Texas Instruments BQ4802LYPWR

Overview

BQ4802LYPWR from Texas Instruments is a 3.3-V parallel real-time clock IC with integrated CPU supervisor, battery-backed SRAM control, and watchdog timer. It provides BCD-formatted time-of-day and century-based calendar functions, supports external 32.768-kHz crystal, delivers <500 nA backup-mode current, and features programmable alarm/periodic interrupts active in battery-backup mode. It is used in telecom base stations and medical equipment for reliable timekeeping during main power loss.

For engineers reviewing the BQ4802LYPWR datasheet, BQ4802LYPWR pinout, BQ4802LYPWR application, or BQ4802LYPWR equivalent, key selection considerations include its 3.3-V operation, CEOUT/VOUT-controlled external SRAM write-protection, 28-pin TSSOP package, open-drain RST/INT outputs, and watchdog timeout programmability via register bits WD0–WD2.

Technical Context

The BQ4802LYPWR integrates a temperature-compensated oscillator interface, power-fail detection (VPFD = 2.4–2.65 V), and conditional chip-enable switchover logic that isolates external SRAM when VCC drops below VPFD. Its internal clock update inhibition (UTI bit) enables glitch-free BCD register reads without affecting time accuracy.

It implements a three-level watchdog input (WDI) with default 1.5-s timeout, programmable via register B bits WD0–WD2, and generates reset via open-drain RST output with 200-ms active-low pulse after VCC recovery. The device uses A0–A3 address lines and DQ0–DQ7 data bus to access 16 bytes of clock/control registers in SRAM-compatible timing.

Key Specifications

Pinout & Package

Package: 28-pin TSSOP (PW), RoHS-compliant, 4.4 mm × 9.7 mm body, 0.65 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar real-time clock with supervisor applications.

Compared with DS1307+DS1232 and M41T81SM6, the BQ4802LYPWR uniquely combines parallel SRAM-compatible timing, autonomous CEOUT/VOUT-controlled external memory backup, and century-based calendar in a single 28-pin TSSOP-reducing BOM count and eliminating timing-critical firmware dependencies during power failure.

Availability

BQ4802LYPWR is available at Aetrix Electronics and suitable for telecom base stations, medical monitoring devices, and industrial servers requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for BQ4802LYPWR 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

Texas Instruments is a global semiconductor leader focused on analog and embedded processing technologies, with decades of expertise in precision timing and power management ICs.

The BQ4802LYPWR belongs to TI's legacy real-time clock and supervisor product line, designed specifically for systems demanding autonomous timekeeping, deterministic reset behavior, and hardware-controlled nonvolatile memory backup during power loss.

FAQ

What is the operating voltage range for the BQ4802LYPWR?

The BQ4802LYPWR operates from 2.7 V to 3.6 V, optimized for 3.3-V systems. This range ensures compatibility with standard LDO outputs and avoids overvoltage stress on internal circuitry. The device draws only 3 mA typical supply current during active operation and less than 0.5 µA in battery-backup mode, supporting long-term operation from a 3-V lithium cell.

How does the BQ4802LYPWR protect external SRAM during power failure?

The BQ4802LYPWR protects external SRAM using two dedicated pins: VOUT supplies the higher of VCC or backup cell voltage to the SRAM VCC pin, while CEOUT goes high to disable writes when VCC falls below the 2.4–2.65 V power-fail threshold. This hardware-level action occurs autonomously-no firmware or host intervention is required-and sustains data integrity even during abrupt power loss.

Can the BQ4802LYPWR maintain time accuracy without an external crystal?

No-the BQ4802LYPWR requires either a 32.768-kHz tuning-fork crystal connected between X1 and X2, or a buffered 32.768-kHz square wave applied to X1 with X2 grounded. The internal oscillator is not self-contained; it relies on this external timing source. With a specified 6-pF-load crystal, the BQ4802LYPWR achieves ±1 minute per month accuracy at 25°C.

What is the function of the UTI bit in the BQ4802LYPWR control register?

The UTI (Update Transfer Inhibit) bit (Register E, D3) halts the transfer of internal real-time counter values to the user-accessible clock registers. When set, it enables glitch-free reads of BCD-formatted time and date without risk of mid-update corruption. The internal oscillator continues running, so clock accuracy is unaffected. After reading, clearing UTI resumes automatic register updates within one second.

Does the BQ4802LYPWR support alarm interrupts while running on battery backup?

Yes-the BQ4802LYPWR supports programmable alarm interrupts (via AIE and ABE bits) that remain fully active in battery-backup mode. Alarm conditions generate an active-low signal on the open-drain INT pin, allowing host systems to wake from low-power sleep or trigger event logging even when main power is absent. This capability is confirmed in the SLUS464C datasheet Section 7.2.