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Analog Devices Inc./Maxim Integrated DS87C520-ECL
- Part No.:
- DS87C520-ECL
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Microcontrollers
- Package:
- 44-TQFP
- Datasheet:
-
DS87C520-ECL.pdf
- Description:
- IC MCU 8BIT 16KB OTP 44TQFP
- Quantity:
- Payment:
- Shipping:
Inventory:3,844
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Product details
Overview
DS87C520-ECL from Maxim Integrated is a high-speed, 8051-compatible microcontroller with 16kB on-chip EPROM, 1kB MOVX-accessible SRAM, and 256 bytes of scratchpad RAM. It executes instructions in 4 clocks/machine cycle (vs. 12 for standard 8051), achieving 33MHz max clock rate and 121ns single-cycle instruction time. It features dual hardware serial ports, programmable watchdog timer, power-fail reset, and ROMSIZE register for dynamic internal/external memory mapping - used in industrial control systems requiring deterministic real-time response.
For engineers reviewing the DS87C520-ECL datasheet, DS87C520-ECL pinout, DS87C520-ECL application, or DS87C520-ECL equivalent, key selection considerations include its 44-pin TQFP package, 33MHz operation at 0°C to +70°C, dual DPTR support for fast block moves, software-configurable MOVX stretch timing (2–9 cycles), and ROMSIZE-controlled memory map flexibility for boot-from-Flash designs.
Technical Context
The DS87C520-ECL implements a redesigned 8051 core eliminating dummy memory cycles, delivering 2.5× average speedup over legacy 8051s at identical crystal frequency. Its architecture supports four-clock-per-machine-cycle execution while retaining full 8051 instruction set compatibility and pinout.
It integrates two full-duplex UARTs (Serial Port 0 and Serial Port 1), three 16-bit timer/counters (with optional 4-clock mode), 13 interrupt sources (including six external), and Power Management Mode enabling CPU clock division by 64 or 1024 for ultra-low-power operation - all controlled via dedicated SFRs including PMR (C4h), ROMSIZE (C2h), and CKCON (8Eh).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Core Architecture | 8051-compatible, 4-clock/machine cycle - eliminates wasted cycles, enabling 2.5× average speedup vs. standard 8051 at same crystal frequency. |
| Max Clock Frequency | 33MHz - enables 82.5MHz apparent instruction throughput (2.5×) and 121ns single-cycle execution time. |
| On-Chip Memory | 16kB EPROM + 1kB MOVX-accessible SRAM + 256B direct RAM - supports standalone operation and flexible external memory expansion via EA pin and ROMSIZE register. |
| Serial Interfaces | Two independent full-duplex UARTs (SP0 and SP1) - allows simultaneous host communication and peripheral bridging without software emulation. |
| Power Management | Programmable clock divider (÷64 or ÷1024) via PMR - reduces machine cycle rate to 187.5kHz or 11.7kHz at 12MHz crystal, cutting active power consumption proportionally. |
| MOVX Timing Control | Software-selectable stretch (2–9 machine cycles) via CKCON - enables reliable interface to slow peripherals (e.g., LCDs, legacy UARTs) without external glue logic. |
| Package & Temp Range | 44-pin TQFP, 0°C to +70°C - surface-mount compatible for compact industrial PCBs with commercial temperature stability. |
Pinout & Package
DS87C520-ECL is housed in a 44-pin Thin Quad Flat Package (TQFP) with 0.8mm lead pitch, optimized for automated assembly and thermal performance in space-constrained applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 38) | Positive Supply | +5V main power input; decoupling required near pin for noise-sensitive high-speed operation. |
| GND (Pins 16, 17, 39) | Digital Ground | Three dedicated ground pins reduce impedance and improve signal integrity across high-frequency I/O and internal core. |
| RST (Pin 4) | Reset Input | Schmitt-triggered active-high input with internal pulldown; supports wired-OR reset sources without external RC network. |
| XTAL1/XTAL2 (Pins 14, 15) | Oscillator Interface | Supports parallel-resonant AT-cut crystals up to 33MHz; XTAL1 accepts external clock source if crystal omitted. |
| P0.0–P0.7 (Pins 37–30) | Multiplexed Address/Data Bus | Open-drain port serving as AD0–AD7; latched by ALE pulse for external memory access - requires pullups when used as GPIO. |
| P1.0–P1.7 (Pins 40–3) | General-Purpose I/O + Alternate Functions | Includes T2/T2EX, RXD1/TXD1, and INT2–INT5 - enables timer capture, second UART, and five additional edge-triggered interrupts. |
| P2.0–P2.7 (Pins 18–25) | High-Order Address Bus / I/O | Provides A8–A15 during external memory access; bidirectional with weak pullup - defaults to address output when EA = VCC and external memory active. |
| P3.0–P3.7 (Pins 5–13) | Multiplexed I/O + System Functions | Carries RXD0/TXD0, INT0/INT1, T0/T1, RD/WR - essential for standard 8051 peripheral interfacing and memory strobe generation. |
| EA (Pin 29) | External Access Control | Active-low input determining boot source: VCC enables internal EPROM; GND forces external program fetch - overrides ROMSIZE register setting. |
| ALE (Pin 26) | Address Latch Enable | Four-cycle-period pulse synchronized to XTAL1; can be disabled via PMR.ALEOFF to reduce EMI - remains functional during external memory accesses regardless of software disable. |
Key Features
| Feature | Design Value |
|---|---|
| Dual Data Pointers (DPTR0/DPTR1) | Eliminates repeated DPTR reloads during block memory moves - cuts instruction count and execution time for data transfers between internal SRAM and external peripherals. |
| ROMSIZE Register (C2h) | Software-selectable internal ROM size (0–16kB) - enables seamless boot-from-external-Flash by temporarily masking internal EPROM, then restoring it post-initialization. |
| Power Management Mode (PMM) | Hardware-supported CPU clock scaling (÷64 or ÷1024) - delivers measurable power reduction in battery-powered telemetry nodes without firmware rewrite. |
| EMI Reduction via ALE Disable | Software-controllable ALE deactivation (PMR.ALEOFF) - lowers radiated emissions in EMC-critical environments like medical instrumentation without sacrificing functionality. |
| Early-Warning Power-Fail Interrupt | Dedicated interrupt triggered before brownout - provides deterministic time window (typically >1ms at 5V±5%) to save state or initiate safe shutdown in industrial PLCs. |
Applications
| Industrial PLC I/O Module | Smart Energy Meter Communication Hub |
|---|---|
Use Scenario: Real-time acquisition and preprocessing of analog/digital sensor inputs in modular PLC backplanes with fieldbus connectivity. IC Role / Device Role / Timing Role: Primary controller executing deterministic ladder logic with sub-millisecond scan times, managing dual UARTs for Modbus RTU and Profibus DP slave interfaces. Use Value: 4-clock core and dual DPTR enable 2.5× faster scan cycle completion vs. legacy 8051, allowing higher I/O density per module without increasing cycle jitter. |
Use Scenario: Aggregating metrology data from multiple ICs and relaying via RS-485 and RF mesh networks in ANSI C12.19-compliant smart meters. IC Role / Device Role / Timing Role: Central communications processor handling concurrent serial protocols (DLMS/COSEM over UART0, proprietary RF stack over UART1), watchdog-monitored firmware updates. Use Value: ROMSIZE-controlled memory mapping allows secure in-field firmware upgrade by switching between internal bootloader and external Flash application image without hardware change. |
| Medical Diagnostic Equipment Front-End | Automotive Body Control Module (BCM) Subsystem |
Use Scenario: Signal conditioning, safety interlock monitoring, and display interface in portable ultrasound or patient monitor front-ends. IC Role / Device Role / Timing Role: Safety-critical subsystem controller with early-warning power-fail interrupt and programmable watchdog - ensures fail-safe shutdown within defined timing budget. Use Value: Power Management Mode reduces active current to <1mA at 11.7kHz machine cycle rate, extending battery life in handheld diagnostics without compromising real-time responsiveness during measurement bursts. |
Use Scenario: Door lock actuation, window lift control, and interior lighting sequencing in cost-sensitive automotive BCMs. IC Role / Device Role / Timing Role: Cost-optimized main MCU replacing legacy 8051s, leveraging pin compatibility to reuse existing PCB layouts while adding second UART for diagnostic CAN gateway bridging. Use Value: 44-pin TQFP footprint matches legacy PLCC variants; dual UARTs eliminate need for external bridge ICs, reducing BOM cost and board area in Tier-2 automotive modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed 8051-compatible microcontroller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS83C520-ECL | Factory mask ROM version (no EPROM); identical pinout, speed, and peripherals but fixed 16kB program memory. | Targeted at high-volume, cost-sensitive production where firmware is finalized and unchangeable. | Select DS83C520-ECL for production runs >10k units with locked firmware; DS87C520-ECL preferred for prototyping, field upgrades, or design iterations. |
| AT89C51ED2-RLTUM | 8051 core with 64kB Flash, USB interface, and enhanced interrupt priority; operates at 33MHz but lacks dual UARTs and ROMSIZE register. | Requires USB host connectivity or larger code space; no native support for dynamic memory map reconfiguration. | Choose AT89C51ED2-RLTUM only when USB device capability or >16kB code space is mandatory; DS87C520-ECL offers superior serial peripheral integration and memory flexibility. |
Compared with DS83C520-ECL, DS87C520-ECL provides field-programmable EPROM for iterative development and firmware updates, while AT89C51ED2-RLTUM trades dual UARTs and ROMSIZE control for USB and larger Flash - making DS87C520-ECL optimal for serial-heavy, memory-map-flexible industrial control where EPROM reprogrammability adds value.
Availability
DS87C520-ECL is available at Aetrix Electronics and suitable for industrial automation, smart metering, and medical diagnostics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for DS87C520-ECL 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 (now part of Analog Devices) designs precision analog, mixed-signal, and high-reliability microcontrollers for demanding industrial, medical, and automotive applications.
The DS87C520-ECL belongs to Maxim's high-speed 8051-compatible microcontroller family, engineered to deliver deterministic real-time performance, robust power management, and seamless legacy 8051 migration - targeting cost-sensitive yet function-rich embedded control systems.
FAQ
What is the maximum operating frequency of the DS87C520-ECL?
The DS87C520-ECL supports a maximum crystal frequency of 33MHz, enabling a machine cycle rate of 8.25MHz (33MHz ÷ 4) and single-cycle instruction execution in 121ns. This is confirmed in the Ordering Information table and Performance Overview section of the official datasheet, where DS87C520-ECL is explicitly rated for 33MHz operation across the 0°C to +70°C temperature range.
Does the DS87C520-ECL support in-system programming (ISP)?
No, the DS87C520-ECL does not support in-system programming. It contains factory-programmed EPROM that requires UV erasure through the quartz window for reprogramming - a feature present only in the windowed CERDIP variant (e.g., DS87C520-WCL). The DS87C520-ECL uses a sealed TQFP package and is programmed prior to shipment; firmware updates require physical device replacement or use of external Flash with ROMSIZE-controlled boot mapping.
How does the ROMSIZE register affect memory mapping in the DS87C520-ECL?
The ROMSIZE register (SFR address C2h) dynamically controls the upper boundary of on-chip EPROM decoding - allowing software to select internal ROM sizes from 0kB to 16kB in steps (e.g., 4kB, 8kB, 16kB). When set to less than 16kB, addresses beyond the selected limit automatically route to external memory via P0/P2, enabling boot-from-Flash configurations. This behavior is documented in the MEMORY RESOURCES and PROGRAM MEMORY ACCESS sections of the DS87C520-ECL datasheet.
Can the DS87C520-ECL operate with a 3.3V supply?
No, the DS87C520-ECL is specified for +5V ±10% operation only. Its VCC pin (Pin 38) requires 4.5V to 5.5V, as stated in the PIN DESCRIPTION section (Page 4) and Electrical Characteristics tables. Attempting 3.3V operation will result in undefined behavior, failed resets, or inability to drive TTL-compatible outputs - it is not a 3.3V-tolerant or dual-voltage device.
What is the purpose of the dual data pointers in the DS87C520-ECL?
The DS87C520-ECL implements two independent 16-bit data pointers (DPTR0 at 82h/83h and DPTR1 at 84h/85h), selectable via DPS bit (SFR 86h). This eliminates the need to save/restore DPTR during block memory moves - accelerating operations like memcpy() between internal SRAM and external peripherals. The feature directly improves throughput in data-intensive applications such as protocol stack buffering or display frame buffer updates, as verified in the DUAL DATA POINTER section (Page 13).
DS87C520-ECL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package/Case:
- 44-TQFP
- Series:
- 87C
- Packaging:
- Tray
- 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:
- OTP
- 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:
DS87C520-ECL FAQ
1.How can I place an order for DS87C520-ECL through Aetrix?
Please submit a Request for Quotation (RFQ) for DS87C520-ECL 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 DS87C520-ECL reliable?
The price and inventory of DS87C520-ECL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS87C520-ECL is usually 5 days.
3.What payment methods are accepted for DS87C520-ECL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS87C520-ECL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS87C520-ECL?
DS87C520-ECL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS87C520-ECL 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 DS87C520-ECL?
For technical support, including DS87C520-ECL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS87C520-ECL requirements.
6.How does Aetrix verify that DS87C520-ECL is sourced from the original manufacturer or authorized distributors?
All DS87C520-ECL 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 DS87C520-ECL meets industry standards.
7.What is the process for return or replacement of DS87C520-ECL?
All DS87C520-ECL units undergo pre-shipment inspection (PSI). If there is an issue with DS87C520-ECL, 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 DS87C520-ECL part is unused and in its original packaging.
Return procedure for DS87C520-ECL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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