3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs AD7822/AD7825/AD7829 FEATURES VDD CONVST EOC A01 A11 A22 PD3 CONTROL LOGIC VIN1 VIN24 VIN34 VIN44 VIN55 VIN65 VIN75 VIN85 INPUT MUX 1A0, A1 2A2 3PD 4V IN2 TO VIN4 5V IN5 TO VIN8 Data acquisition systems, DSP front ends Disk drives Mobile communication systems, subsampling applications 2.5V REF BUF T/H VMID APPLICATIONS COMP 8-BIT HALF FLASH ADC DGND AGND PARALLEL PORT VREF IN/OUT DB7 DB0 CS RD AD7825/AD7829 AD7829 AD7822/AD7825 AD7825/AD7829 AD7829 01321-001 8-bit half-flash ADC with 420 ns conversion time One, four, and eight single-ended analog input channels Available with input offset adjust On-chip track-and-hold SNR performance given for input frequencies up to 10 MHz On-chip reference (2.5 V) Automatic power-down at the end of conversion Wide operating supply range 3 V ± 10% and 5 V ± 10% Input ranges 0 V to 2 V p-p, VDD = 3 V ± 10% 0 V to 2.5 V p-p, VDD = 5 V ± 10% Flexible parallel interface with EOC pulse to allow standalone operation FUNCTIONAL BLOCK DIAGRAM Figure 1. GENERAL DESCRIPTION The AD7822/AD7825/AD7829 are high speed, 1-, 4-, and 8-channel, microprocessor-compatible, 8-bit analog-to-digital converters with a maximum throughput of 2 MSPS. The AD7822/ AD7825/AD7829 contain an on-chip reference of 2.5 V (2% tolerance); a track-and-hold amplifier; a 420 ns, 8-bit halfflash ADC; and a high speed parallel interface. The converters can operate from a single 3 V ± 10% and 5 V ± 10% supply. The AD7822 and AD7825 are available in 20-lead and 24-lead, 0.3" wide, plastic dual in-line packages (PDIP); 20-lead and 24-lead standard small outline packages (SOIC); and 20-lead and 24-lead thin shrink small outline packages (TSSOP). The AD7829 is available in a 28-lead, 0.6" wide PDIP; a 28-lead SOIC; and a 28-lead TSSOP. The AD7822/AD7825/AD7829 combine the convert start and power-down functions at one pin, that is, the CONVST pin. This allows a unique automatic power-down at the end of a conversion to be implemented. The logic level on the CONVST pin is sampled after the end of a conversion when an EOC (end of conversion) signal goes high. If it is logic low at that point, the ADC is powered down. The AD7822 and AD7825 also have a separate power-down pin (see the Operating Modes section). 1. Fast Conversion Time. The AD7822/AD7825/AD7829 have a conversion time of 420 ns. Faster conversion times maximize the DSP processing time in a real-time system. 2. Analog Input Span Adjustment. The VMID pin allows the user to offset the input span. This feature can reduce the requirements of single-supply op amps and take into account any system offsets. 3. FPBW (Full Power Bandwidth) of Track-and-Hold. The track-and-hold amplifier has an excellent high frequency performance. The AD7822/AD7825/AD7829 are capable of converting full-scale input signals up to a frequency of 10 MHz. This makes the parts ideally suited to subsampling applications. 4. Channel Selection. Channel selection is made without the necessity of writing to the part. The parallel interface is designed to allow easy interfacing to microprocessors and DSPs. Using only address decoding logic, the parts are easily mapped into the microprocessor address space. The EOC pulse allows the ADCs to be used in a standalone manner (see the Parallel Interface section.) PRODUCT HIGHLIGHTS Rev. C 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. AD7822/AD7825/AD7829 TABLE OF CONTENTS Features .............................................................................................. 1 Typical Connection Diagram ................................................... 10 Applications....................................................................................... 1 ADC Transfer Function............................................................. 11 General Description ......................................................................... 1 Analog Input ............................................................................... 11 Functional Block Diagram .............................................................. 1 Power-Up Times......................................................................... 14 Product Highlights ....................................................................... 1 Power vs. Throughput................................................................ 15 Revision History ............................................................................... 2 Operating Modes........................................................................ 15 Specifications..................................................................................... 3 Parallel Interface......................................................................... 17 Timing Characteristics ................................................................ 5 Microprocessor Interfacing........................................................... 18 Timing Diagram ........................................................................... 5 AD7822/AD7825/AD7829 to 8051 ......................................... 18 Absolute Maximum Ratings............................................................ 6 AD7822/AD7825/AD7829 to PIC16C6x/PIC16C7x................ 18 ESD Caution.................................................................................. 6 AD7822/AD7825/AD7829 to ADSP-21xx ............................. 18 Pin Configurations and Function Descriptions ........................... 7 Interfacing Multiplexer Address Inputs .................................. 18 Terminology ...................................................................................... 8 AD7822 Standalone Operation ................................................ 19 Circuit Information ........................................................................ 10 Outline Dimensions ....................................................................... 20 Circuit Description..................................................................... 10 Ordering Guide .......................................................................... 25 REVISION HISTORY 8/06—Rev. B to Rev. C Changes to General Description .................................................... 1 Changes to Table 1............................................................................ 3 Changes to Typical Connection Diagram Section ..................... 10 Updated Outline Dimensions ....................................................... 20 Changes to Ordering Guide .......................................................... 25 Changes to Typical Connection Diagram Section........................7 Changes to Analog Input Section....................................................8 Changes to Analog Input Selection Section...................................9 Changes to Power-Up Times Section .......................................... 10 Changes to Power vs. Throughput Section ................................. 11 Added AD7822 Stand-Alone Operation section ....................... 15 10/01—Rev. A to Rev. B Changes to Power Requirements.................................................... 3 Changes to Pin Function Description ........................................... 5 Changes to Circuit Description ...................................................... 7 12/99—Rev. 0 to Rev. A Rev. C | Page 2 of 28 AD7822/AD7825/AD7829 SPECIFICATIONS VDD = 3 V ± 10%, VDD = 5 V ± 10%, GND = 0 V, VREF IN/OUT = 2.5 V. All specifications −40°C to +85°C, unless otherwise noted. Table 1. Parameter DYNAMIC PERFORMANCE Signal to (Noise + Distortion) Ratio 1 Total Harmonic Distortion1 Peak Harmonic or Spurious Noise1 Intermodulation Distortion1 Second-Order Terms Third-Order Terms Channel-to-Channel Isolation1 DC ACCURACY Resolution Minimum Resolution for Which No Missing Codes Are Guaranteed Integral Nonlinearity (INL)1 Differential Nonlinearity (DNL)1 Gain Error1 Gain Error Match1 Offset Error1 Offset Error Match1 ANALOG INPUTS 2 VDD = 5 V ± 10% VIN1 to VIN8 Input Voltage VMID Input Voltage VDD = 3 V ± 10% VIN1 to VIN8 Input Voltage VMID Input Voltage VIN Input Leakage Current VIN Input Capacitance VMID Input Impedance REFERENCE INPUT VREF IN/OUT Input Voltage Range Input Current ON-CHIP REFERENCE Reference Error Temperature Coefficient LOGIC INPUTS Input High Voltage, VINH Input Low Voltage, VINL Input High Voltage, VINH Input Low Voltage, VINL Input Current, IIN Input Capacitance, CIN Version B Unit 48 −55 −55 dB min dB max dB max −65 −65 −70 dB typ dB typ dB typ 8 Bits 8 ±0.75 ±0.75 ±2 ±0.1 ±1 ±0.1 Bits LSB max LSB max LSB max LSB typ LSB max LSB typ Test Condition/Comment fIN = 30 kHz, fSAMPLE = 2 MHz fa = 27.3 kHz, fb = 28.3 kHz fIN = 20 kHz See Analog Input section Input voltage span = 2.5 V VDD 0 VDD − 1.25 1.25 V max V min V max V min VDD 0 VDD − 1 1 ±1 15 6 V max V min V max V min μA max pF max kΩ typ 2.55 2.45 1 100 V max V min μA typ μA max ±50 50 mV max ppm/°C typ 2.4 0.8 2 0.4 ±1 10 V min V max V min V max μA max pF max Default VMID = 1.25 V Input voltage span = 2 V Default VMID = 1 V 2.5 V + 2% 2.5 V − 2% Nominal 2.5 V Rev. C | Page 3 of 28 VDD = 5 V ± 10% VDD = 5 V ± 10% VDD = 3 V ± 10% VDD = 3 V ± 10% 10 nA typical, VIN = 0 V to VDD AD7822/AD7825/AD7829 Parameter LOGIC OUTPUTS Output High Voltage, VOH Version B Unit 4 2.4 V min V min 0.4 0.2 ±1 10 V max V max μA max pF max 200 420 ns max ns max ±1 LSB max 4.5 5.5 2.7 3.3 V min V max V min V max 5 V ± 10%; for specified performance 12 5 0.2 mA max μA max μA typ 8 mA typical Logic inputs = 0 V or VDD 36 mW max 9.58 23.94 mW typ mW typ Output Low Voltage, VOL High Impedance Leakage Current High Impedance Capacitance CONVERSION RATE Track-and-Hold Acquisition Time Conversion Time POWER SUPPLY REJECTION VDD ± 10% POWER REQUIREMENTS VDD VDD Test Condition/Comment ISOURCE = 200 μA VDD = 5 V ± 10% VDD = 3 V ± 10% ISINK = 200 μA VDD = 5 V ± 10% VDD = 3 V ± 10% See Circuit Description section 3 V ± 10%; for specified performance IDD Normal Operation Power-Down Power Dissipation Normal Operation Power-Down 200 kSPS 500 kSPS 1 2 See the Terminology section of this data sheet. Refer to the Analog Input section for an explanation of the analog input(s). Rev. C | Page 4 of 28 VDD = 3 V 24 mW typical AD7822/AD7825/AD7829 TIMING CHARACTERISTICS VREF IN/OUT = 2.5 V. All specifications −40°C to +85°C, unless otherwise noted. Table 2. Parameter 1, 2 t1 t2 t3 t4 t5 t6 t7 t8 t9 3 t10 4 t11 t12 t13 tPOWER UP tPOWER UP 5 V ± 10% 420 20 30 110 70 10 0 0 30 10 5 20 10 15 200 25 1 3 V ± 10% 420 20 30 110 70 10 0 0 30 20 5 20 10 15 200 25 1 Unit ns max ns min ns min ns max ns min ns max ns min ns min ns min ns max ns min ns max ns min ns min ns min μs typ μs max Conditions/Comments Conversion time Minimum CONVST pulse width Minimum time between the rising edge of RD and the next falling edge of convert star EOC pulse width RD rising edge to EOC pulse high CS to RD setup time CS to RD hold time Minimum RD pulse width Data access time after RD low Bus relinquish time after RD high Address setup time before falling edge of RD Address hold time after falling edge of RD Minimum time between new channel selection and convert start Power-up time from rising edge of CONVST using on-chip reference Power-up time from rising edge of CONVST using external 2.5 V reference 1 Sample tested to ensure compliance. See Figure 24, Figure 25, and Figure 26. 3 Measured with the load circuit of Figure 2 and defined as the time required for an output to cross 0.8 V or 2.4 V with VDD = 5 V ± 10%, and time required for an output to cross 0.4 V or 2.0 V with VDD = 3 V ± 10%. 4 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, t10, quoted in the timing characteristics is the true bus relinquish time of the part and, as such, is independent of external bus loading capacitances. 2 TIMING DIAGRAM 200µA 2.1V CL 50pF 200µA IOH 01321-002 TO OUTPUT PIN IOL Figure 2. Load Circuit for Access Time and Bus Relinquish Time Rev. C | Page 5 of 28 AD7822/AD7825/AD7829 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 3. Parameter VDD to AGND VDD to DGND Analog Input Voltage to AGND VIN1 to VIN8 Reference Input Voltage to AGND VMID Input Voltage to AGND Digital Input Voltage to DGND Digital Output Voltage to DGND Operating Temperature Range Industrial (B Version) Storage Temperature Range Junction Temperature PDIP Package, Power Dissipation θJA Thermal Impedance Lead Temperature, (Soldering, 10 sec) SOIC Package, Power Dissipation θJA Thermal Impedance Lead Temperature, Soldering Vapor Phase (60 sec) Infrared (15 sec) TSSOP Package, Power Dissipation θJA Thermal Impedance Lead Temperature, Soldering Vapor Phase (60 sec) Infrared (15 sec) ESD Rating −0.3 V to +7 V −0.3 V to +7 V −0.3 V to VDD + 0.3 V −0.3 V to VDD + 0.3 V −0.3 V to VDD + 0.3 V −0.3 V to VDD + 0.3 V −0.3 V to VDD + 0.3 V 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 105°C/W 260°C 450 mW 75°C/W 215°C 220°C 450 mW 128°C/W 215°C 220°C 1 kV 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. C | Page 6 of 28 AD7822/AD7825/AD7829 26 DB1 2 23 DB4 CONVST 4 25 DB6 22 DB5 CS 5 24 DB7 21 DB6 RD 6 23 AGND 20 DB7 DGND 7 DB1 2 19 DB4 CONVST 4 DB0 3 18 DB5 CS 5 TOP VIEW 19 AGND (Not to Scale) DGND 7 18 VDD RD 6 AD7822 16 DB7 TOP VIEW 15 AGND (Not to Scale) DGND 7 14 VDD 13 VREF IN/OUT PD 9 12 VMID NC 10 11 VIN1 NC = NO CONNECT Figure 3. Pin Configuration 01321-003 EOC 8 AD7825 EOC 8 AD7829 TOP VIEW (Not to Scale) 22 VDD 21 VREF IN/OUT A2 9 20 VMID EOC 8 17 VREF IN/OUT A1 10 19 VIN1 A1 9 16 VMID A0 11 18 VIN2 A0 10 15 VIN1 VIN8 12 17 VIN3 PD 11 14 VIN2 VIN7 13 16 VIN4 VIN4 12 13 VIN3 VIN6 14 15 VIN5 Figure 4. Pin Configuration 01321-004 CS 5 DB5 DB0 3 DB0 3 RD 6 DB4 DB3 DB3 DB6 DB3 27 24 20 17 28 DB2 1 DB2 1 CONVST 4 DB2 1 DB1 2 01321-005 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS Figure 5. Pin Configuration Table 4. Pin Function Descriptions Mnemonic VIN1 to VIN8 VDD AGND DGND CONVST EOC CS PD RD A0 to A2 DB0 to DB7 VREF IN/OUT VMID Description Analog Input Channels. The AD7822 has a single input channel; the AD7825 and AD7829 have four and eight analog input channels, respectively. The inputs have an input span of 2.5 V and 2 V depending on the supply voltage (VDD). This span can be centered anywhere in the range AGND to VDD using the VMID pin. The default input range (VMID unconnected) is AGND to 2 V (VDD = 3 V ± 10%) or AGND to 2.5 V (VDD = 5 V ± 10%). See the Analog Input section of the data sheet for more information. Positive Supply Voltage, 3 V ± 10% and 5 V ± 10%. Analog Ground. Ground reference for track-and-hold, comparators, reference circuit, and multiplexer. Digital Ground. Ground reference for digital circuitry. Logic Input Signal. The convert start signal initiates an 8-bit analog-to-digital conversion on the falling edge of this signal. The falling edge of this signal places the track-and-hold in hold mode. The track-and-hold goes into track mode again 120 ns after the start of a conversion. The state of the CONVST signal is checked at the end of a conversion. If it is logic low, the AD7822/ AD7825/AD7829 powers down (see the Operating Modes section of the data sheet). Logic Output. The end-of-conversion signal indicates when a conversion has finished. The signal can be used to interrupt a microcontroller when a conversion has finished or latch data into a gate array (see the Parallel Interface section). Logic Input Signal. The chip select signal is used to enable the parallel port of the AD7822/AD7825/AD7829. This is necessary if the ADC is sharing a common data bus with another device. Logic Input. The power-down pin is present on the AD7822 and AD7825 only. Bringing the PD pin low places the AD7822 and AD7825 in power-down mode. The ADCs power up when PD is brought logic high again. Logic Input Signal. The read signal is used to take the output buffers out of their high impedance state and drive data onto the data bus. The signal is internally gated with the CS signal. Both RD and CS must be logic low to enable the data bus. Channel Address Inputs. The address of the next multiplexer channel must be present on these inputs when the RD signal goes low. Data Output Lines. They are normally held in a high impedance state. Data is driven onto the data bus when both RD and CS go active low. Analog Input and Output. An external reference can be connected to the AD7822/AD7825/AD7829 at this pin. The on-chip reference is also available at this pin. When using the internal reference, this pin can be left unconnected or, in some cases, it can be decoupled to AGND with a 0.1 μF capacitor. The VMID pin, if connected, is used to center the analog input span anywhere in the range of AGND to VDD (see the Analog Input section). Rev. C | Page 7 of 28 AD7822/AD7825/AD7829 TERMINOLOGY Signal-to-(Noise + Distortion) Ratio The measured ratio of signal-to-(noise + distortion) at the output of the analog-to-digital converter. The signal is the rms amplitude of the fundamental. Noise is the rms sum of all nonfundamental signals up to half the sampling frequency (fS/2), excluding dc. The ratio is dependent upon 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 + Distortion) = (6.02 N + 1.76) dB Thus, for an 8-bit converter, this is 50 dB. Total Harmonic Distortion (THD) The ratio of the rms sum of harmonics to the fundamental. For the AD7822/AD7825/AD7829, it is defined as V 2 + V 3 + V 4 + V 5 + V6 2 THD (dB) = 20 log 2 2 2 2 V1 where V1 is the rms amplitude of the fundamental and V2, V3, V4, V5, and V6 are the rms amplitudes of the second through the sixth harmonics. Peak Harmonic or Spurious Noise 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 parts 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, … . Intermodulation 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), and the third-order terms include (2fa + fb), (2fa − fb), (fa + 2fb), and (fa − 2fb). The AD7822/AD7825/AD7829 are tested using the CCIF standard, where two input frequencies near the top end of the input bandwidth are used. In this case, the second- and thirdorder terms are of different significance. The second-order terms are usually distanced in frequency from the original sine waves, and 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 fundamental expressed in decibels (dB). Channel-to-Channel Isolation A measure of the level of crosstalk between channels. It is measured by applying a full-scale 20 kHz sine wave signal to one input channel and determining how much that signal is attenuated in each of the other channels. The figure given is the worst case across all four or eight channels of the AD7825 and AD7829, respectively. Relative Accuracy or Endpoint Nonlinearity The maximum deviation from a straight line passing through the endpoints of the ADC transfer function. Differential Nonlinearity The difference between the measured and the ideal one LSB change between any two adjacent codes in the ADC. Offset Error The deviation of the 128th code transition (01111111) to (10000000) from the ideal, that is, VMID. Offset Error Match The difference in offset error between any two channels. Zero-Scale Error The deviation of the first code transition (00000000) to (00000001) from the ideal; that is, VMID − 1.25 V + 1 LSB (VDD = 5 V ± 10%), or VMID − 1.0 V + 1 LSB (VDD = 3 V ± 10%). Full-Scale Error The deviation of the last code transition (11111110) to (11111111) from the ideal; that is, VMID + 1.25 V − 1 LSB (VDD = 5 V ± 10%), or VMID + 1.0 V − 1 LSB (VDD = 3 V ± 10%). Rev. C | Page 8 of 28 AD7822/AD7825/AD7829 Gain Error Match The difference in gain error between any two channels. It also applies to situations where a change in the selected input channel takes place or where there is a step input change on the input voltage applied to the selected VIN input of the AD7822/ AD7825/AD7829. It means that the user must wait for the duration of the track-and-hold acquisition time after a channel change/step input change to VIN before starting another conversion, to ensure that the part operates to specification. Track-and-Hold Acquisition Time The time required for the output of the track-and-hold amplifier to reach its final value, within ±1/2 LSB, after the point at which the track-and-hold returns to track mode. This happens approximately 120 ns after the falling edge of CONVST. PSR (Power Supply Rejection) Variations in power supply affect the full-scale transition but not the converter linearity. Power supply rejection is the maximum change in the full-scale transition point due to a change in power supply voltage from the nominal value. Gain Error The deviation of the last code transition (1111 . . . 110) to (1111 . . . 111) from the ideal, that is, VREF − 1 LSB, after the offset error has been adjusted out. Rev. C | Page 9 of 28 AD7822/AD7825/AD7829 CIRCUIT INFORMATION CIRCUIT DESCRIPTION REFERENCE R16 15 DB6 R15 DB5 14 SAMPLING CAPACITOR B HOLD R14 13 OUTPUT DRIVERS SW2 OUTPUT REGISTER T/H 1 VIN A DB7 DECODE LOGIC DB4 DB3 DB2 R13 DB1 DB0 1 R1 TIMING AND CONTROL LOGIC 01321-007 Figure 6 and Figure 7 show simplified schematics of the ADC. When the ADC starts a conversion, the track-and-hold goes into hold mode and holds the analog input for 120 ns. This is the acquisition phase, as shown in Figure 6, when Switch 2 is in Position A. At the point when the track-and-hold returns to its track mode, this signal is sampled by the sampling capacitor, as Switch 2 moves into Position B. The first flash occurs at this instant and is then followed by the second flash. Typically, the first flash is complete after 100 ns, that is, at 220 ns; and the end of the second flash and, hence, the 8-bit conversion result is available at 330 ns (minimum). The maximum conversion time is 420 ns. As shown in Figure 8, the track-and-hold returns to track mode after 120 ns and starts the next acquisition before the end of the current conversion. Figure 10 shows the ADC transfer function. Figure 7. ADC Conversion Phase 120ns TRACK CONVST EOC TRACK HOLD HOLD t2 t1 CS t3 RD VALID DATA DB0 TO DB7 01321-008 The AD7822/AD7825/AD7829 consist of a track-and-hold amplifier followed by a half-flash analog-to-digital converter. These devices use a half-flash conversion technique where one 4-bit flash ADC is used to achieve an 8-bit result. The 4-bit flash ADC contains a sampling capacitor followed by 15 comparators that compare the unknown input to a reference ladder to achieve a 4-bit result. This first flash (that is, coarse conversion) provides the four MSBs. For a full 8-bit reading to be realized, a second flash (that is, fine conversion) must be performed to provide the four LSBs. The 8-bit word is then placed on the data output bus. Figure 8. Track-and-Hold Timing REFERENCE TYPICAL CONNECTION DIAGRAM R16 15 R14 13 OUTPUT DRIVERS B DB4 DB3 DB2 R13 DB1 1 DB0 R1 TIMING AND CONTROL LOGIC Figure 6. ADC Acquisition Phase 01321-006 HOLD DB5 14 SAMPLING CAPACITOR OUTPUT REGISTER T/H 1 DB6 R15 SW2 DECODE LOGIC VIN A DB7 Figure 9 shows a typical connection diagram for the AD7822/ AD7825/AD7829. The AGND and DGND are connected together at the device for good noise suppression. The parallel interface is implemented using an 8-bit data bus. The end of conversion signal (EOC) idles high, the falling edge of CONVST initiates a conversion, and at the end of conversion the falling edge of EOC is used to initiate an interrupt service routine (ISR) on a microprocessor (see the Parallel Interface section for more details.) VREF and VMID are connected to a voltage source such as the AD780, and VDD is connected to a voltage source that can vary from 4.5 V to 5.5 V (see Table 5 in the Analog Input section). When VDD is first connected, the AD7822/AD7825/ AD7829 power up in a low current mode, that is, power-down mode, with the default logic level on the EOC pin on the AD7822 and AD7825 equal to a low. Ensure the CONVST line is not floating when VDD is applied, because this can put the AD7822/AD7825/AD7829 into an unknown state. Rev. C | Page 10 of 28 AD7822/AD7825/AD7829 A suggestion is to tie CONVST to VDD or DGND through a pull-up or pull-down resistor. A rising edge on the CONVST pin causes the AD7829 to fully power up, while a rising edge on the PD pin causes the AD7822 and AD7825 to fully power up. For applications where power consumption is of concern, the automatic power-down at the end of a conversion should be used to improve power performance (see the Power vs. Throughput section). SUPPLY 4.5V TO 5.5V 2.5V AD780 10µF 0.1µF PARALLEL INTERFACE VDD VREF 1.25V TO 3.75V INPUT EOC VIN24 AD7822/ AD7825/ AD7829 RD CS µC/µP CONVST VIN4(VIN85) A01 AGND If, however, an external VMID is applied, the analog input range is from VMID − 1.0 V to VMID + 1.0 V (VDD = 3 V ± 10%), or from VMID − 1.25 V to VMID + 1.25 V (VDD = 5 V ± 10%). A11 A22 DGND PD3 1A0, A1 2A2 3PD 4V IN2 TO VIN4 5V IN5 TO VIN8 01321-009 AD7825/AD7829 AD7829 AD7822/AD7825 AD7825/AD7829 AD7829 Figure 9. Typical Connection Diagram ADC TRANSFER FUNCTION (VDD = 5V) 1LSB = VREF /256 VDD 5.5 5.0 4.5 3.3 3.0 2.7 111...000 10000000 (VDD = 3V) 1LSB = 0.8VREF /256 000...111 000...010 000...001 00000000 1LSB (VDD = 5V) VMID – 1.25V (VDD = 3V) VMID – 1V VMID VMID + 1.25V – 1LSB VMID + 1V – 1LSB ANALOG INPUT VOLTAGE 01321-010 ADC CODE The range of values of VMID that can be applied depends on the value of VDD. For VDD = 3 V ± 10%, the range of values that can be applied to VMID is from 1.0 V to VDD − 1.0 V and from 1.25 V to VDD − 1.25 V when VDD = 5 V ± 10%. Table 5 shows the relevant ranges of VMID and the input span for various values of VDD. Figure 11 illustrates the input signal range available with various values of VMID. Table 5. The output coding of the AD7822/AD7825/AD7829 is straight binary. The designed code transitions occur at successive integer LSB values (that is, 1 LSB, 2 LSBs, and so on). The LSB size = VREF/256 (VDD = 5 V) or the LSB size = (0.8 VREF)/256 (VDD = 3 V). The ideal transfer characteristic for the AD7822/AD7825/ AD7829 is shown in Figure 10. 11111111 111...110 The AD7822 has a single input channel, and the AD7825 and AD7829 have four and eight input channels, respectively. Each input channel has an input span of 2.5 V or 2.0 V, depending on the supply voltage (VDD). This input span is automatically set up by an on-chip VDD detector circuit. A 5 V operation of the ADCs is detected when VDD exceeds 4.1 V, and a 3 V operation is detected when VDD falls below 3.8 V. This circuit also possesses a degree of glitch rejection; for example, a glitch from 5.5 V to 2.7 V up to 60 ns wide does not trip the VDD detector. The VMID pin is used to center this input span anywhere in the range of AGND to VDD. If no input voltage is applied to VMID, the default input range is AGND to 2.0 V (VDD = 3 V ± 10%), that is, centered about 1.0 V; or AGND to 2.5 V (VDD = 5 V ± 10%), that is, centered about 1.25 V. When using the default input range, the VMID pin can be left unconnected, or in some cases, it can be decoupled to AGND with a 0.1 μF capacitor. VMID DB0 TO DB7 VIN1 ANALOG INPUT Figure 10. Transfer Characteristic Rev. C | Page 11 of 28 VMID Internal 1.25 1.25 1.25 1.00 1.00 1.00 VMID Ext Max 4.25 3.75 3.25 2.3 2.0 1.7 VIN Span 3.0 to 5.5 2.5 to 5.0 2.0 to 4.5 1.3 to 3.3 1.0 to 3.0 0.7 to 2.7 VMID Ext Min 1.25 1.25 1.25 1.00 1.00 1.00 VIN Span 0 to 2.5 0 to 2.5 0 to 2.5 0 to 2.0 0 to 2.0 0 to 2.0 Unit V V V V V V AD7822/AD7825/AD7829 2.5V VDD = 5V VREF 5V VMID R4 4V R3 VMID = 3.75V V 3V VMID = 2.5V V AD7822/ AD7825/ AD7829 VIN R2 R1 0V VIN 2V VMID = N/C (1.25V) INPUT SIGNAL RANGE FOR VARIOUS VMID 01321-013 2.5V 1V 0V Figure 13. Accommodating Bipolar Signals Using External VMID EXTERNAL 2.5V VDD = 3V 3V VREF VMID AD7822/ AD7825/ AD7829 R4 2V R3 VMID = 2V VMID = 1.5V V VMID = N/C (1V) 0V R1 VIN VMID Figure 11. Analog Input Span Variation with VMID 0V VMID can be used to remove offsets in a system by applying the offset to the VMID pin as shown in Figure 12, or it can be used to accommodate bipolar signals by applying VMID to a level-shifting circuit before VIN, as shown in Figure 13. When VMID is being driven by an external source, the source can be directly tied to the level-shifting circuitry (see Figure 13). However, if the internal VMID, that is, the default value, is being used as an output, it must be buffered before applying it to the levelshifting circuitry because the VMID pin has an impedance of approximately 6 kΩ (see Figure 14). VIN VIN AD7822/ AD7825/ AD7829 VMID VMID Figure 12. Removing Offsets Using VMID 01321-012 VMID 01321-014 INPUT SIGNAL RANGE FOR VARIOUS VMID VIN R2 01321-011 1V V Figure 14. Accommodating Bipolar Signals Using Internal VMID NOTE: Although there is a VREF pin from which a voltage reference of 2.5 V can be sourced, or to which an external reference can be applied, this does not provide an option of varying the value of the voltage reference. As stated in the specifications for the AD7822/AD7825/AD7829, the input voltage range at this pin is 2.5 V ± 2%. Analog Input Structure Figure 15 shows an equivalent circuit of the analog input structure of the AD7822/AD7825/AD7829. The two diodes, D1 and D2, provide ESD protection for the analog inputs. Care must be taken to ensure that the analog input signal never exceeds the supply rails by more than 200 mV. Doing so causes these diodes to become forward biased and start conducting current into the substrate. A maximum current of 20 mA can be conducted by these diodes without causing irreversible damage to the part. However, it is worth noting that a small amount of current (1 mA) being conducted into the substrate, due to an overvoltage on an unselected channel, can cause inaccurate conversions on a selected channel. Rev. C | Page 12 of 28 AD7822/AD7825/AD7829 Capacitor C2 in Figure 15 is typically about 4 pF and can be primarily attributed to pin capacitance. The resistor, R1, is a lumped component made up of the on resistance of several components, including that of the multiplexer and the trackand-hold. This resistor is typically about 310 Ω. Capacitor C1 is the track-and-hold capacitor and has a capacitance of 0.5 pF. Switch 1 is the track-and-hold switch, and Switch 2 is that of the sampling capacitor, as shown in Figure 6 and Figure 7. 120ns TRACK CHx HOLD CHx TRACK CHx TRACK CHy CONVST t1 EOC CS t3 RD VDD C2 4pF D2 DB0 TO DB7 C1 0.5pF A SW2 R1 310Ω SW1 A0 TO A2 B ADDRESS CHANNEL y 01321-015 Figure 15. Equivalent Analog Input Circuit When in track phase, Switch 1 is closed and Switch 2 is in Position A. When in hold mode, Switch 1 opens and Switch 2 remains in Position A. The track-and-hold remains in hold mode for 120 ns (see the Circuit Description section), after which it returns to track mode and the ADC enters its conversion phase. At this point, Switch 1 opens and Switch 2 moves to Position B. At the end of the conversion, Switch 2 moves back to Position A. Figure 16. Channel Hopping Timing There is a minimum time delay between the falling edge of RD and the next falling edge of the CONVST signal, t13. This is the minimum acquisition time required of the track-and-hold to maintain 8-bit performance. Figure 17 shows the typical performance of the AD7825 when channel hopping for various acquisition times. These results are obtained using an external reference and internal VMID while channel hopping between VIN1 and VIN4 with 0 V on Channel 4 and 0.5 V on Channel 1. 8.5 Analog Input Selection 8.0 On power-up, the default VIN selection is VIN1. When returning to normal operation from power-down, the VIN selected is the same one that was selected prior to initiation of power-down. Table 6 shows the multiplexer address corresponding to each analog input from VIN1 to VIN4(8) for the AD7825 or AD7829. ENOB 7.5 Table 6. A2 0 0 0 0 1 1 1 1 7.0 6.5 6.0 A1 0 0 1 1 0 0 1 1 A0 0 1 0 1 0 1 0 1 Analog Input Selected VIN1 VIN2 VIN3 VIN4 VIN5 VIN6 VIN7 VIN8 5.5 5.0 500 200 100 50 40 30 20 ACQUISITION TIME (ns) 15 10 01321-017 VIN t13 VALID DATA 01321-016 D1 HOLD CHy t2 Figure 17. Effective Number of Bits vs. Acquisition Time for the AD7825 Channel selection on the AD7825 and AD7829 is made without the necessity of a write operation. The address of the next channel to be converted is latched at the start of the current read operation, that is, on the falling edge of RD while CS is low, as shown in Figure 16. This allows for improved throughput rates in “channel hopping” applications. The on-chip track-and-hold can accommodate input frequencies to 10 MHz, making the AD7822/AD7825/AD7829 ideal for subsampling applications. When the AD7825 is converting a 10 MHz input signal at a sampling rate of 2 MSPS, the effective number of bits typically remains above seven, corresponding to a signal-to-noise ratio of 42 dBs, as shown in Figure 18. Rev. C | Page 13 of 28 AD7822/AD7825/AD7829 EXTERNAL REFERENCE 50 fSAMPLE = 2MHz VDD 48 tPOWER-UP 1µs CONVST SNR (dB) 46 CONVERSION INITIATED HERE 44 ON-CHIP REFERENCE 42 VDD tPOWER-UP 25µs 40 1 3 4 5 6 INPUT FREQUENCY (MHz) 8 10 CONVERSION INITIATED HERE 01321-018 38 0.2 01321-019 CONVST Figure 19. AD7829 Power-Up Time Figure 18. SNR vs. Input Frequency on the AD7825 POWER-UP TIMES The AD7822/AD7825/AD7829 have a 1 μs power-up time when using an external reference and a 25 μs power-up time when using the on-chip reference. When VDD is first connected, the AD7822/AD7825/AD7829 are in a low current mode of operation. Ensure that the CONVST line is not floating when VDD is applied. If there is a glitch on CONVST while VDD is rising, the part attempts to power up before VDD has fully settled and can enter an unknown state. To carry out a conversion, the AD7822/AD7825/AD7829 must first be powered up. The AD7829 is powered up by a rising edge on the CONVST pin, and a conversion is initiated on the falling edge of CONVST. Figure 19 shows how to power up the AD7829 when VDD is first connected or after the AD7829 has been powered down using the CONVST pin when using either the on-chip reference or an external reference. When using an external reference, the falling edge of CONVST may occur before the required power-up time has elapsed; however, the conversion is not initiated on the falling edge of CONVST but rather at the moment when the part has completely powered up, that is, after 1 μs. If the falling edge of CONVST occurs after the required power-up time has elapsed, then it is upon this falling edge that a conversion is initiated. When using the on-chip reference, it is necessary to wait the required power-up time of approximately 25 μs before initiating a conversion; that is, a falling edge on CONVST must not occur before the required power-up time has elapsed, when VDD is first connected or after the AD7829 has been powered down using the CONVST pin, as shown in Figure 19. Figure 20 shows how to power up the AD7822 or AD7825 when VDD is first connected or after the ADCs have been powered down, using the PD pin or the CONVST pin, with either the on-chip reference or an external reference. When the supplies are first connected or after the part has been powered down by the PD pin, only a rising edge on the PD pin causes the part to power up. When the part has been powered down using the CONVST pin, a rising edge on either the PD pin or the CONVST pin powers the part up again. As with the AD7829, when using an external reference with the AD7822 or AD7825, the falling edge of CONVST may occur before the required power-up time has elapsed. If this is the case, the conversion is not initiated on the falling edge of CONVST, but rather at the moment when the part has powered up completely, that is, after 1 μs. If the falling edge of CONVST occurs after the required power-up time has elapsed, it is upon this falling edge that a conversion is initiated. When using the on-chip reference, it is necessary to wait the required power-up time of approximately 25 μs before initiating a conversion; that is, a falling edge on CONVST must not occur before the required power-up time has elapsed, when supplies are first connected to the AD7822 or AD7825, or when the ADCs have been powered down using the PD pin or the CONVST pin, as shown in Figure 20. Rev. C | Page 14 of 28 AD7822/AD7825/AD7829 EXTERNAL REFERENCE Figure 22 shows the power vs. throughput rate for automatic full power-down. VDD PD tPOWER-UP 100 tPOWER-UP 1µs 1µs CONVST 10 CONVERSION INITIATED HERE POWER (mW) CONVERSION INITIATED HERE ON-CHIP REFERENCE VDD 1 tPOWER-UP tPOWER-UP 25µs 25µs CONVST CONVERSION INITIATED HERE 01321-020 0 CONVERSION INITIATED HERE 0 50 100 150 200 250 300 350 THROUGHPUT (kSPS) 400 450 500 01321-023 0.1 PD Figure 22. AD7822/AD7825/AD7829 Power vs. Throughput Figure 20. AD7822/AD7825 Power-Up Time 0 POWER VS. THROUGHPUT 2048 POINT FFT SAMPLING 2MSPS fIN = 200kHz –10 Superior power performance can be achieved by using the automatic power-down (Mode 2) at the end of a conversion (see the Operating Modes section). –20 (dB) –30 Figure 21 shows how the automatic power-down is implemented using the CONVST signal to achieve the optimum power performance for the AD7822/AD7825/AD7829. The duration of the CONVST pulse is set to be equal to or less than the power-up time of the devices (see the Operating Modes section). As the throughput rate is reduced, the device remains in its powerdown state longer and the average power consumption over time drops accordingly. –40 –50 –60 FREQUENCY (kHz) 01321-024 –80 0 28 57 85 113 142 170 198 227 255 283 312 340 368 396 425 453 481 510 538 566 595 623 651 680 708 736 765 793 821 850 878 906 935 963 991 –70 Figure 23. AD7822/AD7825/AD7829 SNR tPOWER-UP tCONVERT 1µs 330ns OPERATING MODES POWER-DOWN 01321-022 CONVST tCYCLE 10µs @ 100kSPS Figure 21. Automatic Power-Down For example, if the AD7822 is operated in a continuous sampling mode, with a throughput rate of 100 kSPS and using an external reference, the power consumption is calculated as follows. The power dissipation during normal operation is 36 mW, VDD = 3 V. If the power-up time is 1 μs and the conversion time is 330 ns (@ +25°C), the AD7822 can be said to dissipate 36 mW (maximum) for 1.33 μs during each conversion cycle. If the throughput rate is 100 kSPS, the cycle time is 10 μs and the average power dissipated during each cycle is (1.33/10) × (36 mW) = 4.79 mW. This calculation uses the minimum conversion time, thus giving the best-case power dissipation at this throughput rate. However, the actual power dissipated during each conversion cycle could increase, depending on the actual conversion time (up to a maximum of 420 ns). The AD7822/AD7825/AD7829 have two possible modes of operation, depending on the state of the CONVST pulse approximately 100 ns after the end of a conversion, that is, upon the rising edge of the EOC pulse. Mode 1 Operation (High Speed Sampling) When the AD7822/AD7825/AD7829 are operated in Mode 1, they are not powered down between conversions. This mode of operation allows high throughput rates to be achieved. Figure 24 shows how this optimum throughput rate is achieved by bringing CONVST high before the end of a conversion, that is, before the EOC pulses low. When operating in this mode, a new conversion should not be initiated until 30 ns after the end of a read operation. This allows the track-and-hold to acquire the analog signal to 0.5 LSB accuracy. Rev. C | Page 15 of 28 AD7822/AD7825/AD7829 Mode 2 Operation (Automatic Power-Down) When the AD7822/AD7825/AD7829 are operated in Mode 2 (see Figure 25), they automatically power down at the end of a conversion. The CONVST signal is brought low to initiate a conversion and is left logic low until after the EOC goes high, that is, approximately 100 ns after the end of the conversion. The state of the CONVST signal is sampled at this point (that is, 530 ns maximum after CONVST falling edge), and the AD7822/ AD7825/AD7829 power down as long as CONVST is low. The ADC is powered up again on the rising edge of the CONVST signal. Superior power performance can be achieved in this mode of operation by powering up the AD7822/AD7825/ AD7829 only to carry out a conversion. The parallel interface of the AD7822/AD7825/AD7829 remains fully operational while the ADCs are powered down. A read may occur while the part is powered down, and, therefore, it does not necessarily need to be placed within the EOC pulse, as shown in Figure 25. 120ns TRACK HOLD TRACK HOLD t2 CONVST t1 EOC CS t3 VALID DATA DB0 TO DB7 01321-025 RD Figure 24. Mode 1 Operation tPOWER-UP POWER DOWN HERE CONVST t1 EOC CS VALID DATA DB0 TO DB7 Figure 25. Mode 2 Operation Rev. C | Page 16 of 28 01321-026 RD AD7822/AD7825/AD7829 PARALLEL INTERFACE The parallel interface of the AD7822/AD7825/AD7829 is eight bits wide. Figure 26 shows a timing diagram illustrating the operational sequence of the AD7822/AD7825/AD7829 parallel interface. The multiplexer address is latched into the AD7822/ AD7825/AD7829 on the falling edge of the RD input. The onchip track-and-hold goes into hold mode on the falling edge of CONVST, and a conversion is also initiated at this point. When the conversion is complete, the end of conversion line (EOC) pulses low to indicate that new data is available in the output register of the AD7822/AD7825/AD7829. The EOC pulse stays logic low for a maximum time of 110 ns. However, the EOC pulse can be reset high by a rising edge of RD. This EOC line can be used to drive an edge-triggered interrupt of a microprocessor. CS and RD going low accesses the 8-bit conversion result. It is possible to tie CS permanently low and use only RD to access the data. In systems where the part is interfaced to a gate array or ASIC, this EOC pulse can be applied to the CS and RD inputs to latch data out of the AD7822/ AD7825/AD7829 and into the gate array or ASIC. This means that the gate array or ASIC does not need any conversion status recognition logic, and it also eliminates the logic required in the gate array or ASIC to generate the read signal for the AD7822/ AD7825/AD7829. t2 CONVST t1 t4 EOC t5 CS t7 t6 t8 RD t3 t9 VALID DATA t11 t12 t13 NEXT CHANNEL ADDRESS Figure 26. AD7822/AD7825/AD7829 Parallel Port Timing Rev. C | Page 17 of 28 01321-027 DB0 TO DB7 A0 TO A2 t10 AD7822/AD7825/AD7829 MICROPROCESSOR INTERFACING PIC16C6x/7x1 DB0 TO DB7 PSP0 TO PSP7 1ADDITIONAL CS CS RD RD INT EOC PINS OMITTED FOR CLARITY. Figure 28. Interfacing to the PIC16C6x/ PIC16C7x AD7822/AD7825/AD7829 TO ADSP-21xx Figure 29 shows a parallel interface between the AD7822/ AD7825/AD7829 and the ADSP-21xx series of DSPs. As before, the EOC signal on the AD7822/AD7825/AD7829 provides an interrupt request to the DSP when a conversion ends. ADSP-21xx1 D7 TO D0 80511 LATCH DMS CS ALE A8 TO A15 RD EOC 1ADDITIONAL 01321-028 1ADDITIONAL RD INT AD7822/ AD7825/ AD78291 ADDRESS DECODE LOGIC AD7822/ AD7825/ AD78291 DECODER DB0 TO DB7 A13 TO A0 DB0 TO DB7 AD0 TO AD7 01321-029 AD7822/AD7825/AD7829 TO 8051 Figure 27 shows a parallel interface between the AD7822/AD7825/ AD7829 and the 8051 microcontroller. The EOCsignal on the AD7822/AD7825/AD7829 provides an interrupt request to the 8051 when a conversion ends and data is ready. Port 0 of the 8051 can serve as an input or output port; or, as in this case when used together with the address latch enable (ALE) of the 8051, can be used as a bidirectional low order address and data bus. The ALE output of the 8051 is used to latch the low byte of the address during accesses to the device, while the high order address byte is supplied from Port 2. Port 2 latches remain stable when the AD7822/AD7825/ AD7829 are addressed because they do not have to be turned around (set to 1) for data input, as is the case for Port 0. AD7822/ AD7825/ AD78291 PINS OMITTED FOR CLARITY. Figure 27. Interfacing to the 8051 AD7822/AD7825/AD7829 TO PIC16C6x/PIC16C7x Figure 28 shows a parallel interface between the AD7822/ AD7825/AD7829 and the PIC16C64/PIC16C65/PIC16C74. The EOC signal on the AD7822/AD7825/AD7829 provides an interrupt request to the microcontroller when a conversion begins. Of the PIC16C6x/PIC16C7x range of microcontrollers, only the PIC16C64/PIC16C65/PIC16C74 can provide the option of a parallel slave port. Port D of the microcontroller operates as an 8-bit wide parallel slave port when Control Bit PSPMODE in the TRISE register is set. Setting PSPMODE enables Port Pin RE0 to be the RD output and RE2 to be the CS (chip select) output. For this functionality, the corresponding data direction bits of the TRISE register must be configured as outputs (reset to 0). See the PIC16C6x/PIC16C7x microcontroller user manual. EN CS RD RD IRQ EOC PINS OMITTED FOR CLARITY. 01321-030 The parallel port on the AD7822/AD7825/AD7829 allows the ADCs to be interfaced to a range of many different microcontrollers. This section explains how to interface the AD7822/ AD7825/AD7829 with some of the more common microcontroller parallel interface protocols. Figure 29. Interfacing to the ADSP-21xx INTERFACING MULTIPLEXER ADDRESS INPUTS Figure 30 shows a simplified interfacing scheme between the AD7825/AD7829 and any microprocessor or microcontroller, which facilitates easy channel selection on the ADCs. The multiplexer address is latched on the falling edge of the RD signal, as outlined in the Parallel Interface section, allowing the use of the three LSBs of the address bus to select the channel address. As shown in Figure 30, only Address Bit A3 to Address Bit A15 are address decoded, allowing A0 to A2 to be changed according to desired channel selection without affecting chip selection. Rev. C | Page 18 of 28 AD7822/AD7825/AD7829 AD7822 STANDALONE OPERATION The resulting signal can be used as an interrupt request signal (IRQ) on a DSP, as a WR signal to memory, or as a CLK to a latch or ASIC. The timing for this interface, as shown in Figure 31, demonstrates how, with the CONVST signal alone, a conversion can be initiated, data is latched out, and the operating mode of the AD7822 can be selected. The AD7822, being the single channel device, does not have any multiplexer addressing associated with it and can be controlled with just one signal, that is, the CONVST signal. As shown in Figure 31, the RD and CS pins are both tied to the EOC pin. SYSTEM BUS MICROPROCESSOR READ CYCLE A0 A1 A2 A15 TO A3 ADDRESS DECODE CS CS AD7825/ AD7829 RD ADC I/O ADDRESS A15 TO A3 RD A2 TO A0 MUX ADDRESS DB7 TO DB0 MUX ADDRESS (CHANNEL SELECTION A0 TO A2) LATCHED 01321-031 A/D RESULT DB0 TO DB7 Figure 30. AD7825/AD7829 Simplified Microinterfacing Scheme t1 RD AD7822 CS EOC DB7 TO DB0 DSP/ LATCH/ASIC CONVST t4 EOC CS RD DB0 TO DB7 Figure 31. AD7822 Standalone Operation Rev. C | Page 19 of 28 A/D RESULT 01321-032 CONVST AD7822/AD7825/AD7829 OUTLINE DIMENSIONS 1.060 (26.92) 1.030 (26.16) 0.980 (24.89) 20 11 1 10 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) PIN 1 0.100 (2.54) BSC 0.060 (1.52) MAX 0.210 (5.33) MAX 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) MIN 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) GAUGE PLANE SEATING PLANE 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.430 (10.92) MAX 0.005 (0.13) MIN 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) 0.070 (1.78) 0.060 (1.52) 0.045 (1.14) COMPLIANT TO JEDEC STANDARDS MS-001-AD CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 32. 20-Lead Plastic Dual In-Line Package [PDIP] Narrow Body (N-20) Dimensions shown in inches and (millimeters) 13.00 (0.5118) 12.60 (0.4961) 20 11 7.60 (0.2992) 7.40 (0.2913) 10 2.65 (0.1043) 2.35 (0.0925) 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10 10.65 (0.4193) 10.00 (0.3937) 1.27 (0.0500) BSC 0.51 (0.0201) 0.31 (0.0122) SEATING PLANE 0.75 (0.0295) 0.25 (0.0098) 8° 0° 0.33 (0.0130) 0.20 (0.0079) COMPLIANT TO JEDEC STANDARDS MS-013-AC 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 33. 20-Lead Standard Small Outline Package [SOIC_W] Wide Body (RW-20) Dimensions shown in millimeters and (inches) Rev. C | Page 20 of 28 45° 1.27 (0.0500) 0.40 (0.0157) 060706-A 1 AD7822/AD7825/AD7829 6.60 6.50 6.40 20 11 4.50 4.40 4.30 6.40 BSC 1 10 PIN 1 0.65 BSC 1.20 MAX 0.15 0.05 COPLANARITY 0.10 0.30 0.19 0.20 0.09 0.75 0.60 0.45 8° 0° SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-153-AC Figure 34. 20-Lead Thin Shrink Small Outline Package [TSSOP] (RU-20) Dimensions shown in millimeters 1.280 (32.51) 1.250 (31.75) 1.230 (31.24) 24 13 1 12 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) PIN 1 0.100 (2.54) BSC 0.210 (5.33) MAX 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) MIN 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.060 (1.52) MAX 0.015 (0.38) GAUGE PLANE SEATING PLANE 0.005 (0.13) MIN 0.430 (10.92) MAX 0.070 (1.78) 0.060 (1.52) 0.045 (1.14) COMPLIANT TO JEDEC STANDARDS MS-001-AF CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 35. 24-Lead Plastic Dual In-Line Package [PDIP] Narrow Body (N-24-1) Dimensions shown in inches and (millimeters) Rev. C | Page 21 of 28 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) AD7822/AD7825/AD7829 15.60 (0.6142) 15.20 (0.5984) 13 24 7.60 (0.2992) 7.40 (0.2913) 10.65 (0.4193) 10.00 (0.3937) 12 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10 0.75 (0.0295) 0.25 (0.0098) 2.65 (0.1043) 2.35 (0.0925) 1.27 (0.0500) BSC SEATING PLANE 0.51 (0.0201) 0.31 (0.0122) 8° 0° 1.27 (0.0500) 0.40 (0.0157) 0.33 (0.0130) 0.20 (0.0079) 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 36. 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 0.15 0.05 0.30 0.19 0.10 COPLANARITY 1.20 MAX SEATING PLANE 0.20 0.09 8° 0° 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MO-153-AD Figure 37. 24-Lead Thin Shrink Small Outline Package [TSSOP] (RU-24) Dimensions shown in millimeters Rev. C | Page 22 of 28 45° 060706-A 1 AD7822/AD7825/AD7829 1.565 (39.75) 1.380 (35.05) 28 15 0.580 (14.73) 0.485 (12.31) 1 14 0.625 (15.88) 0.600 (15.24) PIN 1 0.100 (2.54) BSC 0.250 (6.35) MAX 0.195 (4.95) 0.125 (3.17) 0.015 (0.38) GAUGE PLANE 0.015 (0.38) MIN 0.200 (5.08) 0.115 (2.92) SEATING PLANE 0.022 (0.56) 0.014 (0.36) 0.700 (17.78) MAX 0.005 (0.13) MIN 0.015 (0.38) 0.008 (0.20) 0.070 (1.78) 0.030 (0.76) COMPLIANT TO JEDEC STANDARDS MS-011-AB CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 38. 28-Lead Plastic Dual In-Line Package [PDIP] Wide Body (N-28-2) Dimensions shown in inches and (millimeters) 18.10 (0.7126) 17.70 (0.6969) 15 28 7.60 (0.2992) 7.40 (0.2913) 14 2.65 (0.1043) 2.35 (0.0925) 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10 10.65 (0.4193) 10.00 (0.3937) 1.27 (0.0500) BSC 0.51 (0.0201) 0.31 (0.0122) SEATING PLANE 0.75 (0.0295) 0.25 (0.0098) 8° 0° 0.33 (0.0130) 0.20 (0.0079) COMPLIANT TO JEDEC STANDARDS MS-013-AE 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 39. 28-Lead Standard Small Outline Package [SOIC_W] Wide Body (RW-28) Dimensions shown in millimeters and (inches) Rev. C | Page 23 of 28 45° 1.27 (0.0500) 0.40 (0.0157) 060706-A 1 AD7822/AD7825/AD7829 9.80 9.70 9.60 28 15 4.50 4.40 4.30 1 6.40 BSC 14 PIN 1 0.65 BSC 0.15 0.05 COPLANARITY 0.10 0.30 0.19 1.20 MAX SEATING PLANE 0.20 0.09 8° 0° 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MO-153-AE Figure 40. 28-Lead Thin Shrink Small Outline Package [TSSOP] (RU-28) Dimensions shown in millimeters Rev. C | Page 24 of 28 AD7822/AD7825/AD7829 ORDERING GUIDE Model AD7822BN AD7822BNZ 1 AD7822BR AD7822BR-REEL AD7822BR-REEL7 AD7822BRZ1 AD7822BRZ-REEL1 AD7822BRZ-REEL71 AD7822BRU AD7822BRU-REEL AD7822BRU-REEL7 AD7822BRUZ1 AD7822BRUZ-REEL1 AD7822BRUZ-REEL71 AD7825BN AD7825BNZ1 AD7825BR AD7825BR-REEL AD7825BR-REEL7 AD7825BRZ1 AD7825BRZ-REEL1 AD7825BRZ-REEL71 AD7825BRU AD7825BRU-REEL AD7825BRU-REEL7 AD7825BRUZ1 AD7825BRUZ-REEL1 AD7825BRUZ-REEL71 AD7829BN AD7829BNZ1 AD7829BR AD7829BR-REEL AD7829BR-REEL7 AD7829BRZ1 AD7829BRZ-REEL1 AD7829BRZ-REEL71 AD7829BRU AD7829BRU-REEL AD7829BRU-REEL7 AD7829BRUZ1 AD7829BRUZ-REEL1 AD7829BRUZ-REEL71 1 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 −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 Package Description 20-Lead PDIP 20-Lead PDIP 20-Lead SOIC_W 20-Lead SOIC_W 20-Lead SOIC_W 20-Lead SOIC_W 20-Lead SOIC_W 20-Lead SOIC_W 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 20-Lead TSSOP 24-Lead PDIP 24-Lead PDIP 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 28-Lead PDIP 28-Lead PDIP 28-Lead SOIC_W 28-Lead SOIC_W 28-Lead SOIC_W 28-Lead SOIC_W 28-Lead SOIC_W 28-Lead SOIC_W 28-Lead TSSOP 28-Lead TSSOP 28-Lead TSSOP 28-Lead TSSOP 28-Lead TSSOP 28-Lead TSSOP Z = Pb-free part. Rev. C | Page 25 of 28 Package Option N-20 N-20 RW-20 RW-20 RW-20 RW-20 RW-20 RW-20 RU-20 RU-20 RU-20 RU-20 RU-20 RU-20 N-24-1 N-24-1 RW-24 RW-24 RW-24 RW-24 RW-24 RW-24 RU-24 RU-24 RU-24 RU-24 RU-24 RU-24 N-28-2 N-28-2 RW-28 RW-28 RW-28 RW-28 RW-28 RW-28 RU-28 RU-28 RU-28 RU-28 RU-28 RU-28 Linearity Error ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB ±0.75 LSB AD7822/AD7825/AD7829 NOTES Rev. C | Page 26 of 28 AD7822/AD7825/AD7829 NOTES Rev. C | Page 27 of 28 AD7822/AD7825/AD7829 NOTES ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C01321-0-8/06(C) Rev. C | Page 28 of 28