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STMicroelectronics M48T35Y-70MH1F
- Part No.:
- M48T35Y-70MH1F
- Manufacturer:
- STMicroelectronics
- Category:
- Real Time Clocks
- Package:
- 28-SOP (0.350", 8.89mm Width) with SNAPHAT Sockets
- Datasheet:
-
M48T35Y-70MH1F.pdf
- Description:
- IC RTC CLK/CALENDAR PAR 28SOH
- Quantity:
- Payment:
- Shipping:
Inventory:1,093
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Product details
Overview
M48T35Y-70MH1F from STMicroelectronics is a 5 V, 256 Kbit (32 Kb × 8) non-volatile TIMEKEEPER® SRAM integrating ultra-low-power static RAM, real-time clock, power-fail control circuitry, and on-board lithium battery + 32.768 kHz crystal in a CAPHAT™ DIP-28 package. It delivers BCD-coded timekeeping (year/month/day/hour/minute/second), automatic leap-year correction, frequency test output, and VPFD-triggered write protection. Used in industrial control panels requiring persistent time-stamped logging during mains failure.
For engineers reviewing the M48T35Y-70MH1F datasheet, M48T35Y-70MH1F pinout, M48T35Y-70MH1F application, or M48T35Y-70MH1F equivalent, this page provides verified timing accuracy (±35 ppm at 25 °C, improved to +1/–2 ppm with calibration), battery-backed data retention (>7 years), JEDEC 32 Kb × 8 SRAM compatibility, and CAPHAT™ mechanical integration details - all critical for legacy system replacement and long-life embedded design.
Technical Context
The M48T35Y-70MH1F integrates a BiPORT™ SRAM array and quartz oscillator on a single die, with clock registers mapped to upper memory addresses (7FF8h–7FFFh) for byte-wide access via standard SRAM read/write cycles. Its voltage-sense circuit monitors VCC against VPFD (4.2–4.5 V) to trigger automatic write protection and battery switchover at VSO.
Timekeeping uses BCD-encoded registers updated once per second by dedicated clock chain logic; the STOP bit (MSB of seconds register) halts oscillation for shelf storage, and five calibration bits (D4–D0 in 7FF8h) enable ±31-count periodic correction at the ÷256 stage to achieve <±2 ppm accuracy at 25 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 32 Kb × 8 (256 Kbit), JEDEC-compatible SRAM interface |
| Real-time clock | 32.768 kHz crystal oscillator with BCD year/month/day/hour/minute/second registers |
| Accuracy | ±35 ppm at 25 °C (±1.53 min/month); +1/–2 ppm with calibration bits |
| Power-fail threshold | VPFD = 4.2–4.5 V; VSO = battery switchover voltage (exact value device-specific) |
| Data retention | >7 years on internal lithium cell during VCC loss |
| Access time | 70 ns READ/WRITE cycle time (tAVAV), compatible with 14 MHz bus timing |
| Operating voltage | VCC = 4.5–5.5 V, supporting standard 5 V TTL/CMOS systems |
Pinout & Package
Package: 28-pin plastic DIP (PCDIP28), 600 mil width, with integrated CAPHAT™ housing containing lithium button cell and 32.768 kHz crystal.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address inputs | 15-bit address bus for 32 Kb addressing (0000h–7FFFh) |
| DQ0–DQ7 | Data I/O | Bi-directional 8-bit data bus; accesses SRAM and clock registers (7FF8h–7FFFh) |
| E | Chip enable | Active-low chip select; enables memory access and controls power-fail detection timing |
| G | Output enable | Active-low output control; places DQ lines in high-Z when inactive |
| W | Write enable | Active-low WRITE control; initiates SRAM write or clock register update |
| VCC | Supply voltage | 5 V main supply; monitored for VPFD/VSO thresholds to manage battery backup |
| VSS | Ground | Reference return path for both SRAM and clock circuits |
Key Features
| Feature | Design Value |
|---|---|
| Integrated CAPHAT™ package | Self-contained 28-pin DIP with battery and crystal eliminates external components and layout complexity |
| BYTEWIDE™ clock access | Time registers mapped to standard SRAM addresses (7FF8h–7FFFh), enabling direct CPU read/write without custom I²C/SPI drivers |
| Automatic leap-year correction | Hardware-level date logic handles 28/29/30/31-day months through 2100 without firmware intervention |
| Calibration circuitry | Five-bit programmable correction (0–31 counts) adjusts oscillator division at ÷256 stage for <±2 ppm accuracy |
| Power-fail write protection | Voltage-sense circuit asserts high-Z outputs and disables writes within VPFD window (4.2–4.5 V), preventing corruption during brownout |
Applications
| Industrial PLC Data Logger | Medical Device Timestamping |
|---|---|
|
Use Scenario: Standalone programmable logic controller logs sensor events with precise timestamps during AC mains interruption. IC Role / Device Role / Timing Role: Non-volatile SRAM stores event buffers while integrated RTC maintains accurate wall-clock time using internal battery during power loss. Use Value: Eliminates need for external RTC + backup capacitor + EEPROM, reducing BOM count and ensuring timestamp continuity across >7-year maintenance cycles. |
Use Scenario: Portable infusion pump records drug delivery start/stop times and error events for regulatory audit trails. IC Role / Device Role / Timing Role: TIMEKEEPER® provides tamper-resistant, battery-backed BCD time/date stamps synchronized to UTC via factory calibration. Use Value: Meets IEC 62304 Class C software requirements for time-critical medical data integrity without external clock synchronization hardware. |
| Legacy POS Terminal Upgrade | Energy Meter Time-of-Use Billing |
|
Use Scenario: Retrofit of aging point-of-sale terminals requires drop-in replacement for obsolete SRAM+RTC modules with identical pinout. IC Role / Device Role / Timing Role: Pin- and function-compatible JEDEC 32 Kb × 8 SRAM with embedded RTC replaces discrete solutions while retaining existing PCB layout. Use Value: Enables field upgrade without redesign; CAPHAT™ DIP-28 fits original socket, preserving mechanical compatibility and reducing certification effort. |
Use Scenario: Smart electricity meter applies time-of-use tariffs based on utility-defined periods (e.g., peak/off-peak) requiring decade-grade time accuracy. IC Role / Device Role / Timing Role: RTC maintains calendar time with century bit support and ±2 ppm calibrated accuracy to ensure tariff period alignment over 15+ years. Use Value: Avoids revenue leakage from timing drift; built-in calibration eliminates need for periodic manual recalibration or external GPS sync. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar non-volatile timekeeping SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS12887A-IND+ | 5 V, 128 Kbit (16 Kb × 8) NV SRAM + RTC; uses external lithium battery; no integrated crystal; 24-pin DIP | Lacks CAPHAT™ integration - requires separate crystal and battery footprint; lower memory density | Select if board space allows discrete battery/crystal placement and legacy 24-pin socket reuse is mandatory |
| M48T59Y-70MH1F | 5 V, 512 Kbit (64 Kb × 8) variant with identical CAPHAT™ DIP-28 package and enhanced power-fail logic (VPFD = 4.25–4.55 V) | Higher memory capacity supports larger event buffers; same pinout but not memory-mapped compatible due to extended address range | Select when application requires >32 Kb non-volatile storage alongside RTC, and PCB layout accommodates full 64 Kb addressing |
Compared with DS12887A-IND+, M48T35Y-70MH1F reduces component count and improves long-term reliability via integrated CAPHAT™; versus M48T59Y-70MH1F, it offers optimal cost/performance balance for 32 Kb–constrained legacy designs without sacrificing timekeeping fidelity or battery life.
Availability
M48T35Y-70MH1F is available at Aetrix Electronics and suitable for industrial control panels, medical data loggers, legacy POS terminals, and smart energy meters requiring stable component supply across extended product lifecycles.
Supply support for M48T35Y-70MH1F 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, MEMS, and power management devices for automotive, industrial, and consumer markets.
The TIMEKEEPER® product line delivers integrated non-volatile SRAM + RTC solutions targeting applications needing guaranteed time/date persistence during power loss - especially in industrial automation, medical instrumentation, and infrastructure monitoring.
FAQ
What is the battery lifetime under continuous backup conditions?
The internal lithium button cell in the CAPHAT™ package sustains SRAM and RTC operation for a minimum of 7 years when VCC remains below VSO. This rating assumes typical operating temperature (25 °C) and accounts for self-discharge; actual endurance may extend beyond 10 years in cooler environments per STMicroelectronics AN1012.
How does the M48T35Y-70MH1F handle century rollover in year 2100?
It implements century bit (CB) control via the CENTURY ENABLE bit (CEB) in register 7FFCh. When CEB = 1, CB toggles at each century transition (e.g., 2099→2100); when CEB = 0, CB remains static. The device supports leap-year correction through 2100, and application note AN923 details initialization procedures for Y2100 compliance.
Can the crystal oscillator be disabled to conserve battery during storage?
Yes - the STOP bit (D7 of seconds register 7FFFh) halts the 32.768 kHz oscillator immediately. The device ships with STOP = 1. Clearing this bit resumes oscillation within 1 second. This feature reduces battery drain during shelf storage without affecting SRAM data retention.
Is the M48T35Y-70MH1F RoHS compliant and lead-free?
Yes - it meets RoHS Directive 2011/65/EU requirements with lead-free second-level interconnects. The CAPHAT™ DIP-28 package uses matte tin plating on leads, and all materials comply with STMicroelectronics' environmental specifications as documented in the "Environmental information" section (page 26) of datasheet Doc ID 2611 Rev 10.
M48T35Y-70MH1F Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- Timekeeper®
- Package/Case:
- 28-SOP (0.350", 8.89mm Width) with SNAPHAT Sockets
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Leap Year
- 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):
- 2mA @ 4.75V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 28-SOH
M48T35Y-70MH1F FAQ
1.How can I place an order for M48T35Y-70MH1F through Aetrix?
Please submit a Request for Quotation (RFQ) for M48T35Y-70MH1F 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 M48T35Y-70MH1F reliable?
The price and inventory of M48T35Y-70MH1F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M48T35Y-70MH1F is usually 5 days.
3.What payment methods are accepted for M48T35Y-70MH1F?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M48T35Y-70MH1F transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M48T35Y-70MH1F?
M48T35Y-70MH1F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M48T35Y-70MH1F 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 M48T35Y-70MH1F?
For technical support, including M48T35Y-70MH1F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M48T35Y-70MH1F requirements.
6.How does Aetrix verify that M48T35Y-70MH1F is sourced from the original manufacturer or authorized distributors?
All M48T35Y-70MH1F 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 M48T35Y-70MH1F meets industry standards.
7.What is the process for return or replacement of M48T35Y-70MH1F?
All M48T35Y-70MH1F units undergo pre-shipment inspection (PSI). If there is an issue with M48T35Y-70MH1F, 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 M48T35Y-70MH1F part is unused and in its original packaging.
Return procedure for M48T35Y-70MH1F:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M48T35Y-70MH1F 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 USA Inc.
-
PCF85063ATT/AJ
NXP USA Inc.
-
MCP7940NT-E/SN
Microchip Technology
-
MCP7940NT-I/MNY
Microchip Technology
-
MCP79400T-I/SN
Microchip Technology
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