BQ4842YMA-85 RTC with 128Kx8 NVSRAM | Texas Instruments
MPN: BQ4842YMA-85 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
BQ4842YMA-85 Overview
A real-time clock is a clock-and-timing IC that maintains calendar and time information independently of the host processor’s main clock. In the broader hierarchy, an RTC belongs to timing ICs, then clock and calendar devices, then semiconductor-based timekeeping systems. Adding nonvolatile SRAM to the same module allows a controller to retain logs, configuration data, calibration values, or event records while the RTC continues tracking time.
The verified feature set includes an integrated SRAM, real-time clock, CPU supervisor, crystal, power-fail control circuit, and battery. Search results also describe time counted in hundredths of a second through years in BCD format. The RTC uses RAM-like clock access, while the watchdog, reset, interrupt, and battery-low functions support system monitoring and reliable control of embedded equipment.
Because the BQ4842YMA-85 is a parallel-interface device, the host processor must have compatible input, output, and control signals. Its 32-DIP module format favors through-hole assembly and repairable industrial or instrumentation designs rather than compact surface-mount consumer products. The module can be used where persistent records and accurate calendar time are required together, reducing the number of separate timing and memory components.
Typical applications include industrial data loggers, instrument panels, metering equipment, communications systems, and embedded controllers. In each case, the RTC supplies timekeeping while the NVSRAM preserves operating data. Designers should verify the complete electrical limits, pin names, crystal requirements, battery behavior, and reset logic against the manufacturer datasheet before layout or firmware development.
The main design consideration is integration: the BQ4842YMA-85 can simplify a board by combining timekeeping and retained storage, but it requires correct bus timing and dependable backup power. A BQ4842YMA-85 datasheet search should be used to confirm the device variant’s exact electrical characteristics and package details before committing to a production design.
This page combines the verified distributor classification, manufacturer-described features, source links, cross-reference results, and practical integration guidance. It distinguishes verified facts from unavailable parameters so engineers can assess fit without relying on guessed specifications.
Drop-in alternatives for BQ4842YMA-85 — 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:
No drop-in alternatives available for this product.
Request AlternativesBQ4842YMA-85 Specifications
| Product Type | Real-time clock and calendar module with nonvolatile SRAM |
| Device Category | Clock/Timing IC |
| Interface Type | Parallel |
| Integrated Memory | 128Kx8 NVSRAM |
| Time Resolution | Hundredths of a second |
| Calendar Range | Through years |
| Time Encoding | BCD format |
| Clock Access | RAM-like access |
| Integrated Functions | SRAM, real-time clock, CPU supervisor, crystal, power-fail control circuit, and battery |
| Supervision Features | Watchdog timer, reset, interrupts, and battery-low warning |
| Package Type | 32-DIP module |
| Package Length | 15.49 mm (0.610 inch) |
| Manufacturer | Texas Instruments |
| Datasheet Page Count | 18 pages |
BQ4842YMA-85 15.49 mm (0.610 inch) Pin Configuration Guide
Pin configuration for BQ4842YMA-85 (15.49 mm (0.610 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 BQ4842YMA-85.
Refer to the datasheet for full pin configuration.
Typical Applications
BQ4842YMA-85 is suitable for 6 applications: Industrial Data Loggers, Process and Energy Meters, Instrumentation and Test Equipment, Communications and Network Equipment, Embedded Control and Alarm Panels, Portable Battery-Backed Instruments.
Industrial Data Loggers
The BQ4842YMA-85 fits industrial data loggers that need timestamped records alongside retained configuration data. Its verified 128Kx8 NVSRAM stores samples, counters, calibration values, or event records, while the RTC supplies calendar and time information in BCD format. The watchdog, reset, interrupts, battery-low warning, and power-fail control add supervision around the host processor. In a parallel-bus design, the module can reduce the number of separate retention and timing components, although the final design must confirm voltage, temperature, battery, and timing requirements.
Recommended
Process and Energy Meters
The BQ4842YMA-85 is suitable for metering equipment where event time and operating totals must remain associated with stored measurements. The 128Kx8 NVSRAM provides persistent space for interval records or calibration constants, and the integrated power-fail and battery functions can support orderly retention during supply interruptions. The parallel interface allows connection to a host controller with suitable bus timing. Designers should use the verified module dimensions and confirm the exact pinout, RTC accuracy, supply range, and environmental limits from the manufacturer documentation before production release.
Recommended
Instrumentation and Test Equipment
The BQ4842YMA-85 can support instrumentation that must identify measurements by time and preserve setup or calibration information. Its RTC counts hundredths of a second through years and exposes RAM-like clock access, while 128Kx8 NVSRAM provides local retained storage. The CPU supervisor, watchdog, reset, interrupt, and battery-low warning features help the instrument detect and recover from abnormal operation. The 32-DIP module is particularly compatible with through-hole laboratory and industrial assemblies, but the parallel bus and exact pin functions must be verified before layout.
Recommended
Communications and Network Equipment
The BQ4842YMA-85 is appropriate for communications equipment requiring a local time record and retained operational state. A controller can use the RTC for event timestamps and the NVSRAM for counters, configuration flags, or diagnostic history. The power-fail control, watchdog, reset, interrupts, and battery-low warning are useful in remote or unattended equipment where recovering after power disturbances is important. Because the interface is parallel, the host must provide compatible logic levels and timing. Final qualification requires the missing voltage, temperature, accuracy, and pin-level specifications.
Recommended
Embedded Control and Alarm Panels
The BQ4842YMA-85 can serve in embedded control panels where alarms, events, and operating state must survive a reset or power interruption. Its NVSRAM can hold event records and configuration values, while the RTC provides time context for alarms and maintenance logs. The integrated watchdog and reset functions support host supervision, and the battery-low warning can inform maintenance or system shutdown. The through-hole 32-DIP module is practical for repairable equipment, but designers must confirm the pin assignment and signal polarity against the official datasheet.
Recommended
Portable Battery-Backed Instruments
The BQ4842YMA-85 can fit portable instruments where calendar time and retained measurements must remain available after main power is removed. The verified feature set includes a battery, power-fail control, and battery-low warning, while the 128Kx8 NVSRAM can preserve readings or user settings. The watchdog and reset functions can support controlled recovery in unattended instruments. The package’s 32-DIP form factor is better suited to a repairable or through-hole assembly than an ultra-compact handheld design. Battery life, backup current, operating temperature, and RTC accuracy remain items to verify.
Recommended
Recommended Products Summary
Engineering reference data for BQ4842YMA-85 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Device Type | RTC module with NVSRAM |
| Package | 32-DIP module |
| Brand | Texas Instruments |
| Interface | Parallel |
| Integrated Memory | 128Kx8 NVSRAM |
| Time Resolution | Hundredths of a second |
| Time Format | BCD |
| Supervision Features | Watchdog, reset, interrupts, and battery-low warning |
| Power-Fail Control | Integrated |
| Module Length | 15.49 mm (0.610 inch) |
Key Differentiators
- Combines RTC and persistent storage (vs Basic RTC-only module)
- Adds host supervision functions (vs Basic RTC-only module)
- Includes power-fail control (vs RTC without integrated power-fail control)
Design Notes
Treat the BQ4842YMA-85 backup-power path as a separate design constraint. The verified feature set confirms an integrated battery, power-fail control, and battery-low warning, but the supplied data does not specify battery chemistry, voltage, backup current, or retention time. Check those values in the manufacturer datasheet, verify the system supply tolerance during battery backup, and ensure the host can react correctly to the low-battery warning.
Use the verified 32-DIP module dimensions and manufacturer pin drawing as the mechanical authority. Place the module where its crystal, battery, supply, reset, and parallel-bus routing remain accessible, and maintain the specified clearance around any exposed battery or sensitive timing components. Do not derive PCB pad locations from the 15.49 mm body length alone; obtain the complete package drawing first.
The BQ4842YMA-85 uses a parallel interface and RAM-like clock access, so host timing and signal integrity are part of the timing design. Confirm address, data, read/write, chip-enable, interrupt, and reset polarity from the official pinout. Route the bus with short traces, maintain defined levels during power transitions, and validate read/write timing across voltage and temperature corners before finalizing firmware.
The module combines timekeeping, retained storage, supervision, and power-fail behavior, so several mistakes can produce misleading failures. Avoid assuming a basic RTC pinout, substituting an arbitrary crystal, or treating NVSRAM as ordinary volatile RAM. Also avoid powering the module without validating battery polarity, backup behavior, watchdog timing, and reset polarity. Manufacturer documentation should control all of these decisions.
Compliance Information
The supplied verified results do not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is marked not_applicable because this is a timing module rather than an explicitly automotive-qualified product in the provided data.
