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Texas Instruments TMS370C686AFNT
- Part No.:
- TMS370C686AFNT
- Manufacturer:
- Texas Instruments
- Category:
- Microcontrollers
- Package:
- -
- Datasheet:
-
TMS370C686AFNT.pdf
- Description:
- 8-BIT, OTPROM, TMS370 CPU, 5MHZ
- Quantity:
- Payment:
- Shipping:
Inventory:5,130
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Product details
Overview
TMS370C686AFNT from Texas Instruments is an 8-bit CMOS microcontroller with 16 KB on-chip EPROM program memory, 256 bytes of RAM, and 24-bit watchdog timer, designed for automotive and industrial real-time control applications requiring in-circuit programmability and low-power operation.
For engineers reviewing the TMS370C686AFNT datasheet, TMS370C686AFNT pinout, TMS370C686AFNT application, or TMS370C686AFNT equivalent, this page delivers verified technical context, package-specific pin functions, memory mapping details, low-power mode behavior, and validated alternative options for prototyping and production.
Technical Context
The TMS370C686AFNT implements a register-to-register architecture with 256 general-purpose registers and 14 addressing modes, eliminating accumulator bottlenecks. It supports two software-programmable interrupt levels with individual vectors and edge-selectable triggering on INT1–INT3.
Its 16-bit Timer1 provides configurable event counting, input capture, PWM output (T1PWM), and external event input (T1EVT); clocking options include divide-by-4 oscillator or PLL-based divide-by-1 (2–5 MHz SYSCLK). The device uses Von Neumann memory architecture with unified address space spanning EPROM (4000h–7FFFh), RAM (0000h–00FFh), EEPROM (1F00h–1FFFh), and peripheral file (1000h–10FFh).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Core Architecture | 8-bit register-to-register CPU with no accumulator bottleneck; enables direct register arithmetic (e.g., ADD R24,R47) |
| Program Memory | 16 KB EPROM (one-time programmable), mapped at 4000h–7FFFh; supports in-circuit programming with 13 V on MC pin |
| Data Memory | 256 bytes RAM (0000h–00FFh) usable as registers, stack, or data storage; retains contents during STANDBY/HALT modes |
| EEPROM | No on-chip data EEPROM (0 bytes); unlike TMS370C080, TMS370C686AFNT omits 256-byte data EEPROM module |
| Watchdog Timer | 24-bit standard watchdog (not hard or simple counter); resets device on timeout or invalid key write to WD register |
| Operating Voltage | 5 V ±10% (4.5 V–5.5 V); compatible with TTL/CMOS logic levels on all I/O pins |
| Temperature Range | Industrial grade: –40°C to +85°C; qualified for motor control, sensor interface, and embedded industrial systems |
Pinout & Package
Package: 44-pin plastic leaded chip carrier (PLCC-FN), surface-mount compatible with standard PLCC sockets and reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A7 | Port A bidirectional I/O | General-purpose port with register-mapped control; used for digital control signals, status inputs, or LED drivers |
| B0–B7 | Port B bidirectional I/O | Full 8-bit port; supports interrupt-on-change via INT2/INT3 when configured as inputs |
| C0–C5 | Port C bidirectional I/O (6 pins) | Reduced port size for 44-pin FN package; C0–C5 available; C6/C7 not bonded out |
| D3–D7 | Port D bidirectional I/O | D3 doubles as SYSCLK output; enables clock distribution to external peripherals without additional buffer |
| INT1–INT3 | Interrupt inputs / I/O | INT1 is non-maskable; INT2/INT3 are maskable and configurable for rising/falling edge detection |
| T1IC/CR, T1PWM, T1EVT | Timer1 multifunction pins | T1IC/CR: input capture or counter reset; T1PWM: PWM output signal; T1EVT: external event trigger for timer |
| RESET | Reset I/O | Open-drain output indicates internal fault (watchdog/oscillator); input initiates cold start or recovery sequence |
| MC | Mode Control | Enables EPROM write-protection override when 13 V applied; required for in-circuit programming of EPROM |
| XTAL1, XTAL2/CLKIN | Oscillator interface | XTAL1: crystal input or external clock source; XTAL2/CLKIN: crystal output or clock feedback path |
| VCC, VSS | Power supply | VCC = 5 V ±10%; VSS = digital ground reference; decoupling recommended per TI layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Register-to-register instruction set | Eliminates accumulator dependency-enables parallel register operations (e.g., ADD R12,R29) for deterministic timing in control loops |
| Two low-power modes (STANDBY/HALT) | STANDBY retains RAM and runs oscillator/timer; HALT stops all clocks-reduces current to µA range for battery-backed systems |
| Memory-mapped peripheral file | 256-byte PF (1000h–10FFh) organizes I/O, timer, and system control registers into logical 16-byte frames for modular driver development |
| Programmable interrupt priority | Two software-selectable levels (IE1/IE2 bits in Status Register) allow nested handling of time-critical events like PWM sync and fault interrupts |
| In-circuit EPROM programming | Requires only 13 V on MC pin and proper EPCTL register writes-enables field firmware updates without device removal or UV erasers |
Applications
| Automotive Body Control Module | Industrial Motor Starter Interface |
|---|---|
Use Scenario: Centralized control of door locks, window lifts, and mirror adjustment in 12 V vehicle systems. IC Role / Device Role / Timing Role: Main controller executing real-time state machines, reading switch inputs, driving relay/LED outputs, and managing CAN bus communication via external transceiver. Use Value: 16 KB EPROM accommodates full feature set including diagnostics and calibration tables; STANDBY mode enables wake-on-keypress with sub-100 µA quiescent current. |
Use Scenario: Monitoring thermal sensors and contactor status while sequencing motor startup in HVAC or pump systems. IC Role / Device Role / Timing Role: Safety-critical supervisor that validates pre-start conditions, triggers timed ramp-up sequences, and asserts emergency stop on overtemperature or phase loss. Use Value: 24-bit watchdog ensures fail-safe reset on firmware hang; hardware timer capture (T1IC/CR) precisely measures AC line zero-crossing for synchronized triac firing. |
| Consumer Appliance Control Board | Telecom Power Supply Monitor |
Use Scenario: Embedded controller in washing machine or dishwasher managing cycle timing, valve actuation, and user interface. IC Role / Device Role / Timing Role: Primary MCU coordinating electromechanical subsystems using PWM (T1PWM) for pump speed control and input capture for tachometer feedback. Use Value: 256-byte RAM stores runtime variables across power cycles; register-to-register ALU accelerates PID loop execution within 2 µs per iteration. |
Use Scenario: Standalone monitoring unit tracking +5 V, +12 V, and –48 V rails in telecom shelf power systems. IC Role / Device Role / Timing Role: Fault detector sampling analog voltages via external ADC, logging events to nonvolatile memory, and asserting alarm lines on threshold violation. Use Value: Industrial temperature rating (–40°C to +85°C) ensures reliability in uncooled telecom cabinets; RESET pin open-drain output drives shared system fault bus. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit microcontroller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TMS370C380AFN | 4 KB mask-ROM instead of 16 KB EPROM; includes 256-byte data EEPROM; same 44-pin PLCC package and pinout | Suitable for high-volume production where firmware is fixed; lacks field-programmability but offers lower unit cost | Select when firmware stability and cost sensitivity outweigh need for post-deployment updates |
| SE370C686AFZ | Identical 16 KB EPROM and 256-byte RAM; ceramic windowed package (CLCC-FZ) enabling UV-erasable reprogramming during prototyping | Used exclusively in development labs for iterative firmware testing; not rated for production due to reliability characterization limits | Select for early-stage design validation where frequent EPROM rewrites are required before final mask release |
Compared with TMS370C686AFNT, TMS370C380AFN trades field-upgradability for cost and data retention, while SE370C686AFZ provides identical functionality in a non-production-grade package optimized for rapid iteration-not long-term deployment.
Availability
TMS370C686AFNT is available at Aetrix Electronics and suitable for automotive body electronics, industrial motor controls, and consumer appliance designs requiring stable component supply, long-lifecycle support, and legacy microcontroller compatibility.
Supply support for TMS370C686AFNT 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies with over 50 years of microcontroller innovation.
The TMS370Cx8x product line was engineered for cost-sensitive, real-time embedded control in harsh environments-emphasizing noise immunity, wide temperature operation, and integrated peripherals to reduce external component count.
FAQ
What memory types and sizes does the TMS370C686AFNT integrate on-chip?
The TMS370C686AFNT integrates 16 KB of one-time-programmable EPROM for program storage (mapped at 4000h–7FFFh), 256 bytes of static RAM (0000h–00FFh) usable as registers or stack, and no on-chip data EEPROM. Unlike the TMS370C080, it omits the 256-byte data EEPROM block entirely. Program memory is in-circuit programmable using 13 V applied to the MC pin and proper writes to the EPCTL register at P01C.
Does the TMS370C686AFNT support low-power operation, and how is it implemented?
Yes, the TMS370C686AFNT supports two hardware-enforced low-power modes: STANDBY and HALT. In STANDBY mode, the CPU halts but the oscillator and Timer1 remain active-retaining full RAM content and enabling wake-on-interrupt. In HALT mode, all clocks stop, reducing current draw to microamp levels while preserving RAM and peripheral configuration. Both modes are entered via specific instruction sequences and exited by interrupt or reset.
What is the function of the MC pin on the TMS370C686AFNT, and why is it voltage-sensitive?
The MC (Mode Control) pin on the TMS370C686AFNT serves dual roles: it enables EPROM write-protection override when 13 V is applied, permitting in-circuit programming, and it controls EEPROM write-enable when used with data EEPROM variants. For TMS370C686AFNT-which lacks data EEPROM-the 13 V level on MC is strictly required to unlock EPROM programming; absence of this voltage disables all EPROM write operations, ensuring firmware integrity in deployed systems.
How does the TMS370C686AFNT handle system reset sources, and can firmware identify the cause?
The TMS370C686AFNT recognizes three reset sources: external RESET pin assertion, watchdog timeout, and oscillator fault. After reset, firmware can distinguish them by reading flag bits: COLD START (SCCR0.7) for power-up, OSC FLT FLAG (SCCR0.4) for crystal failure, and WD OVRFL INT FLAG (T1CTL2.5) for watchdog overflow. These flags persist across reset and must be explicitly cleared by software-enabling diagnostic logging and adaptive recovery routines in the TMS370C686AFNT application.
Is the TMS370C686AFNT pin-compatible with other devices in the TMS370Cx8x family, and what are the key constraints?
Yes, the TMS370C686AFNT is pin-compatible with other 44-pin PLCC (FN package) members of the TMS370Cx8x family-including TMS370C380AFN and SE370C686AFZ-sharing identical pin assignments, electrical characteristics, and memory map layout. Key constraints include: absence of data EEPROM (vs. TMS370C080), mandatory 13 V on MC for programming (vs. ROM variants), and standard watchdog configuration (vs. hard/simple watchdog options in ROM-A variants).
TMS370C686AFNT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- -
- Series:
- TMS370
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Core Processor:
- -
- Core Size:
- -
- Speed:
- -
- Connectivity:
- -
- Peripherals:
- -
- Number of I/O:
- -
- Program Memory Size:
- -
- Program Memory Type:
- -
- EEPROM Size:
- -
- RAM Size:
- -
- Voltage - Supply (Vcc/Vdd):
- -
- Data Converters:
- -
- Oscillator Type:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
TMS370C686AFNT FAQ
1.How can I place an order for TMS370C686AFNT through Aetrix?
Please submit a Request for Quotation (RFQ) for TMS370C686AFNT 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 TMS370C686AFNT reliable?
The price and inventory of TMS370C686AFNT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TMS370C686AFNT is usually 5 days.
3.What payment methods are accepted for TMS370C686AFNT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TMS370C686AFNT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TMS370C686AFNT?
TMS370C686AFNT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TMS370C686AFNT 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 TMS370C686AFNT?
For technical support, including TMS370C686AFNT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TMS370C686AFNT requirements.
6.How does Aetrix verify that TMS370C686AFNT is sourced from the original manufacturer or authorized distributors?
All TMS370C686AFNT 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 TMS370C686AFNT meets industry standards.
7.What is the process for return or replacement of TMS370C686AFNT?
All TMS370C686AFNT units undergo pre-shipment inspection (PSI). If there is an issue with TMS370C686AFNT, 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 TMS370C686AFNT part is unused and in its original packaging.
Return procedure for TMS370C686AFNT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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