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Analog Devices Inc. LTC3633EUFD#PBF
- Part No.:
- LTC3633EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3633EUFD#PBF.pdf
- Description:
- IC REG BUCK ADJ 3A DL 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:5,206
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Product details
Overview
LTC3633EUFD#PBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic synchronous step-down regulator delivering 3A per channel from 3.6V–15V input, using controlled on-time current-mode architecture with phase-lockable 500kHz–4MHz switching. It supports 180° out-of-phase operation to reduce input/output capacitance requirements and integrates a 2.5V linear regulator and power-good status outputs for point-of-load power in battery-powered instruments and distributed systems.
For engineers reviewing the LTC3633EUFD#PBF datasheet, LTC3633EUFD#PBF pinout, LTC3633EUFD#PBF application, or LTC3633EUFD#PBF equivalent, key selection criteria include dual 3A output capability, programmable frequency via RT resistor, 0.6V reference for low-voltage regulation, Burst Mode® vs forced continuous mode selection, and QFN-28 (4mm × 5mm) thermal performance with exposed PGND pad.
Technical Context
The LTC3633EUFD#PBF implements a constant-frequency, controlled on-time current-mode control loop where the internal one-shot timer's on-time is servoed by a PLL to match either an internal oscillator (set by RT) or an external clock applied to MODE/SYNC. Each channel features independent RUN enable, VFB feedback, ITH compensation, and TRACKSS soft-start/tracking inputs.
It integrates dual high-side/low-side MOSFETs with 130mΩ/65mΩ RDS(ON), supports input overvoltage lockout at 17.5V, provides ±8% PGOOD window with 40µs filter, and delivers 2.5V/10mA from V2P5 while sourcing INTVCC (3.3V) for internal circuitry - all within a single 28-pin QFN package rated for –40°C to 125°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 15V - supports dual-cell Li-ion batteries and 5V/12V intermediate bus systems. |
| Output Current per Channel | 3A continuous - enables compact dual-rail POL supplies without external MOSFETs. |
| Switching Frequency Range | 500kHz to 4MHz - set by RT resistor; allows optimization of inductor size vs efficiency. |
| Feedback Reference Voltage | 0.6V ±1% - enables precise low-output-voltage regulation down to sub-1V with standard resistor dividers. |
| Efficiency | Up to 95% - achieved in forced continuous mode at mid-load; Burst Mode® extends light-load efficiency. |
| Thermal Performance | θJA = 43°C/W - enabled by 4mm × 5mm QFN with soldered exposed PGND pad for PCB heat sinking. |
| Protection Features | Input overvoltage lockout (17.5V), overtemperature shutdown, short-circuit protection, and PGOOD monitoring with ±8% fault threshold. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN with exposed PGND pad (Pin 29), RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGOOD1 (Pin 1) | Channel 1 power-good status | Open-drain output pulled low if VFB1 deviates >±8% from 0.6V; releases at ±5% with 40µs filter. |
| PHMODE (Pin 2) | Phase select control | Tie to GND for in-phase switching; tie to INTVCC for 180° out-of-phase operation between channels. |
| RUN1 (Pin 3) | Channel 1 enable | Active-high enable: >1.22V starts regulation; <1.01V disables channel with shutdown current <500µA. |
| MODE/SYNC (Pin 4) | Mode control / sync input | Ground = forced continuous mode; float or INTVCC = Burst Mode®; external clock = synchronization + forced continuous. |
| RT (Pin 5) | Oscillator frequency programming | Resistor to SGND sets fSW from 500kHz–4MHz; tied to INTVCC defaults to ~2MHz. |
| RUN2 (Pin 6) | Channel 2 enable | Identical function to RUN1, enabling independent control of second channel. |
| SGND (Pin 7) | Signal ground reference | Low-noise analog ground for feedback divider, RT, and compensation networks - separate from PGND. |
| PGOOD2 (Pin 8) | Channel 2 power-good status | Functionally identical to PGOOD1, referenced to VFB2. |
| VFB2 (Pin 9) | Channel 2 feedback input | Connects to resistor divider to set VOUT2; error amplifier compares to 0.6V internal reference. |
| TRACKSS2 (Pin 10) | Channel 2 tracking/soft-start | Internal 1.4µA pull-up enables soft-start with capacitor to SGND; voltage <0.6V forces output tracking. |
| ITH2 (Pin 11) | Channel 2 compensation node | Output of error amplifier; connect RC network for loop stability or tie to INTVCC for internal compensation. |
| VON2 (Pin 12) | Channel 2 on-time control | Sets comparator trip point; tying to VOUT2 makes on-time proportional to output voltage (<6V). |
| SW2 (Pins 13,14) | Channel 2 switch node | Connection to external inductor; swings from ~–0.3V to VIN2 during operation. |
| VIN2 (Pins 15,16) | Channel 2 power input | Independent 3.6V–15V supply input for second channel; powers internal LDO only when active. |
| BOOST2 (Pin 17) | Channel 2 bootstrap supply | Connects to (+) terminal of bootstrap capacitor; swings from ~INTVCC–0.3V to VIN2+INTVCC. |
| V2P5 (Pin 18) | 2.5V auxiliary regulator | Stable 2.5V ±0.04V output capable of 10mA; bypass with ≥1µF ceramic capacitor. |
| INTVCC (Pin 19) | Internal 3.3V supply | 3.3V ±0.2V regulated output powering gate drivers and logic; disabled when both RUN pins are low. |
| BOOST1 (Pin 20) | Channel 1 bootstrap supply | Functionally identical to BOOST2, referenced to VIN1 and SW1. |
| VIN1 (Pins 21,22) | Channel 1 power input | Independent 3.6V–15V supply input; powers INTVCC LDO and channel 1 MOSFETs. |
| SW1 (Pins 23,24) | Channel 1 switch node | Functionally identical to SW2, connected to channel 1 inductor. |
| VON1 (Pin 25) | Channel 1 on-time control | Functionally identical to VON2, referenced to VOUT1. |
| ITH1 (Pin 26) | Channel 1 compensation node | Functionally identical to ITH2; supports external loop compensation or internal default. |
| TRACKSS1 (Pin 27) | Channel 1 tracking/soft-start | Functionally identical to TRACKSS2, enabling coordinated startup or voltage sequencing. |
| VFB1 (Pin 28) | Channel 1 feedback input | Functionally identical to VFB2, used to program VOUT1 via resistor divider. |
| PGND (Pin 29) | Power ground | Exposed thermal pad; must be soldered to PCB plane for electrical return and thermal dissipation. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 3A synchronous buck channels | Integrated high-side/low-side MOSFETs eliminate need for external power switches in dual-rail designs. |
| 180° out-of-phase switching | Reduces RMS input current ripple by interleaving channel pulses, lowering required input capacitance by ~30%. |
| Burst Mode® operation | Extends light-load efficiency by disabling switching until ITH rises above zero-current threshold. |
| Programmable 500kHz–4MHz frequency | Enables use of small 1µH–2.2µH inductors and 10–22µF ceramic output capacitors. |
| 0.6V reference with ±1% tolerance | Supports accurate low-voltage rails (e.g., 1.2V, 1.8V) using standard 1% resistors without trimming. |
| Integrated 2.5V/10mA linear regulator | Provides clean bias for external circuitry (e.g., ADC references, level shifters) without adding discrete LDO. |
Applications
| Point-of-Load Power Supplies | Battery-Powered Instruments |
|---|---|
Use Scenario: Providing tightly regulated 1.2V and 3.3V rails from a 12V intermediate bus in FPGA or ASIC-based embedded systems. IC Role / Device Role / Timing Role: Dual-channel DC/DC converter delivering independent, sequenced, and tracked outputs with fast transient response. Use Value: Eliminates need for two discrete regulators; 180° phase shift reduces input capacitor count and board area by 25–40%. | Use Scenario: Powering mixed-signal data acquisition modules (ADC, op-amps, microcontroller) from dual-cell Li-ion (6V–8.4V). IC Role / Device Role / Timing Role: High-efficiency dual-buck regulator with Burst Mode® extending battery runtime during sleep/idle states. Use Value: Achieves >90% efficiency at 100mA load and <500µA quiescent current in shutdown - critical for multi-day portable operation. |
| Distributed Power Systems | Industrial Control Units |
Use Scenario: Generating isolated 5V and 3.3V supplies across multiple PCB sections in modular PLC backplanes. IC Role / Device Role / Timing Role: Dual-channel POL regulator with independent RUN control and PGOOD status for system-level power sequencing and fault reporting. Use Value: Enables hot-swap capability and graceful power-up/down via TRACKSS soft-start and channel-enable isolation. | Use Scenario: Supplying real-time processor cores and I/O peripherals in DIN-rail mounted controllers operating from 24V DC input. IC Role / Device Role / Timing Role: Robust dual-buck regulator with 15V absolute max input rating and integrated overvoltage/overtemperature protection. Use Value: Survives 30V transients on 24V bus; 125°C junction rating ensures reliability in unventilated enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS543320RJER | Single-channel 3A buck with PMBus interface; no integrated 2.5V LDO or phase-shift capability. | Requires two devices for dual-rail; lacks TRACKSS soft-start and PGOOD sequencing support. | Select when digital telemetry and dynamic margining are required over analog simplicity and dual-channel integration. |
| MP2451DT-LF-Z | Single-channel 2A buck; fixed 2.2MHz frequency; no Burst Mode®, no phase control, no auxiliary LDO. | Needs two ICs plus external LDO for dual-rail; limited to 6V input; no soft-start or tracking. | Select only for cost-sensitive, low-power, single-rail applications where thermal and layout constraints permit discrete implementation. |
Compared with TPS543320RJER and MP2451DT-LF-Z, the LTC3633EUFD#PBF uniquely integrates dual 3A channels, 180° phase shift, Burst Mode®, 2.5V LDO, and analog tracking in one QFN - reducing BOM count by ≥3 components and PCB area by >35% in dual-rail POL designs.
Availability
LTC3633EUFD#PBF is available at Aetrix Electronics and suitable for point-of-load power supplies, battery-powered instruments, and industrial control units requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant manufacturing.
Supply support for LTC3633EUFD#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 full technical and manufacturing continuity for the LTC portfolio, including precision power management ICs with industry-leading efficiency and integration.
The LTC3633EUFD#PBF belongs to Linear's monolithic synchronous buck regulator product line, designed specifically for high-density, high-efficiency dual-rail point-of-load conversion in space-constrained and thermally demanding applications.
FAQ
What is the maximum input voltage rating for the LTC3633EUFD#PBF?
The LTC3633EUFD#PBF has an absolute maximum input voltage rating of 16V on VIN1 and VIN2 pins, with transient tolerance up to 18V. Its overvoltage lockout activates at 17.5V (rising) and resets at 16.5V (falling), protecting internal MOSFETs during bus transients. This makes the LTC3633EUFD#PBF suitable for 12V systems with expected surges, but not for direct connection to unregulated 24V supplies without pre-regulation.
How does the PHMODE pin affect channel timing in the LTC3633EUFD#PBF?
The PHMODE pin on the LTC3633EUFD#PBF selects between in-phase and 180° out-of-phase switching: grounding PHMODE synchronizes both channels' falling edges, while connecting it to INTVCC shifts SW2's falling edge by 180° relative to SW1. This interleaving reduces input RMS current and eases input capacitor sizing - a key advantage in high-current POL applications where the LTC3633EUFD#PBF is commonly deployed.
Can the LTC3633EUFD#PBF operate with only one channel enabled?
Yes, the LTC3633EUFD#PBF supports independent channel operation: pulling RUN1 high enables Channel 1 while keeping RUN2 low disables Channel 2, and vice versa. Both channels share the same INTVCC and V2P5 supplies, but each has dedicated feedback, compensation, and enable paths. This flexibility allows the LTC3633EUFD#PBF to serve as a dual-rail solution or reconfigured as a higher-current single-channel regulator with external paralleling.
What is the purpose of the TRACKSS pins on the LTC3633EUFD#PBF?
The TRACKSS1 and TRACKSS2 pins on the LTC3633EUFD#PBF provide analog voltage tracking and soft-start functionality: applying a ramp voltage (e.g., via RC network to SGND) forces the respective output to follow that ramp, enabling controlled power-up sequencing. An internal 1.4µA pull-up current allows simple soft-start by connecting a capacitor from TRACKSS to SGND - a feature used extensively in FPGA and processor power domains where the LTC3633EUFD#PBF delivers coordinated rail startup.
Does the LTC3633EUFD#PBF require external compensation components?
The LTC3633EUFD#PBF supports both internal and external compensation: tying ITH1 or ITH2 to INTVCC engages the factory-tuned internal compensation network, simplifying design for standard applications. For optimized transient response or non-standard output capacitors, external RC networks can be connected to ITH1/ITH2 - a capability leveraged in high-performance applications where the LTC3633EUFD#PBF replaces discrete controller-FET solutions.
LTC3633EUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 15V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 14.7V
- Current - Output:
- 3A
- Frequency - Switching:
- 500kHz ~ 4MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3633EUFD#PBF FAQ
1.How can I place an order for LTC3633EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3633EUFD#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 LTC3633EUFD#PBF reliable?
The price and inventory of LTC3633EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3633EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3633EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3633EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3633EUFD#PBF?
LTC3633EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3633EUFD#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 LTC3633EUFD#PBF?
For technical support, including LTC3633EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3633EUFD#PBF requirements.
6.How does Aetrix verify that LTC3633EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3633EUFD#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 LTC3633EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3633EUFD#PBF?
All LTC3633EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3633EUFD#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 LTC3633EUFD#PBF part is unused and in its original packaging.
Return procedure for LTC3633EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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