Analog Devices Inc./Maxim Integrated DS1020S-25

Overview

DS1020S-25 from Dallas Semiconductor (now Maxim Integrated) is a programmable 8-bit silicon delay line IC with 0.25 ns incremental delay steps, 10 ± 2 ns inherent delay, 73.75 ns maximum delay, TTL/CMOS-compatible I/O, and dual programming interfaces (3-wire serial or 8-bit parallel). It delivers precise edge-aligned timing in high-speed digital test and synchronization circuits.

For engineers reviewing the DS1020S-25 datasheet, DS1025S-25 pinout, DS1020S-25 application, or DS1020S-25 equivalent, this page provides verified pin functions, real-world delay accuracy data, settling time requirements, daisy-chain capability, and validated alternatives for timing-critical PCB designs.

Technical Context

The DS1020S-25 implements an all-CMOS, user-programmable 8-bit delay register with two independent configuration modes: parallel (S=1) using P0–P7 pins, and serial (S=0) via C/D/Q signals. Delay resolution is fixed at 0.25 ns per LSB across its 256-step range.

It features rising- and falling-edge accuracy within ±6 ns total deviation, supports daisy-chained serial programming of multiple units, and requires 50 µs settling time (tEDV/tPDV) after any delay change before output timing stabilizes to specification.

Key Specifications

Pinout & Package

DS1020S-25 is packaged in a 16-pin SOIC (300-mil width), surface-mountable and vapor-phase solder compatible. Pin numbering follows standard SOIC convention with Pin 1 at top-left corner (notch or dot indicator).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar programmable delay line applications.

Compared with DS1020S-25, the DS1020-25 offers identical timing functionality in a through-hole package-ideal for lab validation-while the MAX9622 trades digital programmability for analog tunability and lower supply voltage, limiting use to non-reconfigurable analog timing loops.

Availability

DS1020S-25 is available at Aetrix Electronics and suitable for test equipment calibration, digital signal deskew, programmable pulse generation, and logic glitch suppression requiring stable component supply and long-term obsolescence management.

Supply support for DS1020S-25 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Dallas Semiconductor, acquired by Maxim Integrated in 2001, specialized in precision timing, memory, and mixed-signal ICs for instrumentation and industrial applications.

The DS1020 family was designed to replace hybrid delay lines with all-silicon reliability and programmability-targeting ATE, communications infrastructure, and high-speed digital system integration.

FAQ

What is the inherent delay of the DS1020S-25, and does it vary with temperature?

The DS1020S-25 has a specified inherent (step-zero) delay of 10 ± 2 ns at 25°C and VCC = 5.0 V. This baseline delay remains stable across the full operating temperature range (0°C to +70°C), as confirmed by characterization data in the official datasheet. The ±2 ns tolerance accounts for unit-to-unit variation but does not include additional thermal drift beyond the stated spec. DS1020S-25 maintains consistent offset behavior under thermal stress, making it suitable for environments where ambient shifts occur.

Can the DS1020S-25 be used in daisy-chain configuration, and what is required to implement it?

Yes, the DS1020S-25 supports daisy-chained serial programming: connect the Q (serial output) of one device to the D (serial input) of the next, with shared C (clock) and E (enable) lines. Each device receives its 8-bit delay value in MSB-first order, requiring 8 × N clock cycles for N devices. A 1 kΩ–10 kΩ pull-up resistor must be placed between Q of the last device and D of the first to enable automatic restoration during readback. DS1020S-25's Q pin is designed explicitly for this topology and drives only other DS1020-series inputs.

Does the DS1020S-25 invert the input signal at the output?

No, the DS1020S-25 provides non-inverting delay functionality: the output reproduces the exact logic state of the input after the programmed delay interval, with no polarity reversal. This behavior is explicitly documented in the device description and functional block diagram. DS1020S-25 is therefore appropriate for applications requiring faithful signal replication-including clock forwarding, data retiming, and synchronous logic interfacing-without introducing unintended inversion that would require downstream correction.

What is the minimum pulse width the DS1020S-25 can reliably delay?

The DS1020S-25 requires input pulse width ≥100% of the programmed delay value, per datasheet specification (tWI ≥ programmed delay). For the DS1020S-25's minimum delay step (0.25 ns), the absolute shortest usable pulse is ~0.25 ns-but practical operation demands compliance with test conditions: 500 ns pulse width is specified for DS1020S-25 in characterization. DS1020S-25 achieves reliable delay fidelity only when input pulses meet or exceed the selected delay value and satisfy rise/fall time (≤3 ns) and amplitude (0–3 V) requirements.

How does the DS1020S-25 handle unused pins in serial versus parallel mode?

In serial mode (S = 0), unused parallel pins P1–P7 must be tied to defined logic levels (VCC or GND) to prevent floating inputs; P0 is multiplexed with Q and may float if unused. In parallel mode (S = 1), serial pins C and D must be similarly terminated. The DS1020S-25's CMOS design mandates this - floating inputs cause increased current draw, timing uncertainty, and potential oscillation. DS1020S-25 documentation explicitly warns against leaving any input unconnected, regardless of active mode.