Aspeed Ast2500 Datasheet =link= -

Technical Report: ASPEED AST2500 Datasheet Review

3.2 Clocking

• Main Oscillator: 25MHz crystal (fundamental mode) connected to XTALI/XO pins.
• PCIe Clock: 100MHz differential clock (HCSL or LVDS levels, depending on configuration).

Chapter 7: Thermal Management & ADC Accuracy

The primary job of the BMC is thermal control. The AST2500 Datasheet dedicates 15 pages to the ADC (Analog to Digital Converter) .

• Spec: 10-bit resolution, 8 channels.
• Voltage Range: 0V to 1.8V (Not 3.3V!). To read 12V rails, you need an external resistor divider (the datasheet provides a formula: R1/R2 = 6.66:1 to scale 12V down to 1.5V).
• Accuracy: ±1% typical, ±3% maximum over temperature.

Thermal Diode vs. Thermistor: The AST2500 has two dedicated Thermal Diode inputs (D1P/D1N). These are designed for reading CPU substrate diodes (transistor junction voltage). Do not plug a standard thermistor (10k NTC) into these pins—the biasing current is wrong. Use the standard ADC pins for thermistors. Aspeed Ast2500 Datasheet

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5. Security Features

• Trusted Platform Module (TPM) 1.2/2.0 support.
• Secure boot from SPI flash (RSA/SHA).
• JTAG lock-down and debug disable fuses.