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Analog Devices Inc./Maxim Integrated DS89C420-MCS
- Part No.:
- DS89C420-MCS
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Microcontrollers
- Package:
- 40-DIP (0.600", 15.24mm)
- Datasheet:
-
DS89C420-MCS.pdf
- Description:
- IC MCU 8BIT 16KB FLASH 40DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,328
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Product details
Overview
DS89C420-MCS from Maxim Integrated (formerly Dallas Semiconductor) is an ultra-high-speed, 8051-compatible microcontroller featuring a 1-cycle-per-instruction architecture, 33MHz maximum crystal speed, 16kB in-system programmable flash memory, and dual full-duplex serial ports. It executes standard 8051 instructions up to 12× faster than legacy cores at the same crystal frequency and targets real-time embedded control in industrial automation and test equipment.
For engineers reviewing the DS89C420-MCS datasheet, DS89C420-MCS pinout, DS89C420-MCS application, or DS89C420-MCS equivalent, this page delivers verified electrical specs, validated package mapping, confirmed I/O and timer resources, and two rigorously cross-checked alternative microcontrollers for 8051-based system upgrades requiring higher throughput and integrated flash.
Technical Context
The DS89C420-MCS implements a fully static CMOS 8051-compatible core with no dummy memory cycles, enabling single-clock machine cycles versus the traditional 12-clock cycle. Its clock-divide register (PMR) supports selectable oscillator-to-system-clock ratios: 1×, 2×, 4×, or 1/1024×, allowing flexible trade-offs between performance and power.
It integrates three 16-bit timer/counters-two configurable for 1- or 12-clock-per-cycle operation-and supports five levels of interrupt priority across 13 interrupt sources, including six external interrupts with edge-selectable triggers on Ports 1 and 3. The device also features ROMSIZE control for dynamic internal program memory sizing (0–16kB) and four paged memory access modes optimized for external RAM and peripheral interfacing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Core Architecture | 1-cycle-per-machine-cycle 8051-compatible CPU; eliminates legacy 12-cycle bottleneck for all instructions |
| Max Clock Speed | 33MHz crystal input; achieves up to 33 MIPS execution rate in 1-cycle mode |
| Memory | 16kB flash (in-system programmable via serial port), 1kB MOVX SRAM, 256B scratchpad RAM |
| I/O & Peripherals | Four 8-bit bidirectional ports, dual UARTs, three 16-bit timers, 13 interrupt sources, five priority levels |
| Power Management | Programmable clock divider (1× to 1/1024×), automatic hardware/software exit from low-power mode |
| Supply & Reset | 4.5V–5.5V operation; power-fail warning (VPFW = 4.2–4.6V), reset trip point (VRST = 3.95–4.35V) |
| Package | 40-pin PDIP (MCS suffix denotes commercial temperature grade: 0°C to +70°C) |
Pinout & Package
DS89C420-MCS is housed in a 40-pin plastic dual in-line package (PDIP) with 0.6-inch body width, compliant with JEDEC MS-001. Pin spacing is 0.1 inch (2.54 mm); lead finish is matte tin.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 40) | Power Supply | +5V main supply; must be decoupled locally with 0.1µF ceramic capacitor |
| GND (Pin 20) | Logic Ground | Reference return for all digital and analog circuitry; connect to system ground plane |
| RST (Pin 9) | Reset Input/Output | Bidirectional Schmitt-triggered reset pin with internal pulldown; enables wire-OR external reset without RC network |
| XTAL1 (Pin 19) | Oscillator Input | Primary crystal or external clock input; also accepts TTL-level clock source when crystal omitted |
| XTAL2 (Pin 18) | Oscillator Output | Crystal amplifier output; connects to crystal's second terminal or left floating for external clock mode |
| P0.0–P0.7 (Pins 39–32) | Multiplexed Address/Data Bus | Open-drain port; provides AD0–AD7 during ALE high, then transitions to bidirectional data bus; requires pullups for I/O use |
| P1.0–P1.7 (Pins 1–8) | General-Purpose I/O | Quasi-bidirectional port with strong pulldown on write-0; supports T2, T2EX, RXD1/TXD1, and INT2–INT5 alternate functions |
| P2.0–P2.7 (Pins 21–28) | Upper Address Bus / I/O | Provides A8–A15 during external memory access; functions as general I/O otherwise; weak pullup on reset |
| P3.0–P3.7 (Pins 10–17) | Multifunction I/O | Standard 8051 alternate functions: RXD0/TXD0, INT0/INT1, T0/T1, WR/RD; all pins have weak pullup on reset |
| EA (Pin 31) | External Access Control | High = execute from internal flash; low = fetch code from external memory; determines boot source at power-up |
| ALE/PROG (Pin 30) | Address Latch Enable / Programming | Drives external latch during Port 0 address phase; toggles at 1/4 crystal frequency in default mode; doubles as parallel programming control |
| PSEN (Pin 29) | Program Store Enable | Active-low chip enable for external program memory; remains low during consecutive page-mode accesses |
Key Features
| Feature | Design Value |
|---|---|
| 1-Cycle Instruction Execution | Eliminates 12-cycle bottleneck: fastest instructions complete in 30ns at 33MHz, enabling deterministic real-time response |
| Dual Data Pointers (DPTR/DPTR1) | Accelerates block memory moves by eliminating pointer reload overhead; supports auto-increment/decrement and toggle select |
| Variable-Length MOVX Timing | Configurable wait states (2–12 machine cycles) via MD bits allow seamless interface with slow peripherals or legacy memory |
| Page Mode Memory Access | Three page modes (1-cycle, 2-cycle, 4-cycle) reduce external memory access latency by reusing address lines across consecutive reads/writes |
| EMI Reduction Mode | Disables ALE during idle periods to suppress radiated emissions-critical for CE/FCC-compliant industrial designs |
| Power-Fail Early Warning | Dedicated VPFW comparator triggers interrupt before reset threshold is reached, enabling graceful shutdown or data save |
Applications
| Industrial Motor Control | Automotive Test Equipment |
|---|---|
Use Scenario: Closed-loop servo drive managing PWM timing, encoder feedback, and fault monitoring in HVAC blower systems. IC Role / Device Role / Timing Role: Real-time controller executing motion algorithms, generating precise 20kHz PWM outputs, and sampling quadrature encoders at 100kHz. Use Value: 33 MIPS throughput ensures sub-10µs loop latency; dual UARTs support CAN gateway bridging and PC diagnostics simultaneously. |
Use Scenario: Portable battery-powered ECU diagnostic tool performing OBD-II protocol translation and sensor simulation. IC Role / Device Role / Timing Role: Host MCU managing USB-to-serial bridge, analog sensor excitation, and EEPROM-based calibration storage. Use Value: In-system programmable flash enables field firmware updates; power-fail warning preserves calibration data during unexpected shutdown. |
| Magstripe Reader/Scanner | Building Security Access Panel |
Use Scenario: High-reliability card reader decoding ISO/IEC 7811 tracks at 50 kbps while supporting anti-tamper detection and LED status feedback. IC Role / Device Role / Timing Role: Signal processor capturing raw magstripe waveforms via high-speed GPIO, applying digital filtering, and validating checksums. Use Value: 1-cycle core executes bit-level decoding in <1µs per bit; dual serial ports handle simultaneous RS-485 panel bus and USB host communication. |
Use Scenario: Networked door controller authenticating RFID badges, logging entries, driving electromagnetic locks, and reporting alarms over Ethernet. IC Role / Device Role / Timing Role: Central security processor managing AES-128 encryption, watchdog supervision, and fail-safe lock actuation timing. Use Value: 16kB flash stores multi-language UI assets and audit logs; programmable watchdog prevents lockout due to software hang. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8051-compatible microcontroller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS87C520-MCS | Same 8051-compatible core but max 25MHz clock; lacks ROMSIZE feature and page mode 2; identical 40-pin PDIP footprint | Suitable for cost-sensitive upgrades where 33MHz speed and advanced memory paging are unnecessary | Select DS87C520-MCS only if design already operates below 25MHz and does not require dynamic flash size selection or enhanced external memory efficiency |
| AT89C51ED2-RLTUM | Atmel 8051 derivative with 64kB flash, USB interface, and 33MHz max; differs in SFR map, interrupt vectoring, and reset behavior | Preferred when USB device functionality or larger code space is required; not pin-compatible with DS89C420-MCS | Choose AT89C51ED2-RLTUM only if USB integration is mandatory and PCB redesign for 44-pin TQFP is acceptable |
Compared with DS87C520-MCS and AT89C51ED2-RLTUM, the DS89C420-MCS uniquely delivers 33MHz deterministic 1-cycle execution in a drop-in 40-pin PDIP package while retaining full 8051 software compatibility-making it optimal for legacy socket upgrades demanding maximum throughput without layout change.
Availability
DS89C420-MCS is available at Aetrix Electronics and suitable for industrial motor control, automotive test equipment, magstripe reader/scanner, and building security access panel applications requiring stable component supply and long-term obsolescence management.
Supply support for DS89C420-MCS 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
Maxim Integrated (acquired by Analog Devices in 2021) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and embedded processing solutions for industrial, automotive, and communications markets.
The DS89C420-MCS belongs to Maxim's ultra-high-speed 8051 microcontroller product line, designed specifically to extend the 8051 ecosystem with modern performance, integrated flash, and power-aware features-targeting cost-constrained, real-time embedded systems needing upgrade paths without software rewrite.
FAQ
What is the maximum crystal frequency supported by the DS89C420-MCS?
The DS89C420-MCS supports a maximum crystal frequency of 33MHz. When configured in 1-cycle-per-instruction mode using the PMR register, this yields a system clock of 33MHz and an instruction throughput of up to 33 million instructions per second (MIPS). Operation at lower frequencies (e.g., 25MHz or 11.0592MHz) is also supported for compatibility or power reduction.
Does the DS89C420-MCS require an external reset circuit?
No, the DS89C420-MCS does not require an external RC reset circuit. Its RST pin includes an internal Schmitt trigger and pulldown resistor, enabling reliable power-on reset with no external components. However, for applications requiring tighter reset timing control or brownout protection beyond the built-in VPFW comparator, a dedicated supervisor IC like the MAX809 may be added.
How is flash memory programmed on the DS89C420-MCS?
Flash memory on the DS89C420-MCS is programmed in-system via its serial port (UART0) using the built-in ROM loader-no external programmer is needed. The process uses standard 8051 serial commands and requires only VCC, GND, RST, XTAL1, and TXD0/RXD0 connections. Parallel programming via ALE/PROG is also supported for factory programming using standard EPROM programmers.
Is the DS89C420-MCS pin-compatible with standard 8051 microcontrollers?
Yes, the DS89C420-MCS is fully pin-compatible with the industry-standard 8051 family in its 40-pin PDIP package (e.g., Intel 8051, Atmel AT89C51). All signal names, pin positions, and basic I/O behavior match. However, some alternate functions (e.g., P1.2–P1.7 for INT2–INT5, dual UARTs) extend beyond baseline 8051 capability and require updated firmware to utilize.
What power-saving modes does the DS89C420-MCS support?
The DS89C420-MCS supports a programmable power management mode (PMM) that reduces CPU execution rate by dividing the system clock by up to 1024, cutting active current from ~75mA to ~40mA in idle mode. It also features automatic hardware/software exit from PMM upon interrupt, ensuring responsive wake-up without firmware polling overhead.
DS89C420-MCS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package/Case:
- 40-DIP (0.600", 15.24mm)
- Series:
- 89C
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Core Processor:
- 8051
- Core Size:
- 8-Bit
- Speed:
- 50MHz
- Connectivity:
- EBI/EMI, SIO, UART/USART
- Peripherals:
- Power-Fail Reset, WDT
- Number of I/O:
- 32
- Program Memory Size:
- 16KB (16K x 8)
- Program Memory Type:
- FLASH
- EEPROM Size:
- -
- RAM Size:
- 1K x 8
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 5.5V
- Data Converters:
- -
- Oscillator Type:
- External
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
DS89C420-MCS FAQ
1.How can I place an order for DS89C420-MCS through Aetrix?
Please submit a Request for Quotation (RFQ) for DS89C420-MCS on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for DS89C420-MCS reliable?
The price and inventory of DS89C420-MCS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS89C420-MCS is usually 5 days.
3.What payment methods are accepted for DS89C420-MCS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS89C420-MCS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS89C420-MCS?
DS89C420-MCS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS89C420-MCS order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for DS89C420-MCS?
For technical support, including DS89C420-MCS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS89C420-MCS requirements.
6.How does Aetrix verify that DS89C420-MCS is sourced from the original manufacturer or authorized distributors?
All DS89C420-MCS products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that DS89C420-MCS meets industry standards.
7.What is the process for return or replacement of DS89C420-MCS?
All DS89C420-MCS units undergo pre-shipment inspection (PSI). If there is an issue with DS89C420-MCS, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The DS89C420-MCS part is unused and in its original packaging.
Return procedure for DS89C420-MCS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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