Texas Instruments LM8333GGR8AXSX/NOPB

Overview

LM8333GGR8AXSX/NOPB from Texas Instruments is a mobile I/O companion IC that offloads keypad scanning and I/O expansion tasks from the host processor in portable electronics. It supports up to 64 standard keys plus 8 special-function keys (72 total), features an I²C-compatible ACCESS.bus interface, a 15-byte FIFO buffer for key-event storage, and delivers <2 µA standby current in Halt mode - enabling ultra-low-power operation in battery-constrained devices like smartphones and PDAs.

For engineers reviewing the LM8333GGR8AXSX/NOPB datasheet, LM8333GGR8AXSX/NOPB pinout, LM8333GGR8AXSX/NOPB application, or LM8333GGR8AXSX/NOPB equivalent, this page provides verified functional specifications, validated WQFN-32 pin mapping, confirmed I²C slave address (0xA2), real-world debounce/active-time programmability, and two documented alternative parts for keyboard controller migration paths.

Technical Context

The LM8333GGR8AXSX/NOPB integrates a fully static RC-based timing architecture with hardware-managed Halt mode entry after configurable inactivity (default 500 ms), reducing current to <2 µA. Its keypad scanner operates at ~4 ms intervals with programmable debounce (1–255 × 3 ms) and detects multi-key press ambiguity (≥3 keys) to trigger error reporting.

It implements a fixed-address I²C slave interface (7-bit address 0xA2) supporting up to 400 kHz transfers, with mandatory watchdog timer requiring WD_OUT-to-RESET connection. Four GPIOs include GEN_IO_0/GEN_IO_1 with edge-triggered interrupt capability and programmable pullup/Hi-Z modes per Table 4.

Key Specifications

Pinout & Package

LM8333GGR8AXSX/NOPB is packaged in a 32-pin WQFN (Package Number NJE0032A), 5 mm × 5 mm, 0.5 mm pitch, wettable flank, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar keyboard controller applications.

Compared with TCA6424A, LM8333GGR8AXSX/NOPB integrates full key-scan logic and event buffering, eliminating host CPU overhead; versus MAX7348, it adds SF key wake-up and PWM functionality at the cost of slightly higher standby current.

Availability

LM8333GGR8AXSX/NOPB is available at Aetrix Electronics and suitable for mobile phones, personal digital assistants, smart handheld devices, and personal media players requiring stable component supply and long-term lifecycle support.

Supply support for LM8333GGR8AXSX/NOPB 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions across industrial, automotive, and consumer markets.

The LM8333 product line was designed specifically for ultra-low-power mobile human-interface applications, integrating keypad scanning, I/O expansion, and watchdog functionality into a single chip-scale package for space-constrained portable devices.

FAQ

What is the I²C slave address of the LM8333GGR8AXSX/NOPB?

The LM8333GGR8AXSX/NOPB uses a fixed 7-bit I²C slave address of 0xA2 (binary 10100010), where bit 0 is the R/W direction bit. Write operations use 0xA2 (0xA2 with R/W=0), and read operations use 0xA3 (0xA2 with R/W=1). This address is hard-coded and not user-programmable. The LM8333GGR8AXSX/NOPB responds only to this address and does not support address selection pins or alternate addresses.

How does the LM8333GGR8AXSX/NOPB handle simultaneous key presses?

The LM8333GGR8AXSX/NOPB detects and reports ambiguity when three or more keys are pressed simultaneously, setting the KEYOVR bit in the error register (0xF0). This condition asserts IRQ and requires host intervention - either discarding ambiguous FIFO entries or implementing custom resolution logic. The LM8333GGR8AXSX/NOPB does not attempt auto-resolution; its design assumes host-level handling of such cases to ensure deterministic behavior in critical UI applications.

Is the watchdog timer optional on the LM8333GGR8AXSX/NOPB?

No, the watchdog timer is mandatory and always enabled in hardware on the LM8333GGR8AXSX/NOPB. Its WD_OUT pin must be connected to the host's RESET input to ensure system reliability. If WD_OUT is left unconnected or tied high, the host may fail to reset under software lockup conditions. The LM8333GGR8AXSX/NOPB does not provide a disable mechanism - continuous I²C activity or explicit host commands are required to prevent watchdog timeout and unintended reset.

Can the LM8333GGR8AXSX/NOPB drive a 5 V keypad matrix?

No, the LM8333GGR8AXSX/NOPB operates exclusively from a 2.25 V to 2.9 V supply (VCC) and is not 5 V tolerant. Its K_OUTx outputs and WAKE_INx inputs are rated for −0.3 V to VCC + 0.3 V only. Driving a 5 V keypad matrix would exceed absolute maximum ratings and risk permanent damage. Interface to higher-voltage keypads requires level-shifting circuitry or external FETs compatible with the LM8333GGR8AXSX/NOPB's voltage domain.

What happens when the LM8333GGR8AXSX/NOPB FIFO buffer overflows?

When the 15-byte FIFO buffer of the LM8333GGR8AXSX/NOPB fills and another key event occurs, the FIFOOVR bit is set in the error register (0xF0) and IRQ is asserted. The LM8333GGR8AXSX/NOPB continues normal operation but discards new events until the host reads existing entries. Host firmware must monitor READ_ERROR (0xF0) and implement timely FIFO consumption - for example, using RPT_FIFO_READ (0x21) to re-read without advancing the pointer after a failed read - to prevent persistent overflow conditions.