BQ4830YMA-85 32KByte RTC Module PDIP-28 (USED)
The BQ4830YMA-85 is a compact PDIP-28 module that integrates a crystal-controlled real-time clock, power-fail control and an internal lithium backup battery with 32,768 bytes of byte-addressable nonvolatile SRAM organized as 32K×8, providing combined timekeeping and data retention in a single drop-in replacement for industry-standard 32K×8 SRAMs used in legacy and embedded systems. The module presents standard address and data bus signals for direct CPU interface and offers dual-port style clock registers that update once per second without interrupting normal SRAM access.
Features
- Integrated 32K×8 nonvolatile SRAM with on-board real-time clock and control registers.
- Crystal timebase with clock/calendar in 24-hour BCD format and software clock calibration.
- Dual-port style clock registers that allow atomic clock updates while SRAM remains accessible.
- Internal lithium battery and power-fail detect circuit to automatically protect data on VCC loss.
- Pin-compatible with industry-standard 32K × 8 SRAMs, enabling simple retrofit into existing designs.
- Unlimited standard SRAM write cycles during normal operation with automatic write-protect on power-fail.
- Typical data retention of 10 years when battery/oscillator are enabled.
- Compact 28-pin DIP module for through-hole mounting and easy prototyping or board replacement.
PINOUT
Specifications
| Parameter | Value |
|---|---|
| Memory Organization | 32,768 bytes (32K × 8) |
| Total Bits | 262,144 bits |
| RTC Registers | 8 bytes mapped at top of memory (addresses 7FF8–7FFF) |
| Clock Format | 24-hour BCD (Year, Month, Date, Day, Hours, Minutes, Seconds, Control) |
| Interface | Parallel address bus A0–A14, data bus DQ0–DQ7, control signals CE, OE, WE |
| Power Control | On-board power-fail detect and automatic deselect / write-protect on VCC drop |
| Backup Battery | Internal lithium cell; isolated during shipping and enabled on first VCC application |
| Data Retention | Minimum 10 years (typical under recommended conditions) |
| Clock Accuracy | Software calibration available; typical better than 1 minute/month after calibration |
| Package | 28-pin PDIP module |
| Operating Voltage | Standard +5V logic supply for read/write and clock operation |
| Operating Modes | Active read/write, standby, CMOS standby, battery-backup mode |
Applications
- Nonvolatile configuration and firmware storage with integrated time stamping for industrial and embedded systems.
- Real-time clock plus backup RAM for dataloggers, meters and instrumentation that require retained logs during power loss.
- Retrofits and repairs of legacy PC/embedded boards that use 32K×8 SRAM with timekeeping features.
- Firmware or parameter storage for appliances, POS equipment and telecommunications gear that benefit from RTC.
- Development and prototyping where compact RTC + SRAM module simplifies design integration.
Package Contents
- 1x BQ4830YMA-85 32KByte RTC Module PDIP-28 (USED).
Documents
| Datasheet | BQ4830YMA |
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