Radiation performance of the L4913 Voltage Regulator N.Boetti 1 , P.Jarron 1 , B.Kisielewski 1,2 , F.Faccio 1 1 CERN, 1211 Geneva 23, Switzerland 2 The Henryk Niewodniczanski Institute of Nuclear Physics, Cracow, Poland Abstract—The radiation-hard voltage regulator L4913 was developed by ST Microelectronics in collaboration with CERN to satisfy the radiation requirements of the LHC. Its radiation hardness has been extensively tested using X-rays, 60 Co, and a pion beam. The regulator appears to tolerate TID levels above 100 Mrad, and 1 MeV equivalent neutron fluence above 1.9x10 15 cm -2 . These levels well exceed the LHC requirements. Keywords—voltage regulator, radiation-hard, total ionizing dose, displacement damage INTRODUCTION I. The electronics installed in the High Energy Physics experiments at the CERN Large Hadron Collider (LHC) will have to survive the radiation environment created by the head- on beam collisions at the center of the detector apparatus. From simulation, we estimate TID levels varying between more than 10 Mrad close to the interaction point and less than 1 krad in the experimental hall during the whole lifetime of the LHC (10 years). The hadron (mainly neutrons, protons and pions) fluence above 100 keV is foreseen to vary between a few 10 14 particles/cm 2 in the inner trackers and calorimeters and 10 9 particles/cm 2 in the experimental hall. Due to the abundance of high-energy hadrons, Single Event Effects (SEEs) are also a crucial issue for electronics components. Compared with Space applications, though, the particle environment will not include heavy ions. A large number of electronic systems in the LHC experiments rely on the presence of voltage regulators on board. Being installed inside the detector apparatus, these crucial components also need to be radiation tolerant. Most of the systems using on-board regulators require radiation tolerance up to a maximum level of 500 krad and 2x10 13 particles/cm 2 . To satisfy this specification, CERN started in 1998 to collaborate with ST Microelectronics (STM) to develop radiation tolerant low drop-out voltage regulators for the LHC. One of the products of this development is the L4913 [1], which is going to be commercialized by STM. In addition to this positive regulator, a negative version is also being developed (L7913) and will be available later this year. Both parts will be qualified to 500 krad and 2x10 13 n/cm 2 CERN has carried out an extensive radiation test effort during the development of the part, and it is continuing the radiation tests for its qualification. This paper summarizes the radiation test results obtained so far, considerably expanding the radiation results already published on this component [2]. EXPERIMENTAL DETAILS II. The L4913 voltage regulator A. The L4913 regulator, whose main characteristics are summarized in Table I, has been developed in a technology (named RHBIP1) that is not conventional for voltage regulators. It is a monolithic integration of complementary vertical high-speed NPN and PNP transistors. The technology choice was driven by radiation hardness requirements, and was made after a preliminary test of ST Microelectronics' conventional power technologies had revealed insufficient radiation hardness for the LHC requirements. The general architecture of the regulator is similar to that of a conventional linear regulator. No further information on the regulator architecture and layout, or of the technology can be disclosed in this paper since STM wishes to keep it confidential. At the beginning of the development, the plan was to have several fixed output voltage regulators (2.5, 3, 3.3, 5 and 8 V) and an adjustable version (between 1.25 and 9 V). Recently, STM has decided to offer only the adjustable version. The parts are packaged in SO-20 packages. TABLE I. MAIN FEATURES OF THE 3 AMP POSITIVE LOW DROP VOLTAGE REGULATOR L4913 Low output capactitance: 1 F Low drop voltage: 0.5 V @ Iout = 1 A and 1.5 V @ Iout = 3 A Overtemperature protection Overstress dynamic protection Overcurrent protection Output short circuit monitoring, signaled by TTL output ON/OFF external control by means of TTL compatible input Adjustable current limitation protects outputs from damaging shortcircuits Remote sensing operation Irradiation details B. During the development phase, prototypes of the voltage regulator have been irradiated with different particle beams. The final component, the one commercialized by STM as L4913, has been tested for TID and displacement damage using a 60 Co source, X-rays and a pion beam. In all cases, the devices were characterized before irradiation, measuring their line and load regulation as shown in Figure 1. During all irradiation tests, the devices were kept The work of B. Kisielewski was partially supported by the Polish Committee for Scientific Research under grant 620/E-77/SPUB-M/CERN/P- 03/DZ295/2000-2002