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Analog Devices Inc. LTC3522EUD#PBF
- Part No.:
- LTC3522EUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LTC3522EUD#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ DL 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:106
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Product details
Overview
LTC3522EUD#PBF from Analog Devices (formerly Linear Technology) is a dual-output synchronous DC/DC converter integrating a 400mA buck-boost and a 200mA buck regulator in a single 3mm × 3mm QFN package. It operates from 2.4V to 5.5V input, delivers regulated outputs at 2.2–5.25V (buck-boost) and 0.6V–VIN (buck), and supports 1MHz fixed-frequency or Burst Mode operation for ultra-low quiescent current. It is used in portable medical instruments and digital cameras requiring compact dual-rail power.
For engineers reviewing the LTC3522EUD#PBF datasheet, LTC3522EUD#PBF pinout, LTC3522EUD#PBF application, or LTC3522EUD#PBF equivalent, key selection criteria include independent shutdown control (SHDN1/SHDN2), dual Power Good flags (PGOOD1/PGOOD2), 25μA combined quiescent current in Burst Mode, thermal/overcurrent protection, and seamless buck/buck-boost/boost mode transition without output discontinuity.
Technical Context
The LTC3522EUD#PBF implements two independent switching regulators sharing a 1MHz oscillator: the buck-boost uses voltage-mode control with a proprietary 4-switch topology enabling continuous conduction across buck, buck-boost, and boost modes; the buck uses current-mode control with internal synchronous rectification and 100% duty-cycle capability for dropout extension. Both converters feature integrated soft-start (600μs nominal) and internal compensation.
Each converter has dedicated feedback inputs (FB1 for buck-boost, FB2 for buck), separate active-low shutdown pins (SHDN1, SHDN2), and open-drain Power Good outputs (PGOOD1, PGOOD2) with ±7.7% to ±12% regulation thresholds and 2.5% hysteresis. The PWM pin globally selects between Burst Mode (variable frequency, low IQ) and forced PWM mode (fixed 1MHz, low noise).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.4V to 5.5V - supports single-cell Li-ion (2.7–4.2V) and regulated 3.3V/5V rails without external pre-regulation. |
| Buck-Boost Output | 2.2V to 5.25V at up to 400mA - enables rail generation above or below input, e.g., 3.3V from 2.7–4.2V battery. |
| Buck Output | 0.6V to VIN at up to 200mA - supports low-voltage logic rails (e.g., 1.8V, 1.2V) with 100% duty cycle for extended battery life. |
| Quiescent Current | 25μA total in Burst Mode - minimizes standby drain in always-on portable devices like PDAs and navigation units. |
| Oscillator Frequency | 0.8MHz to 1.33MHz typical - ensures consistent 1MHz operation while allowing tolerance margin for EMI filtering and layout optimization. |
| Protection Features | Thermal shutdown (150°C), overcurrent limit (0.65–0.85A avg for buck-boost; 300–400mA peak for buck), and UVLO (2.3V) - prevents damage during fault conditions without external circuitry. |
| Package | 16-pin 3mm × 3mm QFN with exposed pad - provides low thermal resistance (θJA = 68°C/W) and high-density integration for space-constrained PCBs. |
Pinout & Package
The LTC3522EUD#PBF is housed in a 16-lead, 3mm × 3mm × 0.75mm plastic QFN package with an exposed thermal pad (Pin 17) that must be soldered to PCB ground. Pin pitch is 0.5mm. PVIN1 and PVIN2 are internally connected in the application and require shared 4.7μF ceramic bypassing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB2 (Pin 1) | Buck converter feedback input | Connects to resistor divider on VOUT2; sets output via 0.594V reference - enables precise 1.8V/1.2V generation with standard resistor ratios. |
| PWM (Pin 2) | Mode select control input | Low = Burst Mode for both converters; High = forced 1MHz PWM - allows system-level noise vs. efficiency trade-off without firmware changes. |
| GND (Pin 3) | Small-signal ground reference | Separate from power grounds (PGND1/PGND2); must be tied to exposed pad and PGNDs at single point to avoid noise coupling into error amplifiers. |
| PGOOD2 (Pin 4) | Buck converter status flag | Open-drain output pulls low if VOUT2 is out of regulation (−7.7%), OT, or UVLO - used for power sequencing and fault reporting in handheld systems. |
| FB1 (Pin 5) | Buck-boost converter feedback input | Connects to resistor divider on VOUT1; sets output via 1.00V reference - supports wide output range (2.2–5.25V) with minimal external components. |
| PGOOD1 (Pin 6) | Buck-boost converter status flag | Open-drain output pulls low if VOUT1 is out of regulation (−10% in Burst Mode), OT, or UVLO - enables independent monitoring of primary rail in dual-supply systems. |
| SHDN1 (Pin 7) | Buck-boost enable/disable control | Active-low; >1.4V = enabled, <0.4V = disabled - allows independent power gating of buck-boost rail (e.g., display backlight) without affecting buck rail. |
| PVIN1 (Pin 8) | Buck-boost high-current input | Supplies switch A; requires local 4.7μF ceramic cap - must be short-traced and tied to PVIN2 to minimize loop inductance and switching noise. |
| PGND2 (Pin 9) | Buck-boost switch C ground return | High-current path for buck-boost inductor return - must use wide, low-inductance PCB trace directly to exposed pad to prevent ground bounce. |
| SW1B (Pin 10) | Buck-boost switch node B | Connects to one end of buck-boost inductor (L1) - forms part of 4-switch H-bridge; carries bidirectional current during buck/boost transitions. |
| SW1A (Pin 11) | Buck-boost switch node A | Connects to other end of buck-boost inductor (L1) - works with SW1B to implement seamless mode transitions without output ripple discontinuity. |
| VOUT1 (Pin 12) | Buck-boost regulated output | Delivers 2.2–5.25V at up to 400mA - connects to low-ESR output capacitor (≥4.7μF) placed adjacent to IC for stability and transient response. |
| PGND1 (Pin 13) | Shared power ground for buck rectifier and buck-boost switches B/C | Common return for high-current paths - must be tied to GND and exposed pad at single point to avoid ground loops and EMI. |
| SW2 (Pin 14) | Buck switch node | Connects to buck inductor (L2) - carries unidirectional pulsed current; requires tight layout with PVIN2 and PGND1 to minimize switching losses. |
| PVIN2 (Pin 15) | Buck input and internal VCC supply | Supplies buck switch and internal circuitry; requires local 4.7μF ceramic cap - shares input with PVIN1; defines system input rail for both converters. |
| SHDN2 (Pin 16) | Buck enable/disable control | Active-low; >1.4V = enabled, <0.4V = disabled - enables independent control of secondary rail (e.g., processor core voltage) during sleep states. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated dual-converter architecture | Eliminates need for two discrete regulators and associated passives - reduces BOM count by ≥12 components and saves ≥25mm² PCB area in portable designs. |
| Seamless 4-switch buck-boost topology | Enables continuous conduction across buck/buck-boost/boost modes - avoids output voltage glitches during battery discharge, critical for camera image sensors and medical ADCs. |
| Independent Power Good flags | PGOOD1 and PGOOD2 provide per-rail health monitoring - supports safe power sequencing in multi-rail systems like PDAs and navigation devices without external supervisors. |
| Internal soft-start (600μs) | Prevents inrush current and output overshoot during startup - eliminates need for external soft-start capacitors and simplifies design validation for battery-powered applications. |
| Dual shutdown control (SHDN1/SHDN2) | Allows independent enable/disable of each converter - enables dynamic power management (e.g., disabling display rail while keeping CPU rail active) to extend runtime. |
Applications
| Portable Medical Instruments | Digital Cameras |
|---|---|
Use Scenario: Powering analog front-end (AFE), microcontroller, and LCD display in handheld glucose meters or pulse oximeters using single Li-ion cell. IC Role / Device Role / Timing Role: LTC3522EUD#PBF generates stable 3.3V (buck-boost) for MCU and 1.8V (buck) for sensor interface, managing battery voltage sag from 4.2V to 2.7V. Use Value: 25μA Burst Mode quiescent current extends battery life beyond 1 week in standby; dual PGOOD signals enable safe shutdown before battery depletion. | Use Scenario: Supplying image sensor bias, ISP core, and LCD backlight in compact digital still cameras. IC Role / Device Role / Timing Role: LTC3522EUD#PBF delivers 2.8V (buck-boost) to CMOS sensor and 1.2V (buck) to ISP, maintaining regulation as battery drops from 4.2V to 3.0V. Use Value: Seamless buck-boost mode transition prevents image corruption during video capture; 1MHz PWM mode reduces EMI near sensitive analog imaging circuits. |
| Personal Navigation Devices | Flash-Based MP3 Players |
Use Scenario: Providing GPS baseband processor (1.2V), RF transceiver (3.3V), and touchscreen controller (2.8V) in automotive-grade PNDs. IC Role / Device Role / Timing Role: LTC3522EUD#PBF uses SHDN1 to gate 3.3V rail during GPS cold start and SHDN2 to manage 1.2V core rail during low-power tracking mode. Use Value: Independent shutdown control reduces system idle current to <30μA; thermal protection ensures reliability in enclosed dashboard environments. | Use Scenario: Powering NAND flash controller (1.8V), audio DAC (3.3V), and OLED display (2.5V) in ultra-thin MP3 players. IC Role / Device Role / Timing Role: LTC3522EUD#PBF regulates 3.3V from Li-ion (2.7–4.2V) using buck-boost and steps down to 1.8V for flash I/O using buck, with Burst Mode during music playback pause. Use Value: 400mA buck-boost output supports high-current OLED backlight bursts; 200mA buck output meets flash programming current requirements. |
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 |
|---|---|---|---|
| TPS65270RGET | Single 3.5A buck + 1.5A buck-boost; wider input (2.7–5.5V); no independent PGOOD outputs; 2.5MHz switching. | Higher current capability but larger 4×4mm QFN; lacks per-rail PGOOD and independent shutdown - unsuitable for safety-critical medical sequencing. | Select only when higher output current (>400mA buck-boost) is required and sequencing simplicity is acceptable. |
| MAX8646ETE+ | Dual 600mA buck only; no buck-boost capability; 2.7–5.5V input; integrated LDOs; 2.25MHz switching. | Cannot generate output above input - cannot replace LTC3522EUD#PBF in Li-ion-to-3.3V applications where VIN may drop below VOUT. | Choose only for dual low-voltage rail generation where input always exceeds both outputs (e.g., 5V system powering 3.3V/1.8V). |
Compared with TPS65270RGET and MAX8646ETE+, the LTC3522EUD#PBF uniquely combines buck-boost and buck topologies with independent PGOOD and shutdown in a 3mm × 3mm footprint - making it the only option for space-constrained, battery-fed systems requiring both above- and below-input voltage rails with robust fault signaling.
Availability
LTC3522EUD#PBF is available at Aetrix Electronics and suitable for portable medical instruments, digital cameras, personal navigation devices, and flash-based MP3 players requiring stable component supply across long production lifecycles.
Supply support for LTC3522EUD#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 acquired Linear Technology in 2017 and maintains its precision analog and power management product lines. Linear pioneered high-efficiency, low-noise DC/DC converters for portable electronics.
The LTC3522EUD#PBF belongs to Linear's high-density dual-output DC/DC converter family, designed specifically for battery-powered portable systems needing multiple regulated rails with minimal board area and ultra-low standby current.
FAQ
What is the maximum output current capability of the buck-boost converter in the LTC3522EUD#PBF?
The LTC3522EUD#PBF buck-boost converter delivers up to 400mA when input voltage exceeds 3V and output is set to 3.3V. At lower input voltages or higher output voltages, the maximum load current decreases - for example, it supports ~300mA at VIN = 2.7V and VOUT = 3.3V. The average current limit is 0.65–0.85A, ensuring robust operation under transient loads without thermal derating in the 3mm × 3mm QFN package.
How does the PWM pin affect operation modes of the LTC3522EUD#PBF?
The PWM pin on the LTC3522EUD#PBF globally controls both converters: when held high, it forces fixed 1MHz PWM operation for low-noise performance; when held low, it enables Burst Mode - where the buck converter automatically transitions between Burst and PWM based on load, while the buck-boost operates in variable-frequency Burst Mode. This pin cannot be left floating and requires a defined logic level for predictable behavior.
Does the LTC3522EUD#PBF support 100% duty cycle operation, and for which converter?
Yes, the LTC3522EUD#PBF buck converter supports true 100% duty cycle operation to maintain regulation as input voltage approaches the output voltage - extending usable battery life in Li-ion applications. The buck-boost converter does not support 100% duty cycle; instead, it seamlessly transitions between buck, buck-boost, and boost modes to maintain regulation across the full 2.4–5.5V input range without dropout.
What protection features are integrated into the LTC3522EUD#PBF?
The LTC3522EUD#PBF integrates thermal shutdown (150°C trip), overcurrent protection (average and peak limits per converter), undervoltage lockout (2.3V), and reverse current limiting on the buck-boost output. Both converters also feature internal soft-start and have dedicated open-drain Power Good outputs (PGOOD1/PGOOD2) that indicate regulation faults, overtemperature, or UVLO - eliminating need for external supervision circuitry.
Can the LTC3522EUD#PBF generate an output voltage higher than its input voltage?
Yes, the LTC3522EUD#PBF buck-boost converter can generate output voltages up to 5.25V from inputs as low as 2.4V - for example, producing 3.3V or 5V from a single Li-ion cell (2.7–4.2V). This is achieved via its proprietary 4-switch topology that operates in boost mode when VIN < VOUT, with seamless transitions between buck, buck-boost, and boost without output discontinuity or control-loop instability.
LTC3522EUD#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, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 2.4V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 200mA, 400mA
- Frequency - Switching:
- 1.07MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LTC3522EUD#PBF FAQ
1.How can I place an order for LTC3522EUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3522EUD#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 LTC3522EUD#PBF reliable?
The price and inventory of LTC3522EUD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3522EUD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3522EUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3522EUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3522EUD#PBF?
LTC3522EUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3522EUD#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 LTC3522EUD#PBF?
For technical support, including LTC3522EUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3522EUD#PBF requirements.
6.How does Aetrix verify that LTC3522EUD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3522EUD#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 LTC3522EUD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3522EUD#PBF?
All LTC3522EUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3522EUD#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 LTC3522EUD#PBF part is unused and in its original packaging.
Return procedure for LTC3522EUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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