The LT1764AEQ-3.3 from Analog Devices is a 3A low-noise low-dropout (LDO) linear regulator with a fixed 3.3V output, 340mV dropout voltage at 3A, and only 40\u00b5VRMS output noise. Operating from 2.7V to 20V input, it is optimized for fast transient response and features controlled quiescent current that does not rise in dropout, in a 5-lead D2PAK (DD-Pak) surface-mount package.<\/p>\n
Product Overview The LT1764AEQ-3.3 from Analog Devices is a 3A low-noise low-dropout (LDO) linear regulator with a fixed 3.3V output, 340mV dropout voltage at 3A, and only 40\u00b5VRMS output noise. Operating from 2.7V to 20V input, it is optimized for fast transient response and features controlled quiescent current that does not rise in dropout, 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":[165],"class_list":["post-6525","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-low-dropout-regulators-ldo","chip_brand-adi"],"acf":{"brief_explanation":"3A LDO regulator, fixed 3.3V, 340mV dropout, 40\u00b5VRMS noise, 2.7-20V input, D2PAK-5","date_code":"","package_case":"D2PAK-5 (DD-Pak, TO-263-5)","in_stock":4200,"datasheet":"https:\/\/www.analog.com\/media\/en\/technical-documentation\/data-sheets\/1764afb.pdf","price":"$3.85","product_introduction":"The LT1764AEQ-3.3 from Analog Devices is a 3A low-dropout linear regulator optimized for fast transient response and ultra-low output noise. The fixed 3.3V output version provides a complete power solution for noise-sensitive RF and high-speed digital circuits. The 340mV dropout voltage at full 3A load enables efficient regulation from a 3.3V input to a 2.5V output or from a 5V input to a 3.3V output. Unlike many LDO regulators, the LT1764A maintains well-controlled quiescent current even in dropout, preventing excessive power dissipation. The 40\u00b5VRMS output noise (10Hz to 100kHz) makes it ideal for powering sensitive RF circuits such as VCOs, PLLs, and mixers where supply noise directly impacts phase noise and spurious performance. The AEQ-3.3 suffix indicates the D2PAK-5 package with fixed 3.3V output.","working_principle":"The LT1764AEQ-3.3 uses a PNP pass transistor in a common-emitter configuration, which allows the dropout voltage to be defined by the VCE(sat) of the pass transistor rather than the gate drive voltage required by PMOS-based LDOs. The 340mV dropout is the saturation voltage of the PNP transistor at 3A. The error amplifier compares a fraction of the output voltage (sensed through the SENSE pin) with an internal 1.21V bandgap reference, driving the base of the PNP pass transistor to maintain regulation. The internal noise reduction pin (NR) can be bypassed with a capacitor to filter the bandgap reference noise, reducing the output noise to 40\u00b5VRMS. The fast transient response is achieved through a wideband error amplifier and careful compensation. The SHDN pin disables the device, reducing supply current to <1\u00b5A. The reverse battery protection circuit prevents damage when the input voltage is reversed, eliminating the need for an external protection diode.","pin_description":"
| Pin<\/th> | Name<\/th> | Function<\/th><\/tr> | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1<\/td> | SHDN<\/td> | Shutdown control (high=on, low=shutdown, <1\u00b5A)<\/td><\/tr> | ||||||||||||
| 2<\/td> | IN<\/td> | Input supply (2.7V~20V, bypass with 10\u00b5F)<\/td><\/tr> | ||||||||||||
| 3<\/td> | GND<\/td> | Ground (tab and pin)<\/td><\/tr> | ||||||||||||
| 4<\/td> | OUT<\/td> | Regulated 3.3V output (bypass with 10\u00b5F min)<\/td><\/tr> | ||||||||||||
| 5<\/td> | SENSE<\/td> | Output voltage sense (connect to load for remote sensing)<\/th><\/tr><\/table>","application_scenarios":"The LT1764AEQ-3.3 is commonly used as a post-regulator after a switching converter, where the low 40\u00b5VRMS noise cleans up the switching ripple that would otherwise degrade sensitive analog circuit performance. In RF transceivers, it powers VCOs and PLLs where supply noise directly translates to phase noise. For 3.3V to 2.5V conversion, the 340mV dropout allows regulation with minimal headroom. In battery-powered instruments, the <1\u00b5A shutdown current preserves battery life during sleep modes. The reverse battery protection eliminates the Schottky diode that would otherwise be needed, reducing forward drop and cost.","alternative_models":"
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