1. Device Overview & Purpose

️· What it is: The DS1021 is a precision silicon delay line. It's a digitally programmable delay element, meaning it provides a very accurate and controllable delay for electronic signals.
️· Primary Use: It's used for synchronizing signals in digital systems, precise timing control, pulse stretching, and similar applications where an exact and reproducible delay is needed.
️· Key Features:
- Digitally Programmable: Delay is controlled by digital inputs.
- High Accuracy: Provides highly accurate and repeatable delay times.
- Low Jitter: Jitter refers to variation in the delay, and this device minimizes it.
- Dual Functionality: Supports both parallel (latchable) and serial (clock-based) modes.

2. Specifications & Electrical Characteristics

️· Supply Voltage (VCC): 4.75V to 5.25V.
️· Operating Temperature: 0°C to 70°C.
️· Absolute Maximum Ratings: Define voltage limits, temperature range, and other stress conditions to avoid permanent damage.
️· DC Electrical Characteristics: Outline input voltage levels (VIH, VIL), leakage current, supply current, and output current limits.
️· AC Electrical Characteristics: This is the most important section for understanding timing:
- Clock Frequency (fC): Up to 10 MHz in serial mode.
- Delay Accuracy: Detailed in Table 2, specifying delay times for specific program settings. Accuracy is defined based on rising and falling edge measurements.
- Timing Diagrams: Figures 5-8 show detailed timing for parallel (latch and non-latch) and serial modes, defining setup and hold times for data and clock signals.
- tPLH/tPHL: These are key parameters - they are the delay times themselves (rising and falling edges), determined by the program settings. Refer to Table 2 for specific values.

3. Operating Modes

️· Parallel Mode (S = 1):
- Allows direct programming of the delay using parallel inputs.
- Can operate in two ways:
■ Non-Latched: The delay occurs immediately when the inputs change.
■ Latched: The delay is triggered by the enable signal (E).
️· Serial Mode (S = 0):
- Uses a clock signal to control the delay. The delay is synchronized with the clock.
- Requires careful consideration of setup and hold times for data and clock signals.

4. Key Timing Parameters (Serial Mode)

️· tDSC (Data Setup to Clock): Minimum time data must be stable *before* the clock edge arrives.
️· tDHC (Data Hold from Clock): Minimum time data must remain stable *after* the clock edge.
️· tEQV (Enable to Serial Output Valid): Time between enable signal becoming active and the serial output becoming valid.
️· tEQZ (Enable to Serial Output High Z): Time between when the enable is inactive, and output goes into a high impedance state.

5. Important Considerations

️· Load: The DS1021 is primarily designed to drive other DS1021s.
️· Power-Up Sequence: Requires a specific power-up sequence (tPU) to ensure proper operation.
️· Capacitance: Limited input capacitance.
️· Temperature Dependence: Delay times can be affected by temperature changes.
️· Input Rise/Fall Times: Fast input rise/fall times are important for predictable delay.

6. Test Conditions

️· Ambient Temperature: 25°C ± 3°C
️· Supply Voltage (VCC): 5.0V ± 0.1V
️· Specific input voltage and impedance levels defined.
️· Measurements made with a time interval counter.