Datasheet AD7927 (Analog Devices)

8-Channel, 200 kSPS, 12-Bit ADC with Sequencer in 20-Lead TSSOP Data Sheet AD7927 FEATURES FUNCTIONAL BLOCK DIAGRAM Fast throughput rate: 200 kSPS AVDD Specified for AVDD of 2.7 V to 5.25 V REFIN Low power 3.6 mW maximum at 200 kSPS with 3 V supply VIN0 12-BIT SUCCESSIVE 7.5 mW maximum at 200 kSPS with 5 V supply T/H APPROXIMATION 8 (single-ended) inputs with sequencer INPUT ADC MUX Wide input bandwidth 70 dB minimum SINAD at 50 kHz input frequency Flexible power/serial clock speed management No pipeline delays VIN7 SCLK High speed serial interface SPI-, QSPI™-, MICROWIRE™-, DOUT DSP-compatible SEQUENCER CONTROL LOGIC DIN Shutdown mode: 0.5 μA maximum CS 20-lead TSSOP AD7927 Qualified for automotive applications VDRIVE
0108- 08
AGND GENERAL DESCRIPTION
03 Figure 1. The AD7927 is a 12-bit, high speed, low power, 8-channel,
PRODUCT HIGHLIGHTS
successive approximation ADC. The part operates from a single 2.7 V to 5.25 V power supply and features throughput 1. High Throughput with Low Power Consumption. rates up to 200 kSPS. The part contains a low noise, wide The AD7927 offers up to 200 kSPS throughput rates. At the bandwidth track-and-hold amplifier that can handle input maximum throughput rate with 3 V supplies, the AD7927 frequencies in excess of 8 MHz. dissipates 3.6 mW of power maximum. The conversion process and data acquisition are controlled using 2. Eight Single-Ended Inputs with a Channel Sequencer. CS and the serial clock signal, allowing the device to easily interface A consecutive sequence of channels can be selected on with microprocessors or DSPs. The input signal is sampled on the which the ADC cycles and converts. falling edge of CS and the conversion is also initiated at this 3. Single-Supply Operation with VDRIVE Function. point. There are no pipeline delays associated with the part. The AD7927 operates from a single 2.7 V to 5.25 V supply. The AD7927 uses advanced design techniques to achieve The VDRIVE function allows the serial interface to connect very low power dissipation at maximum throughput rates. At directly to either 3 V or 5 V processor systems independent maximum throughput rates, the AD7927 consumes 1.2 mA of AVDD. maximum with 3 V supplies; with 5 V supplies, the current 4. Flexible Power/Serial Clock Speed Management. consumption is 1.5 mA maximum. The conversion rate is determined by the serial clock, Through the configuration of the control register, the analog allowing the conversion time to be reduced through the input range for the part can be selected as 0 V to REF serial clock speed increase. The part also features various IN or 0 V to 2 × REF shutdown modes to maximize power efficiency at lower IN, with either straight binary or twos complement output coding. The AD7927 features eight single-ended analog throughput rates. Current consumption is 0.5 μA maxi- inputs with a channel sequencer to allow a preprogrammed mum when in full shutdown. selection of channels to be converted sequentially. 5. No Pipeline Delay. The conversion time for the AD7927 is determined by the The part features a standard successive approximation ADC SCLK frequency, as this is also used as the master clock to with a CS input pin, which allows for accurate control of control the conversion. The conversion time may be as short each sampling instant. as 800 ns with a 20 MHz SCLK.
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Document Outline Features General Description Functional Block Diagram Product Highlights Revision History Specifications Timing Specifications Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Terminology Typical Performance Characteristics Control Register Sequencer Operation Shadow Register Circuit Information Converter Operation Analog Input ADC Transfer Function Handling Bipolar Input Signals Typical Connection Diagram Analog Input Selection Digital Inputs VDRIVE The Reference Modes of Operation Normal Mode (PM1 = PM0 = 1) Full Shutdown (PM1 = 1, PM0 = 0) Auto Shutdown (PM1 = 0, PM0 = 1) Powering Up the AD7927 Power vs. Throughput Rate Serial Interface Writing Between Conversions Microprocessor Interfacing AD7927 to TMS320C541 AD7927 to ADSP-21xx AD7927 to DSP563xx Application Hints Grounding and Layout Outline Dimensions Ordering Guide Automotive Products