Texas Instruments TMS370C156AFNT

Overview

TMS370C156AFNT from Texas Instruments is an 8-bit CMOS microcontroller with OTP EPROM program memory (16 KB), 512-byte data EEPROM, 512-byte RAM, eight-channel 8-bit ADC, dual 16-bit timers, SCI and SPI interfaces, and 24-bit watchdog timer - used in automotive engine control units and industrial motor controllers.

For engineers reviewing the TMS370C156AFNT datasheet, TMS370C156AFNT pinout, TMS370C156AFNT application, or TMS370C156AFNT equivalent, this page delivers verified electrical specs, package mapping (68-pin PLCC), functional pin roles, real-world use cases, and two validated alternative parts for legacy design continuity and supply assurance.

Technical Context

The TMS370C156AFNT implements a register-to-register architecture with no accumulator requirement, enabling direct arithmetic between any two general-purpose registers. It supports both microcomputer (single-chip) and microprocessor (external bus) operating modes selected via the MC pin.

Its clock system offers PLL-based divide-by-1 (2–5 MHz SYSCLK) or crystal-based divide-by-4 (0.5–5 MHz SYSCLK) operation. Memory expansion uses non-multiplexed 16-bit address and 8-bit data buses with five independent chip-select outputs (CSE1/CSE2/CSH1/CSH2/CSH3) and WAIT signal support for asynchronous peripheral interfacing.

Key Specifications

Pinout & Package

68-pin plastic leaded chip carrier (PLCC) package with 46 bidirectional I/O pins, 9 dedicated input pins, and separate VCC/VSS domains for digital core (VCC1/VSS1), I/O (VCC2/VSS2), and ADC (VCC3/VSS3).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with TMS370C156AFNT, TMS370C356AFNT replaces OTP EPROM with mask ROM for cost efficiency at scale, while TMS370C256AFNT is a functionally identical alternate with matching memory configuration and timing - both preserve the same 68-pin PLCC footprint and peripheral register set.

Availability

TMS370C156AFNT is available at Aetrix Electronics and suitable for automotive ECU designs, industrial motor controllers, telecom supervisory modules, and consumer appliance main control boards requiring stable component supply across extended product lifecycles.

Supply support for TMS370C156AFNT 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and power management ICs for industrial, automotive, and communications markets.

The TMS370Cx5x family was designed for cost-sensitive, real-time embedded control in harsh environments - integrating OTP EPROM, ADC, timers, and serial interfaces into a single 8-bit MCU optimized for automotive and industrial motor control.

FAQ

What is the memory configuration of the TMS370C156AFNT?

The TMS370C156AFNT features 16 KB of OTP EPROM program memory, 512 bytes of on-chip RAM, and 512 bytes of data EEPROM. It has no on-chip ROM or mask-programmed memory. This configuration supports firmware updates only during initial programming - making it ideal for low-volume production runs where mask ROM NRE costs are prohibitive. The TMS370C156AFNT does not include external memory expansion circuitry by default but supports it via software-configurable Port D pins.

Does the TMS370C156AFNT support PLL-based clock multiplication?

Yes, the TMS370C156AFNT supports PLL-based clock generation through its divide-by-1 mode, delivering SYSCLK frequencies from 2 MHz to 5 MHz when driven by an external crystal or clock source. This mode bypasses the internal divide-by-4 oscillator path and enables higher throughput for time-critical tasks like PWM generation and ADC sampling. The PLL is enabled automatically when the MC pin is asserted high during reset sequence, and its stability is monitored by the on-chip oscillator fault circuit.

How many ADC channels does the TMS370C156AFNT provide, and what is their resolution?

The TMS370C156AFNT integrates a single eight-channel 8-bit analog-to-digital converter (ADC1) with inputs AN0 through AN7. Each channel provides 8-bit resolution (0–255 counts) referenced to VCC3 and VSS3. AN1–AN7 can also serve as positive reference inputs, allowing ratiometric measurements. The ADC supports software-triggered conversions with conversion times dependent on SYSCLK frequency - typically under 25 µs at 5 MHz SYSCLK - and stores results in dedicated data registers accessible via memory-mapped I/O.

Can the TMS370C156AFNT operate in low-power modes, and how are they controlled?

Yes, the TMS370C156AFNT supports two hardware-controlled low-power modes: STANDBY and HALT. STANDBY stops CPU execution but maintains oscillator and timer operation, allowing wake-up via interrupts. HALT stops all clocks including the oscillator and timers, retaining only RAM and register contents. Both modes are entered via software instruction (STOP) and exited by interrupt or RESET assertion. The TMS370C156AFNT's low-power capability is validated across −40°C to +85°C, making it suitable for battery-powered telemetry nodes and energy-conscious industrial sensors.

What package type and pin count does the TMS370C156AFNT use?

The TMS370C156AFNT is packaged in a 68-pin plastic leaded chip carrier (PLCC) with J-lead geometry, designated by the "FNT" suffix. It provides 46 bidirectional I/O pins, 9 dedicated input pins, and multiple VCC/VSS pairs for digital core, I/O, and ADC domains. The PLCC-68 footprint is compatible with industry-standard sockets and reflow profiles, and its thermal characteristics support operation up to +85°C ambient. Pin compatibility is maintained across the TMS370Cx56 subfamily, including TMS370C256AFNT and TMS370C356AFNT.