Timing, Housekeeping and Control – REQUIRED
Figure 4-3: Power on Timing
Table 4-9: Power Supply Timing
Description | Value | |||
Legacy Timings1 | Required | Recommended for ALPM | ||
T0 | AC power on time | - | <2s | - |
T1 | Power-on time | < 500 ms | < 200 ms | <150 ms |
T2 | Rise time | - | 0.2 – 20 ms | - |
T3 | PWR_OK delay | 100 ms2 – 500 ms | 100 ms2 – 250 ms | 100 ms2 – 150 ms |
T4 | PWR_OK rise time | - | < 10 ms | - |
T5 | AC loss to PWR_OK hold-up time3 | - | > 16 ms | - |
T6 | PWR_OK inactive to DC loss delay | - | > 1 ms | - |
- Value in the Legacy column list timings for power supplies designed before the year 2020. In 2020, the T1 and T3 timings have moved from the Legacy timing to the new Required column for all new power supply designs.
- T3 minimum time faster than 100 ms is not recommended for previous generation motherboards and systems. All design tolerances must be considered before allowing T3 faster than 100 ms.
- A T3 time less than 100 ms may be designed based on system requirements and a need to provide faster PSU and system turn on capability. However, PSU and system designers are highly recommended to verify and ensure no PSU and system compatibility problems exist, especially for previous generation motherboards and systems.
- T5 to be defined for both max/min load condition.
- PSUs are recommended to label or indicate the timing value for system designer and integrator reference for T1 and T3. This allows system designers to optimize “turn on” time within the system.
- T3 minimum time faster than 100 ms is not recommended for previous generation motherboards and systems. All design tolerances must be considered before allowing T3 faster than 100 ms.