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STMicroelectronics M48T129V-85PM1
- Part No.:
- M48T129V-85PM1
- Manufacturer:
- STMicroelectronics
- Category:
- Real Time Clocks
- Package:
- 32-DIP Module (0.600", 15.24mm)
- Datasheet:
-
M48T129V-85PM1.pdf
- Description:
- IC RTC CLOCK/CALENDAR PAR 32DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,981
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Product details
Overview
M48T129V-85PM1 from STMicroelectronics is a self-contained, battery-backed TIMEKEEPER® SRAM integrating 128 Kbit × 8 (1 Mbit) non-volatile static RAM, real-time clock (RTC), power-fail control, lithium coin cell, and 32.768 kHz quartz crystal in a single 32-pin plastic DIP module. It operates at 3.0–3.6 V, provides BCD-coded century/year/month/day/hour/minute/second, automatic leap-year correction, and maintains data + time for ≥10 years on battery backup. Used in industrial control panels requiring persistent time-stamped logging during AC power loss.
For engineers reviewing the M48T129V-85PM1 datasheet, M48T129V-85PM1 pinout, M48T129V-85PM1 application, or M48T129V-85PM1 equivalent, key selection criteria include VPFD trip point (2.7–3.0 V), tAVQV access time (85 ns), battery-low flag (BL bit), software-controlled clock calibration, and alarm interrupt capability in battery backup mode.
Technical Context
The M48T129V-85PM1 implements a BiPORT™ dual-port architecture: external SRAM array (131,072 × 8) shares address/data bus with 16 dedicated TIMEKEEPER® registers mapped to fixed high-address locations (1FFF0h–1FFFFh). Clock updates occur once per second via internal oscillator; register reads/writes halt incrementing to prevent torn reads.
Its power management includes voltage-sense circuitry that triggers write protection when VCC drops into the 2.7–3.0 V VPFD window, then switches to internal lithium cell below VSO (~2.5 V). The watchdog timer supports reset or IRQ output, and alarm functionality compares user-programmed BCD values against live clock registers with repeat modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 128 Kbit × 8 (1 Mbit) SRAM with unlimited write cycles; directly replaces standard 128K×8 SRAMs without timing constraints. |
| Supply Voltage | 3.0–3.6 V nominal; enables compatibility with 3.3 V microcontroller systems and eliminates level-shifting requirements. |
| VPFD Range | 2.7–3.0 V; defines precise voltage window for automatic write-protection and chip deselect during brownout conditions. |
| tAVQV (Access Time) | 85 ns max; determines minimum read cycle duration for reliable interface timing with 12 MHz+ bus clocks. |
| Battery Life | ≥10 years at 25 °C; guaranteed data retention and RTC operation using integrated lithium cell-no external battery management needed. |
| Clock Accuracy | ±20 ppm typical over 0–70 °C; achieved via factory-trimmed 32.768 kHz crystal and software calibration register (1FFF8h). |
| Alarm Output | IRQ/FT pin asserts open-drain interrupt in both main power and battery backup modes; supports event-triggered wake-up. |
Pinout & Package
Package: PMDIP32 - 32-pin plastic dual in-line package, 600 mil width, through-hole mounting, RoHS-compliant lead-free interconnects.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A16 | Address Inputs | 17-bit address bus for accessing full 131,072-byte SRAM space and TIMEKEEPER® registers (1FFF0h–1FFFFh). |
| DQ0–DQ7 | Data I/O | 8-bit bidirectional data bus; supports standard SRAM read/write protocols and TIMEKEEPER® register access. |
| E | Chip Enable | Active-low enable controlling device selection; initiates read/write cycles and interacts with W/G for timing control. |
| G | Output Enable | Active-low control for data bus tristating; used with E to manage output timing and avoid bus contention during writes. |
| W | Write Enable | Active-low signal defining write cycle boundaries; must be synchronized with address stability and E timing. |
| RST | Reset Output | Open-drain reset signal asserted during power-on or watchdog timeout; requires external pull-up for system reset generation. |
| IRQ/FT | Interrupt / Frequency Test | Open-drain output for alarm interrupts or oscillator frequency test mode; active in both VCC and battery backup modes. |
| VCC | Power Supply | Main 3.0–3.6 V supply; monitored continuously for VPFD detection and automatic switchover to internal battery. |
| VSS | Ground | System reference ground; shared return path for SRAM, RTC, oscillator, and power-sense circuitry. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Crystal & Battery | Eliminates external component sourcing, layout complexity, and qualification effort for RTC subsystems. |
| Software-Controlled Calibration | Adjusts clock drift via 1FFF8h calibration register-enables ±5 ppm accuracy after field tuning without hardware change. |
| BiPORT™ Register Architecture | Separates live clock counters from user-accessible registers, enabling glitch-free reads without halting timekeeping. |
| Programmable Alarm Repeat Modes | Five RPT bits support daily, monthly, or custom periodic alarms-reducing host MCU polling overhead in energy-sensitive designs. |
| Power-On Reset (POR) | Generates valid reset pulse even during battery backup; ensures deterministic state recovery after unexpected power loss. |
Applications
| Industrial PLC HMI Panels | Medical Diagnostic Loggers |
|---|---|
Use Scenario: Persistent timestamping of operator actions and fault events during mains power interruption. IC Role / Device Role / Timing Role: TIMEKEEPER® SRAM serves as system time-of-day source and non-volatile event buffer with atomic clock + memory update. Use Value: Guarantees accurate, gap-free timestamps across power cycles-critical for FDA audit trails and regulatory compliance reporting. |
Use Scenario: Recording patient vital sign measurements with precise UTC-aligned timestamps during portable device battery discharge. IC Role / Device Role / Timing Role: Provides battery-backed RTC and storage for time-stamped waveform metadata independent of host processor state. Use Value: Enables post-hoc chronological reconstruction of clinical events without relying on host clock synchronization or network time. |
| Energy Meter Data Historians | Building Automation Controllers |
Use Scenario: Storing 15-minute interval kWh consumption data with tamper-proof timestamps during grid outages. IC Role / Device Role / Timing Role: Acts as secure, self-powered timekeeper and SRAM buffer-retaining billing-grade time stamps and usage counters. Use Value: Meets ANSI C12.1 and IEC 62056 requirements for time accuracy and data integrity under brownout/failure conditions. |
Use Scenario: Scheduling HVAC setpoint changes and occupancy-based lighting control across extended facility power failures. IC Role / Device Role / Timing Role: Maintains real-time schedule execution engine and alarm-driven actuation logic during backup power mode. Use Value: Preserves building operational continuity without external time server dependency or manual resynchronization. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery-backed RTC + SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS12887A-150+ (Maxim) | 5 V only; 200 ns access time; no software calibration; uses external crystal and battery. | Lacks 3.3 V compatibility and integrated crystal/battery-requires additional board area and qualification effort. | Select only if legacy 5 V design mandates pin-for-pin replacement and long-term DS12887A availability is confirmed. |
| M48T35-25PC1 (STMicroelectronics) | Smaller 64 Kbit × 8 SRAM; same 3.3 V VPFD range; identical pinout but reduced memory depth. | Suitable for cost-sensitive designs where 128 KB is excessive-saves PCB area but limits log buffer depth. | Choose when application requires only basic RTC + smaller non-volatile buffer and lower BOM cost is prioritized. |
Compared with M48T129V-85PM1, DS12887A-150+ demands external components and lacks calibration, while M48T35-25PC1 trades memory capacity for footprint reduction-neither matches its integrated 1 Mbit + precision RTC + 10-year battery in one DIP package.
Availability
M48T129V-85PM1 is available at Aetrix Electronics and suitable for industrial control panels, medical diagnostic loggers, and smart energy metering systems requiring stable component supply despite its "not recommended for new design" status.
Supply support for M48T129V-85PM1 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.
M48T129V-85PM1 belongs to the TIMEKEEPER® family-engineered to deliver fully integrated, drop-in RTC + non-volatile memory solutions for applications demanding guaranteed timekeeping and data retention during power loss.
FAQ
What is the function of the IRQ/FT pin?
The IRQ/FT pin is an open-drain output serving two roles: it asserts as an interrupt signal (IRQ) when alarm or watchdog conditions occur, and functions as a frequency test output (FT) when enabled via the TIMEKEEPER® register map. It remains active during battery backup mode, enabling low-power wake-up without main power, and requires an external pull-up resistor to operate correctly in either mode.
How does the M48T129V-85PM1 handle leap year calculation?
The M48T129V-85PM1 automatically corrects for 28-, 29- (leap year), 30-, and 31-day months using internal logic tied to the BCD-coded year register. Leap year adjustment is valid until year 2100 and requires no host software intervention-the RTC hardware increments date registers correctly across February boundaries without firmware involvement.
Can the internal battery be replaced?
No-the lithium button cell is hermetically sealed inside the PMDIP32 module and not user-replaceable. STMicroelectronics specifies ≥10 years of data retention and clock operation at 25 °C; end-of-life is defined by battery depletion, after which the device loses timekeeping and non-volatile memory retention capability permanently.
What happens during a power failure mid-write cycle?
If VCC drops during a WRITE cycle, data at the currently addressed SRAM location may become corrupted, but all other memory contents-including TIMEKEEPER® registers-are preserved. The power-fail circuit disables writes before VCC falls below VPFD (min), protecting the majority of stored data and ensuring clock operation continues uninterrupted on battery power.
M48T129V-85PM1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- Timekeeper®
- Package/Case:
- 32-DIP Module (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, Watchdog Timer
- Memory Size:
- -
- Time Format:
- HH:MM:SS (24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- Parallel
- Voltage - Supply:
- 3V ~ 3.6V
- Voltage - Supply, Battery:
- -
- Current - Timekeeping (Max):
- 3mA @ 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 32-PMDIP Module
M48T129V-85PM1 FAQ
1.How can I place an order for M48T129V-85PM1 through Aetrix?
Please submit a Request for Quotation (RFQ) for M48T129V-85PM1 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 M48T129V-85PM1 reliable?
The price and inventory of M48T129V-85PM1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M48T129V-85PM1 is usually 5 days.
3.What payment methods are accepted for M48T129V-85PM1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M48T129V-85PM1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M48T129V-85PM1?
M48T129V-85PM1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M48T129V-85PM1 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 M48T129V-85PM1?
For technical support, including M48T129V-85PM1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M48T129V-85PM1 requirements.
6.How does Aetrix verify that M48T129V-85PM1 is sourced from the original manufacturer or authorized distributors?
All M48T129V-85PM1 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 M48T129V-85PM1 meets industry standards.
7.What is the process for return or replacement of M48T129V-85PM1?
All M48T129V-85PM1 units undergo pre-shipment inspection (PSI). If there is an issue with M48T129V-85PM1, 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 M48T129V-85PM1 part is unused and in its original packaging.
Return procedure for M48T129V-85PM1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M48T129V-85PM1 Tags
-
MCP7940N-I/SN
Microchip Technology
-
MCP7940MT-I/MNY
Microchip Technology
-
PCF85063ATL/1,118
NXP USA Inc.
-
MCP7940NT-I/SN
Microchip Technology
-
MCP7940NT-I/MS
Microchip Technology
-
MCP7940N-I/MS
Microchip Technology
-
PCF85063AT/AY
NXP USA Inc.
-
PCF85063TP/1Z
NXP Semiconductors
-
PCF85063ATT/AJ
NXP USA Inc.
-
MCP7940NT-E/SN
Microchip Technology
-
MCP7940NT-I/MNY
Microchip Technology
-
MCP79400T-I/SN
Microchip Technology
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