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STMicroelectronics M48T18-100PC1
- Part No.:
- M48T18-100PC1
- Manufacturer:
- STMicroelectronics
- Category:
- Real Time Clocks
- Package:
- 28-DIP Module (0.600", 15.24mm)
- Datasheet:
-
M48T18-100PC1.pdf
- Description:
- IC RTC CLK/CALENDAR PAR 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,641
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Product details
Overview
M48T18-100PC1 from STMicroelectronics is a 5 V, 64 Kbit (8 Kb × 8) non-volatile TIMEKEEPER® SRAM integrating ultra-low-power static RAM, real-time clock, power-fail control circuitry, and on-board lithium battery and crystal in a CAPHAT™ DIP package. It provides BYTEWIDE™ RAM-like access to BCD-coded time/date registers (year, month, day, date, hours, minutes, seconds), delivers ±1 minute/month clock accuracy at 25 °C, and features automatic WRITE protection during power failure. It is used in industrial control panels requiring persistent timekeeping and data retention during mains loss.
For engineers reviewing the M48T18-100PC1 datasheet, M48T18-100PC1 pinout, M48T18-100PC1 application, or M48T18-100PC1 equivalent, key selection criteria include VPFD voltage window (4.2–4.5 V), battery-backed data retention ≥10 years, CAPHAT™ DIP mechanical integration, and compatibility with DS1643 and JEDEC 8 K × 8 SRAM sockets.
Technical Context
The M48T18-100PC1 integrates a 32.768 kHz quartz oscillator, BiPORT™ dual-port memory architecture, and voltage-sense switching circuitry on a single die. Its clock chain updates eight dedicated SRAM locations (1FF8h–1FFFh) once per second with BCD-formatted time data, while the SRAM array operates as standard 8 K × 8 asynchronous static RAM under normal VCC.
Power management includes a two-threshold detection system: VPFD (4.2–4.5 V) triggers automatic chip deselect and WRITE protection, and VSO (typ. 4.25 V) initiates seamless switchover to internal lithium battery. The open-drain INT pin asserts within 10–40 µs of VCC crossing VPFD, enabling host MCU power-fail response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 64 Kbit (8 K × 8) SRAM with non-volatile retention via integrated battery |
| Supply voltage | 4.5 V to 5.5 V - defines operating range and VPFD window (4.2–4.5 V) |
| Clock accuracy | ±1 minute/month at 25 °C - enables long-term timestamping without external calibration |
| Access time | 100 ns max - supports direct replacement in 8 K × 8 SRAM sockets without timing redesign |
| Data retention | ≥10 years on internal battery - eliminates need for external backup power design |
| Package | PCDIP28 CAPHAT™ - integrates crystal and 48 mAh lithium cell in single through-hole DIP |
| Pin compatibility | JEDEC-standard 8 K × 8 SRAM and DS1643 - allows drop-in replacement in legacy designs |
Pinout & Package
The M48T18-100PC1 is housed in a 28-pin plastic DIP (PCDIP28) with integrated CAPHAT™ top containing the lithium battery and 32.768 kHz crystal. This self-contained mechanical package eliminates external backup components and simplifies PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address inputs | 13-bit address bus for accessing 8,192 memory locations or clock registers (1FF8h–1FFFh) |
| DQ0–DQ7 | Data I/O | Bi-directional 8-bit data bus supporting BYTEWIDE™ read/write of SRAM and clock registers |
| E1, E2 | Chip enable inputs | Active-low (E1) and active-high (E2) dual CE logic enabling JEDEC-compliant timing control |
| G | Output enable | Three-state control for data bus; high-Z during WRITE to prevent contention |
| W | WRITE enable | Active-low signal initiating WRITE cycles; must be synchronized with E1/E2 per AC specs |
| INT | Open-drain interrupt | Asserts on VCC drop into VPFD window; requires external pull-up for host MCU notification |
| VCC, VSS | Power supply | 5 V supply and ground; internal voltage sense circuit monitors VCC for power-fail detection |
Key Features
| Feature | Design Value |
|---|---|
| Integrated CAPHAT™ package | Combines silicon, crystal, and battery in one PCDIP28 unit - eliminates socket redesign and external component sourcing |
| BYTEWIDE™ clock access | Time/date stored in standard SRAM addresses (1FF8h–1FFFh) - enables use of existing memory-mapped read/write routines |
| Software-controlled calibration | Control register bit adjusts oscillator trim - supports high-accuracy applications without hardware modification |
| Automatic power-fail protection | VPFD-triggered WRITE disable and high-Z outputs - prevents corruption during brownout without firmware intervention |
| Leap-year compensation | Hardware correction for 28/29/30/31-day months - ensures accurate calendar operation through year 2100 |
Applications
| Industrial HMI Panels | Energy Metering Systems |
|---|---|
Use Scenario: Embedded panel displays requiring persistent timestamps for event logging and firmware update tracking across power cycles. IC Role / Device Role / Timing Role: Non-volatile timekeeper and data buffer - maintains RTC and stores last-boot configuration in same device. Use Value: Eliminates separate RTC + EEPROM design; reduces BOM count and PCB area while guaranteeing time continuity during grid outages. | Use Scenario: Smart electricity meters needing tamper-proof time-stamped consumption records for billing compliance. IC Role / Device Role / Timing Role: Secure time source and metering data cache - clocks energy pulses and buffers readings during communication latency. Use Value: Internal battery-backed retention meets IEC 62053-21 requirements for 10-year data integrity without external supercapacitors. |
| Medical Diagnostic Equipment | Building Automation Controllers |
Use Scenario: Portable ultrasound or patient monitors requiring FDA-compliant audit trails with precise timestamps for clinical events. IC Role / Device Role / Timing Role: Certified time reference and session log storage - synchronizes sensor sampling and stores diagnostic metadata. Use Value: Hardware-enforced write protection during power loss ensures regulatory traceability; BCD format simplifies timestamp parsing in safety-critical firmware. | Use Scenario: HVAC controllers logging temperature setpoints, occupancy schedules, and alarm history across seasonal power interruptions. IC Role / Device Role / Timing Role: Calendar-aware scheduler and fault log keeper - drives weekly programming and retains error codes for maintenance diagnostics. Use Value: Leap-year handling and decade-long battery life eliminate service visits for clock battery replacement in inaccessible ceiling-mounted units. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock + non-volatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS1643-100+ (Maxim Integrated) | Same pinout and function but uses external battery; no integrated crystal; wider VPFD (4.5–4.75 V) | Requires separate crystal and battery holder; less compact than CAPHAT™ solution | Select when board space allows discrete backup components and higher VPFD threshold is needed for noisy 5 V rails |
| M48T35Y-100PC1 (STMicroelectronics) | Higher density (256 Kbit), same CAPHAT™ DIP package; identical VPFD and clock accuracy | Provides extended memory for larger event logs; same footprint and thermal profile | Select when future firmware growth demands >8 KB non-volatile storage without changing PCB layout |
Compared with DS1643-100+, M48T18-100PC1 reduces bill-of-materials and assembly steps via integrated crystal/battery; compared with M48T35Y-100PC1, it offers optimal cost/performance balance for applications needing only 8 KB of persistent memory.
Availability
M48T18-100PC1 is available at Aetrix Electronics and suitable for industrial HMI panels, energy metering systems, and medical diagnostic equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant through-hole packaging.
Supply support for M48T18-100PC1 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 designing and manufacturing microcontrollers, analog ICs, and memory solutions for industrial, automotive, and consumer applications.
The TIMEKEEPER® product line targets applications demanding autonomous, battery-backed timekeeping and data retention - optimized for reliability in mains-powered systems subject to intermittent outages.
FAQ
What is the battery lifetime specification for M48T18-100PC1 under continuous backup conditions?
The internal lithium button cell guarantees ≥10 years of data and clock retention when VCC remains below the switchover voltage (VSO). This rating assumes typical operating temperature (25 °C) and accounts for self-discharge; actual field life may extend beyond 12 years in cooler environments. Battery capacity is fixed at 48 mAh and not user-replaceable.
How does the M48T18-100PC1 handle leap years and month-end date rollovers?
Hardware logic automatically corrects for 28-, 29- (leap year), 30-, and 31-day months without firmware intervention. The calendar engine is validated through year 2100 and requires no software updates. Date rollover occurs at midnight, and the seconds register increments continuously - ensuring accurate time progression across all calendar anomalies.
Can the INT pin be left unconnected if power-fail interrupt functionality is not used?
No - the INT pin is an open-drain output requiring an external pull-up resistor even when unused. Leaving it floating risks noise-induced false interrupts and violates the device's electrical specification. A 4.7 kΩ pull-up to VCC is recommended per STMicroelectronics' application guidance to ensure stable high-Z state during normal operation.
Is the M48T18-100PC1 compatible with 3.3 V systems?
No - the M48T18-100PC1 is strictly a 5 V device with VCC operating range of 4.5 V to 5.5 V. Its VPFD window (4.2–4.5 V) and internal voltage detection circuitry are designed for 5 V rail monitoring. Interfacing with 3.3 V logic requires level-shifting on all address, data, and control lines, and is not supported by the manufacturer for reliable operation.
M48T18-100PC1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- Timekeeper®
- Package/Case:
- 28-DIP Module (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Leap Year, Watchdog Timer
- Memory Size:
- -
- Time Format:
- HH:MM:SS (24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- Parallel
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Supply, Battery:
- -
- Current - Timekeeping (Max):
- 3mA @ 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Through Hole
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 28-PCDIP, CAPHAT®
M48T18-100PC1 FAQ
1.How can I place an order for M48T18-100PC1 through Aetrix?
Please submit a Request for Quotation (RFQ) for M48T18-100PC1 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 M48T18-100PC1 reliable?
The price and inventory of M48T18-100PC1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M48T18-100PC1 is usually 5 days.
3.What payment methods are accepted for M48T18-100PC1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M48T18-100PC1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M48T18-100PC1?
M48T18-100PC1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M48T18-100PC1 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 M48T18-100PC1?
For technical support, including M48T18-100PC1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M48T18-100PC1 requirements.
6.How does Aetrix verify that M48T18-100PC1 is sourced from the original manufacturer or authorized distributors?
All M48T18-100PC1 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 M48T18-100PC1 meets industry standards.
7.What is the process for return or replacement of M48T18-100PC1?
All M48T18-100PC1 units undergo pre-shipment inspection (PSI). If there is an issue with M48T18-100PC1, 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 M48T18-100PC1 part is unused and in its original packaging.
Return procedure for M48T18-100PC1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M48T18-100PC1 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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