The parametric data for the OPA4H014-SEP show the device passes up to 30 krad(Si) under HDR. No functional failures were observed on any samples, and all tested parameters were found to remain within the limits of the production ATE test program (and thus within the data sheet limits).

One-time characterization shows that all parameters except for the input bias current remain within the specified data sheet limits up to 50 krad(Si). Input bias current (I_B) for the OPA4H014-SEP is specified as ±0.5 pA typical and ±10 pA maximum at T_A = 25°C. The input bias current was measured at V_S = ±9 V, with test limits of ±6 pA for guardbanding purposes.

After irradiation to 50 krad(Si), a mean post-irradiation I_B value of 11.93 pA and maximum post-irradiation I_B value of 14.77 pA were recorded for the inverting inputs. A mean post-irradiation I_B value of 14.06 pA and maximum post-irradiation I_B value of 16.08 pA were recorded for the noninverting inputs. The increase in I_B was observed on all three of the devices tested, with bias currents in excess of the data sheet specification for all four channels except in the case of unit 10 (which had a single channel remain within the test limits). The input offset current remained within the data sheet specification for all devices, implying the damage mechanism can affect both the inverting and non-inverting inputs in a comparable manner.

Note also that while the value of I_B is specified as ±10 pA maximum at T_A = 25°C, the value is specified as ±3 nA across the device operating temperature range (T_A = –55°C to +125°C), and all of the I_B data recorded at 50 krad(Si) remained well within this limit.