Datasheet AD7912, AD7922 (Analog Devices)

2-Channel, 2.35 V to 5.25 V, 1 MSPS, 10-/12-Bit ADCs AD7912/AD7922 FEATURES FUNCTIONAL BLOCK DIAGRAM VDD Fast throughput rate: 1 MSPS Specified for VDD of 2.35 V to 5.25 V Low power: 4.8 mW typ at 1 MSPS with 3 V supplies VIN0 10-/12-BIT MUX T/H SUCCESSIVE 15.5mW typ at 1 MSPS with 5 V supplies APPROXIMATION VIN1 ADC Wide input bandwidth: 71 dB minimum SNR at 100 kHz input frequency Flexible power/serial clock speed management No pipeline delays SCLK High speed serial interface: CS SPI®/QSPI™/MICROWIRE™/DSP compatible AD7912/AD7922 CONTROL LOGIC DOUT Standby mode: 1 µA maximum DIN Daisy-chain mode 8-lead TSOT package
04351-0-001
GND 8-lead MSOP package
Figure 1.
APPLICATIONS
Several AD7912/AD7922 can be connected together in a daisy
Battery-powered systems:
chain. The AD7912/AD7922 feature a daisy-chain mode that
Personal digital assistants
allows the user to read the conversion results from the ADCs
Medical instruments
contained in the chain. The AD7912/AD7922 use advanced
Mobile communications
design techniques to achieve very low power dissipation at high
Instrumentation and control systems
throughput rates. The reference for the part is taken internally
Data acquisition systems
from VDD, thereby allowing the widest dynamic input range to
High speed modems
the ADC.
Optical sensors PRODUCT HIGHLIGHTS GENERAL DESCRIPTION
1. 2-channel, 1 MSPS, 10-/12-bit ADCs in TSOT package. The AD7912/AD79221 are 10-bit and 12-bit, high speed, low 2. High throughput with low power consumption. power, 2-channel successive approximation ADCs, respectively. 3. Flexible power/serial clock speed management. The parts operate from a single 2.35 V to 5.25 V power supply The conversion rate is determined by the serial clock. The and feature throughput rates of up to 1 MSPS. The parts contain parts also feature a power-down mode to maximize power a low noise, wide bandwidth track-and-hold amplifier, which efficiency at lower throughput rates. Average power can handle input frequencies in excess of 6 MHz. consumption is reduced when the power-down mode is used while not converting. Current consumption is 1 µA The conversion process and data acquisition are controlled maximum and 50 nA typically when in power-down mode. using CS and the serial clock, allowing the devices to interface 4. Daisy-chain mode. with microprocessors or DSPs. The conversion rate is 5. No pipeline delay. determined by the SCLK signal. The input signal is sampled on The parts feature a standard successive approximation ADC the falling edge of CS and the conversion is also initiated at this with accurate control of the sampling instant via a CS input point. The channel to be converted is selected through the DIN and once-off conversion control. pin, and the mode of operation is controlled by CS. The serial data stream from the DOUT pin has a channel identifier bit and mode identifier bit, which provide information about the converted channel and the current mode of operation. 1 Protected by U.S. Patent Number 6,681,332.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS SPECIFICATIONS AD7912 SPECIFICATIONS AD7922 SPECIFICATIONS TIMING SPECIFICATIONS TIMING DIAGRAMS TIMING EXAMPLES Timing Example 1 Timing Example 2 ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TERMINOLOGY TYPICAL PERFORMANCE CHARACTERISTICS CIRCUIT INFORMATION CONVERTER OPERATION ADC TRANSFER FUNCTION TYPICAL CONNECTION DIAGRAM ANALOG INPUT DIGITAL INPUTS DIN INPUT DOUT OUTPUT MODES OF OPERATION NORMAL MODE POWER-DOWN MODE POWER-UP TIME DAISY-CHAIN MODE DAISY-CHAIN EXAMPLE POWER VS. THROUGHPUT RATE SERIAL INTERFACE MICROPROCESSOR INTERFACING AD7912/AD7922 to TMS320C541 Interface AD7912/AD7922 to ADSP-218x AD7912/AD7922 to DSP563xx Interface APPLICATION HINTS GROUNDING AND LAYOUT EVALUATING AD7912/AD7922 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE