The purpose of this study is to characterize the single-event-effects (SEE) performance due to heavy-ion irradiation of the TPS7H4010-SEP. SEE performance was verified at two common output voltage rails of 1.8V and 3.3V. Heavy-ions ranging from an LETEFF of 1.33 to 43 MeV·cm2/mg were used to irradiate 10 production devices. Flux of ≈104 and 105 ions/cm2 ·s and fluences of ≈106 and 107 ions/cm2 per run were used for the characterization. The results demonstrated that the TPS7H4010-SEP is SEL and SEB/SEGR-free up to 43 MeV·cm2/mg, at T = 125°C and T = 10°C, respectively, and across the full electrical specifications. SET and SEFI performance for output voltage excursions ≥ |3%| from the nominal voltage and PGOOD ≤ VOUT/2 are presented and discussed.
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The TPS7H4010-SEP is a space-enhanced-plastic, 3.5V to 32V input, 6A, synchronous step-down voltage converter. The device provides exceptional efficiency and output accuracy in a very small solution size. Peak current-mode control is employed. Additional features such as adjustable switching frequency, synchronization to an external clock, FPWM option, power-good flag, precision enable, adjustable soft start, and tracking provide both flexible and easy-to-use solutions for a wide range of applications.
The TPS7H4010-SEP requires few external components and has a pinout designed for simple PCB layout with optimal EMI and thermal performance. Protection features include thermal shutdown, input undervoltage lockout, cycle-by-cycle current limiting, and hiccup short-circuit protection. The device is offered in a 30-pin WQFN plastic package. General device information and test conditions are listed in Table 2-1. For more detailed technical specifications, user-guides, and application notes please go to TPS7H4010-SEP product page.
| DESCRIPTION(1) | DEVICE INFORMATION |
|---|---|
| TI Part Number | TPS7H4010-SEP |
| Orderable Number | TPS7H4010MRNPTSEP |
| Device Function | Point-of-load (POL) Switching Regulator |
| Technology | Linear BiCMOS 8 (LBC8 ) |
| Exposure Facility | Radiation Effects Facility, Cyclotron Institute, Texas A&M University (25 MeV/nucleon) |
| Heavy Ion Fluence per Run | 5.65 × 105 – 1 × 107 ions/cm2 |
| Irradiation Temperature | 10°C (for SEB/SEGR testing), 25°C (for SET testing), and 125°C (for SEL testing) |
The primary concern for the TPS7H4010-SEP is the robustness against destructive single-event effects (DSEE): single-event latch-up (SEL), single-event burnout (SEB), and single-event gate rupture (SEGR). In mixed technologies such as the BiCMOS process used on the TPS7H4010-SEP, the CMOS circuitry introduces a potential for SEL susceptibility.
SEL can occur if excess current injection caused by the passage of an energetic ion is high enough to trigger the formation of a parasitic cross-coupled PNP and NPN bipolar structure (formed between the p-sub and n-well and n+ and p+ contacts) [1,2]. The parasitic bipolar structure initiated by a single-event creates a high-conductance path (inducing a steady-state current that is typically orders-of-magnitude higher than the normal operating current) between power and ground that persists (is “latched”) until power is removed, the device is reset, or until the device is destroyed by the high-current state. The TPS7H4010-SEP was tested for SEL at the maximum recommended voltage of 32 V, maximum load current of 6 A, and VOUT of 3.3 and 1.8 V. The device exhibited no SEL with heavy-ions with LETEFF = 43 MeV·cm2/mg at flux ≈105 ions/cm2·s, fluences of ≈107 ions/cm2, and a die temperature of 125°C.
Since this device is designed to conduct large currents (up to 6 A) and withstand up to 32 V during the off-state, the power LDMOS introduces a potential susceptibility for SEB and SEGR [2]. The TPS7H4010-SEP was evaluated for SEB/SEGR at full load conditions of 6 A, and a maximum voltage of 32 V in both the enabled and disabled modes. Because it has been shown that MOSFET susceptibility to burnout decreases with temperature [2], the device was evaluated while operating under sub-ambienttemperatures. The devices were cooled-down (or "chilled") by using VORTEC tube (model 611). During the SEB/SEGR testing, not a single current event was observed, demonstrating that the TPS7H4010-SEP is SEB/SEGR-free up to LETEFF = 43 MeV·cm2/mg at a flux of ≈105 ions/cm2·s, fluences of ≈107 ions/cm2, and a die temperature of ≈10°C.
The TPS7H4010-SEP was characterized for SET and SEFIs at flux of ≈104 ions/cm2·s, fluences of 3 × 106 ions/cm2, at room temperature. The device was characterized at PVIN = 12 V to VOUT = 3.3 V and PVIN = 5 V to VOUT = 1.8 V at full load of 6-A. Under these conditions the device showed 2 different single-event transients (SET) signatures and 1 single-event functional interrupt (SEFI) under heavy-ion irradiation. All observed types of SETs were self-recoverable without the need of external intervention. The observed transients can be classified as: