The STLQ50C33R from STMicroelectronics is an ultra-low quiescent current LDO linear regulator providing a fixed 3.3V output at up to 50 mA from a 2.3V to 12V input. With just 3.5 \u00b5A typical quiescent current and 200 mV dropout at 25 mA, it is designed for battery-powered applications requiring long standby time in a compact SOT-323-5 package.<\/p>\n
Product Overview The STLQ50C33R from STMicroelectronics is an ultra-low quiescent current LDO linear regulator providing a fixed 3.3V output at up to 50 mA from a 2.3V to 12V input. With just 3.5 \u00b5A typical quiescent current and 200 mV dropout at 25 mA, it is designed for battery-powered applications requiring long standby time in […]<\/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-6511","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-low-dropout-regulators-ldo","chip_brand-st"],"acf":{"brief_explanation":"LDO regulator, 3.3V fixed, 50mA, 3.5\u00b5A Iq, 200mV dropout, 2.3-12Vin, SOT-323-5","date_code":"","package_case":"SOT-323-5 (2.0 x 1.25 mm)","in_stock":7400,"datasheet":"https:\/\/www.st.com\/resource\/en\/datasheet\/stlq50.pdf","price":"$0.25","product_introduction":"The STLQ50C33R from STMicroelectronics is a BiCMOS low-dropout linear regulator optimized for ultra-low power consumption. The 3.5 \u00b5A typical quiescent current is achieved through a PMOS pass element design that eliminates the base current required by NPN or PNP pass element LDOs. This makes the device ideal for applications that spend most of their time in standby, where the quiescent current dominates the total power budget. The fixed 3.3V output with \u00b12% accuracy provides a reliable supply for microcontrollers and sensors. The wide 2.3V to 12V input range allows direct operation from single-cell Li-ion, multi-cell alkaline, or 12V industrial supplies. The SOT-323-5 package occupies minimal board space in compact designs.","working_principle":"The STLQ50C33R uses a PMOS pass transistor as the series element between input and output. The error amplifier compares a fraction of the output voltage (through an internal resistor divider) with the internal bandgap reference (1.23V), and drives the PMOS gate to maintain regulation. The PMOS pass element is key to the low quiescent current: unlike bipolar pass elements that draw base current proportional to load current, the PMOS gate draws essentially zero DC current. The dropout voltage is determined by the RDS(on) of the PMOS transistor and the load current (VDO = IO \u00d7 RDS(on)), resulting in 200 mV at 25 mA. The internal thermal shutdown circuit monitors the junction temperature and turns off the pass element at 160\u00b0C, protecting the device from damage due to excessive power dissipation.","pin_description":"
| Pin<\/th> | Name<\/th> | Function<\/th><\/tr> | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1<\/td> | IN<\/td> | Input voltage (2.3-12V)<\/td><\/tr> | ||||||||||||
| 2<\/td> | GND<\/td> | Ground<\/td><\/tr> | ||||||||||||
| 3<\/td> | EN<\/td> | Enable (active high, connect to IN for always-on)<\/td><\/tr> | ||||||||||||
| 4<\/td> | NC\/BP<\/td> | No connect or bypass capacitor for noise reduction<\/td><\/tr> | ||||||||||||
| 5<\/td> | OUT<\/td> | Regulated 3.3V output<\/td><\/tr><\/table>","application_scenarios":"The STLQ50C33R is ideal for IoT sensor nodes where the 3.5 \u00b5A quiescent current ensures months of battery life during sleep intervals between transmissions. For microcontroller power supplies, it provides a clean 3.3V rail from a single Li-ion cell (3.0-4.2V) with minimal dropout. As an RTC backup regulator, the ultra-low quiescent current preserves battery capacity during long power-off periods. In industrial sensor applications, the wide 12V input range allows direct connection to industrial supply rails without pre-regulation. The thermal shutdown and short-circuit protection provide robustness in field deployments.","alternative_models":"
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