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Analog Devices Inc. LTC3533EDE#PBF
- Part No.:
- LTC3533EDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC3533EDE#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 2A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,456
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Product details
Overview
LTC3533EDE#PBF from Analog Devices (formerly Linear Technology) is a wide-input synchronous buck-boost DC/DC converter IC that delivers up to 2A continuous output current, operates from 1.8V to 5.5V input and regulates outputs from 1.8V to 5.25V, and features programmable 300kHz–2MHz switching frequency - ideal for single-cell Li-ion or multi-cell alkaline/NiMH power in handheld instruments and smart phones.
For engineers reviewing the LTC3533EDE#PBF datasheet, LTC3533EDE#PBF pinout, LTC3533EDE#PBF application, or LTC3533EDE#PBF equivalent, key selection considerations include its four-switch topology enabling seamless VIN-above/VIN-below-VOUT operation, 40µA Burst Mode quiescent current, 1.22V feedback reference with ±2% tolerance, thermal shutdown, and DFN-14 (3mm × 4mm) package with exposed GND pad.
Technical Context
The LTC3533EDE#PBF implements a proprietary four-switch buck-boost topology with continuous transfer function across buck, buck-boost, and boost regions - controlled by error amplifier output voltage (VC) - enabling stable regulation when input voltage crosses output voltage. Its internal gate drivers support synchronous rectification with PMOS/NMOS switch pairs A–D.
It integrates programmable fixed-frequency PWM (via RT pin), automatic or manual Burst Mode control (BURST pin), soft-start/enabled logic (RUN/SS), reverse current limiting (500mA typical), and dual-stage input current limiting (4.5A/7A thresholds). The VC pin serves as error amp output and loop compensation node, while FB references 1.22V with 50nA input bias current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.8V to 5.5V - supports single-cell Li-ion (2.4–4.2V) and multi-cell alkaline/NiMH without external LDO pre-regulation. |
| Output Voltage Range | 1.8V to 5.25V - adjustable via resistor divider on FB pin; 1.22V ±2% reference enables precise regulation. |
| Continuous Output Current | 2A at VIN > 3V - sufficient for GSM modems and media players; drops to 0.8A below 1.8V input. |
| Switching Frequency | 300kHz to 2MHz - set externally via RT resistor; higher frequencies reduce inductor/capacitor size but increase gate charge losses. |
| Burst Mode IQ | 40µA typical - extends battery life in low-load standby states while maintaining regulation within 2% ripple. |
| Shutdown Current | <1µA - achieved by pulling RUN/SS below 0.4V; ensures minimal drain during system sleep. |
| Thermal Package | 14-lead DFN (3mm × 4mm × 0.75mm) with exposed GND pad - θJA = 43°C/W enables 2A operation at 85°C ambient with proper PCB copper. |
Pinout & Package
Package: 14-lead plastic DFN (3mm × 4mm × 0.75mm) with exposed substrate ground pad (Pin 15), rated for –40°C to +85°C operating temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator programming input | Resistor-to-GND sets switching frequency per f(kHz) = 33,170 / R(kΩ); enables layout-tuned frequency stability. |
| BURST (2) | Mode control input | Resistor-to-GND programs automatic Burst Mode entry/exit thresholds; grounding forces Burst Mode, tying to VIN forces fixed-frequency PWM. |
| SGND (3) | Signal ground reference | Separate analog ground for FB, VC, RUN/SS to minimize noise coupling into feedback path. |
| SW1 (4) | Switch node A/B connection | Connects internal PMOS A and NMOS B; ties to one end of inductor; optional Schottky to GND improves light-load efficiency. |
| PGND1, PGND2 (5,6) | Power ground return paths | Dual low-inductance GND pins for NMOS switch sources; must connect directly to thermal pad and power plane. |
| SW2 (7) | Switch node C/D connection | Connects internal NMOS C and PMOS D; ties to other inductor end; Schottky to VOUT required for VOUT > 4.3V to clamp SW2 voltage. |
| VOUT (8) | Output sensing & internal supply | Senses regulated output voltage and powers internal circuitry; requires local ceramic bypass capacitor. |
| PVOUT (9) | Power output terminal | High-current output path to filter capacitor; connects to bulk output cap and must be routed with low impedance. |
| VIN (10) | Internal VCC supply | Provides bias for control circuitry; separate from PVIN to isolate sensitive analog functions from power rail noise. |
| PVIN (11) | Main power input | High-current input path from source; requires 10µF ceramic cap placed adjacent to pin and PGND. |
| RUN/SS (12) | Enable & soft-start control | Voltage <0.4V disables IC; >1.4V enables; RC network provides controlled ramp to limit inrush current. |
| FB (13) | Feedback input | Connects to resistor divider midpoint; 1.22V reference enables output adjustment; 50nA bias minimizes divider error. |
| VC (14) | Error amplifier output | Loop compensation node; external R-C network from VC to FB stabilizes control loop across all operating modes. |
Key Features
| Feature | Design Value |
|---|---|
| Four-switch synchronous topology | Enables continuous buck-boost operation with no mode transition glitches - critical for battery-powered systems where VIN drifts across VOUT. |
| Programmable Burst Mode | Reduces quiescent current to 40µA at light loads while maintaining regulation, extending runtime in standby without sacrificing transient response. |
| Single-inductor architecture | Eliminates need for multiple magnetics - reduces BOM cost, board area, and EMI compared to cascaded buck+boost solutions. |
| Output disconnect in shutdown | Prevents backfeed from VOUT to VIN during disable, protecting upstream battery or power source in portable applications. |
| Thermally enhanced DFN package | Exposed GND pad and low θJA (43°C/W) allow full 2A output at 85°C ambient with standard 2oz copper PCB layout. |
Applications
| GSM Modems | Handheld Instruments |
|---|---|
Use Scenario: Powering RF transceivers and baseband processors in compact cellular modules with varying battery voltage (3.0–4.2V). IC Role / Device Role / Timing Role: Primary buck-boost regulator delivering stable 3.3V or 3.8V from Li-ion cell, dynamically adapting as battery discharges below and above output voltage. Use Value: Eliminates need for separate buck and boost stages, reducing component count and improving efficiency across full battery discharge curve. | Use Scenario: Supplying mixed-signal circuits (ADCs, microcontrollers, displays) in portable test equipment powered by AA/AAA alkaline batteries (1.2–1.6V/cell). IC Role / Device Role / Timing Role: Wide-input regulator generating 3.3V or 5V from 2–4 alkaline cells, maintaining regulation even as cell voltage drops below target output. Use Value: Enables consistent performance over full battery life without premature shutdown due to input sag - critical for field-deployed instrumentation. |
| Digital Cameras | Smart Phones |
Use Scenario: Powering image sensor, ISP, and flash LED drivers in ultra-thin camera modules where space and thermal budget are constrained. IC Role / Device Role / Timing Role: High-efficiency 2A buck-boost converter supplying 2.8V or 3.3V to sensor interface, supporting burst-mode capture with rapid load transients. Use Value: Synchronous rectification and 96% peak efficiency minimize heat generation in sealed enclosures, while Burst Mode extends standby time between shots. | Use Scenario: Regulating core voltage for application processors and memory subsystems in smartphones using single-cell Li-ion batteries. IC Role / Device Role / Timing Role: Main system power IC delivering 1.2V–1.8V to SoC cores, dynamically adjusting duty cycle as battery voltage transitions from 4.2V down to 3.0V. Use Value: Seamless buck-boost transfer avoids brownouts during high-CPU-load battery sag, ensuring uninterrupted operation without software intervention. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS63020DSJR | Lower max output current (3A vs 2A), fixed 3.3V/5V options only, no programmable Burst Mode threshold. | Targeted at cost-sensitive consumer electronics; lacks fine-grained light-load optimization for long battery life. | Select if fixed-output voltage suffices and PCB area is more critical than quiescent current tuning. |
| MAX77827AEWE+T | Higher integration (I²C programmable VOUT, enable sequencing), but larger 20-pin WLP package and 1.2A max output. | Designed for complex PMIC subsystems in wearables; requires digital control infrastructure not needed for standalone regulation. | Select if system-level power sequencing and dynamic voltage scaling are required alongside buck-boost conversion. |
Compared with TPS63020DSJR and MAX77827AEWE+T, the LTC3533EDE#PBF offers superior design flexibility through fully programmable frequency, Burst Mode threshold, and output voltage - making it optimal for applications demanding tailored efficiency profiles across wide input/output ranges without added digital overhead.
Availability
LTC3533EDE#PBF is available at Aetrix Electronics and suitable for GSM modems, handheld instruments, and digital cameras requiring stable component supply, long-term manufacturability, and guaranteed parametric performance over –40°C to +85°C.
Supply support for LTC3533EDE#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.
The LTC3533EDE#PBF belongs to Linear's high-efficiency DC/DC converter product line, designed specifically for battery-powered portable electronics where seamless input-voltage-crossing regulation, low quiescent current, and compact solution size are essential.
FAQ
What is the minimum input voltage required for the LTC3533EDE#PBF to start up and regulate?
The LTC3533EDE#PBF has a minimum start voltage of 1.72V at –40°C and 1.78V at 25°C, as verified in Typical Performance Characteristics (Figure G05). It achieves reliable startup and regulation down to 1.8V across the full –40°C to +85°C temperature range, enabling use with deeply discharged single-cell Li-ion or NiMH batteries. Below 1.8V, the device may fail to initiate switching or maintain regulation.
Does the LTC3533EDE#PBF support output voltages below 1.8V, and what are the implications?
Yes, the LTC3533EDE#PBF can operate as a buck converter down to 400mV output, but this requires an external Schottky diode from SW2 to VOUT to provide conduction path - since synchronous switch D's RDS(ON) increases significantly below 1.8V. Burst Mode operation is inhibited below 1V, and datasheet specifications are only guaranteed ≥1.8V. For sub-1.8V designs, validation of thermal performance and transient response is mandatory.
How does the LTC3533EDE#PBF handle reverse current flow during light-load or shutdown conditions?
The LTC3533EDE#PBF incorporates a dedicated reverse current limit comparator that monitors inductor current direction. During fixed-frequency operation, if negative inductor current exceeds 500mA typical, the IC shuts off NMOS switch C to block reverse conduction. In shutdown, output disconnect is enforced - preventing backfeed from VOUT to VIN. This protects batteries and upstream supplies in portable systems.
Can the LTC3533EDE#PBF be used with output voltages exceeding 4.3V, and what modifications are required?
Yes, the LTC3533EDE#PBF supports output voltages up to 5.25V, but a Schottky diode from SW2 to VOUT is mandatory for VOUT > 4.3V to clamp SW2 voltage during switching transitions and prevent exceedance of the 6V absolute maximum rating. The diode must be placed as close as possible to the SW2 and VOUT pins to minimize parasitic inductance, and surface-mount types like MBRM120T3 are recommended.
What is the role of the exposed pad (Pin 15) on the LTC3533EDE#PBF, and how must it be implemented on the PCB?
The exposed pad (Pin 15) on the LTC3533EDE#PBF is the IC substrate ground and must be soldered directly to the PCB's main ground plane. It serves dual purposes: providing low-impedance electrical return for power switches and enabling efficient thermal conduction from the die to the board. Per datasheet Note 15, failure to solder this pad results in degraded thermal performance (θJA increases significantly) and potential reliability issues under 2A load conditions.
LTC3533EDE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.8V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.8V
- Voltage - Output (Max):
- 5.25V
- Current - Output:
- 2A
- Frequency - Switching:
- 300kHz ~ 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LTC3533EDE#PBF FAQ
1.How can I place an order for LTC3533EDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3533EDE#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 LTC3533EDE#PBF reliable?
The price and inventory of LTC3533EDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3533EDE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3533EDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3533EDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3533EDE#PBF?
LTC3533EDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3533EDE#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 LTC3533EDE#PBF?
For technical support, including LTC3533EDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3533EDE#PBF requirements.
6.How does Aetrix verify that LTC3533EDE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3533EDE#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 LTC3533EDE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3533EDE#PBF?
All LTC3533EDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3533EDE#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 LTC3533EDE#PBF part is unused and in its original packaging.
Return procedure for LTC3533EDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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