LT1374CR - 4.5A 500kHz Buck Switch Reg | Analog Devices
MPN: LT1374CR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.99 | $7.99 |
| 10 | $7.45 | $74.50 |
| 100 | $6.55 | $655.00 |
| 500 | $5.85 | $2,925.00 |
| 1,000 | $5.2 | $5,200.00 |
LT1374CR Overview
A buck (step-down) switching regulator is a switched-mode DC-DC converter that uses an inductor, a power switch, and a rectifier to transfer energy from a higher input rail to a lower output rail at high efficiency. The LT1374CR belongs to the broader hierarchy of voltage regulators -> DC-DC converters -> switching regulators -> power management ICs. The 500 kHz constant switching frequency permits a small 1.8 µH saturating inductor and all-ceramic input/output capacitors, simplifying the bill of materials and shrinking the solution footprint compared to 100-200 kHz predecessors.
Key features include a 0.07 ohm saturating internal NPN switch for low dropout loss, 2.5 mA quiescent supply current, 20 µA shutdown current, current-mode topology for fast transient response and good loop stability, and full cycle-by-cycle short-circuit protection. The device is offered in both fixed 5 V output (LT1374CR-5) and adjustable (LT1374CR) versions, with optional shutdown/synchronization via the LT1374CR-SYNC variant. The exposed thermal tab provides a low theta-JA path to dissipate up to several watts at full 4.5 A load.
The current-mode architecture samples inductor current each cycle and feeds it into a PWM comparator against the error amplifier output, giving inherent line-rejection and a single-pole compensation network. Synchronization to an external 600 kHz clock is supported on SYNC parts, allowing multiple regulators to phase-lock and reduce input RMS ripple. Thermal shutdown and cycle-by-cycle current limiting protect against output shorts and overload conditions, while the wide 5 V to 25 V VIN range covers 12 V and 24 V industrial bus rails without a preregulator.
Typical applications include 5 V to 12 V distributed power systems, industrial 24 V bus converters, automotive accessory power (with appropriate transient protection), battery chargers, and distributed point-of-load regulation for FPGAs, DSPs, and microcontrollers. A high-current variant such as the LT1374CR is especially valuable where a discrete switching controller plus external MOSFET would otherwise occupy too much PCB area.
When laying out the LT1374CR, keep the input ceramic bypass capacitor within 5 mm of the VIN pin, use a low-ESR inductor rated for 5 A saturation, and connect the exposed tab to a 1 square-inch copper pour for thermal relief. Watch the maximum VIN rating of 25 V and provide a TVS or fuse for inductive load transients on industrial rails. SYNC and fixed-5-variants share the same 7-pin DDPAK footprint for PCB reuse.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, giving procurement engineers and designers a single source for LT1374CR decisions.
Drop-in alternatives for LT1374CR — 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:
LT1374CR#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT1374CR-5
✅ Drop-In📋 Reference alternative (not in catalog)
LT1374CR-SYNC
✅ Drop-In📋 Reference alternative (not in catalog)
LT1374HVCR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LT1374CR Maximum Ratings & Electrical Characteristics
| Topology | Buck (Step-Down), SEPIC |
| Input Voltage Range | 5 V to 25 V |
| Output Voltage Range | 2.42 V to 21.5 V (adjustable) |
| Switch Current | 4.5 A |
| Switching Frequency | 500 kHz (constant) |
| Quiescent Current | 2.5 mA |
| Shutdown Current | 20 µA |
| Internal Switch RDS(on) | 0.07 ohm (saturating) |
| Control Topology | Current-mode PWM |
| Short-Circuit Protection | Cycle-by-cycle current limit |
| Thermal Shutdown | Yes |
| Output Type | Adjustable |
| Operating Temperature Range | -40C to +125C (industrial) |
| Package | TO-263-8 / DDPAK (7 Leads + Tab) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (PBF suffix) |
LT1374CR Pin Configuration
| Pin 1 | VIN — Input supply voltage (5 V to 25 V); bypass with 10 µF ceramic to GND |
| Pin 2 | SW — Switch node; connects to inductor and catch diode cathode |
| Pin 3 | GND — Ground reference; tie directly to exposed tab |
| Pin 4 | FB / SHDN — Feedback (LT1374CR adjustable) or SHDN (LT1374CR-SYNC) |
| Pin 5 | VC — Compensation node for error amplifier; add RC network to ground |
| Pin 6 | VC BYPASS — Internal 3.1 V reference bypass; 1 nF ceramic to ground |
| Pin 7 | BOOST — Boost supply for switch driver; diode from VIN to BOOST |
Typical Applications
LT1374CR is suitable for 6 applications: 24V Industrial Bus Point-of-Load, Distributed Power 12V to 5V/3.3V Conversion, Battery Charger / USB Power Delivery, Automotive 12V Accessory Power, FPGA/DSP Core and I/O Rails, SEPIC Topology for Buck-Boost Conversion.
24V Industrial Bus Point-of-Load
The LT1374CR's 5 V to 25 V input range and 4.5 A switch current make it a strong fit for stepping 24 V industrial bus rails down to 5 V, 12 V, or 15 V intermediate rails for PLCs, industrial sensors, and motor-drive auxiliary power. Placed after a TVS diode and common-mode choke, the LT1374CR delivers up to 3 A continuous at 5 VOUT from 24 VIN with efficiency above 85 percent thanks to the 0.07 ohm internal switch. The 500 kHz switching frequency allows all-ceramic input/output capacitors and a 1.8 µH inductor, shrinking the solution area versus legacy 100 kHz regulators like the LM2576.
Recommended
Distributed Power 12V to 5V/3.3V Conversion
In distributed-power architectures, the LT1374CR efficiently converts a 12 V intermediate bus to local 5 V or 3.3 V rails powering FPGAs, DSPs, and microcontrollers. The 4.5 A switch rating supports high-current cores; the 2.5 mA quiescent current keeps light-load losses acceptable for always-on subsystems. Its 500 kHz constant frequency allows a small 1.8 µH inductor and ceramic-only output capacitance, freeing PCB area versus 100-200 kHz predecessors. The current-mode control loop also yields fast transient response for load steps from DSP cores.
Recommended
Battery Charger / USB Power Delivery
The LT1374CR's 5 V to 25 V input range and high switch current suit it for stepping an automotive or industrial battery down to charge a 1-4 cell Li-ion battery stack with current-mode control for accurate CC/CV transition. Using the SEPIC topology enabled by the LT1374CR, designers can create a buck-boost charger accepting inputs both above and below the battery voltage without reversing polarity. The exposed thermal tab dissipates several watts at full charge current, while the 20 µA shutdown current extends standby life.
Recommended
Automotive 12V Accessory Power
With a 5 V to 25 V input range covering nominal 12 V automotive rails plus load-dump headroom (when paired with a TVS clamp), the LT1374CR powers infotainment, dashboard, and accessory subsystems from the vehicle battery. The 4.5 A switch current drives high-current USB chargers, lighting, and body-control modules. Wide -40C to +125C operation handles under-hood and cabin temperature extremes. The exposed DDPAK tab mounts directly to a chassis-grounded heatsink or copper pour for sustained 3-4 A output at elevated ambient.
Recommended
FPGA/DSP Core and I/O Rails
The LT1374CR delivers the high-current, low-ripple 5 V, 3.3 V, or 2.5 V rails demanded by FPGA I/O banks and DSP core supplies from a 12 V or 24 V backplane. The 500 kHz switching frequency is well above most FPGA clock harmonics, simplifying EMI filter design, while current-mode control provides fast transient response for load steps when the FPGA enters or exits low-power states. The exposed thermal tab and 4.5 A switch rating easily sustain 2-3 A continuous to feed multiple FPGA I/O banks plus a downstream LDO for the core voltage.
Recommended
SEPIC Topology for Buck-Boost Conversion
The LT1374CR supports SEPIC (Single-Ended Primary Inductor Converter) topology, making it valuable when the input voltage can swing both above and below the desired output voltage. A typical application is generating a stable 12 V rail from a battery that swings 9-18 V across charge and discharge cycles. The LT1374CR's 4.5 A switch handles the higher SEPIC currents at low VIN, and the 500 kHz frequency keeps magnetics small. Designers reference AN-1488 from ADI for SEPIC component selection and compensation.
Recommended
Recommended Products Summary
Engineering reference data for LT1374CR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT1374IR | LT1374CR#PBF | LT1374CR-5 | LT1374CR-SYNC | LT1374HVCR |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | TO-263-7 (DDPAK) | TO-220-7 (through-hole) | TO-263-7 (DDPAK) - same | TO-263-7 (DDPAK) - same | TO-263-7 (DDPAK) - same | TO-263-7 (DDPAK) - same |
| Switch Current | 4.5 A | 4.5 A | 4.5 A | 4.5 A | 4.5 A | 4.5 A |
| Switching Frequency | 500 kHz | 500 kHz | 500 kHz | 500 kHz | 500 kHz | 500 kHz |
| Input Voltage Range | 5 V to 25 V | 5 V to 25 V | 5 V to 25 V | 5 V to 25 V | 5 V to 25 V | 5 V to 32 V |
| Output Type | Adjustable (2.42 V to 21.5 V) | Adjustable | Adjustable | Fixed 5 V | Adjustable | Adjustable |
| SYNC Pin | No | No | No | No | Yes (with SHDN) | No |
| Lead-Free / RoHS | Yes (PBF) | Yes (PBF) | Yes (lead-free suffix) | Yes (PBF) | Yes (PBF) | Yes (PBF) |
Key Differentiators
- 500 kHz switching frequency shrinks magnetics (vs LM2596S-ADJ)
- 4.5 A internal switch is highest in this family (vs LT1374CR-5 (fixed 5V))
- Wide 5 V to 25 V input covers 12 V and 24 V industrial buses (vs LT1374HVCR)
- Synchronization option for noise-sensitive multi-rail designs (vs LT1374CR (standard))
Design Notes
Estimated: at VIN=12 V, VOUT=5 V, and 3.5 A continuous load, the LT1374CR's 0.07 ohm switch RDS(on) dissipates roughly 0.86 W plus a few hundred mW of switching loss. With the DDPAK package theta-JA around 30 C/W on a 1 square-inch copper pour, junction temperature rises ~26 C above ambient. For full 4.5 A output at high VIN/VOUT differential, attach the exposed tab to a heatsink or expand the copper pour to 4 square inches to keep Tj below 125 C. Verify with a thermocouple in your application.
Place the input ceramic bypass capacitor within 5 mm of the VIN pin, with a direct ground return to the GND pin and exposed tab. Keep the switch node (SW) trace short and away from sensitive analog traces, since the 500 kHz edge can radiate 100 MHz harmonics. Use a low-ESR 10 µF X7R ceramic on VIN plus a 22 µF X7R ceramic on VOUT; place the VC bypass 1 nF capacitor as close to pin 6 as possible to stabilize the internal reference.
Do not exceed the 25 V absolute maximum on VIN; for automotive load-dump transients above 25 V, add a TVS diode such as SMBJ26A rated for the highest expected transient. The BOOST pin requires a small-signal diode (e.g. 1N4148 or BAV99) from VIN and a 0.1 µF ceramic to ground; omitting this diode prevents the internal switch driver from saturating and reduces efficiency by 10-20 percent. Also ensure the catch diode on SW is a fast-recovery Schottky (MBRS140 or equivalent); slow rectifiers cause excess switching loss and EMI.
Route the feedback trace away from the switch node and inductor to avoid noise injection; if a long trace is unavoidable, place a 1 nF ceramic from FB to ground to filter switching noise. Connect the exposed thermal tab directly to a large ground copper pour with multiple thermal vias (at least 9 vias of 0.3 mm diameter) to spread heat into inner PCB planes. Use a star-ground configuration tying input capacitor ground, output capacitor ground, and IC GND to a single point near the IC tab to minimize ground bounce.
Compliance Information
RoHS/REACH compliance per ADI product page; AEC-Q100 not qualified - for automotive designs requiring qualification, choose AEC-Q100 parts such as TI TPS54340BDDA or ON NCP3170A. Lead-free (matte tin) finish on #PBF suffix variants.
