Kbc1126nu Datasheet Hot -

| Device | Base I/O | IRQ | DMA | |--------|----------|-----|-----| | Floppy | 3F0h/370h | 6 | 2 | | Parallel | 378h/278h | 7 | 3 (ECP) | | UART A | 3F8h | 4 | - | | UART B | 2F8h | 3 | - | | KBC (keyboard) | 60h/64h | 1 | - | | KBC (mouse) | 60h/64h | 12 | - | | HWM | 290h (typical) | - | - |

| Pin Group | Qty | Description | |-----------|-----|-------------| | LPC bus | 7 | LCLK, LFRAME#, LAD[3:0], LDRQ#, SERIRQ | | Keyboard/Mouse | 4 | KBCK, KBDA, MSCK, MSDA | | UART A & B | 8 | TX/RX + handshake (RTS, CTS, DSR, DTR, DCD, RI) | | Parallel Port | 17 | 8 data, 5 status, 4 control (ECP/EPP) | | Floppy Disk | 12 | DRV0, DRV1, STEP, DIR, WDATA, etc. | | Fan tach/PWM | 4 | FANIN0-1, FANPWM0-1 | | Analog Inputs | 8 | VIN1-8 (voltage monitoring) | | GPIO | up to 24 | Programmable I/O | | Power | 12 | VCC, VSB, VBAT, GND |

Since the full datasheet is NDA-protected by Microchip, here are the critical specs for troubleshooting:

| Parameter | Value | |--------------------|---------------------------------| | Supply voltage | 3.3V ± 5% | | Standby current | ~50 µA | | Active current | 15–25 mA (depending on clock) | | LPC clock | 33 MHz | | Package | 128-LQFP (14x14mm, 0.4mm pitch) | | ADC inputs | 8 channels, 10-bit | | PWM outputs | 4 (fan, backlight, etc.) |

The internal 8051 firmware is not included in any public datasheet. It must be extracted from a working motherboard or provided by the OEM. Without the firmware, the KBC1126NU will not function as a keyboard/mouse controller.

KBC1126-NU Keyboard Controller (KBC) and Super I/O integrated circuit manufactured by (now part of Microchip Technology

. It is commonly found in laptop motherboards, such as those from Dell and HP. Technical Overview

It manages low-level system functions including keyboard input, touchpad interfacing, thermal monitoring (fan control), and power sequencing. Package Type: It typically comes in a 156-pin VFQFN

(Exposed Pad) package designed for surface mounting (SMD/SMT). Related Models: It is part of a family that includes the

, which also features integrated ADC and DAC capabilities with "SentinelAlert" for mobile power management. Datasheet & Support

Finding a full public datasheet for this specific chip can be difficult as SMSC often restricted these documents to OEMs. However, you can find technical summaries and pinout information through the following resources: Datasheet Repositories: Preliminary data and package specs are often hosted on AllDatasheet Jotrin Electronics Inventory & Pricing: For current stock levels or procurement, sites like Win-Source

provide availability status, though supply for this specific part is often limited. Troubleshooting "Hot" Issues If your KBC1126-NU chip is running physically , it usually indicates a hardware failure: Internal Short:

The chip may have failed internally, drawing excessive current. External Short: kbc1126nu datasheet hot

A shorted capacitor or component on one of its power rails (often the +3.3V_ALW or +5V_ALW lines) can cause the controller to overheat. Power Surge:

Overvoltage from a faulty power adapter or charging circuit can damage the chip's internal logic.

Summary report — KBC1126NU datasheet (hot)

If you want, I can now fetch and extract pinout, electrical specs, and block diagram from a selected PDF. Which source should I use?

is a highly integrated Keyboard Controller (KBC) and System I/O chip manufactured by

(now part of Microchip Technology). It is a common component in laptop motherboards, responsible for managing the keyboard, touchpad, power sequencing, and thermal monitoring. ctlabbd.com KBC1126NU Overview

The chip belongs to the SMSC family of mobile controllers and is typically found in professional-grade laptops like the HP EliteBook and ProBook series. Manufacturer SMSC (Microchip) Package Type : TQFP-128 (128-pin Thin Quad Flat Pack). Operating Temperature : Specified for an extended range of negative 40 raised to the composed with power cap C 105 raised to the composed with power cap C Primary Functions Keyboard and touchpad interface management. System power-on/off sequencing (ACPI management). Communication with the BIOS through the LPC bus. Battery charging and monitoring logic. Troubleshooting: Why is the KBC1126NU "Hot"? In the world of laptop motherboard repair

, a "hot" KBC chip is a classic symptom of a hardware failure. If the chip is burning to the touch immediately after connecting power, it usually indicates one of the following: ctlabbd.com Internal Short Circuit

: The most common reason for a hot KBC1126NU is an internal short. This often happens if there was a liquid spill or a surge on one of the power rails (like the +3.3V always-on rail). External Short on a Power Rail | Device | Base I/O | IRQ |

: If a capacitor or another component connected to the KBC's VCC pins is shorted to ground, the chip may attempt to draw excessive current, causing it to overheat. LDO Regulator Failure

: Many laptops use a 3V/5V regulator IC to power the KBC. If this regulator fails and sends a higher voltage (e.g., 19V from the adapter) directly to the KBC, the chip will overheat and likely die instantly. Peripheral Short

: Since the KBC connects to the keyboard and touchpad, a short in the keyboard membrane can sometimes feed back into the chip, though this usually causes specific pin failure rather than the entire chip getting hot. Technical Resources & Datasheets

While the full, detailed datasheet for the "NU" variant can sometimes be difficult to find publicly, it is closely related to the KBC1122 series , which features: Mobile KBC with Super I/O SFI, ADC, and DAC Support SMSC SentinelAlert for system monitoring.

You can find technical specifications and pinout references on distributor sites like AllDatasheet

Are you experiencing a "no power" issue with a laptop, or are you looking for a specific pinout diagram for a repair? KBC1126NU Datasheet, PDF - ALLDATASHEET.COM KBC1126NU Datasheet, PDF - Datasheet Search Engine. ALLDATASHEET.COM KBC1126NU Datasheet, PDF - ALLDATASHEET.COM

Mobile KBC with Super I/O, SFI, ADC and DAC with SMSC SentinelAlert. ALLDATASHEET.COM KBC1126NU stock, price, datasheet. – ic2ic.com

KBC1126NU Datasheet: Essential Specs and Thermal Management The KBC1126NU is a highly integrated Keyboard Controller (KBC) from Microchip/SMSC, commonly found in premium laptops and workstations. Because it manages critical system functions, engineers and repair technicians often look for the KBC1126NU datasheet to troubleshoot power issues or "hot" operating conditions. ⚡ Core Specifications

The KBC1126NU isn't just for typing; it is the brain of the motherboard's low-level operations. Processor: 8051-based microcontroller core. Interface: LPC (Low Pin Count) bus interface. Memory: Integrated ROM and RAM for firmware execution. I/O Support: PS/2 ports, PWM outputs, and numerous GPIOs.

Management: Handles ACPI power states (S0-S5) and battery charging logic. 🌡️ Why is your KBC1126NU running hot?

If you find the chip is physically hot to the touch, it usually indicates a hardware failure rather than a software bug. Common Causes of Overheating

Internal Short: A failure within the silicon often causes immediate overheating upon applying power. Likely content in the datasheet (based on similar

Voltage Rail Spike: If the 3.3V standby rail is pushing higher voltage, the KBC will overheat.

Peripheral Short: A shorted USB port, keyboard, or touchpad can pull excessive current through the KBC pins.

Liquid Damage: Corrosion between high-voltage pins and signal pins is a frequent culprit. 🔍 Troubleshooting Steps

If the chip is "hot" and the laptop won't power on, follow this diagnostic flow:

Check Resistance: Measure resistance to ground on the 3.3V VCC pins.

Isolate Peripherals: Disconnect the keyboard and touchpad to see if the temperature drops.

Inspect Voltage: Ensure the LDO or power management IC (PMIC) is outputting exactly 3.3V.

Thermal Imaging: Use a thermal camera to see if a specific corner of the chip is glowing, which identifies the failing internal block. 🛠️ Replacement Tips

Replacing a KBC1126NU requires precision and the right tools.

Pin Alignment: It is a high-density QFP package; use plenty of flux.

Firmware: Some versions require external SPI Flash programming, while others are "blank" and pull code from the main BIOS.

Heat Shielding: Protect surrounding plastic connectors with Kapton tape during hot-air soldering. If you need to dig deeper, I can help you find: The exact pinout for the power rails The schematic symbols for motherboard repair Recommendations for compatible replacement chips

Do you have a multimeter handy to check the resistance on the VCC pins? AI responses may include mistakes. Learn more