Kb926qf Datasheet (2027)

: Always-on 3.3V power plane supplying the IC core. This voltage must be present as soon as the AC adapter is plugged in or a charged battery is connected.

Measure the standby power rail directly at the decoupling capacitors adjacent to the chip. If +3VALW is missing, the issue lies further back in the primary power generation circuit, rather than with the EC chip itself. Step 2: Analyze the Clock and Reset State

Input from the physical power button. Pressing the button drops this pin from 3.3V to 0V, signaling the EC to start the boot sequence. kb926qf datasheet

Because the Embedded Controller is exposed to external interfaces (like the keyboard, power button, and charging port), it is highly susceptible to electrical surges and liquid damage.

| | Description & Practical Notes | | :--- | :--- | | LPC_FRAME# | Indicates the start of an LPC cycle. A low signal indicates the host is initiating communication. If this pin is inactive, the EC cannot communicate with the chipset. | | LPC_AD[3:0] | The 4-bit multiplexed address/data bus. A lack of activity on these pins with a clock present typically points to a BIOS configuration issue. | | PCI_RST# | A reset signal from the chipset (often via a resistor) that initializes the EC to a known state. This signal should be high (3.3V) for normal operation. | | SIRQ | A serialized interrupt request line that allows the EC to interrupt the host CPU. An oscilloscope is needed to see activity here. | : Always-on 3

LPC Data lines used to communicate low-level instructions continuously between the chipset/PCH and the EC.

Tells the EC that an AC power adapter is connected. Usually requires a specific voltage divider value to read as "high". 3. Communication and Programming Interfaces If +3VALW is missing, the issue lies further

The KB926QF is a widely used keyboard controller and embedded controller (EC) chip found in numerous laptop motherboards. Manufactured by ENE Technology, this IC plays a critical role in managing system power, keyboard inputs, and hardware monitoring.

Controlling power, charging, and caps lock LEDs. Technical Specifications Specification Manufacturer ENE Technology Package Type LQFP-128 (128 pins) Interface LPC (Low Pin Count) Bus Core Architecture 8051-based or proprietary 8-bit microcontroller core Operating Voltage (VCC) 3.3V (Typically labeled as +3VALW or +3V_EC) Firmware Storage External SPI Flash ROM (shared or dedicated) Key Pinout Functions

: The KB926QF is the gatekeeper for the laptop's power states. It monitors the physical power button, transitions the system through ACPI states (S0–S5), and safely fires up the peripheral voltage regulators (+3VS5, +5VS5, VCC_CORE) in a strict chronological order.

The KB926QF has been confirmed in several specific laptop motherboard designs, including (used in laptops like the Toshiba Satellite A300), the LA-5751P motherboard used in the Lenovo G460 and Lenovo G560, the LA-3981P from Compaq/HP series, and the HP CQ40 motherboard. It is also found in the Toshiba AC100 netbook.