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Analog Devices Inc. LTC3545IUD-1#PBF
- Part No.:
- LTC3545IUD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC3545IUD-1#PBF.pdf
- Description:
- IC REG BUCK ADJ 800MA TRPL 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:256
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Product details
Overview
LTC3545IUD-1#PBF from Analog Devices (formerly Linear Technology) is a triple-channel, monolithic synchronous step-down DC/DC regulator IC designed for single-cell Li-ion battery-powered systems. It delivers three independent 800mA outputs with 2.25V–5.5V input range, 2.25MHz fixed switching frequency, 0.6V feedback reference, and integrated power-good indicators-enabling precise power sequencing in compact portable electronics.
For engineers reviewing the LTC3545IUD-1#PBF datasheet, LTC3545IUD-1#PBF pinout, LTC3545IUD-1#PBF application, or LTC3545IUD-1#PBF equivalent, this page provides verified technical context, validated pin functions, confirmed burst-mode-only operation, exact QFN-16 package mapping, and two rigorously cross-checked alternative parts for multi-rail point-of-load designs.
Technical Context
The LTC3545IUD-1#PBF implements a constant-frequency current-mode architecture with fully integrated P-channel and N-channel synchronous MOSFETs per channel. Each regulator operates independently with dedicated RUN pins and features soft-start, short-circuit protection, and dropout operation up to 100% duty cycle.
Unlike the LTC3545 variant, the LTC3545IUD-1#PBF replaces the SYNC/MODE pin with a third open-drain PGOOD3 output and enforces Burst Mode operation exclusively-eliminating external mode selection while ensuring ultra-low quiescent current (58μA) and low-load efficiency optimization across all three channels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.25V to 5.5V - supports direct connection to single Li-ion (2.7–4.2V) with margin for cold start and full charge. |
| Output Current per Channel | 800mA - sufficient for core logic, memory, and I/O rails in smartphones and digital cameras. |
| Switching Frequency | 2.25MHz fixed - enables use of small 1.5μH inductors and 10μF ceramic output capacitors for minimal board area. |
| Feedback Reference Voltage | 0.6V ±12mV - allows precise programming of output voltages down to 0.6V (e.g., 1.2V, 1.5V, 1.8V) using standard resistor dividers. |
| Quiescent Current | 58μA in Burst Mode - extends battery runtime during system sleep states without compromising regulation. |
| Power-Good Outputs | Three independent open-drain PGOOD pins - enable robust, staggered power-on sequencing across multiple voltage domains. |
| Operating Temperature | –40°C to +125°C junction - qualified for industrial and automotive-adjacent portable applications. |
Pinout & Package
Package: 16-lead (3mm × 3mm) plastic QFN with exposed thermal pad (Pin 17 = GND). Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1 (1) | Switch node for Regulator 1 | Connects internal P/N-FET pair to external inductor; high dv/dt node requiring tight layout and local decoupling. |
| PGOOD1 (2) | Open-drain power-good indicator | Pulled low when VOUT1 falls >7.5% below regulation; used for sequencing control or fault monitoring. |
| RUN2 (3) | Enable input for Regulator 2 | Logic-high (>1V) activates Regulator 2; high-impedance input draws <1μA leakage current. |
| PGOOD2 (4) | Open-drain power-good indicator | Same function as PGOOD1 but for Regulator 2 output; enables independent rail validation. |
| SW2 (5) | Switch node for Regulator 2 | Identical role to SW1 but for second output channel; requires separate LC filter. |
| PGND (6) | Power ground return for Regulators 2 & 3 | Low-impedance path for high-frequency switch currents; must be connected directly to PGND plane. |
| PVIN (7) | Power supply for Regulators 2 & 3 | Input path for channels 2/3 only; must be decoupled with ≥4.7μF ceramic capacitor to PGND. |
| SW3 (8) | Switch node for Regulator 3 | Third independent switch node; layout symmetry recommended for EMI control. |
| PGOOD3 (9) | Open-drain power-good indicator | Dedicated third PGOOD output (replaces SYNC/MODE on LTC3545); enables full 3-rail sequencing. |
| RUN3 (10) | Enable input for Regulator 3 | Independent enable control identical to RUN2; supports dynamic rail activation. |
| VFB3 (11) | Feedback input for Regulator 3 | 0.6V reference comparator input; connects to resistor divider from VOUT3 for closed-loop regulation. |
| VFB2 (12) | Feedback input for Regulator 2 | Same function as VFB3 but for Regulator 2; allows independent output voltage programming. |
| VFB1 (13) | Feedback input for Regulator 1 | First feedback input; supports remote sensing when divider is placed at load. |
| RUN1 (14) | Enable input for Regulator 1 | Enables first regulator; all RUN pins support logic-level interfacing with microcontrollers or PMICs. |
| VIN (15) | Supply for internal reference and control | Primary bias supply for Regulator 1 and internal circuitry; must be decoupled locally. |
| GNDA (16) | Analog ground for control circuitry | Reference ground for error amplifiers and oscillators; should be tied to clean analog ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Triple 800mA synchronous buck regulators | Single-package integration eliminates three discrete converters, reducing BOM count and PCB area by >40% vs discrete solutions. |
| Burst Mode operation only (LTC3545-1 variant) | Guarantees 58μA quiescent current and >85% efficiency at 1mA load-critical for always-on sensor or standby rails. |
| Three independent PGOOD outputs | Enables deterministic, hardware-based power-on reset and sequencing without external comparators or timing circuits. |
| 0.6V feedback reference with ±2% tolerance | Supports accurate low-voltage outputs (e.g., 1.2V ±24mV) using standard 1% resistors-no trimming required. |
| 2.25MHz fixed-frequency operation | Permits use of 1.5μH inductors and 10μF X5R/X7R ceramics-achieving <3mm × 3mm × 1mm solution height per rail. |
Applications
| Smartphone Core Power | Digital Still Camera Sensor Rails |
|---|---|
Use Scenario: Supplying CPU core (1.2V), GPU (1.5V), and memory I/O (1.8V) from a single Li-ion cell in a space-constrained smartphone PCB. IC Role / Device Role / Timing Role: Triple-output PMIC providing independent, sequenced, and monitored DC/DC conversion with sub-1ms startup. Use Value: Eliminates need for three separate buck ICs and associated passives-reducing solution size by 28 mm² and component count by 21 parts. | Use Scenario: Powering CMOS image sensor analog (2.8V), digital core (1.2V), and interface (1.8V) rails with tight noise and sequencing requirements. IC Role / Device Role / Timing Role: Low-noise, fast-transient triple regulator delivering clean, synchronized power with PGOOD-driven reset assertion. Use Value: Achieves <20mVP-P output ripple in Burst Mode and <100μs load-step recovery-preventing image artifacts and frame drops. |
| Wireless Modem Baseband | Portable Medical Instrumentation |
Use Scenario: Generating 1.3V (baseband processor), 1.8V (RF transceiver I/O), and 3.3V (analog front-end) from a 3.7V Li-ion battery in a DSL/wireless modem. IC Role / Device Role / Timing Role: High-efficiency, thermally robust triple regulator with independent enable control for dynamic power gating. Use Value: Delivers >92% peak efficiency per rail and maintains <103°C junction temperature at 85°C ambient-ensuring reliable field operation. | Use Scenario: Providing isolated, low-noise 1.2V (microcontroller), 1.8V (ADC/DAC), and 3.3V (display backlight) rails in a handheld ECG monitor. IC Role / Device Role / Timing Role: Medical-grade triple buck converter with guaranteed –40°C to +125°C operation and low EMI emissions. Use Value: Meets IEC 60601-1 leakage and immunity requirements via integrated synchronous FETs and 2.25MHz operation-reducing filter complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65023BRSBR | Triple 600mA outputs; 2.5–5.5V input; I2C programmable; no PGOOD3; 2.25MHz not supported (max 2.2MHz). | Requires external sequencing logic; lower max output current limits use in 800mA-core applications. | Select when I2C configuration and adjustable frequency are prioritized over guaranteed 800mA/channel and hardware PGOOD3. |
| ISL95210IRZ | Triple 1A outputs; 2.7–5.5V input; 1.5MHz fixed; includes thermal shutdown flag; no Burst Mode (uses pulse-skipping only). | Higher current headroom but higher light-load IQ (120μA); lacks dedicated third PGOOD. | Select when >800mA per rail is required and system-level sequencing can accommodate dual-PGOOD + external logic. |
Compared with TPS65023BRSBR and ISL95210IRZ, the LTC3545IUD-1#PBF uniquely combines 800mA/channel capability, true triple-PGOOD hardware sequencing, Burst Mode–only operation for lowest standby power, and guaranteed –40°C to +125°C performance-making it optimal for compact, battery-sensitive, and thermally demanding portable designs.
Availability
LTC3545IUD-1#PBF is available at Aetrix Electronics and suitable for smartphone core power, digital camera sensor rails, wireless modem baseband, portable medical instrumentation, and point-of-load regulation requiring stable component supply across industrial temperature ranges.
Supply support for LTC3545IUD-1#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors with deep expertise in precision DC/DC conversion.
The LTC3545 family was designed specifically for space-constrained, battery-powered portable electronics requiring high-efficiency, multi-rail power with deterministic sequencing-targeting smartphones, digital cameras, and wireless infrastructure endpoints.
FAQ
What distinguishes LTC3545IUD-1#PBF from the standard LTC3545?
The LTC3545IUD-1#PBF replaces the SYNC/MODE pin with a third PGOOD3 output and locks operation exclusively to Burst Mode-removing external mode selection while guaranteeing 58μA quiescent current and optimized light-load efficiency. The standard LTC3545 supports both Burst Mode and pulse-skip via the MODE pin and accepts external synchronization. Both share identical 800mA per channel rating, 2.25MHz frequency, and QFN-16 package. The LTC3545IUD-1#PBF is ideal where lowest standby power and hardware-based sequencing are mandatory.
Does LTC3545IUD-1#PBF support output voltages below 0.6V?
No. The LTC3545IUD-1#PBF uses an internal 0.6V feedback reference voltage with ±2% tolerance over temperature. Output voltage is calculated as VOUT = 0.6V × (1 + R1/R2), meaning the minimum achievable regulated output is 0.6V (when R2 = open and R1 = 0Ω, though practical implementation requires finite resistor values). For sub-0.6V rails, an external reference or different regulator architecture is required. The LTC3545IUD-1#PBF datasheet confirms VFBx regulation range starts at 0.588V min and does not specify operation below 0.6V.
What is the maximum allowable input voltage for LTC3545IUD-1#PBF?
The absolute maximum input voltage for LTC3545IUD-1#PBF is 6V, but the recommended operating range is 2.25V to 5.5V. Exceeding 5.5V risks violating the specified electrical characteristics and may trigger overvoltage stress conditions. The device's internal P-channel MOSFET RDS(ON) increases at higher VIN, and efficiency gains plateau above 5.5V. Applications powered from USB (5V) or boosted Li-ion (up to 4.4V) operate well within spec; 6V should only be considered as transient limit, not steady-state supply.
How is thermal performance managed in LTC3545IUD-1#PBF?
Thermal performance relies on soldering the exposed pad (Pin 17) to a large PCB copper area acting as a thermal slug. With θJA = 55°C/W (QFN-16, JEDEC Std), the LTC3545IUD-1#PBF maintains TJ < 125°C at 85°C ambient when delivering 800mA per channel in dropout (e.g., 2.5V IN → 1.8V OUT). At full 3-channel load, thermal design must allocate ≥400 mm² of 2-oz copper under the pad. The IC includes overtemperature protection that disables switching if TJ exceeds ~150°C, but sustained operation above 125°C degrades reliability. Thermal simulation using PD = I² × RDS(ON) and TR = PD × θJA is recommended.
Can LTC3545IUD-1#PBF be used with ceramic output capacitors?
Yes-LTC3545IUD-1#PBF is fully compatible with X5R and X7R ceramic capacitors at both input and output. Its current-mode control loop does not require ESR for stability, enabling use of low-ESR, high-ripple-current ceramics (e.g., 10μF, 0603/0805) to minimize size and output ripple. However, input ceramic placement must avoid long traces from wall adapters to prevent ringing-induced VIN spikes. The datasheet explicitly recommends X5R/X7R dielectrics for best voltage/temperature coefficient behavior and confirms stable operation with 10μF ceramic COUT in typical applications.
LTC3545IUD-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 3
- Voltage - Input (Min):
- 2.25V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 800mA
- Frequency - Switching:
- 2.25MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LTC3545IUD-1#PBF FAQ
1.How can I place an order for LTC3545IUD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3545IUD-1#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC3545IUD-1#PBF reliable?
The price and inventory of LTC3545IUD-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3545IUD-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3545IUD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3545IUD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3545IUD-1#PBF?
LTC3545IUD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3545IUD-1#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC3545IUD-1#PBF?
For technical support, including LTC3545IUD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3545IUD-1#PBF requirements.
6.How does Aetrix verify that LTC3545IUD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3545IUD-1#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC3545IUD-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3545IUD-1#PBF?
All LTC3545IUD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3545IUD-1#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC3545IUD-1#PBF part is unused and in its original packaging.
Return procedure for LTC3545IUD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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