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Texas Instruments LM8328TME/NOPB
- Part No.:
- LM8328TME/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Specialized
- Package:
- 25-WFBGA, DSBGA
- Datasheet:
-
LM8328TME/NOPB.pdf
- Description:
- IC INTFACE SPECIALIZED 25DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:250
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Product details
Overview
LM8328TME/NOPB from Texas Instruments is a mobile I/O companion IC designed to offload keypad scanning and general-purpose I/O expansion from host processors. It integrates an 8×12 keypad scanner with 8 special-function keys, three independent PWM outputs for LED brightness control, and an I²C-compatible ACCESS.bus slave interface operating at 100 kHz/400 kHz - all powered from a single 1.8V ±10% supply in a 25-pin DSBGA package.
For engineers reviewing the LM8328TME/NOPB datasheet, LM8328TME/NOPB pinout, LM8328TME/NOPB application, or LM8328TME/NOPB equivalent, key selection considerations include its on-chip RC oscillator (no external clock required), programmable HALT mode entry delay (default 1020 ms), 15-byte key event FIFO with multi-key support (up to 4 simultaneous presses), and dedicated PWM script buffer (64 bytes per channel) enabling autonomous LED animation sequences without host intervention.
Technical Context
The LM8328TME/NOPB implements a register-based command interpreter accessed exclusively via its I²C-compatible ACCESS.bus interface, supporting auto-increment addressing for efficient multi-byte register access. Its keypad scan engine operates on a fixed 4-ms interval with configurable settle (4–16 ms) and debounce (4–16 ms) times, storing events in a FIFO accessible through EVTCODE and KBDCODE registers.
PWM functionality uses a dedicated 32.768 kHz internal clock source to drive three independent timers, each with a 64-byte script buffer supporting RAMP, SET_PWM, GO_TO_START, BRANCH, TRIGGER, and END commands - enabling self-sustaining LED modulation sequences such as smooth fade-in/fade-out or synchronized color transitions across multiple channels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 1.8 V ±10% - enables direct integration into low-voltage mobile SoC power domains without level-shifting. |
| Operating Temperature | −40°C to +85°C - qualified for industrial and consumer handheld environments including cordless phones and smart handhelds. |
| I²C Speed Modes | Standard-mode (100 kHz) and Fast-mode (400 kHz) - supports responsive host communication while maintaining compatibility with legacy controllers. |
| Keypad Support | Up to 8×12 matrix + 8 SF keys = 104 total keys - provides scalable input handling for feature-rich portable devices. |
| PWM Channels | Three independent outputs with dedicated 64-byte script buffers - allows autonomous execution of complex LED timing sequences without CPU polling. |
| Key Event Buffer | 15-byte FIFO with multi-key detection (up to 4 simultaneous presses) - ensures reliable capture of rapid keypress sequences during user interaction. |
| HALT Mode Current | Minimized static current in Halt mode (data sheet Figure 3 shows sub-1 µA at 1.98 V, 25°C) - extends battery life in always-on portable applications. |
Pinout & Package
LM8328TME/NOPB is housed in a 25-ball DSBGA (Die Size Ball Grid Array) package with 0.4 mm pitch, optimized for space-constrained mobile PCB layouts. Pin functions are dynamically configurable post-reset, with all 25 balls serving dual roles across keypad scanning, GPIO, PWM output, interrupt signaling, and bus interface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RESETN (C1) | Active-low system reset input | Allows host-controlled hardware reset; asserted low after POR until RSTINTCLR register (0x84) is written with 0x01. |
| VCC (C4) | Primary power supply | Accepts 1.8 V ±10%; powers all internal logic, keypad drivers, and PWM circuitry. |
| SCL (D1) | I²C-compatible clock input | Open-drain, requires external pull-up; supports clock stretching up to 100 µs during busy operations. |
| SDA (E1) | I²C-compatible data bidirectional line | Open-drain, shares bus arbitration handling per I²C spec; auto-increment enabled by default for multi-byte transfers. |
| KPX0–KPX7 (A5, B4, D2, E2, A1, B1, A3, A4) | Keypad column / GPIO inputs | Configurable as keypad X-lines (inputs with on-chip pull-ups) or general-purpose inputs/outputs. |
| KPY0–KPY11 (D5, C5, B5, D4, B2, A2, B3, C2, D3, E4, E5, E3) | Keypad row / GPIO / PWM / IRQ outputs | KPY8–KPY10 serve as PWM0–PWM2 outputs; KPY11 doubles as IRQN interrupt output and PWM2 alternate function. |
| GND (C3) | Reference ground | Single ground connection; layout requires low-inductance return path to minimize noise coupling into sensitive analog PWM paths. |
Key Features
| Feature | Design Value |
|---|---|
| On-chip RC oscillator | Eliminates need for external crystal or clock source - reduces BOM count and board area in cost-sensitive handheld designs. |
| Programmable HALT mode trigger delay | Host-configurable inactivity timeout (default 1020 ms) - balances responsiveness and ultra-low-power operation based on use-case requirements. |
| Dedicated 15-byte key event FIFO | Stores press/release events with timestamp-like ordering - prevents loss of rapid keystrokes during host interrupt latency or polling intervals. |
| Three-channel PWM with 64-byte script buffers | Enables autonomous LED animations (e.g., breathing, pulsing, cross-fading) without host CPU involvement - frees processor cycles for higher-layer tasks. |
| Register-based command interpreter | Supports full device configuration via standardized I²C register writes - simplifies firmware integration and eliminates proprietary protocol stacks. |
Applications
| Cordless Phone Keypad Interface | Smart Handheld Device I/O Expansion |
|---|---|
Use Scenario: Scanning 32-key membrane keypad with 8 special-function buttons in a DECT cordless handset. IC Role / Device Role / Timing Role: Dedicated keypad controller and interrupt generator - handles matrix scanning, debouncing, and event buffering independently of baseband processor. Use Value: Reduces host MCU wake-up frequency by >90% versus software-based scanning; IRQN pin signals only valid key events, minimizing power-wasting polling. | Use Scenario: Adding 16 GPIOs and RGB LED dimming capability to a resource-constrained ARM Cortex-M0+ wearable platform. IC Role / Device Role / Timing Role: I/O expander and autonomous LED controller - maps unused MCU pins to KPX/KPY lines while executing PWM scripts from internal buffers. Use Value: Enables smooth LED transitions (e.g., battery-level indicators) using only 3 I²C register writes - no real-time timer interrupts or PWM peripheral allocation required on host. |
| Keyboard Application with Multi-Key Detection | Low-Power Remote Control Interface |
Use Scenario: Supporting simultaneous key combinations (e.g., Ctrl+Alt+Del) in a compact wireless keyboard with 48 keys. IC Role / Device Role / Timing Role: Keypad event manager with multi-press resolution - stores up to four concurrent keycodes in KBDCODE[3:0] and full sequence in EVTCODE FIFO. Use Value: Guarantees accurate detection of chorded inputs even during fast typing; eliminates ghosting via hardware-scanned matrix validation. | Use Scenario: IR remote control with backlight LED and tactile feedback requiring <5 µA standby current. IC Role / Device Role / Timing Role: Ultra-low-power I/O supervisor - enters HALT mode after 1.02 s of inactivity and wakes only on keypress or I²C address match. Use Value: Achieves sub-1 µA quiescent current in HALT mode (per datasheet Fig. 3), extending coin-cell battery life to >12 months in typical usage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I/O companion and keypad controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TCA6424A | 24-bit I²C GPIO expander with interrupt but no integrated keypad scan or PWM; requires external firmware for key matrix handling. | Lacks native keypad scanning engine and autonomous PWM scripting - suitable only when host MCU handles scanning logic. | Select when needing pure GPIO expansion without embedded keyscan or LED control logic. |
| PCA9557 | 8-bit I²C GPIO expander with basic interrupt; no keypad support, no PWM, no HALT mode, and no internal oscillator. | Requires external clock, external debounce logic, and host-driven scanning - significantly increases firmware complexity and power consumption. | Choose only for simple digital I/O extension where cost is primary constraint and advanced features are unnecessary. |
Compared with TCA6424A and PCA9557, LM8328TME/NOPB delivers integrated keypad scanning, autonomous PWM execution, and ultra-low-power HALT mode - reducing host processing load, eliminating external components, and enabling true set-and-forget human interface subsystems in battery-powered devices.
Availability
LM8328TME/NOPB is available at Aetrix Electronics and suitable for cordless phone interfaces, smart handheld I/O expansion, keyboard applications, low-power remote controls, and LED-backlit keypad systems requiring stable component supply and long-term manufacturability.
Supply support for LM8328TME/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 specializing in analog, embedded processing, and connectivity technologies, with leadership in power management, signal chain, and microcontrollers.
The LM8328TME/NOPB belongs to TI's Mobile I/O Companion product line, engineered specifically to reduce host processor overhead in portable electronics by integrating keypad scanning, GPIO expansion, and programmable LED control into a single low-voltage, low-power IC.
FAQ
What is the default I²C slave address of the LM8328TME/NOPB after power-on reset?
The LM8328TME/NOPB defaults to I²C slave address 0x88 after power-on reset or Global Call Reset. This address can be reprogrammed via the ACCESS.bus interface, but the device will revert to 0x88 upon receiving a Global Call Reset command (write 0x06 to slave address 0x00). The LM8328TME/NOPB supports standard- and fast-mode I²C communication at 100 kHz and 400 kHz respectively, with clock stretching handled automatically during internal processing delays.
How does the LM8328TME/NOPB handle multiple simultaneous key presses?
The LM8328TME/NOPB supports up to four simultaneous key presses using dedicated KBDCODE0–KBDCODE3 registers. When a second key is pressed, KBDCODE0's MULTIKEY flag is set and the keycode is stored in KBDCODE1; subsequent presses populate KBDCODE2 and KBDCODE3. All events are also logged in the 15-byte EVTCODE FIFO for sequential retrieval. The LM8328TME/NOPB ensures no key event loss during rapid input by combining hardware-based scanning with buffered storage independent of host polling speed.
Can the LM8328TME/NOPB generate PWM signals without host intervention?
Yes, the LM8328TME/NOPB supports fully autonomous PWM operation using its on-chip 32.768 kHz clock and per-channel 64-byte script buffers. Once a script (e.g., RAMP, SET_PWM, BRANCH) is loaded into a PWM buffer and execution is started, the LM8328TME/NOPB executes it independently - modulating LED brightness, triggering other PWM channels via TRIGGER commands, and asserting interrupts upon completion - all without host CPU involvement.
What is the purpose of the IRQN pin on the LM8328TME/NOPB, and how is it initialized after reset?
The IRQN pin on the LM8328TME/NOPB serves as an open-drain interrupt output that signals key events, hardware errors, or PWM script completion. After power-on reset, IRQN is driven low due to the PORIRQ signal and remains latched until the host writes 0x01 to the RSTINTCLR register (address 0x84). This initialization ensures predictable interrupt behavior and prevents spurious wakeups during system boot. The LM8328TME/NOPB allows polarity configuration and supports wake-up from HALT mode on rising/falling edge or pulse detection.
Does the LM8328TME/NOPB require an external clock source for operation?
No, the LM8328TME/NOPB includes an internal RC oscillator and requires no external clock source for core functionality including keypad scanning, I²C communication, and PWM generation. Its internal clock drives the keypad scan engine and the 32.768 kHz PWM timer base - enabling complete operation from a single 1.8V supply. External clocks are neither required nor supported; the LM8328TME/NOPB is designed for minimal external component count in space- and cost-constrained mobile applications.
LM8328TME/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 25-WFBGA, DSBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Mobile Communications
- Interface:
- I2C
- Voltage - Supply:
- 1.62V ~ 1.98V
- Supplier Device Package:
- 25-DSBGA
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
LM8328TME/NOPB FAQ
1.How can I place an order for LM8328TME/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM8328TME/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM8328TME/NOPB reliable?
The price and inventory of LM8328TME/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM8328TME/NOPB is usually 5 days.
3.What payment methods are accepted for LM8328TME/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM8328TME/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM8328TME/NOPB?
LM8328TME/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM8328TME/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM8328TME/NOPB?
For technical support, including LM8328TME/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM8328TME/NOPB requirements.
6.How does Aetrix verify that LM8328TME/NOPB is sourced from the original manufacturer or authorized distributors?
All LM8328TME/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM8328TME/NOPB meets industry standards.
7.What is the process for return or replacement of LM8328TME/NOPB?
All LM8328TME/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM8328TME/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM8328TME/NOPB part is unused and in its original packaging.
Return procedure for LM8328TME/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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