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Analog Devices Inc./Maxim Integrated DS89C420-QCL
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- Part No.:
- DS89C420-QCL
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Microcontrollers
- Package:
- 44-LCC (J-Lead)
- Datasheet:
-
DS89C420-QCL.pdf
- Description:
- IC MCU 8BIT 16KB FLASH 44PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,996
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Product details
Overview
DS89C420-QCL from Maxim Integrated (formerly Dallas Semiconductor) is an ultra-high-speed, 8051-compatible microcontroller with 16kB flash, 1kB MOVX RAM, and dual full-duplex serial ports. It executes standard 8051 instructions up to 12× faster than legacy cores at same crystal frequency, achieves 33 MIPS at 33MHz, and operates from 0°C to +70°C in 44-pin PLCC package. It targets real-time embedded control in motor drives, magstripe readers, and industrial automation.
For engineers reviewing the DS89C420-QCL datasheet, DS89C420-QCL pinout, DS89C420-QCL application, or DS89C420-QCL equivalent, this page delivers verified technical context, validated pin functions, confirmed timing behavior under 33MHz operation, and precise alternative part comparisons for drop-in or performance-upgrade scenarios.
Technical Context
The DS89C420-QCL implements a 1-clock-per-machine-cycle architecture-unlike legacy 12-clock 8051 cores-enabling single-cycle instruction execution down to 30ns at 33MHz. Its PMR register controls clock division (1× to 1/1024× oscillator), while MD2–MD0 bits configure MOVX access timing across 2–12 machine cycles for flexible peripheral interfacing.
It integrates dual data pointers with auto-increment/decrement/toggle select, seven external interrupts (INT0–INT5 plus T2EX), five interrupt priority levels, and programmable watchdog timer. Power management mode reduces CPU speed by factor of 1024, with automatic hardware exit on interrupt.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Core Architecture | 1-clock-per-cycle 8051-compatible core; eliminates dummy cycles, enabling true 33 MIPS at 33MHz |
| Max Clock Speed | 33MHz crystal input; supports external clock up to 33MHz with tCHCX/tCLCX ≥10ns |
| Memory | 16kB on-chip flash (in-system programmable via serial port), 256B internal RAM, 1kB MOVX RAM |
| I/O & Peripherals | Four 8-bit bidirectional ports; three 16-bit timers; two full-duplex UARTs; 13 interrupt sources |
| Power Management | Programmable clock divider (1× to 1/1024×); automatic hardware/software exit from stop/idle modes |
| Supply Range | 4.5V to 5.5V; power-fail warning threshold at 4.2–4.6V; reset trip at 3.95–4.35V |
| Operating Temp | 0°C to +70°C - validated for commercial-grade industrial control and consumer equipment |
Pinout & Package
DS89C420-QCL uses a 44-pin Plastic Leaded Chip Carrier (PLCC) package with J-lead configuration, 1.27mm pitch, and body size 16.5mm × 16.5mm. Pin 1 is marked by corner notch; pin numbering proceeds counterclockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| P1.0–P1.7 | Port 1 I/O / Timer2 I/O / Serial1 / INT2–INT5 | Primary general-purpose I/O; supports high-drive pulldown and weak pullup; enables concurrent timer capture, serial comms, and edge-triggered interrupts |
| P2.0–P2.7 | Port 2 I/O / A8–A15 Address Bus | Upper address byte for external memory; retains I/O functionality when EA = VCC; supports page-mode addressing in external bus cycles |
| P0.0–P0.7 | Port 0 I/O / AD0–AD7 Multiplexed Bus | Open-drain bidirectional bus; provides LSB address during ALE high, then transitions to data bus; requires external pullups for I/O use |
| P3.0–P3.7 | Port 3 I/O / RXD0/TXD0/INT0–INT1/T0/T1/WR/RD | Dedicated control signals for external memory interface (RD/WR), serial comms, and timer inputs; enables zero-wait-state parallel memory access |
| XTAL1/XTAL2 | Clock Input/Output | Supports fundamental-mode AT-cut crystals up to 33MHz; XTAL1 accepts external clock source; startup time ≤8ms (11.0592MHz) |
| RST | Bidirectional Reset | Schmitt-triggered active-high input with internal 50–170kΩ pulldown; no external RC required; supports wire-OR reset sources |
| EA | External Access Control | High = execute from internal flash; low = fetch code from external memory; allows hybrid memory mapping |
| ALE/PROG | Address Latch Enable / Programming Mode | Drives external latch (e.g., 74LS373); pulse width configurable per page mode; doubles as PROG pin for parallel programming |
Key Features
| Feature | Design Value |
|---|---|
| 1-Cycle Instruction Execution | Reduces critical loop latency by up to 12× vs. legacy 8051; enables deterministic 30ns min instruction timing at 33MHz |
| Dual Data Pointers (DPTR/DPTR1) | Eliminates software overhead in block memory moves; auto-increment/decrement/toggle select accelerates DMA-like transfers |
| Page Mode Memory Access | Three configurable page modes (1/2/4-cycle) optimize external SRAM/ROM bandwidth; reduces ALE/PSEN toggling for EMI reduction |
| EMI Reduction Mode | Disables ALE during idle cycles; lowers radiated emissions without sacrificing functional timing or requiring layout changes |
| In-System Flash Programming | Serial-port-based reprogramming in final assembly; no external programmer needed; supports field firmware updates |
| Power-Fail Detection | Integrated VPFW comparator triggers early-warning interrupt before reset; enables graceful shutdown and nonvolatile state save |
Applications
| Motor Control | Magstripe Reader/Scanner |
|---|---|
Use Scenario: Closed-loop servo control with PWM generation, encoder feedback sampling, and safety monitoring in HVAC blowers or appliance motors. IC Role / Device Role / Timing Role: Real-time deterministic controller executing PID loops at ≤100µs intervals; uses T0/T1 for encoder counting and P1.0/P1.1 for T2 capture/reload. Use Value: 33MHz core enables sub-10µs interrupt latency and precise 1µs PWM resolution-critical for torque ripple suppression and acoustic noise reduction. |
Use Scenario: High-speed decoding of ISO/ABA magnetic stripe data in point-of-sale terminals and access control systems. IC Role / Device Role / Timing Role: Synchronous serial receiver (Mode 0) sampling track data at 5–10kHz; uses P3.0/P3.1 for dedicated UART0 and P1.2/P1.3 for UART1 diagnostics. Use Value: Single-cycle instruction timing ensures reliable bit-level sampling at 33MHz without cycle-counting jitter; dual UARTs support simultaneous reader comms and host reporting. |
| Industrial PLC I/O Module | Uninterruptible Power Supply (UPS) Monitoring |
Use Scenario: Digital I/O expansion node with isolated inputs, relay drivers, and Modbus RTU communication in factory automation cabinets. IC Role / Device Role / Timing Role: Deterministic scan engine polling 32+ discrete inputs via Port 0/2; uses INT2–INT5 for fast edge-triggered event capture on safety interlocks. Use Value: Five-level interrupt priority ensures immediate response to emergency stop signals while maintaining background Modbus polling at 9.6kbps. |
Use Scenario: Battery voltage monitoring, inverter status tracking, and graceful shutdown sequencing during AC mains failure in line-interactive UPS units. IC Role / Device Role / Timing Role: Power-fail supervisor triggering early-warning interrupt at 4.375V; executes backup save routine before VRST (4.125V) forces reset. Use Value: On-chip VPFW/VRST comparators eliminate external supervisor ICs; 1kB MOVX RAM preserves volatile state across brownout events. |
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-QCL | Same PLCC-44 package; lower max clock (25MHz); no ROMSIZE feature; lacks second UART and INT2–INT5 | Legacy drop-in for cost-sensitive designs where 33MHz speed and dual serial ports are unnecessary | Choose DS87C520-QCL only if existing firmware relies on 12-clock timing and external memory access patterns match original 8051 |
| AT89C51ED2-RLTUM | 44-TQFP only; 64kB flash; USB interface; no PLCC option; different SFR map and reset behavior | Requires PCB redesign; suited for USB-connected devices needing larger code space but not 33MHz deterministic timing | Select AT89C51ED2-RLTUM only when USB host/device capability is mandatory and layout change is acceptable |
Compared with DS89C420-QCL, DS87C520-QCL offers lower cost and proven stability in mature designs but sacrifices 32% peak throughput and advanced peripherals; AT89C51ED2-RLTUM adds USB and flash capacity but abandons PLCC compatibility and introduces timing model divergence that impacts real-time predictability.
Availability
DS89C420-QCL is available at Aetrix Electronics and suitable for motor control, magstripe reader/scanner, and industrial PLC I/O modules requiring stable component supply across extended production lifecycles.
Supply support for DS89C420-QCL 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 leader in precision analog, mixed-signal, and high-reliability semiconductor solutions for industrial, automotive, and communications markets.
The DS89C420-QCL belongs to Maxim's ultra-high-speed 8051 microcontroller family, designed specifically for legacy 8051 code migration paths requiring deterministic real-time performance, in-system programmability, and commercial-temperature industrial robustness.
FAQ
What is the maximum crystal frequency supported by DS89C420-QCL?
The DS89C420-QCL supports a maximum crystal frequency of 33MHz, enabling up to 33 million instructions per second (MIPS) in 1-clock-per-cycle mode. This is validated across the 0°C to +70°C operating range and requires load capacitance matching per crystal manufacturer specifications. The DS89C420-QCL's internal oscillator circuitry is optimized for fundamental-mode AT-cut crystals up to this frequency.
Does DS89C420-QCL require an external reset circuit?
No, DS89C420-QCL does not require an external RC reset circuit. Its RST pin includes an internal Schmitt trigger and a 50–170kΩ pulldown resistor, enabling reliable power-on reset detection and supporting wire-OR'd external reset sources. The device guarantees a minimum 65,536-cycle synchronous reset delay after crystal startup-1.99ms at 33MHz-ensuring stable initialization without external components.
How does DS89C420-QCL handle backward compatibility with legacy 8051 code?
The DS89C420-QCL executes all standard 8051 instructions with identical flag effects and memory addressing, ensuring binary compatibility for most firmware. However, timing-critical routines (e.g., software delays, UART bit-banging) must be adjusted due to 12× faster execution. Timers default to 12-clock-per-cycle mode to preserve legacy timing; they can be reconfigured to 1-clock mode for enhanced responsiveness.
Can DS89C420-QCL program its flash memory in-system?
Yes, DS89C420-QCL supports in-system programming (ISP) of its 16kB flash memory via the primary serial port (P3.0/P3.1) using the built-in ROM loader. No external programmer is required-firmware updates can be performed in the final assembled system using standard UART commands. Programming requires VCC = 4.5–5.5V and follows documented command sequences with 85–100µs PROG pulse widths.
What power management modes does DS89C420-QCL offer?
DS89C420-QCL provides three low-power states: Idle Mode (CPU halted, peripherals active), Stop Mode (oscillator stopped, RAM retained), and programmable Clock Divide Mode (reducing system clock from 1× to 1/1024× oscillator). All modes support automatic hardware exit on interrupt, and the power-fail comparator triggers early-warning interrupts to enable controlled state preservation before reset.
DS89C420-QCL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package/Case:
- 44-LCC (J-Lead)
- Series:
- 89C
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Core Processor:
- 8051
- Core Size:
- 8-Bit
- Speed:
- 33MHz
- 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:
- Surface Mount
- Supplier Device Package:
DS89C420-QCL FAQ
1.How can I place an order for DS89C420-QCL through Aetrix?
Please submit a Request for Quotation (RFQ) for DS89C420-QCL 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-QCL reliable?
The price and inventory of DS89C420-QCL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS89C420-QCL is usually 5 days.
3.What payment methods are accepted for DS89C420-QCL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS89C420-QCL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS89C420-QCL?
DS89C420-QCL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS89C420-QCL 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-QCL?
For technical support, including DS89C420-QCL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS89C420-QCL requirements.
6.How does Aetrix verify that DS89C420-QCL is sourced from the original manufacturer or authorized distributors?
All DS89C420-QCL 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-QCL meets industry standards.
7.What is the process for return or replacement of DS89C420-QCL?
All DS89C420-QCL units undergo pre-shipment inspection (PSI). If there is an issue with DS89C420-QCL, 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-QCL part is unused and in its original packaging.
Return procedure for DS89C420-QCL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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