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Analog Devices Inc. LTC3445EUF#TRPBF
- Part No.:
- LTC3445EUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3445EUF#TRPBF.pdf
- Description:
- IC REG TRPL BCK/LNR 1.5MHZ 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,924
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Product details
Overview
LTC3445EUF#TRPBF from Analog Devices (formerly Linear Technology) is a highly integrated power management IC featuring a synchronous buck regulator, two adjustable LDOs, a PowerPath™ controller, and an I²C interface - all in a 24-lead 4mm × 4mm QFN package. It delivers up to 600mA from the buck stage (0.85V–1.55V programmable), supports 50mA per LDO with 0.3V dropout, operates from 2.5V–5.5V input, and enables dynamic battery backup selection for portable microprocessor systems like Intel PXA27x.
For engineers reviewing the LTC3445EUF#TRPBF datasheet, LTC3445EUF#TRPBF pinout, LTC3445EUF#TRPBF application, or LTC3445EUF#TRPBF equivalent, key selection considerations include I²C-programmable output voltage slew rate (0.9–11.3 mV/µs), spread-spectrum switching (reducing EMI), Burst Mode® operation (360µA active / 27µA shutdown), and PowerPath-controlled VCC_BATT sourcing from main battery or coin-cell backup.
Technical Context
The LTC3445EUF#TRPBF implements a current-mode synchronous buck regulator with internal P- and N-channel MOSFETs (RDS(ON) = 0.45Ω / 0.325Ω), programmable 1.5MHz constant or spread-spectrum switching, and 6-bit DAC-controlled output (0.85V–1.55V in ~14.7mV steps). Its dual LDOs use external resistor dividers to set outputs from 0.6V to (VCC2 – 0.3V), each delivering up to 50mA with 0.3V dropout at full load.
The PowerPath controller dynamically selects between VCC1 (main battery), VTRACK (tracked supply), and VBACKUP (coin cell) to maintain VCC_BATT, while BATTFAULT provides open-drain fault signaling below 2.5V VCC1. The I²C interface supports standard (100kHz) and fast mode (400kHz), enabling real-time configuration of buck voltage, slew rate, and spread-spectrum depth without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Buck Output Range | 0.85V to 1.55V, digitally programmable via 6-bit DAC register with 14.7mV typical step size |
| Max Buck Output Current | 600mA at VCC1 = 3V / VOUT = 1.3V; derated at lower input voltages (e.g., ~400mA at VCC1 = 2.5V) |
| LDO Output Capability | Two independent 50mA LDOs, each with ≤0.3V dropout at full load and 0.6V feedback reference |
| Input Voltage Range | 2.5V to 5.5V for VCC1/VCC2; supports single Li-ion battery operation with full functionality |
| Quiescent Current | 360µA typical operating current; drops to 27µA in shutdown mode |
| Switching Frequency | 1.5MHz nominal (1.2–1.8MHz range); configurable spread-spectrum dither (0%, 7.4%, 14.8%, 22.4%) |
| I²C Interface Speed | Supports both standard (100kHz) and fast mode (400kHz) timing; address bits ADD7/ADD6 strappable to VCC1 or GND |
Pinout & Package
Package: 24-lead (4mm × 4mm) plastic QFN with exposed pad (Pin 25 = GND, must be soldered to PCB ground for thermal and electrical performance).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VTRACK (1) | PowerPath tracking sense input | Monitors external supply to regulate VCC_BATT within ±200mV when ≥3V; must be ≤ VCC1 |
| VBACKUP (2) | Backup battery input | Connects coin cell (2V–5.5V); supplies VCC_BATT when VCC1 falls below 2.4V |
| VCC1 (3,10) | Main input power supply | 2.5V–5.5V primary input; powers buck, logic, and I²C; both pins must be connected |
| PGOOD (4) | Open-drain fault indicator | Asserts low if buck, LDO1, or LDO2 output falls out of regulation |
| ADD7 (5) | I²C address bit 7 | Strappable to VCC1 or GND to configure one of four device addresses |
| SDA (6) | I²C bidirectional data line | Open-drain interface; requires external pull-up; supports read/write operations |
| NC (7) | No connect | Not internally bonded; must remain unconnected |
| SCL (8) | I²C clock input | Drives serial communication timing; requires external pull-up |
| ADD6 (9) | I²C address bit 6 | Strappable to VCC1 or GND to complete 2-bit I²C address selection |
| GND (11) | Buck N-FET source reference | Primary ground return for buck switch node; connects to exposed pad |
| SW (14) | Buck switch node | Connects to external inductor; carries high-frequency pulsed current |
| RUN (15) | Enable/disable control | Logic-high (>1.5V) enables all regulators; <0.3V forces shutdown (<35µA IQ) |
| FB (17) | Buck feedback input | Resistor divider sets output voltage; referenced to 0.6V internal DAC-adjusted threshold |
| VCC_BATT (18) | PowerPath regulated output | Auto-switched output (3V or VTRACK-tracked) for system backup rail |
| BATTFAULT (19) | Open-drain battery fault flag | Pulls low when VCC1 drops below 2.5V; indicates main battery failure |
| LDO1FB (20) | LDO1 feedback input | Resistor divider sets LDO1 output; referenced to 0.6V internal bandgap |
| LDO1 (21) | LDO1 regulated output | Delivers up to 50mA; output = 0.6V × (1 + R1/R2) |
| VCC2 (22) | LDO supply input | 2.5V–5.5V input for both LDOs; decoupling required near pin |
| LDO2 (23) | LDO2 regulated output | Delivers up to 50mA; output = 0.6V × (1 + R1/R2) |
| LDO2FB (24) | LDO2 feedback input | Resistor divider sets LDO2 output; referenced to same 0.6V bandgap |
| Exposed Pad (25) | Thermal & electrical ground | Mandatory PCB solder connection for thermal dissipation and signal integrity |
Key Features
| Feature | Design Value |
|---|---|
| I²C-programmable buck slew rate | Four selectable rates (0.9–11.3 mV/µs) enable controlled voltage transitions during dynamic core scaling |
| Spread-spectrum switching | Configurable frequency dither (up to 22.4%) reduces peak EMI by spreading energy across spectrum |
| Burst Mode® operation | Reduces quiescent current to 6µA in sleep state while maintaining regulation via output capacitor hold-up |
| PowerPath automatic battery switchover | Seamlessly transitions VCC_BATT from main battery to coin-cell backup without software intervention or glitches |
| Dual independent LDOs | Each supports external resistor programming and delivers stable 50mA output with <15mV load regulation |
Applications
| Intel PXA27x Microprocessor Supply | Portable Medical Instruments |
|---|---|
Use Scenario: Powering Intel PXA27x application processors requiring tightly regulated core (VCC_CORE), I/O (VCC_IO), and backup rails. IC Role / Device Role / Timing Role: LTC3445EUF#TRPBF serves as the primary PMIC, generating VCC_CORE (buck), VCC_IO (LDO1), and VCC_BATT (PowerPath) with I²C-configurable sequencing and voltage margins. Use Value: Eliminates need for discrete regulators and battery switchover circuitry; enables dynamic core voltage scaling via I²C slew control to match processor DVFS states. | Use Scenario: Battery-powered handheld diagnostic devices (e.g., pulse oximeters, glucose meters) requiring long runtime and reliable backup during main battery replacement. IC Role / Device Role / Timing Role: LTC3445EUF#TRPBF manages main Li-ion supply, powers analog front-end (LDO2), digital logic (LDO1), and preserves SRAM state via VCC_BATT during hot-swap of primary battery. Use Value: PowerPath ensures zero-interruption backup with <200mV tracking error; Burst Mode extends battery life beyond 100 hours in standby. |
| Industrial Handheld Terminals | Wearable Health Monitors |
Use Scenario: Ruggedized inventory scanners and field service terminals operating across wide temperature ranges (-40°C to +85°C). IC Role / Device Role / Timing Role: LTC3445EUF#TRPBF provides robust power delivery with thermal-aware buck regulation, fault reporting (PGOOD/BATTFAULT), and I²C-accessible diagnostics for remote monitoring. Use Value: Integrated fault flags simplify host MCU supervision; spread-spectrum mode meets Class B EMC requirements without added shielding. | Use Scenario: Ultra-low-power wearable sensors (ECG, SpO₂) worn continuously for multi-day monitoring. IC Role / Device Role / Timing Role: LTC3445EUF#TRPBF supplies sensor analog chain (LDO2), digital subsystem (LDO1), and maintains RTC/sleep-state memory (VCC_BATT) from coin cell during deep-sleep cycles. Use Value: 27µA shutdown current minimizes coin-cell drain; programmable buck voltage allows optimal trade-off between sensor SNR and battery longevity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multi-rail power management applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65132ARSLR | Single buck + dual LDO, but no PowerPath or I²C interface; fixed 1.2V/1.8V LDO outputs; no programmable slew or spread-spectrum | Best suited for cost-sensitive, non-backup applications where voltage flexibility and EMI control are secondary | Select only if I²C control, battery switchover, and EMI reduction are unnecessary |
| MAX8667ETE+ | Similar integration (buck + dual LDO + I²C), but lacks PowerPath; uses different feedback architecture (0.5V ref); max buck current 400mA | Applicable where coin-cell backup is handled externally, and lower buck current suffices for simpler SoCs | Choose when PowerPath functionality is not required and footprint compatibility with 16-pin TQFN is preferred |
Compared with TPS65132ARSLR and MAX8667ETE+, the LTC3445EUF#TRPBF uniquely combines I²C-programmable buck voltage/slew, spread-spectrum EMI reduction, and autonomous PowerPath battery switchover - making it the only option supporting seamless, glitch-free backup in compact portable microprocessor systems.
Availability
LTC3445EUF#TRPBF is available at Aetrix Electronics and suitable for portable medical instruments, industrial handheld terminals, and wearable health monitors requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3445EUF#TRPBF 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.
The LTC3445EUF#TRPBF belongs to Linear's PowerPath™ PMIC family, designed specifically for space-constrained, battery-powered applications demanding intelligent power routing, multi-rail regulation, and I²C configurability - especially in portable computing and medical instrumentation.
FAQ
What is the maximum output current capability of the buck regulator in LTC3445EUF#TRPBF?
The LTC3445EUF#TRPBF buck regulator delivers up to 600mA when VCC1 = 3V and VOUT = 1.3V. At lower input voltages (e.g., VCC1 = 2.5V), the maximum output current decreases to approximately 400mA due to reduced duty cycle headroom and higher conduction losses. The datasheet specifies this derating curve in Figure 3 ("Buck Maximum Peak Current vs VCC1").
Does LTC3445EUF#TRPBF support spread-spectrum switching, and how is it configured?
Yes, LTC3445EUF#TRPBF supports spread-spectrum switching to reduce conducted and radiated EMI. It is enabled and controlled via two bits (REG5[1:0]) in the I²C register map: 00 = off (1.5MHz constant), 01 = 7.4% spread, 10 = 14.8%, and 11 = 22.4%. This dithering lowers peak noise amplitude without affecting regulation accuracy or efficiency.
How does the PowerPath controller in LTC3445EUF#TRPBF manage battery backup?
The LTC3445EUF#TRPBF PowerPath controller automatically selects VCC_BATT source based on three inputs: VCC1 (main battery), VTRACK (tracked supply), and VBACKUP (coin cell). When VCC1 > 2.8V and VTRACK ≥ 3V, VCC_BATT tracks VTRACK within ±200mV; if VTRACK drops below 3V, VCC_BATT defaults to 3V from VCC1; if VCC1 falls below 2.4V, VBACKUP takes over - all without host intervention.
Can the LDO outputs of LTC3445EUF#TRPBF be adjusted, and what is their dropout voltage?
Yes, both LDOs in LTC3445EUF#TRPBF are externally adjustable using resistor dividers on LDO1FB/LDO2FB pins, with output range from 0.6V to (VCC2 – 0.3V). Each delivers up to 50mA with a guaranteed dropout voltage of ≤0.3V at full load, enabling stable regulation even as VCC2 approaches the LDO output voltage.
What is the function of the RUN pin on LTC3445EUF#TRPBF, and what happens when it is pulled low?
The RUN pin on LTC3445EUF#TRPBF is the master enable input. Pulling it above 1.5V enables all regulators and logic; pulling it below 0.3V forces full shutdown, reducing total supply current to ≤35µA. The pin must never be left floating and must remain ≤ VCC1. In shutdown, all outputs (buck, LDOs, VCC_BATT) are disabled and PGOOD/BATTFAULT go high-impedance.
LTC3445EUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Topology:
- Step-Down (Buck) (1), Linear (LDO) (2)
- Number of Outputs:
- 3
- Frequency - Switching:
- 1.5MHz
- Voltage/Current - Output 1:
- 0.85V ~ 1.55V, 600mA
- Voltage/Current - Output 2:
- Adj to 0.6V, 50mA
- Voltage/Current - Output 3:
- Adj to 0.6V, 50mA
- w/LED Driver:
- No
- w/Supervisor:
- No
- w/Sequencer:
- No
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LTC3445EUF#TRPBF FAQ
1.How can I place an order for LTC3445EUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3445EUF#TRPBF 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 LTC3445EUF#TRPBF reliable?
The price and inventory of LTC3445EUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3445EUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3445EUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3445EUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3445EUF#TRPBF?
LTC3445EUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3445EUF#TRPBF 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 LTC3445EUF#TRPBF?
For technical support, including LTC3445EUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3445EUF#TRPBF requirements.
6.How does Aetrix verify that LTC3445EUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3445EUF#TRPBF 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 LTC3445EUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3445EUF#TRPBF?
All LTC3445EUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3445EUF#TRPBF, 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 LTC3445EUF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3445EUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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