Datasheet AD7908, AD7918, AD7928 (Analog Devices) - 9

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Data Sheet AD7908/AD7918/AD7928 TIMING SPECIFICATIONS
AVDD = 2.7 V to 5.25 V, VDRIVE ≤ AVDD, REFIN = 2.5 V, TA = TMIN to TMAX, unless otherwise noted.1
Table 4. Limit at TMIN, TMAX AD7908/ AD7918/ AD7928 Parameter AVDD = 3 V AVDD = 5 V Unit Description
f 2 SCLK 10 10 kHz min 20 20 MHz max tCONVERT 16 × tSCLK 16 × tSCLK tQUIET 50 50 ns min Minimum quiet time required between CS rising edge and start of next conversion t2 10 10 ns min CS to SCLK setup time t 3 3 35 30 ns max Delay from CS until DOUT three-state disabled t 3 4 40 40 ns max Data access time after SCLK falling edge t5 0.4 × tSCLK 0.4 × tSCLK ns min SCLK low pulse width t6 0.4 × tSCLK 0.4 × tSCLK ns min SCLK high pulse width t7 10 10 ns min SCLK to DOUT valid hold time t 4 8 15/45 15/35 ns min/max SCLK falling edge to DOUT high impedance t9 10 10 ns min DIN setup time prior to SCLK falling edge t10 5 5 ns min DIN hold time after SCLK falling edge t11 20 20 ns min 16th SCLK falling edge to CS high t12 1 1 μs max Power-up time from full power-down/auto shutdown mode 1 Sample tested at 25°C to ensure compliance. All input signals are specified with tr = tf = 5 ns (10% to 90% of AVDD) and timed from a voltage level of 1.6 V. See Figure 2. The 3 V operating range spans from 2.7 V to 3.6 V. The 5 V operating range spans from 4.75 V to 5.25 V. 2 Mark/space ratio for the SCLK input is 40/60 to 60/40. 3 Measured with the load circuit of Figure 2 and defined as the time required for the output to cross 0.4 V or 0.7 × VDRIVE. 4 t8 is 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, t8, quoted in the timing characteristics is the true bus relinquish time of the part and is independent of the bus loading.
I 200µA OL TO OUTPUT 1.6V PIN CL 50pF
002
200µA IOH
03089- Figure 2. Load Circuit for Digital Output Timing Specifications Rev. E | Page 9 of 28 Document Outline Features General Description Functional Block Diagram Product Highlights Revision History Specifications AD7908 Specifications AD7918 Specifications AD7928 Specifications Timing Specifications Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Terminology Typical Performance Characteristics Performance Curves 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 Reference Modes of Operation Normal Mode (PM1 = PM0 = 1) Full Shutdown Mode (PM1 = 1, PM0 = 0) Auto Shutdown Mode (PM1 = 0, PM0 = 1) Powering Up the AD7908/AD7918/AD7928 Power vs. Throughput Rate Serial Interface Microprocessor Interfacing AD7908/AD7918/AD7928 to TMS320C541 AD7908/AD7918/AD7928 to ADSP-21xx AD7908/AD7918/AD7928 to DSP563xx Application Hints Grounding and Layout Evaluating the AD7908/AD7918/AD7928 Performance Outline Dimensions Ordering Guide Automotive Products