STMicroelectronics M4T28-BR12SH1

Overview

M4T28-BR12SH from STMicroelectronics is a 4-pin SNAPHAT® top module integrating a 48 mAh lithium carbon monofluoride (Li(CF)) battery and 32.768 kHz crystal, designed to snap onto 28-pin SOIC real-time clock (RTC) or TIMEKEEPER® ICs after surface-mount assembly. It provides backup power and timing reference while avoiding thermal exposure during reflow. Used in industrial control panels requiring long-term data retention and accurate timekeeping under ambient temperatures of 0–70°C.

For engineers reviewing the M4T28-BR12SH datasheet, M4T28-BR12SH pinout, M4T28-BR12SH application, or M4T28-BR12SH equivalent, key selection factors include battery capacity (48 mAh), crystal load capacitance (12.5 pF), nominal voltage (2.8 V), mechanical retention force (>100 g shock resistance), and UL Component Recognition (E89556).

Technical Context

The M4T28-BR12SH is a passive, two-piece mechanical-electrical interface that delivers power and timing to companion SOIC-packaged RTC/Timekeeper ICs (e.g., M41Txx series). It contains no active circuitry - all functionality relies on physical mating with gold-plated press-fit sockets on the host SOIC.

Its four-pin interface supplies VBAT+ and VBAT− for backup power and connects X1/X2 terminals to the integrated 32.768 kHz tuning-fork crystal. Contact reliability is ensured by six independent contact fingers per socket and molded retaining clips enabling >100 g mechanical shock survivability.

Key Specifications

Pinout & Package

The M4T28-BR12SH is a 4-pin SNAPHAT® housing (SH package) with molded plastic body and gold-plated press-fit pins. Dimensions: 21.08–21.84 mm length × 14.22–14.99 mm width × 9.78 mm height (typical), compliant with ECOPACK® environmental standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RTC backup power and crystal integration applications.

Compared with M4T32-BR12SH, the M4T28-BR12SH offers lower cost and smaller width for commercial-temperature applications, while DS12CR887+DS3231SN trades modularity and thermal resilience for higher timing precision and reduced component count.

Availability

M4T28-BR12SH is available at Aetrix Electronics and suitable for industrial PLCs, medical infusion pumps, smart energy meters, and point-of-sale terminals requiring stable component supply with field-serviceable backup power and timing.

Supply support for M4T28-BR12SH 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 microcontrollers, analog ICs, MEMS, and power devices for industrial, automotive, and consumer markets.

The M4T28-BR12SH belongs to ST's TIMEKEEPER® accessory product line, engineered specifically to extend RTC functionality through thermally isolated, modular backup power and crystal integration - targeting high-reliability embedded systems where solder-process survivability and long-term serviceability are critical.

FAQ

Can the M4T28-BR12SH be wave-soldered with the host SOIC?

No. Wave soldering the assembled SNAPHAT® top onto the SOIC will damage the battery and crystal due to excessive heat exposure. The SNAPHAT must be snapped onto the PCB-mounted SOIC only after all surface-mount reflow processes are complete. ST explicitly cautions against wave soldering in Section 2 and 4.4 of the datasheet.

What is the maximum insertion force recommended for the M4T28-BR12SH?

ST specifies a maximum insertion force of 40 pounds (178 N) to avoid battery damage or die cracking. Average insertion force measured is <13 pounds, and Figure 2 shows force stabilizes after 4–5 insertions. Manual presses must be calibrated to enforce this limit, as exceeding it risks irreversible mechanical failure.

Does the M4T28-BR12SH require external load capacitors for the crystal?

No. The integrated 32.768 kHz crystal is pre-matched to 12.5 pF load capacitance, matching standard RTC oscillator input requirements. No external capacitors are needed - the crystal and its load network are fully contained within the SNAPHAT housing and electrically optimized for direct connection to compatible SOIC RTCs like the M41Txx series.

How is battery disposal handled for the M4T28-BR12SH?

The unit contains a non-rechargeable lithium carbon monofluoride (Li(CF)) button cell. Per Section 7 of the datasheet, it must be recycled or disposed of per local/national regulations and the battery manufacturer's instructions. It contains no mercury, cadmium, or lead, and carries ST's ECOPACK® environmental compliance marking.