The L4940D2T5-TR from STMicroelectronics is a 1.5A, 5V fixed-output very low dropout voltage regulator in a D2PAK (TO-263) package. With 450mV typical dropout at 1A and reverse polarity protection, it targets battery-powered and automotive power supply applications.<\/p>\n
| Output Voltage<\/td>\n | 5.0 V (+\/-2% over line, load, temperature)<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| Corriente de salida<\/td>\n | 1.5 A<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| Input Voltage<\/td>\n | Up to 17 V<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| Dropout Voltage<\/td>\n | 450 mV typical at 1 A, 900 mV max at 1.5 A<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| Corriente de reposo<\/td>\n | 5 mA typical at light load<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| PSRR<\/td>\n | 68 dB typical at 120Hz, 1A<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| Short-Circuit Current<\/td>\n | 2.7 A typical<\/td>\n<\/tr>\n | ||||||||||||||||||||||||||||||||||||
| Temperatura de funcionamiento<\/td>\n | -40C to +150C (junction)<\/td>\n<\/tr>\n<\/table>\nCaracter\u00edsticas<\/h2>\nAplicaciones<\/h2>\nProduct Overview The L4940D2T5-TR from STMicroelectronics is a 1.5A, 5V fixed-output very low dropout voltage regulator in a D2PAK (TO-263) package. With 450mV typical dropout at 1A and reverse polarity protection, it targets battery-powered and automotive power supply applications. Key Specifications Output Voltage 5.0 V (+\/-2% over line, load, temperature) Output Current 1.5 A Input […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[13,32],"tags":[],"chip_brand":[142],"class_list":["post-7262","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-low-dropout-regulators-ldo","chip_brand-st"],"acf":{"brief_explanation":"1.5A 5V LDO, 450mV Vdo@1A, D2PAK, reverse polarity, thermal shutdown, 68dB PSRR","date_code":"","package_case":"D2PAK \/ TO-263-3 (10.30 x 8.70 x 4.50 mm, exposed tab)","in_stock":9485,"datasheet":"https:\/\/www.st.com\/resource\/en\/datasheet\/l4940.pdf","price":"$1.03 @ 1ku","product_introduction":"The L4940D2T5-TR from STMicroelectronics is a 1.5A, 5V fixed-output very low dropout positive voltage regulator in a D2PAK (TO-263-3) surface-mount package. The L4940 series is specifically designed for battery-powered equipment, offering very low input-to-output voltage drop to reduce consumption and prolong battery life. The 450mV typical dropout voltage at 1A output current allows the regulator to maintain 5V output from input voltages as low as 5.45V, making efficient use of battery capacity. The D2PAK package with exposed thermal tab provides excellent thermal performance, enabling full 1.5A output current with appropriate PCB copper heatsinking. The device employs internal current limiting with anti-saturation circuit to protect against output overload and short circuits. The thermal shutdown circuit disables the regulator when the junction temperature exceeds the safe limit, providing protection against excessive power dissipation. Reverse polarity protection prevents damage from incorrect battery installation. The 68dB PSRR at 120Hz effectively rejects input ripple from rectified AC sources. The +\/-2% output voltage accuracy is maintained over the full input voltage, output current, and temperature range.","working_principle":"The L4940D2T5-TR uses a PNP pass transistor low-dropout regulator topology. (1) PNP Pass Element: The PNP transistor connects between input and output. Unlike NPN-pass regulators that require at least 2-3V headroom (VBE + VCEsat + VBE), the PNP pass element requires only the VCEsat voltage, achieving the low 450mV typical dropout. (2) Voltage Regulation: An internal bandgap reference generates a stable voltage. The error amplifier compares a fraction of the output voltage with the reference and drives the PNP base to maintain regulation. (3) Anti-Saturation Circuit: When the input-to-output differential is very low, the PNP transistor approaches saturation, which can cause excessive ground current. The anti-saturation circuit limits the base drive to prevent deep saturation, controlling the ground current increase in dropout conditions. (4) Current Limiting: An internal current-sensing circuit monitors the output current and limits it to approximately 2.7A during overload conditions. (5) Thermal Shutdown: A temperature sensor monitors the junction temperature. When it exceeds approximately 150C, the pass transistor is turned off. After cooling below the hysteresis threshold, regulation resumes. (6) Reverse Polarity: An internal circuit blocks reverse current flow when the input voltage is negative, protecting the regulator and the load.","pin_description":"
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