LT3045HMSE#PBF - 500mA Ultra-Low Noise LDO | Analog Devices
MPN: LT3045HMSE#PBF ✓ ActiveLT3045HMSE#PBF Overview
An LDO (Low-Dropout) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input voltage is very close to the output voltage. In the system hierarchy, an LDO is a subset of linear regulators, which are themselves a category of voltage regulators within the broader power management IC family. The LT3045 belongs to the ultra-low-noise category designed for noise-sensitive analog/RF loads that cannot tolerate the ripple typical of switching regulators.
Key features include a 260 mV typical dropout voltage at full 500 mA load, 2.2 mA quiescent current that drops to sub-1 µA in shutdown, programmable current limit, and a power-good indicator. The exposed-pad MSOP-12 package achieves a thermal resistance of approximately 33 °C/W, supporting sustained 500 mA operation without external heatsinking at moderate VIN-VOUT differentials.
The LT3045 is architected as a precision current reference with a unity-gain amplifier on the output. This unique topology delivers constant output noise, PSRR, bandwidth, and load regulation independent of the programmed output voltage - a key advantage over conventional series-pass LDOs whose noise and bandwidth scale with VOUT.
Typical applications include RF PLL/VCO power supplies, high-speed data converter references, precision instrumentation front-ends, medical imaging, and post-regulation after switching converters. Designers favor the LT3045 wherever sub-1 µVrms noise is required without the switching artifacts of a buck regulator.
When designing with the LT3045, treat the exposed pad as the primary thermal path and provide at least 1 cm² of copper pour to keep junction temperature below 125 °C. Use a minimum 10 µF X7R input/output capacitor to maintain stability and PSRR; ESR must stay below 50 mΩ.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical thermal/PCB design notes not found in the standalone Analog Devices datasheet, helping engineers shorten the BOM selection and PCB bring-up cycle.
Drop-in alternatives for LT3045HMSE#PBF — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LT3045HMSE#PBF (same form factor and footprint) — differing in Input Voltage Range, Package.
LT3045IMSE#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT3045HMSE#TRPBF
✅ Drop-InContact for price
View Datasheet →LT3045HMSE#WPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT3042EMSE#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT3045EDD#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT3045HMSE#PBF Maximum Ratings & Electrical Characteristics
| Output Type | Adjustable (positive) |
| Output Voltage Range | 0 V to 15 V |
| Maximum Output Current | 500 mA |
| Input Voltage Range | 1.8 V to 20 V |
| Dropout Voltage | 260 mV typical at 500 mA |
| Output Noise | 0.8 uVrms (10 Hz to 100 kHz) |
| PSRR | 76 dB at 1 kHz |
| Quiescent Current | 2.2 mA typical |
| Shutdown Current | < 1 µA |
| Operating Temperature | -40 °C to +125 °C |
| Package | 12-pin MSOP-EP (MSE) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| RoHS Status | Compliant |
| Enable Pin | Yes (active-high SHDN) |
LT3045HMSE#PBF Pin Configuration
| Pin 1 | IN — Input supply voltage |
| Pin 2 | IN — Input supply voltage (tie to pin 1) |
| Pin 3 | SHDN — Active-high shutdown/enable input |
| Pin 4 | PGOOD — Power-good indicator output |
| Pin 5 | ILIM — Current limit programming |
| Pin 6 | GND — Signal ground |
| Pin 7 | SET — Output voltage programming input |
| Pin 8 | OUT — Regulated output voltage |
| Pin 9 | OUT — Regulated output voltage (tie to pin 8) |
| Pin 10 | NC — Not connected (per datasheet) |
| Pin 11 | NC — Not connected (per datasheet) |
| Pin 12 | NC — Not connected (per datasheet) |
Typical Applications
LT3045HMSE#PBF is suitable for 6 applications: RF PLL/VCO Power Supply, High-Speed ADC/DAC Reference Power, Precision Instrumentation Front-End, Medical Imaging Equipment, Post-Regulation After Switching Converters, Audio DAC and Studio Equipment.
RF PLL/VCO Power Supply
The LT3045HMSE#PBF delivers 500mA at 0.8 uVrms noise and 76 dB PSRR at 1 kHz, making it ideal for powering RF PLL and VCO circuits where supply noise directly translates into phase noise and degraded EVM. Placed between a switching pre-regulator and the PLL/VCO AVDD rail, it suppresses switching ripple by more than 70 dB at audio frequencies. The wide 20 V input range lets it post-regulate from a 12 V or 15 V system rail down to the 3.3 V PLL supply without thermal stress. Compared to a buck regulator alone, the LT3045 eliminates switching spurs from contaminating the synthesizer output.
Recommended
High-Speed ADC/DAC Reference Power
The LT3045HMSE#PBF's 0.8 uVrms output noise floor and 76 dB PSRR at 1 kHz make it the preferred post-regulator for high-resolution SAR and pipeline ADCs whose SNR is degraded by supply noise. Driving a 16-bit ADC reference from the LT3045's unity-gain output buffer preserves conversion linearity across the full input range. The 500 mA capacity supports reference buffers driving multiple ADCs in parallel. The 0 V to 15 V adjustable output covers unipolar and bipolar reference voltages from a single IC, simplifying BOM versus discrete reference + buffer chains.
Recommended
Precision Instrumentation Front-End
The LT3045HMSE#PBF powers the analog front-end of precision instrumentation - including weigh scales, strain-gauge amplifiers, and electrochemical sensor signal chains - where 0.8 uVrms noise is below the sensor's own noise floor. The unity-gain buffer topology maintains constant noise and bandwidth from 0 V to 15 V, allowing the same part to power both low-voltage op-amps and higher-voltage excitation rails. The sub-1 µA shutdown current extends battery life in portable instrumentation that sleeps between measurements, while the 500 mA capability supports lab-bench multi-channel designs.
Recommended
Medical Imaging Equipment
The LT3045HMSE#PBF's 0.8 uVrms noise and high PSRR are critical for ultrasound transducer bias, MRI gradient-driver analog rails, and patient-monitoring front-ends where supply noise directly couples into diagnostic accuracy. The 12-pin MSOP-EP package fits compact handheld ultrasound probes while delivering 500 mA for multi-channel beamformer ASICs. Its wide 0 V to 15 V output range supports both low-voltage FPGA rails and higher-voltage analog front-end supplies from a single LDO, reducing board area and BOM count in cost-sensitive medical designs.
Recommended
Post-Regulation After Switching Converters
The LT3045HMSE#PBF is widely deployed as a post-regulator after a switching buck or buck-boost converter to clean up switching ripple without sacrificing conversion efficiency. At 20 V input tolerance, it accepts outputs from common 12 V and 15 V intermediate rails, and its 260 mV dropout keeps power dissipation manageable even when the post-regulated rail is close to the buck output. The unity-gain architecture maintains 76 dB PSRR across all output voltages, eliminating the VOUT-dependent PSRR degradation seen in conventional LDOs and enabling single-part reuse across multiple rails.
Recommended
Audio DAC and Studio Equipment
The LT3045HMSE#PBF powers professional audio DACs and studio pre-amplifiers where 0.8 uVrms noise is far below the audible threshold and well under the DAC's own noise floor. Its high PSRR cleans residual switching ripple from upstream USB-PD or PoE rails, eliminating audible buzz in headphone amplifiers. The wide 0 V to 15 V output range covers both ±15 V op-amp rails and single-supply DAC AVDD pins from one IC, simplifying power architecture in mixing consoles. Sub-1 µA shutdown current preserves battery life in portable field recorders that idle between takes.
Recommended
Recommended Products Summary
Engineering reference data for LT3045HMSE#PBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT3045IMSE#PBF | LT3045HMSE#TRPBF | LT3045HMSE#WPBF | LT3042EMSE#PBF |
|---|---|---|---|---|---|
| Package | 12-pin MSOP-EP (MSE) | 12-pin MSOP-EP (MSE) - same | 12-pin MSOP-EP (MSE) - same | 12-pin MSOP-EP (MSE) - same | 12-pin MSOP-EP (MSE) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Output Current | 500 mA | 500 mA | 500 mA | 500 mA | 200 mA (-60%) |
| Input Voltage Range | 1.8 V to 20 V | 1.8 V to 20 V | 1.8 V to 20 V | 1.8 V to 20 V | 1.8 V to 20 V |
| Output Noise | 0.8 uVrms | 0.8 uVrms | 0.8 uVrms | 0.8 uVrms | 0.8 uVrms |
| PSRR (1 kHz) | 76 dB | 76 dB | 76 dB | 76 dB | 76 dB |
| Output Voltage Range | 0 V to 15 V | 0 V to 15 V | 0 V to 15 V | 0 V to 15 V | 0 V to 15 V |
| Grade / AEC-Q100 | H (high-grade) | I (industrial) | H (high-grade) | W (AEC-Q100 automotive) | E (extended) |
| Packaging | Tube (#PBF) | Tube | Tape & Reel | Tube (automotive) | Tube |
Key Differentiators
- Wide output voltage range with constant noise/PSRR (vs LT3042EMSE#PBF)
- Single-package automotive grade option (vs LT3045HMSE#PBF)
- Higher input voltage tolerance than competing LDOs (vs TPS7A4701 (TI VQFN-20))
Design Notes
The 12-pin MSOP-EP package relies on the exposed pad as the primary thermal path. Estimated: at VIN=5.5V, VOUT=5.0V, and 500mA load, power dissipation is approximately 0.25W. With junction-to-ambient thermal resistance around 33 °C/W on a 1 cm² copper pour, junction temperature rise is approximately 8 °C above ambient - well within the 125 °C limit. For higher VIN-VOUT deltas (e.g., 12V to 3.3V at 500mA = 4.35W dissipated), increase the PCB copper area to at least 4 cm² or add a topside thermal copper pour connected to the exposed pad to keep junction temperature below 100 °C.
Place input and output capacitors as close as possible to the IN and OUT pins respectively. Use a minimum 10 µF X7R ceramic capacitor on the input and a minimum 10 µF X7R on the output to maintain stability and PSRR. Keep capacitor ESR below 50 mΩ across all operating conditions. Connect IN pins 1 and 2 together, and OUT pins 8 and 9 together, using wide copper pours to minimize parasitic resistance. The exposed pad must be soldered to a continuous ground plane with multiple thermal vias.
Do not float the SHDN pin - tie it to IN through a 100 kΩ resistor if not actively driven, otherwise the LDO remains in an undefined state. The PGOOD pin is open-drain and requires an external pull-up resistor (typically 100 kΩ to OUT). Do not exceed 20 V on the IN pin even momentarily - the absolute maximum rating is 20 V. The SET pin is high-impedance and must be protected from contamination; use a guarded routing pattern and minimize trace length to prevent leakage-induced output voltage error.
Compliance Information
RoHS and REACH compliant per #PBF suffix designation. Standard part is not AEC-Q100 qualified - choose LT3045HMSE#WPBF for automotive applications. Halogen-free status not explicitly listed in retrieved web data.
