LT1931AIS5#TRPBF - 2.2MHz Inverting 1A DC/DC Converter | ADI
MPN: LT1931AIS5#TRPBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.85 | $4.85 |
| 10 | $4.36 | $43.60 |
| 100 | $3.88 | $388.00 |
| 500 | $3.49 | $1,745.00 |
| 1,000 | $3.1 | $3,100.00 |
LT1931AIS5#TRPBF Overview
A DC/DC switching regulator (also called a switch-mode converter or SMPS) is an electronic circuit that uses energy storage elements (inductors, capacitors) and high-frequency switching to convert one DC voltage to another with high efficiency (typically 85-95%) versus a linear regulator. The inverting topology (often implemented as a Cuk or buck-boost variant) flips the polarity of the input voltage - so a +5 V input becomes -5 V at the output - using a single inductor and coupling capacitor. Inverting converters sit in the power management IC hierarchy alongside buck, boost, and SEPIC converters, all feeding downstream analog and mixed-signal systems.
Key features include 2.2 MHz fixed-frequency operation (A suffix), 1 A integrated power switch, wide 2.45 V to 16 V input range, low output ripple, and the ability to use tiny surface-mount components 2 mm or less in height. The ThinSOT-23-5 footprint enables compact designs while the 2.2 MHz switching frequency keeps the converter above the AM broadcast band and outside common 455 kHz IF stages, simplifying EMI filtering.
Technically, the LT1931A uses constant-frequency current-mode control for clean loop compensation and fast transient behavior. The high-side 1 A switch supports high peak inductor currents needed to deliver hundreds of mA at voltages from -5 V down to -34 V. Compared to charge-pump negative regulators, the LT1931A delivers much higher output current and supports higher power levels without the source-current spikes that couple back into the input rail.
Typical applications include negative bias supplies for op-amps and LCD panels, portable instrumentation, GaN and SiC gate-driver negative rails, automotive sensor interfaces, and industrial analog front-ends. The wide input range also makes it suitable for 12 V bus systems and battery-powered equipment where a small, hot-rail-tolerant negative rail is required.
When designing with the LT1931A, select a Schottky catch diode with low reverse leakage and adequate voltage margin (30 V or more for high-Vout designs), and use ceramic input/output capacitors rated for the peak currents seen in Cuk topology. The exposed backside thermal pad of the ThinSOT helps dissipate the 1 A switch losses, but the small footprint limits continuous output to a few hundred mA without airflow.
This page consolidates distributor pricing (DigiKey, Mouser, LCSC), verified same-family drop-in alternatives (LT1931AIS5#TRMPBF, LT1931AES5#TRPBF), and practical design notes not found in the standalone datasheet.
Drop-in alternatives for LT1931AIS5#TRPBF — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LT1931AIS5#TRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1931AES5#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1931IS5#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1931AES5#TRMPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1931CS5#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1931HS5#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1931AIS5#TRPBF Maximum Ratings & Electrical Characteristics
| Topology | Inverting (Cuk) DC/DC Converter |
| Switching Frequency | 2.2 MHz (LT1931A) |
| Input Voltage Range | 2.45 V to 16 V |
| Output Voltage Range | Down to -34 V (negative) |
| Integrated Switch Current | 1 A (peak) |
| Output Current Capability | Up to 350 mA at -5 V from 5 V input |
| Output Ripple | 1 mV P-P typical (at -5 V/150 mA from 5 V in) |
| Configuration | Buck-Boost / Inverting (Cuk) |
| Number of Outputs | 1 |
| Package | ThinSOT-23-5 (TSOT-23-5) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C (industrial) |
| MSL Level | 1 (Unlimited) |
| RoHS Status | ROHS3 Compliant |
| REACH Status | REACH Unaffected |
| Lead-Free | Yes (Pb-free finish) |
LT1931AIS5#TRPBF Pin Configuration
| Pin 1 | SHDN — Shutdown (active high, tie to VCC for always-on) |
| Pin 2 | SW — Switch node - connect to inductor |
| Pin 3 | GND — Ground reference |
| Pin 4 | VCC — Input supply voltage (2.45 V to 16 V) |
| Pin 5 | FB — Feedback - sets negative output via external resistor divider |
Typical Applications
LT1931AIS5#TRPBF is suitable for 6 applications: Negative Bias Supply for Op-Amps and ADC Front-Ends, LCD and OLED Display Bias Generation, Portable and Battery-Powered Instrumentation, GaN and SiC Gate Driver Negative Rails, Industrial Sensor Signal Conditioning, Automotive Sensor and Infotainment Power.
Negative Bias Supply for Op-Amps and ADC Front-Ends
The LT1931AIS5#TRPBF generates a clean -5 V to -15 V rail from a +5 V or +12 V input, ideal for powering op-amps (e.g., AD8628, AD797) and precision ADC front-ends that require symmetric dual supplies. Its 1 mV P-P ripple and 350 mA output at -5 V from 5 V in keep the negative rail quiet enough not to inject noise into low-level analog signal paths. The 2.2 MHz switching frequency sits above most amplifier unity-gain bandwidths, so post-LC filtering is rarely required.
Recommended
LCD and OLED Display Bias Generation
Small portable displays need negative gate-off voltages typically between -8 V and -25 V. The LT1931AIS5#TRPBF delivers up to -34 V output in the same ThinSOT-23-5 footprint, fitting beside the display connector where a charge pump would be too noisy or too current-limited. The Cuk topology's continuous input current avoids the source spikes that cause pixel artifacts in TFT/OLED panels, while the 1 A internal switch easily handles the 50-200 mA bias load.
Recommended
Portable and Battery-Powered Instrumentation
Battery-powered test gear, handheld multimeters, and portable data loggers often need a negative rail from a single Li-ion cell. The LT1931AIS5#TRPBF operates down to 2.45 V input and can run from a nearly-discharged 3.0 V Li-ion cell, producing -5 V for op-amp front-ends or sensor excitation. Its 1 MHz+ switching frequency enables tiny 2 mm inductors, keeping the converter footprint well under 50 mm^2 - critical for handheld form factors.
Recommended
GaN and SiC Gate Driver Negative Rails
Wide-bandgap power transistors (GaN HEMTs, SiC MOSFETs) often need a small negative bias (-3 V to -8 V) to ensure full enhancement-mode turn-off and avoid false triggering. The LT1931AIS5#TRPBF provides a tightly-regulated negative rail from the +12 V bus that powers the half-bridge, with sub-1 mV P-P ripple that prevents gate-oxide stress from switching noise. The 1 A peak switch handles the inrush when the gate capacitance charges at turn-on.
Recommended
Industrial Sensor Signal Conditioning
Industrial analog front-ends for strain gauges, thermocouples, and load cells frequently run from +/-15 V rails but need to operate from a single 24 V industrial bus. The LT1931AIS5#TRPBF converts +24 V to -15 V at up to 150 mA with high efficiency, eliminating the need for a second isolated supply rail. The MSL 1 floor-life rating simplifies board kitting for high-mix industrial assembly lines.
Recommended
Automotive Sensor and Infotainment Power
Automotive 12 V battery rails and infotainment systems need compact negative bias generators for TFT displays, audio DACs, and AM/FM tuner IF stages. The LT1931AIS5#TRPBF's 16 V max input tolerates 12 V load-dump transients (with input protection), while the 2.2 MHz oscillator keeps switching noise out of the AM broadcast band (530-1700 kHz). The ThinSOT-23-5 footprint fits behind the head-unit display connector where board space is severely constrained.
Recommended
Recommended Products Summary
Engineering reference data for LT1931AIS5#TRPBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT1931AIS5#TRMPBF | LT1931AES5#TRPBF | LT1931IS5#TRPBF | LT1931AES5#TRMPBF | LT1931CS5#TRPBF | LT1931HS5#TRPBF |
|---|---|---|---|---|---|---|---|
| Package | ThinSOT-23-5 | ThinSOT-23-5 - same | ThinSOT-23-5 - same | ThinSOT-23-5 - same | ThinSOT-23-5 - same | ThinSOT-23-5 - same | ThinSOT-23-5 - same |
| Brand | Analog Devices | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same |
| Topology | Inverting (Cuk) | Inverting (Cuk) | Inverting (Cuk) | Inverting (Cuk) | Inverting (Cuk) | Inverting (Cuk) | Inverting (Cuk) |
| Switching Frequency | 2.2 MHz | 2.2 MHz | 2.2 MHz | 1.2 MHz (-45%) | 2.2 MHz | 1.2 MHz (-45%) | 2.2 MHz |
| Integrated Switch Current | 1 A | 1 A | 1 A | 1 A | 1 A | 1 A | 1 A |
| Input Voltage Range | 2.45 V to 16 V | 2.45 V to 16 V | 2.45 V to 16 V | 2.45 V to 16 V | 2.45 V to 16 V | 2.45 V to 16 V | 2.45 V to 16 V |
| Output Ripple (typ) | 1 mV P-P | 1 mV P-P | 1 mV P-P | 1 mV P-P | 1 mV P-P | 1 mV P-P | 1 mV P-P |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +150 C (extended) |
| Unit Price (qty-1, as of 2026-10-08) | $4.85 | ~$4.85 (same die) | ~$4.50 | ~$4.20 | ~$4.50 | ~$4.20 | ~$5.80 (high-temp) |
Key Differentiators
- Highest power inverting SOT-23 DC/DC in ADI's portfolio (vs ICL7660 / LT1054 charge pumps)
- 2.2 MHz switching keeps EMI out of AM broadcast band (vs LT1931IS5#TRPBF (1.2 MHz))
- Continuous input current avoids charge-pump source spikes (vs ICL7660 / LT1054 charge pumps)
Design Notes
Keep the input capacitor (C1), output capacitor (C3), catch diode, and feedback divider traces short and tight to the LT1931AIS5#TRPBF ThinSOT-23-5 pads. The Cuk topology requires a coupling capacitor (C2) carrying pulsed current - place it directly between SW and the output node with wide traces to minimize loop area. Estimated: with 4-layer 1-oz copper and 10 mm^2 thermal pad soldered down, the LT1931A dissipates roughly 300-400 mW at 100 mA load before requiring airflow.
Do not confuse the LT1931A with the LT1930 (boost) or LT1935 (different boost IC); both share the ThinSOT-23-5 footprint but neither inverts polarity. Also avoid using a generic Schottky diode with insufficient reverse voltage - the catch diode must withstand the maximum negative output plus input, which can reach 50 V for -34 V outputs. The SHDN pin must not be left floating; tie it to VCC through a 100 kohm resistor if always-on operation is desired.
Although the 2.2 MHz fundamental lies above the AM broadcast band, harmonics of the switch-node waveform can still couple into adjacent analog traces. Place a small ferrite bead on the input and consider shielded inductors for the SW-node inductor. Estimated: a 4-layer board with 0.5 oz copper and proper stitching vias typically achieves CISPR 22 Class B with 6-10 dB margin using the LT1931A's standard BOM.
Compliance Information
ROHS3 compliant and REACH unaffected per distributor data (DigiKey, Mouser). MSL 1 (unlimited floor life) per ADI datasheet 1931fa. Halogen-free status not stated in verified web data. No AEC-Q100 automotive qualification - consider LT1931-Q1 variants for automotive.
