Intel 315889-002 manual Sustained Current A, Time Duration s

Output Voltage Requirements

The continuous load current (ICCTDC) can also be referred to as the Thermal Design Current (TDC). It is the sustained DC equivalent current that the processor is capable of drawing indefinitely and defines the current that is used for the voltage regulator temperature assessment. At TDC, switching FETs may reach maximum allowed temperatures and may heat the baseboard layers and neighboring components. The envelope of the system operating conditions, establishes actual component and baseboard temperatures. This includes voltage regulator layout, processor fan selection, ambient temperature, chassis configuration, etc. To avoid heat related failures, baseboards should be validated for thermal compliance under the envelope of the system’s operating conditions. It is proposed that voltage regulator thermal protection be implemented for all designs (Section 6.2).

The maximum load current (ICCMAX) represents the maximum peak current that the processor is capable of drawing. It is the maximum current the VRM/EVRD must be electrically designed to support without tripping any protection circuitry.

The maximum step load current (IccStep) is the max dynamic step load that the processor is expected to impose on its Vcc power rail within the Iccmin and Iccmax range, where the Iccmin is the processor’s min load, constituted by its leakage current.

The amount of time required by the VR to supply current to the processor is dependent on the processor’s operational activity. As previously mentioned, the processor is capable of drawing IccTDC indefinitely; therefore, the VR must be able to supply (ICCTDC) indefinitely. Refer to Figure 2-1for the time durations required by the VR to supply current for various processor loads.

It is expected that the maximum load current (ICCMAX) can be drawn for periods up to 10 ms. Further, it is expected that the load current averaged over a period of

100 seconds or greater, will be equal to or less than the thermal design current

(ICCTDC).

Figure 2-1. VRM/EVRD 11.0 Load Current vs. Time

Icc MAX
Sustained Current (A)
Icc TDC
0.01	0.10	1.00	10.00	100.0	1000.0
		Time Duration (s)

Table 2-2shows the ICC guidelines for any flexible motherboard (FMB) frequencies supported by the VRM/EVRD 11.0 in Table 1-1. For designers who choose to design their VR thermal solution to the ICCTDC current, it is recommended that voltage regulator thermal protection circuitry be implemented (see Section 6.2).

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