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Analog Devices Inc. LTC3520EUF#TRPBF
- Part No.:
- LTC3520EUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3520EUF#TRPBF.pdf
- Description:
- IC REG BUCK BOOST ADJ DL 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,738
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Product details
Overview
LTC3520EUF#TRPBF from Analog Devices (formerly Linear Technology) is a dual-output synchronous DC/DC converter integrating a 1A buck-boost and a 600mA buck regulator in a single 24-lead 4mm × 4mm QFN package. It supports 2.2V–5.5V input, delivers 3.3V/500mA (buck-boost) and 1.8V/600mA (buck), and features pin-selectable Burst Mode® operation for ultra-low quiescent current (55μA typ. in Burst Mode). It is used in portable media players and GPS receivers requiring compact, high-efficiency dual-rail power.
For engineers reviewing the LTC3520EUF#TRPBF datasheet, LTC3520EUF#TRPBF pinout, LTC3520EUF#TRPBF application, or LTC3520EUF#TRPBF equivalent, key selection criteria include its dual-converter architecture, programmable 100kHz–2MHz switching frequency, uncommitted gain block for LDO/battery-good functions, thermal/overcurrent protection, and –40°C to 85°C operating range.
Technical Context
The LTC3520EUF#TRPBF implements two independent control architectures: the buck converter uses current-mode PWM with internal synchronous rectification and 100% duty-cycle capability; the buck-boost employs a proprietary four-switch topology enabling seamless transition between buck, buck-boost, and boost modes without inductor current discontinuity. Both share a common oscillator whose frequency is set by an external RT resistor.
It integrates an uncommitted transconductance amplifier (gain = 80dB) configurable as a battery-good comparator or LDO controller via external PNP, with AIN threshold at 0.786V (typ.) and AOUT sink/source capability of 17mA/18μA. Shutdown current is <1μA, and Burst Mode entry is controlled separately per converter via PWM1/PWM2 pins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.2V to 5.5V - supports single-cell Li-ion (2.7–4.2V) and USB-powered systems without pre-regulation. |
| Buck-Boost Output | 2.2V to 5.25V, 1A max at VOUT = 3.3V and VIN ≥ 3V - enables output regulation above, below, or equal to input voltage. |
| Buck Output | 0.8V to VIN, 600mA max - includes 100% duty-cycle dropout operation for extended battery runtime. |
| Switching Frequency | Programmable 100kHz to 2MHz via RT pin - allows trade-off between efficiency, size, and EMI performance. |
| Quiescent Current | 55μA typical (both converters in Burst Mode) - enables >1-year battery life in always-on portable devices. |
| Package | 24-lead 4mm × 4mm QFN, 0.75mm height - provides high thermal performance and minimal PCB footprint. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and consumer portable applications. |
| Protection Features | Thermal shutdown, overcurrent limit (1.25A buck-boost forward, 0.8A buck), and <1μA shutdown mode - ensures robust system-level reliability. |
Pinout & Package
24-lead (4mm × 4mm) plastic QFN package with exposed pad (Pin 25) soldered to PCB ground. Pin pitch: 0.5mm. Height: 0.75mm. RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SVIN (1) | Small-signal power supply | Powers internal circuitry; must be tied to PVIN1/PVIN2/PVIN3 and bypassed with ≥0.1μF ceramic capacitor. |
| AOUT (2) | Uncommitted amplifier output | Sinks up to 17mA; used for LDO pass transistor drive or open-drain battery-good indicator. |
| AIN (3) | Non-inverting amplifier input | Threshold reference input (0.786V typ.); sets battery-good trip point when used as comparator. |
| RT (4) | Oscillator frequency programming | Resistor-to-ground sets switching frequency (e.g., 54.9kΩ → 1MHz); enables optimization of efficiency vs. size. |
| PWM1 (5) | Buck-boost mode control | High = fixed-frequency PWM; Low = variable-frequency Burst Mode (reduced light-load noise/efficiency trade-off). |
| SD1 (6) | Buck-boost shutdown | Active-low enable; >1.4V = enabled, <0.4V = disabled - allows independent power sequencing. |
| SD2 (7) | Buck shutdown | Active-low enable; decouples buck rail during sleep or fault conditions without affecting buck-boost. |
| SD3 (8) | Amplifier shutdown | Disables uncommitted gain block to eliminate its 45μA quiescent draw when unused. |
| PVIN2 (9) | Buck high-current input | Carries buck converter input current; requires ≥22μF local ceramic bypass to PGND2. |
| SW2 (10) | Buck switch node | Connects to buck inductor; handles high di/dt; layout critical for EMI and efficiency. |
| PGND2 (11) | Buck power ground | Low-impedance return path for buck NMOS; must be short/wide trace to minimize noise coupling. |
| PWM2 (12) | Buck mode control | Configurable Burst Mode entry point via resistor (e.g., 301kΩ → ~75mA threshold) or hard-wired logic. |
| SS2 (13) | Buck soft-start | External capacitor sets soft-start duration (tSS ≈ 0.15·CSS in ms); prevents inrush into downstream loads. |
| FB2 (14) | Buck feedback input | 0.790V reference; regulates VOUT2 via resistor divider; input bias current ≤50nA minimizes divider error. |
| VC1 (15) | Buck-boost error amp output | Compensation node; connects to FB1 via RC network; clamped internally during Burst Mode. |
| SGND (16) | Small-signal ground | Reference for analog blocks (AIN, FB1/FB2, VC1); must tie to exposed pad and PGNDs at single point. |
| SS1 (17) | Buck-boost soft-start | External capacitor sets soft-start time; ensures monotonic VOUT1 ramp without overshoot. |
| FB1 (18) | Buck-boost feedback input | 0.782V reference; regulates VOUT1; precision enables stable output across input/output voltage ranges. |
| VOUT1 (19) | Buck-boost output | Main regulated output; requires low-ESR ceramic capacitor (e.g., 47μF) placed adjacent to pin. |
| SW1B (20) | Buck-boost switch node B | One side of buck-boost inductor; works with SW1A to implement four-switch topology. |
| PGND1 (21) | Buck-boost power ground | High-current return for NMOS switches; shares ground plane with exposed pad and SGND. |
| SW1A (22) | Buck-boost switch node A | Second buck-boost switch node; complements SW1B to enable bidirectional energy transfer. |
| PVIN1/PVIN3 (23/24) | Buck-boost high-current inputs | Parallel paths for buck-boost input current; each requires ≥22μF local ceramic bypass. |
| Exposed Pad (25) | Thermal & electrical ground | Mandatory solder connection to PCB ground plane; primary thermal path (θJA = 37°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| Dual synchronous converters in one package | Eliminates need for two separate ICs and associated passives, reducing solution size by >40% vs. discrete implementation. |
| Four-switch buck-boost topology | Enables continuous conduction mode across all VIN/VOUT ratios, minimizing output ripple and improving efficiency at light loads. |
| Pin-selectable Burst Mode® | Reduces total quiescent current to 55μA while maintaining regulation - critical for battery-powered standby operation. |
| Uncommitted transconductance amplifier | Configurable as battery-good comparator (0.786V threshold) or LDO controller, adding third regulated rail without extra IC. |
| Independent shutdown and soft-start | Allows precise power sequencing (e.g., enable buck-boost before buck) and eliminates inrush-induced system resets. |
| Integrated protection suite | Includes thermal shutdown, cycle-by-cycle overcurrent limiting, and undervoltage lockout - reduces external fault-handling components. |
Applications
| Portable Media Players | Digital Cameras |
|---|---|
|
Use Scenario: Powering SoC core (1.8V), memory interface (3.3V), and image sensor bias (1.5V) from single Li-ion cell. IC Role / Device Role / Timing Role: Dual-output DC/DC converter providing tightly regulated, low-noise rails with independent sequencing and load transient response. Use Value: Enables 3.3V/500mA (VOUT1) and 1.8V/600mA (VOUT2) simultaneously from 2.7–4.2V input, extending playback time by 18% vs. linear regulators. |
Use Scenario: Supplying CMOS image sensor (1.5V), ISP processor (1.8V), and LCD backlight driver (3.3V) in compact camera module. IC Role / Device Role / Timing Role: High-efficiency dual converter delivering fast load-step response (<100μs) and low output ripple (<20mVpp) for noise-sensitive imaging. Use Value: Achieves >90% efficiency at 200mA load on both rails, reducing thermal dissipation in sealed enclosure and preventing image artifacts. |
| Handheld PCs / PDAs | GPS Receivers |
|
Use Scenario: Generating 3.3V I/O rail and 1.2V core voltage for ARM-based application processor in always-connected handheld device. IC Role / Device Role / Timing Role: Dual converter with 100% duty-cycle buck operation maintains core voltage during battery droop, avoiding brownout resets. Use Value: Delivers 600mA at 1.2V with <1% load regulation from 3.0V to 2.2V input, ensuring stable CPU operation down to end-of-life battery voltage. |
Use Scenario: Powering GPS baseband IC (1.8V), RF front-end (3.3V), and backup SRAM (1.5V) in automotive-grade navigation unit. IC Role / Device Role / Timing Role: Industrial-temperature-rated dual converter with thermal shutdown and robust ESD protection (±2kV HBM). Use Value: Supports –40°C to +85°C operation with <1.5% output voltage drift over temperature, ensuring reliable satellite lock in extreme environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS63020DSJR | Single-inductor buck-boost only (no separate buck channel); 2A output; fixed 2.5MHz switching frequency; no uncommitted amplifier. | Lacks independent buck rail and LDO/comparator functionality; suitable only where single-output flexibility suffices. | Choose when board space is more constrained than feature count, and third rail can be generated externally. |
| MAX8646ETL+ | Two independent buck converters (not buck-boost); 1.2A/1.2A outputs; integrated MOSFETs; no Burst Mode; higher quiescent current (120μA). | Cannot regulate output above input; unsuitable for wide-input-range or battery-voltage-tracking applications. | Prefer when both rails are strictly step-down and high light-load efficiency is secondary to cost or simplicity. |
Compared with TPS63020DSJR and MAX8646ETL+, the LTC3520EUF#TRPBF uniquely combines buck-boost and buck topologies with an uncommitted amplifier, enabling three regulated outputs from one IC while maintaining sub-1μA shutdown and programmable frequency - critical for multi-rail portable systems with dynamic voltage requirements.
Availability
LTC3520EUF#TRPBF is available at Aetrix Electronics and suitable for portable media players, digital cameras, and GPS receivers requiring stable component supply, long-term lifecycle support, and guaranteed industrial-temperature performance.
Supply support for LTC3520EUF#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and consumer markets.
The LTC3520 belongs to Linear's Power Management product line, designed specifically for space-constrained, battery-powered portable electronics requiring high-efficiency dual-output regulation with advanced power sequencing and ultra-low quiescent current.
FAQ
What is the maximum output current capability of the LTC3520EUF#TRPBF buck-boost converter?
The LTC3520EUF#TRPBF buck-boost converter delivers up to 1A continuous output current at VOUT = 3.3V when VIN ≥ 3V. At lower input voltages (e.g., VIN = 2.5V), maximum output current decreases due to duty-cycle and thermal limits; typical capability is 500mA at 3.3V with VIN = 2.5V. The datasheet specifies forward current limit as 1.25A (LTC3520E grade) under test conditions.
How does the uncommitted gain block in the LTC3520EUF#TRPBF function as a battery-good indicator?
The LTC3520EUF#TRPBF's uncommitted gain block uses AIN as non-inverting input with 0.786V (typ.) threshold. When AIN voltage drops below this level - e.g., from a resistor divider off the battery - AOUT transitions low, signaling "battery low." AOUT sinks up to 17mA, allowing direct drive of an LED or microcontroller GPIO. No external comparator is needed, reducing BOM count and layout area.
Can the LTC3520EUF#TRPBF operate with input voltage below its minimum specified 2.2V?
No - absolute maximum ratings specify SVIN, PVIN1–3 must remain ≥ –0.3V, but operation below 2.2V violates the functional specification. Undervoltage lockout activates at ~2.2V (rising), disabling both converters. Attempting to operate below this risks unstable regulation, increased quiescent current, or failure to start. For sub-2.2V applications, consider dedicated low-VIN boost converters.
What is the purpose of the exposed pad (Pin 25) on the LTC3520EUF#TRPBF, and how must it be connected?
The exposed pad (Pin 25) on the LTC3520EUF#TRPBF serves as the primary thermal dissipation path and electrical ground reference. It must be soldered directly to a solid PCB ground plane using ≥4 thermal vias (0.3mm diameter) to inner/outer ground layers. Failure to connect it results in junction temperature rise >30°C and potential thermal shutdown - the datasheet specifies θJA = 37°C/W assumes full pad soldering.
Does the LTC3520EUF#TRPBF support independent enable/disable of its buck and buck-boost converters?
Yes - the LTC3520EUF#TRPBF provides fully independent control: SD1 (Pin 6) enables/disables the buck-boost converter, SD2 (Pin 7) controls the buck converter, and SD3 (Pin 8) disables the uncommitted amplifier. Each is active-low with TTL-compatible thresholds (≥1.4V = high, ≤0.4V = low), enabling flexible power sequencing - e.g., bring up VOUT1 first, then VOUT2 after stabilization.
LTC3520EUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 2.2V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 600mA, 1A
- Frequency - Switching:
- 100kHz ~ 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LTC3520EUF#TRPBF FAQ
1.How can I place an order for LTC3520EUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3520EUF#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 LTC3520EUF#TRPBF reliable?
The price and inventory of LTC3520EUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3520EUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3520EUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3520EUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3520EUF#TRPBF?
LTC3520EUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3520EUF#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 LTC3520EUF#TRPBF?
For technical support, including LTC3520EUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3520EUF#TRPBF requirements.
6.How does Aetrix verify that LTC3520EUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3520EUF#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 LTC3520EUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3520EUF#TRPBF?
All LTC3520EUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3520EUF#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 LTC3520EUF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3520EUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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