3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs AD7822/AD7825/AD7829 FEATURES FUNCTIONAL BLOCK DIAGRAM V 1 1 2 3 8-bit half-flash ADC with 420 ns conversion time DD CONVST EOC A0 A1 A2 PD One, four, and eight single-ended analog input channels Available with input offset adjust CONTROL COMP LOGIC 2.5V On-chip track-and-hold REF SNR performance given for input frequencies up to 10 MHz V IN1 On-chip reference (2.5 V) 4 BUF V V REF IN/OUT IN2 4 Automatic power-down at the end of conversion V IN3 8-BIT 4 INPUT V HALF IN4 Wide operating supply range T/H MUX 5 V FLASH IN5 3 V 10% and 5 V 10% 5 ADC DB7 V PARALLEL IN6 5 PORT DB0 V IN7 Input ranges 5 V IN8 0 V to 2 V p-p, VDD = 3 V 10% 0 V to 2.5 V p-p, V = 5 V 10% V DD MID AGND DGND CS RD EOC Flexible parallel interface with pulse to allow 1 A0, A1 AD7825/AD7829 2 A2 AD7829 standalone operation 3 PD AD7822/AD7825 4 V TO V AD7825/AD7829 IN2 IN4 APPLICATIONS 5 V TO V AD7829 IN5 IN8 Data acquisition systems, DSP front ends Figure 1. Disk drives Mobile communication systems, subsampling applications GENERAL DESCRIPTION The AD7822 and AD7825 are available in 20-lead and 24-lead, The AD7822/AD7825/AD7829 are high speed, 1-, 4-, and 0.3 wide, plastic dual in-line packages (PDIP) 20-lead and 8-channel, microprocessor-compatible, 8-bit analog-to-digital 24-lead standard small outline packages (SOIC) and 20-lead converters with a maximum throughput of 2 MSPS. The AD7822/ and 24-lead thin shrink small outline packages (TSSOP). The AD7825/AD7829 contain an on-chip reference of 2.5 V AD7829 is available in a 28-lead, 0.6 wide PDIP a 28-lead (2% tolerance) a track-and-hold amplifier a 420 ns, 8-bit half- SOIC and a 28-lead TSSOP. flash ADC and a high speed parallel interface. The converters can operate from a single 3 V 10% and 5 V 10% supply. PRODUCT HIGHLIGHTS The AD7822/AD7825/AD7829 combine the convert start and 1. Fast Conversion Time. The AD7822/AD7825/AD7829 have a conversion time of 420 ns. Faster conversion times power-down functions at one pin, that is, the CONVST pin. maximize the DSP processing time in a real-time system. This allows a unique automatic power-down at the end of a conversion to be implemented. The logic level on the CONVST 2. Analog Input Span Adjustment. The VMID pin allows the pin is sampled after the end of a conversion when an EOC (end user to offset the input span. This feature can reduce the of conversion) signal goes high. If it is logic low at that point, requirements of single-supply op amps and take into the ADC is powered down. The AD7822 and AD7825 also have account any system offsets. a separate power-down pin (see the Operating Modes section). 3. FPBW (Full Power Bandwidth) of Track-and-Hold. The track-and-hold amplifier has an excellent high The parallel interface is designed to allow easy interfacing to frequency performance. The AD7822/AD7825/AD7829 microprocessors and DSPs. Using only address decoding logic, are capable of converting full-scale input signals up to a the parts are easily mapped into the microprocessor address frequency of 10 MHz. This makes the parts ideally suited space. The EOC pulse allows the ADCs to be used in a stand- to subsampling applications. alone manner (see the Parallel Interface section.) 4. Channel Selection. Channel selection is made without the necessity of writing to the part. 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 01321-001AD7822/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 Changes to Typical Connection Diagram Section........................7 8/06Rev. B to Rev. C Changes to Analog Input Section....................................................8 Changes to General Description .................................................... 1 Changes to Analog Input Selection Section...................................9 Changes to Table 1............................................................................ 3 Changes to Power-Up Times Section .......................................... 10 Changes to Typical Connection Diagram Section..................... 10 Changes to Power vs. Throughput Section................................. 11 Updated Outline Dimensions ....................................................... 20 Added AD7822 Stand-Alone Operation section ....................... 15 Changes to Ordering Guide .......................................................... 25 12/99Rev. 0 to Rev. A 10/01Rev. A to Rev. B Changes to Power Requirements.................................................... 3 Changes to Pin Function Description ........................................... 5 Changes to Circuit Description ...................................................... 7 Rev. C Page 2 of 28