Datasheet AD7933, AD7934 (Analog Devices)

4-Channel, 1.5 MSPS, 10-Bit and 12-Bit Parallel ADCs with a Sequencer AD7933/AD7934 FEATURES FUNCTIONAL BLOCK DIAGRAM Throughput rate: 1.5 MSPS VDD AGND Specified for VDD of 2.7 V to 5.25 V AD7933/AD7934 Low power VREFIN/ VREFOUT 6 mW maximum at 1.5 MSPS with 3 V supplies 2.5V VREF 13.5 mW maximum at 1.5 MSPS with 5 V supplies VIN0 CLKIN 4 analog input channels with a sequencer 12-/10-BIT I/P SAR ADC T/H CONVST Software configurable analog inputs MUX AND CONTROL BUSY 4-channel single-ended inputs VIN3 2-channel fully differential inputs 2-channel pseudo differential inputs SEQUENCER Accurate on-chip 2.5 V reference ±0.2% maximum @ 25°C, 25 ppm/°C maximum (AD7934) PARALLEL INTERFACE/CONTROL REGISTER V 70 dB SINAD at 50 kHz input frequency DRIVE No pipeline delays High speed parallel interface—word/byte modes
01 0 3-
Full shutdown mode: 2 μA maximum
71
DB0 DB11 CS RD WR W/B DGND
03
28-lead TSSOP package
Figure 1.
GENERAL DESCRIPTION
The AD7933/AD7934 are 10-bit and 12-bit, high speed, low These parts use advanced design techniques to achieve very low power, successive approximation (SAR) analog-to-digital power dissipation at high throughput rates. They also feature converters (ADCs). The parts operate from a single 2.7 V to flexible power management options. An on-chip control 5.25 V power supply and feature throughput rates up to 1.5 MSPS. register allows the user to set up different operating conditions, The parts contain a low noise, wide bandwidth, differential track- including analog input range and configuration, output coding, and-hold amplifier that handles input frequencies up to 50 MHz. power management, and channel sequencing. The AD7933/AD7934 feature four analog input channels with a
PRODUCT HIGHLIGHTS
channel sequencer that allows a preprogrammed selection of 1. High throughput with low power consumption. channels to be sequentially converted. These parts can accept 2. Four analog inputs with a channel sequencer. either single-ended, fully differential, or pseudo differential 3. Accurate on-chip 2.5 V reference. analog inputs. 4. Single-ended, pseudo differential or fully differential The conversion process and data acquisition are controlled analog inputs that are software selectable. using standard control inputs that allow for easy interfacing to 5. Single-supply operation with VDRIVE function. microprocessors and DSPs. The input signal is sampled on the The VDRIVE function allows the parallel interface to connect directly to 3 V or 5 V processor systems independent of V falling edge of CONVST, and the conversion is also initiated at DD. 6. No pipeline delay. this point. 7. Accurate control of the sampling instant via a CONVST The AD7933/AD7934 has an accurate on-chip 2.5 V reference input and once-off conversion control. that is used as the reference source for the analog-to-digital conversion. Alternatively, this pin can be overdriven to provide
Table 1. Related Devices
an external reference.
Device No. of Bits No. of Channels Speed
AD7938/AD7939 12/10 8 1.5 MSPS AD7938-6 12 8 625 kSPS AD7934-6 12 4 625 kSPS
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Document Outline FEATURES FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS AD7933 SPECIFICATIONS AD7934 SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY CONTROL REGISTER SEQUENCER OPERATION Writing to the Control Register to Program the Sequencer CIRCUIT INFORMATION CONVERTER OPERATION ADC TRANSFER FUNCTION TYPICAL CONNECTION DIAGRAM ANALOG INPUT STRUCTURE ANALOG INPUTS Single-Ended Mode Differential Mode Driving Differential Inputs Using an Op Amp Pair Pseudo Differential Mode ANALOG INPUT SELECTION Traditional Multichannel Operation (SEQ0 = SEQ1 = 0) Using the Sequencer: Consecutive Sequence (SEQ0 = 1, SEQ1 = 1) REFERENCE Digital Inputs VDRIVE Input PARALLEL INTERFACE Reading Data from the AD7933/AD7934 Writing Data to the AD7933/AD7934 POWER MODES OF OPERATION Normal Mode (PM1 = PM0 = 0) Autoshutdown (PM1 = 0; PM0 = 1) Autostandby (PM1 = 1; PM0 = 0) Full Shutdown Mode (PM1 = 1; PM0 = 1) POWER vs. THROUGHPUT RATE MICROPROCESSOR INTERFACING AD7933/AD7934 to ADSP-21xx Interface AD7933/AD7934 to ADSP-21065L Interface AD7933/AD7934 to TMS32020, TMS320C25, and TMS320C5x Interface AD7933/AD7934 to 80C186 Interface APPLICATION HINTS GROUNDING AND LAYOUT EVALUATING THE AD7933/AD7934 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE