BQ4822YMA-70 - 8Kx8 NVSRAM RTC Module | Texas Instruments
MPN: BQ4822YMA-70 ✗ End of Life| Qty | Unit Price | Extended |
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| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
BQ4822YMA-70 Overview
A real-time clock is a clock-and-timing integrated circuit that maintains calendar and time information independently of the host processor. This device belongs to the RTC module and nonvolatile data-storage hierarchy, combining a crystal-based timekeeper, 8Kx8 SRAM, power-fail circuitry, and a battery backup path. That combination lets a controller recover timestamp and configuration data after mains or system power is removed.
The BQ4822Y family is described as an RTC module with 8Kx8 NVSRAM, watchdog timer, up reset, interrupts, and battery-low warning features. Its RAM-like clock access and industry-standard x 8 SRAM compatibility simplify integration with parallel bus-oriented embedded systems. The verified distributor listings also identify alarm, leap-year, supervisor, and real-time-clock functions, while the listed clock frequency is 0.032 MHz.
Typical applications include industrial controllers that must preserve event logs, communications equipment requiring timestamped events, embedded systems with brownout recovery, and battery-backed instrumentation that needs calendar data and retained parameters. The host processor can read and write the module through a parallel interface while the RTC maintains time independently during power loss.
Designers should preserve the module’s battery-backed architecture, validate the host bus and interrupt polarity, and check the exact pin assignments against the manufacturer datasheet before layout. The supplied search data confirms the 28-DIP module and 5 V supply description, but it does not provide a complete electrical timing table, so unverified current, accuracy, memory-retention, and temperature values are intentionally not asserted here.
This page consolidates the verified distributor identity, package information, functional description, and engineering guidance while separating confirmed facts from unavailable parameters. It is intended to support component selection, data retrieval, comparison planning, and first-pass hardware design review without inventing values absent from the supplied sources.
Drop-in alternatives for BQ4822YMA-70 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
BQ4822YMA
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
BQ4822YMA-70TI
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
BQ4822YMA-70I
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
M48T18-100PC1
✅ Drop-In📋 Reference alternative (not in catalog)
M48T18-100PC1
✅ Drop-In📋 Reference alternative (not in catalog)
BQ4822YMA-70 Specifications
| Product Type | Battery-backed real-time clock and calendar module |
| Nonvolatile Memory | 8Kx8 bit NVSRAM |
| Supply Voltage | 5 V |
| Interface | Parallel x 8 SRAM-compatible access |
| Package | 28-pin DIP module |
| Package Width | 15.49 mm (0.61 inch) |
| Clock Frequency | 0.032 MHz |
| Time Format | HH:MM:SS:hh in 24-hour BCD format |
| Time Resolution | Hundredths of a second through years |
| Watchdog Timer | Integrated |
| Reset Function | Up reset |
| Interrupt Support | Integrated interrupts |
| Battery Low Warning | Integrated battery-low warning |
| Power-Fail Circuit | Integrated power-fail circuit |
| Alarm Feature | Alarm function indicated in distributor data |
| Leap-Year Handling | Leap-year feature indicated in distributor data |
| Supervisor Function | CPU supervisor function indicated in distributor data |
| Mounting Type | Through-hole DIP module |
BQ4822YMA-70 15.49 mm (0.61 inch) Pin Configuration Guide
Pin configuration for BQ4822YMA-70 (15.49 mm (0.61 inch) package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for BQ4822YMA-70.
Refer to the datasheet for full pin configuration.
Typical Applications
BQ4822YMA-70 is suitable for 6 applications: Industrial Data Logging, Battery-Backed Communications Equipment, Embedded Instrumentation, Embedded Process Control, Power-Fail Recovery Systems, Alarm and Event-Timestamped Systems.
Industrial Data Logging
The BQ4822YMA-70 fits industrial controllers that must retain timestamps and a small amount of operational state when the main supply fails. Its verified 8Kx8 NVSRAM provides limited nonvolatile storage, while the RTC tracks hundredths of seconds through years in BCD format. A host controller can use the power-fail and battery-related functions to place a compact event marker or configuration snapshot into memory before shutdown. The 28-DIP through-hole package is practical for systems designed around a conventional leaded footprint, but the designer must confirm electrical timing, bus direction, and supply requirements against the datasheet.
Recommended
Battery-Backed Communications Equipment
The BQ4822YMA-70 is useful in communications equipment that needs event time and retained configuration data across power interruptions. The integrated RTC and 8Kx8 NVSRAM reduce the number of separate timing and storage components, while watchdog and up-reset functions support recovery of an embedded controller. A communications system can timestamp alarms, store a short outage history, or preserve a network node identity through a power cycle. Because the supplied data does not state the exact interface timing or battery current, the implementation should verify bus timing, standby behavior, and retention duration before selecting passive components or software timeout values.
Recommended
Embedded Instrumentation
The BQ4822YMA-70 fits embedded measurement equipment that must retain calibration or event metadata when its primary supply is interrupted. The RTC supplies calendar and sub-second time information, and the 8Kx8 NVSRAM can hold a small status block rather than a full measurement archive. Its watchdog, reset, interrupt, and power-fail features help the host recover from abnormal states or orderly shutdowns. The design should keep the module’s backup battery path isolated correctly, follow the manufacturer’s supply sequencing requirements, and treat the NVSRAM as limited auxiliary storage rather than a general-purpose data logger.
Recommended
Embedded Process Control
The BQ4822YMA-70 can support process-control nodes that require a local time reference and retained operating state. Its BCD calendar format, sub-second counting, watchdog timer, up reset, and interrupts allow a controller to timestamp process events and react to stalled software or abnormal power conditions. The integrated NVSRAM can preserve a small recipe identifier, counter snapshot, or alarm state through a power interruption. The module is best suited where a leaded 28-DIP footprint and parallel interface are acceptable. Firmware must handle the module’s access protocol and power-fail sequence rather than assuming every generic RTC command set is compatible.
Recommended
Power-Fail Recovery Systems
The BQ4822YMA-70 is a strong fit for systems where orderly recovery after supply loss is more important than high storage capacity. Its integrated power-fail circuit, battery-backed RTC, NVSRAM, watchdog timer, and up-reset functions support a design that records a shutdown state and restarts with a known calendar reference. The 8Kx8 NVSRAM is intentionally small, so the application should store only essential state such as a fault code, boot counter, or configuration checksum. The exact warning threshold, response time, and retention conditions must be established from the manufacturer datasheet before setting software deadlines.
Recommended
Alarm and Event-Timestamped Systems
The BQ4822YMA-70 suits alarm panels and event-driven controllers that need an independent timestamp when the main clock is unavailable. The verified function list includes an alarm, leap-year handling, interrupts, and time counting through years, while the NVSRAM can preserve a short event record or alarm state during power loss. A host can use the interrupt output to wake from a low-power state, read the calendar, and then record the event through its system-specific communication path. The engineer should verify interrupt polarity, oscillator accuracy, and alarm-resolution details in the manufacturer documentation because those values were not present in the supplied snippets.
Recommended
Recommended Products Summary
Engineering reference data for BQ4822YMA-70 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BQ4822YMA | BQ4822YMA-70TI | BQ4822YMA-70I | M48T18-100PC1 |
|---|---|---|---|---|---|
| Package | 28-pin DIP module | 28-pin DIP module | 28-pin DIP module | 28-pin DIP module | 28-pin DIP module |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | STMicroelectronics |
| Product Category | Battery-backed RTC with NVSRAM | RTC family member | RTC family member | RTC family member | Parallel RTC |
Key Differentiators
- Integrated nonvolatile data storage with calendar timekeeping (vs M48T18-100PC1)
- Recovery-oriented integrated supervision functions (vs M48T18-100PC1)
- Parallel system integration (vs M48T18-100PC1)
Design Notes
Treat the RTC supply and backup path as separate design concerns. Follow the manufacturer’s recommended supply sequencing, battery connection, decoupling, and power-fail limits; the supplied snippets identify a 5 V supply description and battery-backed operation but do not provide capacitor values or warning thresholds. Do not infer the battery chemistry or charging arrangement from the module name. Confirm the exact datasheet before laying out the backup network.
Keep the 28-DIP module footprint, crystal-related connections, backup battery path, and parallel bus routing consistent with the manufacturer reference layout. Because the supplied data does not provide the complete pin map, verify every pin against the current Texas Instruments datasheet before routing. Avoid long uncontrolled bus traces, provide a defined ground reference, and keep sensitive timing or backup paths away from noisy switching nodes where the package architecture permits.
Do not assume that every parallel 28-DIP RTC is interchangeable. BQ4822YMA-70 is identified as an 8Kx8 NVSRAM RTC with watchdog, reset, interrupt, battery-low warning, and power-fail functions, but the supplied comparison result does not prove that M48T18-100PC1 shares memory organization, command set, pinout, voltage, or timing. Verify the manufacturer pin assignments and timing specifications before redesigning an existing board.
The NVSRAM is only 8Kx8 bits, so firmware should store essential state rather than assume unlimited event logging. Define an overflow policy, protect frequently updated data, and coordinate writes with the power-fail signal so the system does not begin a critical transaction when the supply is unstable. The supplied data does not specify write endurance or retention time, so those limits must be obtained from the datasheet.
Compliance Information
The supplied distributor results identify the device and its electrical category but do not provide verified RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declarations.
