M4T28-BR12SH1 - 48mAh SNAPHAT Lithium Battery + 32.768 kHz Crystal | STMicroelectronics
料号： M4T28-BR12SH1 ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $5.92 | $5.92 |
| 10 | $5.34 | $53.40 |
| 100 | $4.72 | $472.00 |
| 500 | $4.18 | $2,090.00 |
| 1,000 | $3.65 | $3,650.00 |
M4T28-BR12SH1 概述
A lithium coin-cell backup battery is a primary (non-rechargeable) lithium cell that keeps volatile memory and real-time clock registers alive when the system main rail collapses; for non-volatile SRAM supervisors and RTCs it sits in the same supply hierarchy as a coin cell, a supercap-backed supply, and a buck/boost hold-up rail. In the TIMEKEEPER family the SNAPHAT module also carries the 32.768 kHz tuning-fork crystal so that the combined Battery+Crystal pair forms a complete timekeeping sub-assembly — the IC underneath just exposes a top-of-package cavity that the SNAPHAT clips into.
Key features include a 48 mAh nominal capacity with lithium chemistry (long-shelf-life primary cell), an integrated 32.768 kHz crystal specified for 12.5 pF load capacitance, a typical operating voltage of 2.8 V and a detachable SNAPHAT housing that allows board-level assembly of the SOIC base before the lithium part is added. ST publishes a multi-year backup time figure and an estimated self-discharge shelf life at +25 °C so the engineer can size RTC retention against product life.
Inside the SNAPHAT housing, the lithium coin cell is connected through the SOIC pinout's Vbat/RET pins while the crystal ties to the RTC's oscillator pins; the SNAPHAT body itself provides the mechanical alignment and the battery contact springs. Because the same SNAPHAT accepts both M4T28-BR12SH1 and M4T32-BR12SH1 variants, the top is reusable across ST's 28- and 44-pin TIMEKEEPERS with no board change.
Typical applications are RTC + NVRAM backup in industrial controllers, point-of-sale terminals, metering and data-logging equipment, medical instruments needing tamper-proof time, and any system where the lithium cell must be replaced without re-flowing the base SOIC IC. The M4T28-BR12SH1 is the matching SNAPHAT for the M48T201, M48T58, M48T35 and M48T08/18 TIMEKEEPER family.
Design consideration: do not expose the SNAPHAT to reflow temperatures above +220 °C — it must be snapped on only after the SOIC base has been soldered. Storage below +30 °C and low humidity extends shelf life, and polarity on the SNAPHAT must match the SOIC base markings to avoid reverse-charging the lithium cell.
This page consolidates distributor pricing, exact SNAPHAT specifications, drop-in alternatives from the M4Txx-BR12SH family, and design guidance that supplements the STMicroelectronics datasheet — synthesized for engineers who must select, source, and qualify a TIMEKEEPER battery+crystal module quickly.
直接替换替代料： M4T28-BR12SH1 ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
M4T32-BR12SH1
✅ 直接替换📋 参考替代料（不在目录中）
M4T28-BR12SH
✅ 直接替换📋 参考替代料（不在目录中）
M4T32-BR12SH
✅ 直接替换📋 参考替代料（不在目录中）
M4T28-BR12SH1 最大额定值与电气特性
| Battery Chemistry | Lithium (primary, non-rechargeable) |
| Nominal Capacity | 48 mAh |
| Nominal Voltage | 2.8 V |
| Integrated Crystal Frequency | 32.768 kHz |
| Crystal Load Capacitance | 12.5 pF |
| Housing Type | SNAPHAT® (detachable top) |
| Compatible Base Package | SOIC-28 and SOIC-44 TIMEKEEPER® cavities |
| 工作温度 | -40 °C to +85 °C |
| Storage Temperature | -55 °C to +125 °C (recommended ≤ +30 °C for shelf life) |
| Self-Discharge (estimated, +25 °C) | ~1 % per year |
| Mounting Method | Snap-on (post-reflow) |
| Compatible TIMEKEEPER Family | M48T201, M48T58, M48T35, M48T08, M48T18 |
| RoHS 状态 | Compliant |
| Lead-Free | Yes |
| MSL 等级 | 1 (unlimited floor life once snapped) |
M4T28-BR12SH1 soic-28 and soic-44 timekeeper® cavities 引脚配置指南
M4T28-BR12SH1（soic-28 and soic-44 timekeeper® cavities 封装）的引脚配置。 该数字 IC 包含 GPIO、通信接口（UART、SPI、I2C）和电源引脚。请参阅制造商数据手册以了解复用引脚功能和配置选项。对嵌入式系统设计和 PCB 布局至关重要。
暂无详细引脚数据： M4T28-BR12SH1.
请参阅 数据手册 以查看完整引脚配置。
典型应用
M4T28-BR12SH1 适用于 6 应用s: Industrial Controller RTC + NVRAM Backup, Point-of-Sale Terminal Time & Audit Log Backup, Energy Metering and Data-Logger Hold-Up, Medical Instrument Time-Stamping, Telecom / Networking Equipment RTC Backup, Security / Surveillance DVR Timestamp.
Industrial Controller RTC + NVRAM Backup
The M4T28-BR12SH1 is the SNAPHAT® top supplied as the OEM battery+crystal for ST's M48T201, M48T58, M48T35, M48T08 and M48T18 TIMEKEEPER® base ICs used in PLCs, motor drives and industrial HMIs. With a 48 mAh lithium cell and a tight-tolerance 32.768 kHz crystal at 12.5 pF load, the SNAPHAT keeps the RTC accurate within ±5 ppm and retains NVRAM (typically 44 to 256 Kbytes) for 3-5 years at +25 °C. According to the ST datasheet the SOIC base handles Vcc-to-Vbat switchover in hardware, so the MCU wakes up with a valid wall-clock timestamp after a brown-out — no firmware timekeeping recovery is required after power loss.
推荐
Point-of-Sale Terminal Time & Audit Log Backup
POS terminals need tamper-evident real-time clocks and audit-log retention that survives main-power loss and tamper-switch events. The M4T28-BR12SH1 SNAPHAT supplies 48 mAh of lithium backup at 2.8 V and a matched 32.768 kHz / 12.5 pF crystal so that the M48T35 / M48T201 base IC keeps the secure audit log timestamped correctly across power cycles. The detachable SNAPHAT also lets service shops swap the lithium cell without re-soldering the base SOIC, simplifying field maintenance. According to ST application notes, the SNAPHAT's hardware battery-low flag alerts the terminal ahead of end-of-life so the merchant is warned before backup integrity is compromised.
推荐
Energy Metering and Data-Logger Hold-Up
Electricity, gas and water meters must retain time-stamped interval data across AC-line disturbances to support billing, demand-response and tamper detection. The M4T28-BR12SH1 provides a 48 mAh lithium hold-up source and 32.768 kHz crystal for the M48T18 / M48T08 TIMEKEEPER base IC, keeping the meter's RTC and NVRAM alive for the multi-year battery-replacement interval typical of utility-meter deployments. The SNAPHAT housing supports factory-precalibrated crystal loading and field battery replacement, both of which meter manufacturers cite as cost advantages. Compared to a discrete coin-cell holder, the M4T28-BR12SH1 cuts PCB area by roughly 60 % and avoids vibration-loosening of mechanical contacts.
推荐
Medical Instrument Time-Stamping
Patient monitors, infusion pumps and laboratory analyzers require audit-grade time stamping for regulatory compliance (FDA 21 CFR Part 11, EU MDR). Pairing the M4T28-BR12SH1 SNAPHAT with an M48T201 or M48T58 base IC delivers a hardware RTC that survives complete power loss and maintains a ±5 ppm-accurate time base from the integrated 32.768 kHz / 12.5 pF crystal. The SNAPHAT's detachable lithium cell means the calibration date can be logged, the battery can be replaced during scheduled maintenance, and the audit log survives the swap. According to ST's medical-market collateral, the SNAPHAT family is qualified across several medical grade products.
推荐
Telecom / Networking Equipment RTC Backup
Routers, switches and base stations require RTC accuracy for log correlation, certificate validity checks and synchronization across the network. The M4T28-BR12SH1 provides a 48 mAh lithium source paired with a 32.768 kHz / 12.5 pF crystal that holds the TIMEKEEPER base IC within ±5 ppm over 0-70 °C, enough for telecom-grade logging without network-time-protocol polling. When the line card goes into brown-out, the SNAPHAT keeps the M48T base in battery mode and the RTC continues to advance. Compared to a 32.768 kHz crystal + supercapacitor design, the lithium SNAPHAT delivers smaller footprint and longer hold-up at the cost of field replaceability.
推荐
Security / Surveillance DVR Timestamp
Video recorders and access-control panels must keep a tamper-evident wall-clock timestamp on every clip and badge event; loss of time on power-down destroys the audit chain. The M4T28-BR12SH1 SNAPHAT holds the M48T201 / M48T08 base IC alive for 3-5 years at +25 °C, providing a 48 mAh lithium supply and a matched 32.768 kHz crystal so the recorded wall-clock stays accurate even after a prolonged outage. The SNAPHAT's replaceable top makes the battery a service item rather than a board-level repair. Compared to a discrete RTC module + supercap pair, the M4T28-BR12SH1 integrated solution reduces BOM cost and PCB area while keeping the time base synchronized with NVRAM retention in one IC.
推荐
推荐产品汇总
工程参考数据： M4T28-BR12SH1 ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | M4T32-BR12SH1 | M4T28-BR12SH | M4T32-BR12SH |
|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Package / Housing | SNAPHAT® top | SNAPHAT® top — same housing | SNAPHAT® top — same housing | SNAPHAT® top — same housing |
| Battery Capacity | 48 mAh | 48 mAh | 48 mAh | 48 mAh |
| Nominal Voltage | 2.8 V | 2.8 V | 2.8 V | 2.8 V |
| Crystal Frequency | 32.768 kHz | 32.768 kHz | 32.768 kHz | 32.768 kHz |
| Crystal Load Capacitance | 12.5 pF | 12.5 pF | 12.5 pF | 12.5 pF |
| Compatible TIMEKEEPER Base | M48T201 / M48T58 / M48T35 / M48T08 / M48T18 | M48T02 / M48T04 / M48T32 family | M48T28 family (same as M4T28-BR12SH1) | M48T32 family |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
关键差异点
- Snap-on replaceability keeps lithium off the reflow profile （对比 Discrete CR2032 holder + 32.768 kHz crystal pair)
- Factory-matched 12.5 pF crystal load capacitance （对比 M48T201 with discrete third-party 32.768 kHz crystal)
- Single catalog part covers 28- and 44-pin SOIC TIMEKEEPER bases （对比 Discrete battery holder dedicated to one SOIC footprint)
设计说明
Estimated: do NOT expose the M4T28-BR12SH1 SNAPHAT to reflow profiles above ~220 °C — the primary lithium cell is not rated for the standard SAC305 reflow of ~245 °C peak. Solder the SOIC base first, let it cool, then snap the SNAPHAT on by hand or with a low-force press. If you must swap a SNAPHAT in the field, do not use a hot-air station on the SNAPHAT — pull the old top off with the snap-tool and clip the new top into the cavity. Exposing the SNAPHAT to reflow can crack the battery seal and cause rapid capacity loss or leakage.
Estimated retention math: at +25 °C the M48T201 base IC draws roughly 1 µA from Vbat; with the M4T28-BR12SH1's 48 mAh capacity the resulting backup time is approximately 48 mAh ÷ 1 µA ≈ 4.8 years (ignoring self-discharge). At +70 °C the IC's Vbat leakage roughly triples AND the lithium self-discharge rises, cutting retention to ~1 year; at -10 °C the cell still delivers ~80 % of its rated capacity. Derate every time-of-day estimate by 50 % for engineering safety margin unless your design supports a battery-low flag.
Crystal-load-capacitance warning: the 32.768 kHz crystal inside the M4T28-BR12SH1 is specified at 12.5 pF load, which is hard-coded by ST to match the M48T oscillator stage. Do NOT substitute a 6 pF or 7 pF tuning-fork crystal — doing so will pull the oscillator away from 32.768 kHz, slowing the wall-clock and drifting up to 60 seconds per day. The integrated crystal is one of the reasons to use the SNAPHAT rather than a discrete M48T + crystal design.
合规信息
RoHS compliant per STMicroelectronics product page. Primary lithium cell — check local regulations for transport (UN3090 / UN3091) and recycling (EU Battery Directive) before shipping.
