8 Single-Event Transients (SET)

The primary focus of SETs were heavy-ion-induced transient upsets on EN1, EN4, or FAULT. SET testing was done at room temperature using ¹⁶⁵Ho heavy-ions which produced a LET_EFF of 75MeV·cm²/mg. The output signals were monitored by two different scopes, a NI PXIe-5172 and a MSO58. Two PXIe-5172s were used to monitor EN1 and FAULT while the MSO was monitoring EN4. The MSO was triggered using an edge-negative at 2.64V. The PXIe-5172 was triggered with an edge-negative at –20% below the high voltage when in waiting to Sequence DOWN state. During the testing when the state machine was in the waiting to Sequence UP state, the trigger was set to 0.66V or 0.36V with an edge-positive trigger.

The PXIe-5172 sample rate was set to 2MS/s with a record length of 1M points (or samples). The MSO sample rate was set to 1GS/s and had its horizontal divisions set to 20µs/div (for a total of 200µs). The device was tested with DLY_TMR disabled (OPEN). Each SENSEx was connected to an external power supply via a resistive divider with R_TOP = 24.5kΩ and R_BOTTOM = 1.5kΩ. Under this configuration the external voltage was controlled to provide an overdrive voltage of ±20mV (typically). The device was tested under the following conditions.

1. Waiting to Sequence UP State (with a –20mV by forcing VOUTx to 6.27V).
2. Waiting to Sequence DOWN State (with a +20mV by forcing VOUTx to 6.19V).

The device was tested on the EVM in two configurations, one shown on Figure 3-5 where capacitors are present on VSENSEx (the nominal case) and one shown on Figure 3-5 where no capacitors were present (worst-case). The device was also tested under two typical voltages for IN (5V and 12V) and PULL_UPx (3.3V and 1.8V). Under these configurations not a single transient was recorded on EN1, EN4, or FAULT. This demonstrates the TPS7H3014 is SET-free. The SET test conditions and results for three units are shown in Table 8-3.