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Analog Devices Inc. LTC3633IFE#PBF
- Part No.:
- LTC3633IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3633IFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 3A DL 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,302
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Product details
Overview
LTC3633IFE#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 (10mA), power-good outputs, and overvoltage/overtemperature protection - deployed in distributed point-of-load supplies for industrial instrumentation and battery-powered systems.
For engineers reviewing the LTC3633IFE#PBF datasheet, LTC3633IFE#PBF pinout, LTC3633IFE#PBF application, or LTC3633IFE#PBF equivalent, key selection considerations include its dual 3A output capability, 0.6V reference enabling low-voltage rails (e.g., 1.2V, 1.8V), selectable Burst Mode® vs forced continuous operation, external frequency synchronization via MODE/SYNC, and TSSOP-28 package thermal performance (θJA = 25°C/W).
Technical Context
The LTC3633IFE#PBF implements a constant-frequency controlled on-time current-mode control loop where the top MOSFET on-time is set by an internal one-shot timer, and valley current is sensed across the bottom MOSFET's RDS(ON). An internal PLL locks the on-time to either the internal oscillator (set by RT resistor) or an external clock applied to MODE/SYNC, ensuring stable frequency under line/load transients.
Each channel features independent RUN enable inputs, VFB feedback pins referenced to 0.6V, TRACKSS soft-start/tracking inputs with 1.4µA pull-up, and dedicated ITH compensation nodes. Phase shift is selected via PHMODE (0° or 180°), while MODE/SYNC configures Burst Mode® (high efficiency at light load) or forced continuous conduction - with automatic forced mode activation during external sync.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 15V - supports dual-cell Li-ion batteries and standard 5V/12V intermediate bus rails. |
| Output Current per Channel | 3A continuous - enables compact dual-rail PoL conversion without external MOSFETs. |
| Switching Frequency Range | 500kHz to 4MHz - programmable via RT resistor; allows optimization of inductor size vs efficiency. |
| Feedback Reference Voltage | 0.6V ±1% - enables precise low-output voltages (e.g., 1.2V with 1:1 divider) and tight regulation. |
| Efficiency | Up to 95% - achieved in forced continuous mode at full load; Burst Mode® extends light-load efficiency. |
| Thermal Resistance θJA | 25°C/W - measured in TSSOP-28 package, enabling higher power density than QFN variant under same PCB layout. |
| Protection Features | Input overvoltage lockout (17.5V trip), overtemperature shutdown, short-circuit protection, and PGOOD status with 40µs filtering. |
Pinout & Package
Package: 28-Lead Plastic TSSOP (FE), exposed pad (Pin 29) connected to PGND for thermal and electrical integrity. θJA = 25°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH1 / ITH2 | Error amplifier output & compensation node | Connects to RC network for loop stability; tie to INTVCC for internal compensation. |
| VIN1 / VIN2 | Channel 1/2 power input | Independent inputs allow dual-supply operation; powers internal LDO (INTVCC) from VIN1. |
| SW1 / SW2 | Channel 1/2 switch node | Connects to external inductor; voltage swings from ~–0.3V to VIN; requires low-inductance layout. |
| BOOST1 / BOOST2 | Floating gate drive supply | Bootstrap capacitor connects between BOOSTx and SWx to enable high-side N-MOSFET drive. |
| RUN1 / RUN2 | Channel enable inputs | Active-high logic: >1.22V enables; <1.01V disables; hysteresis prevents chatter. |
| PGOOD1 / PGOOD2 | Open-drain power-good outputs | Pulled low if VFB deviates >±8%; releases at ±5%; includes 40µs glitch filter. |
| TRACKSS1 / TRACKSS2 | Tracking/soft-start input | Internal 1.4µA pull-up enables soft-start with external capacitor; <0.6V forces tracking mode. |
| MODE/SYNC | Mode select & sync input | Ground = forced continuous; float/INTVCC = Burst Mode®; external clock = sync + forced mode. |
| PHMODE | Phase select input | Ground = 0° in-phase; INTVCC = 180° out-of-phase - reduces input RMS current ripple. |
| V2P5 | Dedicated 2.5V LDO output | 10mA capable; bypass with ≥1µF ceramic; tie to INTVCC if unused. |
| INTVCC | Internal 3.3V regulator output | Powers control circuitry; disabled when both RUN pins are low; decouple with ≥1µF ceramic. |
| PGND | Power ground (exposed pad) | Must be soldered to PCB plane for thermal dissipation and low-impedance return path. |
Key Features
| Feature | Design Value |
|---|---|
| Controlled on-time current-mode architecture | Enables stable operation at ultra-low duty cycles (e.g., 5% at 2.25MHz) with fast transient response. |
| 180° interleaved channel operation | Reduces input capacitor RMS current by ~30%, relaxing CIN sizing and lowering supply noise. |
| User-selectable Burst Mode® or forced continuous mode | Burst Mode® cuts quiescent current to 500µA per channel; forced mode ensures fixed frequency for EMI control. |
| Integrated 2.5V/10mA linear regulator (V2P5) | Provides clean bias for external circuitry (e.g., ADC references, sensors) without requiring separate LDO. |
| External frequency synchronization | Accepts TTL/CMOS clock on MODE/SYNC to align switching with system timing or reduce beat frequencies. |
| Output voltage tracking and soft-start | TRACKSS pins support power sequencing (e.g., core before I/O) and inrush current limiting via capacitor timing. |
Applications
| Industrial Point-of-Load Power | Battery-Powered Test Equipment |
|---|---|
Use Scenario: Dual-rail FPGA or SoC power delivery in programmable logic controllers with strict thermal limits and dynamic load steps. IC Role / Device Role / Timing Role: Primary dual-channel DC/DC converter supplying 1.2V core and 3.3V I/O rails from 12V backplane, with synchronized soft-start and tracking. Use Value: 180° phase shift lowers input ripple, reducing bulk capacitor count; 0.6V reference enables accurate low-voltage regulation critical for sub-1V logic. | Use Scenario: Portable oscilloscope or multimeter requiring long battery life and stable analog/digital supply rails. IC Role / Device Role / Timing Role: Dual-output buck regulator powering 1.8V ADC/DAC and 5V display interface from dual-cell Li-ion (6V–8.4V). Use Value: Burst Mode® operation achieves <500µA total quiescent current at light load, extending runtime; integrated V2P5 powers precision voltage references. |
| Distributed Telecom Power Systems | Medical Diagnostic Instrumentation |
Use Scenario: Compact remote radio unit (RRU) with isolated digital and RF subsystems needing tightly regulated, low-noise supplies. IC Role / Device Role / Timing Role: Dual-channel regulator generating 2.5V analog and 1.5V digital rails from 48V intermediate bus (via front-end DC/DC), with external sync to baseband clock. Use Value: MODE/SYNC pin accepts 10MHz system clock to eliminate switching noise heterodyning; PGOOD signals feed FPGA configuration sequencer. | Use Scenario: Portable ultrasound or ECG device requiring ultra-low EMI and rail sequencing for signal chain integrity. IC Role / Device Role / Timing Role: Dual-output regulator supplying 3.3V microcontroller and 1.2V ADC core, with TRACKSS1/2 enabling safe power-up order and soft-start. Use Value: Controlled on-time architecture minimizes output voltage deviation during 2A load transients; overvoltage protection safeguards sensitive analog front-end. |
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 |
|---|---|---|---|
| TPS543B20RTWR | Single-chip dual 3A output; supports 4.5V–18V input; uses D-CAP3 control; no integrated 2.5V LDO. | Lacks dedicated V2P5 rail; requires external bias for analog circuitry; higher min input voltage. | Select when board space is constrained and external 2.5V supply exists; verify loop stability with D-CAP3 compensation. |
| ISL85415EVAL1Z | Single-channel 5A buck; supports 3.5V–60V input; includes PMBus interface; no phase-shift capability. | Not dual-channel; requires two units for dual-rail design; adds digital control overhead. | Choose for wide-input industrial applications needing telemetry or adaptive voltage scaling; not suitable for direct pin-for-function replacement. |
Compared with TPS543B20RTWR and ISL85415EVAL1Z, the LTC3633IFE#PBF uniquely integrates dual 3A channels, 180° interleaving, a 2.5V LDO, and analog tracking/soft-start in a single TSSOP-28 package - simplifying dual-rail designs where component count, sequencing control, and low-noise analog bias are critical.
Availability
LTC3633IFE#PBF is available at Aetrix Electronics and suitable for industrial point-of-load power, battery-powered instrumentation, and medical diagnostic equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC3633IFE#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3633 belongs to ADI's Power by Linear™ family of monolithic DC/DC regulators, engineered for high-efficiency, low-noise, and thermally robust point-of-load conversion in space-constrained industrial and portable systems.
FAQ
What is the maximum input voltage rating for the LTC3633IFE#PBF?
The LTC3633IFE#PBF has an absolute maximum input voltage rating of 16V on VIN1 and VIN2 pins, with transient tolerance up to 18V. Its operational input range is 3.6V to 15V. Input overvoltage protection activates at 17.5V (rising) and resets at 16.5V (falling), suspending switching until safe conditions return - a critical safeguard for systems powered by unregulated sources like automotive or battery packs.
Does the LTC3633IFE#PBF support output voltage tracking between channels?
Yes, the LTC3633IFE#PBF supports precise output voltage tracking via dedicated TRACKSS1 and TRACKSS2 pins. Applying a ramp voltage (e.g., from an RC network) to these pins forces the respective FB inputs to follow that voltage during startup, enabling controlled power sequencing - such as ramping a 1.2V core rail before a 3.3V I/O rail. The internal 1.4µA pull-up current allows simple soft-start implementation with a single capacitor to SGND.
How does the phase-shift feature of the LTC3633IFE#PBF improve system-level performance?
The LTC3633IFE#PBF's 180° out-of-phase operation, enabled by the PHMODE pin, interleaves the input current pulses from both channels. This reduces peak and RMS input current by up to 30%, significantly lowering voltage ripple on the input supply and relaxing requirements for input bulk capacitance. In practice, this enables smaller, lower-cost input capacitors and cleaner power delivery to sensitive analog or RF subsystems sharing the same input rail.
Can the LTC3633IFE#PBF operate with only one channel enabled?
Yes, the LTC3633IFE#PBF supports independent channel control via RUN1 and RUN2 pins. Either channel can be disabled by pulling its RUN pin below 1.01V, placing it in shutdown with <13µA quiescent current. The enabled channel continues full operation, maintaining regulation, PGOOD status, and all protections - making the LTC3633IFE#PBF suitable for flexible power architectures where rail demand varies dynamically across subsystems.
What thermal performance can be expected from the LTC3633IFE#PBF in its TSSOP-28 package?
The LTC3633IFE#PBF in the TSSOP-28 (FE) package has a specified junction-to-ambient thermal resistance (θJA) of 25°C/W under standard JEDEC 2-layer board conditions. This is lower than the QFN variant (43°C/W), enabling higher continuous power delivery in thermally constrained layouts. To achieve this rating, the exposed PGND pad (Pin 29) must be fully soldered to a minimum 1-in² copper pour with multiple thermal vias to inner ground planes.
LTC3633IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LTC3633IFE#PBF FAQ
1.How can I place an order for LTC3633IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3633IFE#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 LTC3633IFE#PBF reliable?
The price and inventory of LTC3633IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3633IFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3633IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3633IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3633IFE#PBF?
LTC3633IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3633IFE#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 LTC3633IFE#PBF?
For technical support, including LTC3633IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3633IFE#PBF requirements.
6.How does Aetrix verify that LTC3633IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3633IFE#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 LTC3633IFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3633IFE#PBF?
All LTC3633IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3633IFE#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 LTC3633IFE#PBF part is unused and in its original packaging.
Return procedure for LTC3633IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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