LT1964ES5-SD#PBF is a high-performance, low-noise, micropower, 200 mA low-dropout (LDO) linear regulator designed and manufactured by Analog Devices Inc. (following its acquisition of Linear Technology). It belongs to the ultra-low-noise LT1964 family, engineered specifically for powering noise-sensitive analog and RF circuitry in battery-powered and portable applications, where sub-microamp quiescent current, exceptional power supply rejection ratio (PSRR), and stability with tiny ceramic capacitors are critical.
The “ES5” suffix denotes the 5-lead SOT-23 package, one of the smallest standard surface-mount footprints available (2.9 mm × 1.6 mm); the “-SD” indicates a fixed 3.3 V output voltage; and the “#PBF” signifies Pb-free, RoHS-compliant construction, supplied in tape-and-reel format (typically 3,000 units per reel).
â ī¸ Critical Clarification:
The LT1964ES5-SD#PBF is not a general-purpose LDO. It is optimized for ultra-low-noise, micropower operation — achieving 20 µVRMS output noise (10 Hz–100 kHz) and only 20 µA quiescent current, while delivering up to 200 mA. This makes it uniquely suited for:
- Always-on sensor nodes (e.g., IoT temperature/humidity sensors),
- RF signal chains (VCOs, PLLs, LNAs) where PSRR > 70 dB at 1 MHz prevents switching noise from degrading phase noise,
- Hearing aids, wearables, and implantable medical devices requiring multi-year battery life.
Its SOT-23-5 (ES5) package, though small, includes an exposed pad (EP) for thermal enhancement — enabling full 200 mA load capability when properly soldered.
Introduction
The LT1964ES5-SD#PBF delivers best-in-class performance in an ultra-compact form factor:
đš Ultra-low noise: 20 µVRMS (10 Hz–100 kHz) — among the lowest noise figures available in any SOT-23 LDO, essential for high-SNR audio, precision ADCs, and low-phase-noise RF synthesis;
đš Micropower operation: 20 µA quiescent current (typ.), dropping to < 1 µA in shutdown mode — enables >10-year battery life on a single CR2032 coin cell (220 mAh) when powering a 1 µA sleep-mode microcontroller;
đš High PSRR: 75 dB @ 120 Hz, 70 dB @ 1 MHz, 40 dB @ 10 MHz, outperforming most competing micropower LDOs by 15–20 dB in the critical 1–10 MHz range;
đš Low dropout voltage: 300 mV (typ.) @ 200 mA, enabling efficient operation from single-cell Li-ion (3.0–4.2 V) or alkaline (3×AA = 4.5 V) supplies to power 3.3 V logic and analog circuits;
đš Stable with ultra-small ceramic capacitors: Requires only 1 µF (min) — no ESR constraints — simplifying design and improving reliability vs. tantalum or aluminum electrolytics.
It operates from an input range of 1.8 V to 20 V, making it suitable not only for post-regulation of switching supplies but also for direct regulation from 3.3 V, 5 V, or 12 V rails. Its SOT-23-5 (ES5) package, with exposed thermal pad, achieves θJA ≈ 220°C/W — supporting full 200 mA load at +60°C ambient when thermally optimized (e.g., with ≥ 4 thermal vias under EP).
Key Features
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Micropower & Low Dropout:
• Output current: up to 200 mA;
• Dropout voltage: 300 mV (typ.) @ 200 mA, 450 mV (max);
• Input voltage range: 1.8 V to 20 V;
• Quiescent current: 20 µA (typ.), < 1 µA (shutdown).
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Ultra-Low Noise & High PSRR:
• Output noise: 20 µVRMS (10 Hz–100 kHz) — ideal for 16+ bit SAR/Σ-Δ ADCs and low-noise op-amps;
• PSRR: 75 dB @ 120 Hz, 70 dB @ 1 MHz, 40 dB @ 10 MHz — superior suppression of switcher ripple and digital noise.
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Fast Transient Response & Stability:
• Load transient recovery: < 10 µs to ±1% for 100 mA step (with 4.7 µF ceramic output cap);
• Stable with ≥ 1 µF ceramic output capacitors — no minimum ESR required;
• No external compensation needed.
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Robust Protection & Operation:
• Reverse-battery protection: survives –20 V on IN (no damage, no reverse current);
• Thermal shutdown with hysteresis;
• Current limiting — foldback type for safe short-circuit operation;
• Shutdown pin (SD) with precise 1.2 V threshold and hysteresis.
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Fixed 3.3 V Output & SOT-23-5 (ES5) Package:
• Output voltage: 3.3 V (±2% initial accuracy, ±3% over line/load/temp);
• Package: 5-lead SOT-23 (2.9 mm × 1.6 mm) with exposed thermal pad (ES5) — industry-standard, compact, and manufacturable;
• RoHS-compliant, Pb-free, and qualified for –40°C to +125°C junction temperature.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices Inc. (formerly Linear Technology) |
| Product Series |
LT1964 Family (Low-Noise, Micropower LDOs) |
| Model |
LT1964ES5-SD#PBF |
| Function |
Fixed-Output Low-Dropout Linear Regulator |
| Output Voltage |
3.3 V (fixed), ±2% initial, ±3% over conditions |
| Max Output Current |
200 mA |
| Input Voltage Range |
1.8 V to 20 V |
| Dropout Voltage (200 mA) |
300 mV (typ.), 450 mV (max) |
| Output Noise (10 Hz–100 kHz) |
20 µVRMS |
| PSRR @ 1 MHz |
70 dB |
| Load Transient Recovery |
< 10 µs (±1%, 100 mA step, 4.7 µF out) |
| Min Output Capacitance |
1 µF ceramic (X5R/X7R) |
| Shutdown Threshold (SD) |
1.2 V (typ.), with hysteresis |
| Operating Junction Temp. |
–40°C to +125°C |
| Package |
5-Lead SOT-23 with Exposed Pad (ES5) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Packaging |
Tape-and-Reel (PBF), typically 3,000 units/reel |
Typical Applications
đš Battery-Powered Sensor Nodes: IoT environmental monitors, asset trackers, and smart agriculture sensors — leveraging 20 µA IQ and 1.8 V min input to run for years on AA/AAA or coin cells.
đš RF & Wireless Transceivers: Powering Bluetooth LE, Zigbee, LoRa, and NB-IoT SoCs (e.g., nRF52840, EFR32, SX1276) — using high PSRR to prevent DC-DC switching noise from degrading receiver sensitivity (SNR) and transmit spectral purity.
đš Wearable & Medical Electronics: Hearing aids, pulse oximeters, glucose monitors, and implantable telemetry — enabled by ultra-low noise (preserves signal integrity) and micropower (extends battery life).
đš Precision Analog Front-Ends: Supplying low-noise op-amps (e.g., LT1028, ADA4898), reference buffers (e.g., ADR45xx), and sensor signal conditioners — where LDO noise directly limits system resolution.
đš Portable Test Equipment: Handheld oscilloscopes, DMMs, and spectrum analyzers — benefiting from fast transient response and wide VIN tolerance for multi-chemistry battery support (Li-ion, NiMH, alkaline).
đš Industrial Edge Devices: Wireless vibration sensors, predictive maintenance nodes, and distributed temperature loggers — using robust reverse-voltage and thermal protection for field reliability.
Development & Design Notes
đ§ Thermal Management:
- The ES5 package’s exposed pad (EP) must be soldered to a ≥ 25 mm² internal ground plane using ≥ 4 thermal vias (0.25 mm) — essential for dissipating up to 200 mW (at 4.2 V → 3.3 V @ 200 mA) without exceeding TJ = 125°C.
- For continuous 200 mA operation above +50°C ambient, add a small copper pour or use forced airflow (>50 LFM).
đ§ Output Capacitor Selection & Layout:
- Use low-ESR, X5R or X7R ceramic capacitors (e.g., 4.7 µF, 0603 or 0805 size). Avoid high-ESR types — they degrade PSRR and transient response.
- Place output capacitors within 2 mm of VOUT and GND pins, with short, wide traces — minimizes inductance and preserves high-frequency PSRR.
- Add a 100 nF ceramic capacitor in parallel with the main output cap, placed closest to the IC — improves high-frequency bypassing (1–10 MHz).
đ§ Input Decoupling & Ripple Rejection:
- Use a 2.2 µF ceramic + 100 nF ceramic at the input — located < 3 mm from IN and GND pins. This reduces high-frequency noise coupling into the LDO control loop.
- For best PSRR, ensure the input supply itself has low impedance up to 10 MHz — consider adding a ferrite bead + 100 nF cap between upstream switcher and LT1964 if PSRR margin is tight.
đ§ Shutdown & Sequencing Integration:
- Tie SD to a supervisor IC (e.g., LTC2906) or microcontroller GPIO. Add a 10 nF capacitor from SD to GND for noise immunity.
- Use the shutdown function for deep-sleep modes (e.g., wake every hour for sensor read) — reduces system IQ to < 1 µA.
đ§ Reliability & Long-Term Stability:
- LT1964 exhibits < 0.3% output voltage drift over 10 years (per Linear reliability reports) — suitable for calibration-critical applications.
- For functional safety (IEC 61508 SIL-2), combine thermal monitoring (via external NTC on EP copper) with watchdog-timed readback of output voltage via optional external ADC — ADI provides FIT rate (11) and FMEDA data.
