up by the reference buffer in partial sleep mode while in full sleep mode this capacitor slowly discharges. This explains why the wake-up time is shorter in partial sleep mode. In both sleep modes the clock oscillator circuit is powered down. Rev. A | Page 15 of 24 AD7492 tCONVERT CONVST tWAKEUP BUSY CS 01128-021 RD DBx Figure 21. Mode 2 Operation VDRIVE Power vs. Throughput The VDRIVE pin is used as the voltage supply to the digital output drivers and the digital input circuitry. It is a separate supply from AVDD and DVDD. The purpose of using a separate supply for the digital input/output interface is that the user can vary the output high voltage, VOH, and the logic input levels, VINH and VINL, from the VDD supply to the AD7492. For example, if AVDD and DVDD are using a 5 V supply, the VDRIVE pin can be powered from a 3 V supply. The ADC has better dynamic performance at 5 V than at 3 V, so operating the part at 5 V, while still being able to interface to 3 V parts, pushes the AD7492 to the top bracket of high performance 12-bit ADCs. Of course, the ADC can have its VDRIVE and DVDD pins connected together and be powered from a 3 V or 5 V supply. The trigger levels are VDRIVE × 0.7 and VDRIVE × 0.3 for the digital inputs. The pins that are powered from VDRIVE are DB11 to DB0, CS, RD, CONVST, and BUSY. The two modes of operation for the AD7492 produces different power vs. throughput performances, Mode 1 and Mode 2; see the Operating Modes section of the data sheet for more detailed descriptions of these modes. Mode 2 is the sleep mode (partial/full) of the part and it achieves the optimum power performance. Mode 1 Figure 22 shows the AD7492 conversion sequence in Mode 1 using a throughput rate of 500 kSPS. At 5 V supply, the current consumption for the part when converting is 3 mA and the quiescent current is 1.8 mA. The conversion time of 880 ns contributes 6.6 mW to the overall power dissipation in the following way: (880 ns/2 μs) × (5 × 3 mA) = 6.6 mW The contribution to the total power dissipated by the remaining 1.12 μs of the cycle is 5.04 mW As previously mentioned, the PS/FS pin is used to control the type of power-down mode that the AD7492 can enter into if operated in Mode 2. This pin can be hardwired either high or low, or even controlled by another device. It is important to note that toggling the PS/FS pin while in power-down mode does not switch the part between partial sleep and full sleep modes. To switch from one sleep mode to another, the AD7492 has to be powered up and the polarity of the PS/FS pin changed. It can then be powered down to the required sleep mode. (1.12 μs/2 μs) × (5 × 1.8 mA) = 5.04 mW Thus the power dissipated during each cycle is 6.6 mW + 5.04 mW = 11.64 mW CONVST tCONVERT POWER-UP It is recommended that the user performs a dummy conversion after power-up, as the first conversion result could be incorrect. This also ensures that the part is in the correct mode of operation. The recommended power-up sequence is as follows: 1. GND tQUIESCENT BUSY 1.12µs 880ns 2µs Figure 22. Mode 1 Power Dissipation 2. VDD 3. VDRIVE 4. Digital Inputs 5. VIN Rev. A | Page 16 of 24 01128-022 PS/FS PIN AD7492 Mode 2 (Full Sleep Mode) Figure 25, Figure 26, and Figure 27 show a typical graphical representation of power vs. throughput for the AD7492 when in Mode 1 @ 5 V and 3 V, Mode 2 in full sleep mode @ 5 V and 3 V, and Mode 2 in partial sleep mode @ 5 V and 3 V. Figure 23 shows the AD7492 conversion sequence in Mode 2, full sleep mode, using a throughput rate of approximately 100 kSPS. At 5 V supply the current consumption for the part when converting is 3 mA, while the full sleep current is 1 μA maximum. The power dissipated during this power-down is negligible and thus not worth considering in the total power figure. During the wake-up phase, the AD7492 draws typically 1.8 mA. Overall power dissipated is 12 10 tCONVERT 6 4 3V 500µs tQUIESCENT BUSY 0 0 9.5ms 200 01128-023 880ns 100 10ms 300 900 1000 90 100 90 100 3.5 Mode 2 (Partial Sleep Mode) 3.0 2.5 POWER (mV) Figure 24 shows the AD7492 conversion sequence in Mode 2, partial sleep mode, using a throughput rate of 1 kSPS. At 5 V supply, the current consumption for the part when converting is 3 mA, while the partial sleep current is 250 μA maximum. During the wake-up phase, the AD7492 typically draws 1.8 mA. Power dissipated during wake-up and conversion is 2.0 5V 1.5 3V 1.0 (880 ns/1 ms) × (5 × 3 mA) + (20 μs/1 ms) × (5 × 1.8 mA) = 193.2 mW 0.5 Power dissipated during power-down is 0 0 10 20 30 (979 μs/1 ms) × (5 × 250 μA) = 1.22 mW 70 50 60 40 THROUGHPUT (kHz) 80 Figure 26. Power vs. Throughput (Mode 2 in Full Sleep Mode @ 5 V and 3 V) Overall power dissipated is 2.5 193.2 μW + 1.22 mW = 1.41 mW tWAKEUP 800 Figure 25. Power vs. Throughput (Mode 1 @ 5 V and 3 V) Figure 23. Full Sleep Power Dissipation CONVST 400 500 600 700 THROUGHPUT (kHz) 01128-025 2 01128-026 tWAKEUP POWER (mV) 8 (880 ns/10 ms) × (5 × 3 mA) + (500 μs/10 ms) × (5 × 1.8 mA) = 451.32 μW CONVST 5V tCONVERT 5V 2.0 979µs 1ms 1.5 3V 1.0 0.5 Figure 24. Partial Sleep Power Dissipation 0 0 10 20 30 70 40 50 60 THROUGHPUT (kHz) 80 Figure 27. Power vs. Throughput (Mode 2 in Partial Sleep Mode @ 5 V and 3 V) Rev. A | Page 17 of 24 01128-027 880ns 01128-024 tQUIESCENT BUSY POWER (mV) 20µs AD7492 GROUNDING AND LAYOUT The analog and digital power supplies are independent and separately pinned out to minimize coupling between analog and digital sections within the device. To complement the excellent noise performance of the AD7492, it is imperative that care be given to the PCB layout. Figure 28 shows a recommended connection diagram for the AD7492. All of the AD7492 ground pins should be soldered directly to a ground plane to minimize series inductance. The AVDD pin, DVDD pin, and VDRIVE pin should be decoupled to both the analog and digital ground planes. The REF OUT pin should be decoupled to the analog ground plane with a minimum capacitor value of 100 nF. This capacitor helps to stabilize the internal reference circuit. The large value capacitors decouple low frequency noise to analog ground, the small value capacitors decouple high frequency noise to digital ground. All digital circuitry power pins should be decoupled to the digital ground plane. The use of ground planes can physically separate sensitive analog components from the noisy digital system. The two ground planes should be joined in only one place and should not overlap so as to minimize capacitive coupling between them. If the AD7492 is in a system where multiple devices require AGND-to-DGND connections, the connection should still be made at one point only, a star ground point, established as close as possible to the AD7492. 10µF 0.1µF 47µF + ANALOG SUPPLY 5V AVDD AGND DGND 2.5V 100nF + + Separate power supplies for AVDD and DVDD are desirable, but if necessary, DVDD can share its power connection to AVDD. The digital supply (DVDD) must not exceed the analog supply (AVDD) by more than 0.3 V in normal operation. MICROPROCESSOR INTERFACING ADSP-2185 to AD7492 Interface Figure 29 shows a typical interface between the AD7492 and the ADSP-2185. The ADSP-2185 processor can be used in one of two memory modes, full memory mode and host mode. The Mode C pin determines in which mode the processor works. The interface in Figure 29 is set up to have the processor working in full memory mode, allowing full external addressing capabilities. AD7492 VDRIVE OPTIONAL REF OUT 01128-028 10µF 1nF POWER SUPPLIES When the AD7492 has finished converting, the BUSY line requests an interrupt through the IRQ2 pin. The IRQ2 interrupt has to be set up in the interrupt control register as edgesensitive. The data memory select (DMS) pin latches in the address of the ADC into the address decoder. The read operation is started. DVDD 1nF Noise to the analog power line can be further reduced by use of multiple decoupling capacitors as shown in Figure 28. Decoupling capacitors should be placed directly at the power inlet to the PCB and also as close as possible to the power pins of the AD7492. The same decoupling method should be used on other ICs on the PCB, with the capacitor leads as short as possible to minimize lead inductance. Figure 28. Typical Decoupling Circuit A0 TO A15 ADSP-21851 DMS Noise can be minimized by applying the following simple rules to the PCB layout: • Analog signals should be kept away from digital signals. • Fast switching signals like clocks should be shielded with digital ground to avoid radiating noise to other sections of the board and clock signals should never be run near the analog inputs. • Avoid running digital lines under the device as this couples noise onto the die. • The power supply lines to the AD7492 should use as large a trace as possible to provide a low impedance path and reduce the effects of glitches on the power supply line. Rev. A | Page 18 of 24 AD7492 ADDRESS DECODER RD D0 TO D23 CS BUSY IRQ2 MODE C CONVST ADDRESS BUS RD 100kΩ DB0 TO DB9 (DB11) DATA BUS 1ADDITIONAL PINS OMITTED FOR CLARITY. Figure 29. ADSP-2185 to AD7492 Interface 01128-029 + • Avoid crossover of digital and analog signals and place traces that are on opposite sides of the board at right angles to each other. AD7492 OPTIONAL ADSP-21065Lto AD7492 Interface Figure 30 shows a typical interface between the AD7492 and the ADSP-21065L SHARC® processor. This interface is an example of one of three DMA handshake modes. The MSX control line is actually three memory select lines. Internal ADDR25–24 are decoded into MS3-0, these lines are then asserted as chip selects. The DMAR1 (DMA Request 1) is used in this setup as the interrupt to signal end of conversion. The rest of the interface is standard handshaking operation. A0 TO A15 CONVST ADDRESS BUS AD7492 TMS320C251 IS ADDRESS DECODER CS BUSY STRB RD R/W READY OPTIONAL MSC ADDRESS LATCH AD7492 DMD0 TO DMD15 ADDRESS DECODER DMAR1 RD Figure 31. TMS320C25 to AD7492 Interface CS PIC17C4x to AD7492 Interface BUSY Figure 32 shows a typical parallel interface between the AD7492 and PIC17C4x. The microcontroller sees the ADC as another memory device with its own specific memory address on the memory map. The CONVST signal can be controlled by either the microcontroller or an external source. The BUSY signal provides an interrupt request to the microcontroller when a conversion ends. The INT pin on the PIC17C4x must be configured to be active on the negative edge. Port C and Port D of the microcontroller are bidirectional and used to address the AD7492 and to read in the 12-bit data. The OE pin on the PIC can be used to enable the output buffers on the AD7492 and perform a read operation. RD DB0 TO DB9 (DB11) DATA BUS 1ADDITIONAL DATA BUS 1ADDITIONAL PINS OMITTED FOR CLARITY. ADDRESS BUS ADSP-21065L1 D0 TO 31 DB0 TO DB9 (DB11) 01128-031 CONVST PINS OMITTED FOR CLARITY. Figure 30. ADSP-21065L to AD7492 Interface TMS320C25 to AD7492 Interface Figure 31 shows an interface between the AD7492 and the TMS320C25. The CONVST signal can be applied from the TMS320C25 or from an external source. The BUSY line interrupts the digital signal processor when conversion is completed. The TMS320C25 does not have a separate RD output to drive the AD7492 RD input directly. This has to be generated from the processor STRB and R/W outputs with the addition of some glue logic. The RD signal is OR-gated with the MSC signal to provide the WAIT state required in the read cycle for correct interface timing. The following instruction is used to read the conversion from the AD7492: OPTIONAL CONVST PIC17C4x1 DB0 TO DB9 (DB11) AD0 TO AD15 AD7492 ADDRESS LATCH ALE ADDRESS DECODER RD BUSY OE INT IN D,ADC 1ADDITIONAL where: D is the data memory address. ADC is the AD7492 address. CS PINS OMITTED FOR CLARITY. Figure 32. PIC17C4x to AD7492 Interface The read operation must not be attempted during conversion. Rev. A | Page 19 of 24 01128-032 MSX ADDRESS BUS 01128-030 ADDR 0 TO ADDR 23 AD7492 OPTIONAL Figure 33 shows the AD7492 interfaced to the 80C186 microprocessor. The 80C186 DMA controller provides two independent high speed DMA channels where data transfer can occur between memory and I/O spaces. (The AD7492 occupies one of these I/O spaces.) Each data transfer consumes two bus cycles, one cycle to fetch data and the other to store data. AD0 TO AD15 A16 TO A19 ALE Rev. A | Page 20 of 24 CONVST ADDRESS LATCH AD7492 ADDRESS BUS 80C1861 After the AD7492 has finished the conversion, the BUSY line generates a DMA request to Channel 1 (DRQ1). Because of the interrupt, the processor performs a DMA read operation that resets the interrupt latch. Sufficient priority must be assigned to the DMA channel to ensure that the DMA request is serviced before the completion of the next conversion. This configuration can be used with 6 MHz and 8 MHz 80C186 processors. ADDRESS/DATA BUS ADDRESS DECODER DRQ1 Q CS R BUSY S RD RD DATA BUS 1ADDITIONAL PINS OMITTED FOR CLARITY. Figure 33. 80C186 to AD7492 Interface DB0 TO DB9 (DB11) 01128-033 80C186 to AD7492 Interface AD7492 OUTLINE DIMENSIONS 15.60 (0.6142) 15.20 (0.5984) 24 13 7.60 (0.2992) 7.40 (0.2913) 1 10.65 (0.4193) 10.00 (0.3937) 12 2.65 (0.1043) 2.35 (0.0925) 0.75 (0.0295) × 45° 0.25 (0.0098) 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 1.27 (0.0500) BSC 0.10 8° SEATING 0.33 (0.0130) 0° PLANE 0.20 (0.0079) 0.51 (0.020) 0.31 (0.012) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-013-AD CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 34. 24-Lead Standard Small Outline Package [SOIC_W] Wide Body (RW-24) Dimensions shown in millimeters and (inches) 7.90 7.80 7.70 24 13 4.50 4.40 4.30 1 6.40 BSC 12 PIN 1 0.65 BSC 1.20 MAX 0.15 0.05 0.30 0.19 SEATING PLANE 0.10 COPLANARITY 0.20 0.09 8° 0° 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MO-153-AD Figure 35. 24-Lead Thin Shrink Small Outline Package [TSSOP] (RU-24) Dimensions shown in millimeters ORDERING GUIDE Model AD7492AR AD7492AR–REEL AD7492AR–REEL7 AD7492ARZ 1 AD7492ARZ–REEL1 AD7492ARZ–REEL71 AD7492BR AD7492BR-REEL AD7492BR–REEL7 AD7492BRZ1 AD7492AR-5 AD7492AR-5–REEL Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Resolution (Bits) 12 12 12 12 12 12 12 12 12 12 12 12 Throughput Rate (MSPS) 1 1 1 1 1 1 1 1 1 1 1.25 1.25 Rev. A | Page 21 of 24 Package Description 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W Package Option RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 AD7492 Model AD7492AR-5–REEL7 AD7492ARZ-51 AD7492BR-5 AD7492BR-5–REEL AD7492BR-5–REEL7 AD7492BRZ-51 AD7492ARU AD7492ARU–REEL AD7492ARU–REEL7 AD7492ARUZ1 AD7492ARUZ–REEL1 AD7492ARUZ–REEL71 AD7492ARU-5 AD7492ARU-5–REEL AD7492ARU-5–REEL7 AD7492ARUZ-51 AD7492ARUZ-5–REEL1 AD7492ARUZ-5–REEL71 AD7492ARUZ-41 AD7492ARUZ-4REEL1 AD7492ARUZ-4REEL71 AD7492BRU AD7492BRU–REEL AD7492BRU–REEL7 AD7492BRUZ1 AD7492BRU-5 AD7492BRU-5–REEL AD7492BRU-5–REEL7 AD7492BRUZ-51 EVAL-AD7492CB 2 EVAL-CONTROL BRD2 3 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Resolution (Bits) 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 Throughput Rate (MSPS) 1.25 1.25 1.25 1.25 1.25 1.25 1 1 1 1 1 1 1.25 1 .25 1.25 1.25 1.25 1.25 0.4 0.4 0.4 1 1 1 1 1.25 1.25 1.25 1.25 1 Package Description 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead SOIC_W 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP 24-Lead TSSOP Z = Pb–free part. This can be used as a standalone evaluation board or in conjunction with the EVAL-CONTROL BRD2 for evaluation/demonstration purposes. 3 This board is a complete unit allowing a PC to control and communicate with all Analog Devices evaluation boards ending in the CB designators. 2 Rev. A | Page 22 of 24 Package Option RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 Evaluation Board Controller Board AD7492 NOTES Rev. A | Page 23 of 24 AD7492 NOTES ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D01128-0-5/06(A) Rev. A | Page 24 of 24