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Analog Devices Inc. LTC3838IUHF#PBF
- Part No.:
- LTC3838IUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3838IUHF#PBF.pdf
- Description:
- IC REG CTRLR BUCK 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,246
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Product details
Overview
LTC3838IUHF#PBF from Analog Devices (formerly Linear Technology) is a dual-channel, PolyPhase® synchronous step-down DC/DC controller driving all-N-channel MOSFETs. It delivers ±0.67% output voltage accuracy on Channel 1 via differential sensing, supports 4.5V–38V input and 0.6V–5.5V output ranges, and enables fast transient response with controlled-on-time valley current mode control - used in high-density point-of-load converters for computing and datacom systems.
For engineers reviewing the LTC3838IUHF#PBF datasheet, LTC3838IUHF#PBF pinout, LTC3838IUHF#PBF application, or LTC3838IUHF#PBF equivalent, key selection criteria include differential remote-sense capability (±500mV ground offset tolerance), 30ns minimum on-time, dual-channel phase programmability, DTR-based overshoot suppression, and QFN-38 thermal performance for industrial-grade power delivery.
Technical Context
The LTC3838IUHF#PBF implements valley current mode control with controlled-on-time architecture, enabling constant-frequency operation independent of VIN, VOUT, and load. Its dual-loop design separates Channel 1's precision differential regulation (0.6V reference, ±0.67% accuracy) from Channel 2's ±1% regulation or PolyPhase interleaving capability.
It integrates load-release transient detection (DTR) to reduce overshoot during rapid load drops, supports RSENSE or DCR current sensing with VRNG-programmable thresholds (30mV–100mV), and offers programmable switching frequency (200kHz–2MHz) with external synchronization via MODE/PLLIN and phase-adjustable CLKOUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V - supports wide-input industrial, telecom, and server rails without pre-regulation. |
| Output Voltage Accuracy (Ch1) | ±0.67% over temperature with differential sensing - maintains regulation despite ±500mV remote ground deviation. |
| Min. On-Time / Off-Time | 30ns / 90ns - enables high VIN-to-low VOUT conversion (e.g., 36V→0.6V at 500kHz) without pulse-skipping. |
| Switching Frequency Range | 200kHz to 2MHz - adjustable via RT resistor or synchronizable to external clock for EMI reduction. |
| Current Sense Threshold Range | 30mV to 100mV per channel - selectable via VRNG pins for optimal DCR/RSENSE trade-offs and noise immunity. |
| Thermal Package | 38-pin (5mm × 7mm) QFN with exposed PGND pad - θJA = 34°C/W, rated for –40°C to 125°C junction operation. |
| Protection Features | Overvoltage (±7.5%), undervoltage, current limit foldback, and short-circuit protection - ensures robust system-level fault handling. |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN (UHF), exposed PGND pad (Pin 39), RoHS-compliant, rated for –40°C to 125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 24) | Main input supply rail | Accepts 4.5V–38V; powers internal bias circuits and supplies DRVCC regulator input. |
| TG1/TG2 (Pins 20, 31 / 24, 35) | Top gate drivers | Drive N-MOSFET gates with swing between SWx and BOOSTx; support high-side switching up to 38V. |
| BG1/BG2 (Pins 22, 29 / 26, 33) | Bottom gate drivers | Drive low-side N-MOSFET gates from PGND to DRVCC; integrated pull-down resistance ≤0.8Ω. |
| VOUTSENSE1+/– (Pins 12, 13) | Differential output sense inputs (Ch1) | Enable ±500mV remote ground tolerance; regulate VOUT1 to 0.6V × divider ratio with ±0.67% accuracy. |
| SENSE1+/–, SENSE2+/– (Pins 14,15,37,36 / 18,19,3,2) | Differential current sense inputs | Support Kelvin RSENSE or DCR sensing; VRNG-programmable threshold (30–100mV) for accurate valley-current control. |
| DTR1/DTR2 (Pins 16, 35 / 20, 1) | Load-release transient detection | Reduces VOUT overshoot by forcing BG off during rapid load drop; internal 2.5µA pull-up to INTVCC. |
| TRACK/SS1/SS2 (Pins 11, 1 / 15, 5) | Soft-start and tracking control | Internal 1µA pull-up enables capacitor-based ramp; also accepts external voltage for output tracking during startup. |
| PHASMD (Pin 4) | Channel phase selector | Sets Ch2 relative phase to Ch1 (180°/180°/240°) and CLKOUT phase (60°/90°/120°) via SGND/floating/INTVCC. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-channel PolyPhase® control | Enables interleaved operation for reduced input/output ripple and higher effective switching frequency without layout complexity. |
| Differential remote sensing (Ch1) | Maintains ±0.67% regulation accuracy even when remote output ground deviates ±500mV from local SGND - critical for PCB plane IR drop. |
| Controlled-on-time valley current mode | Delivers fast transient response and stable constant-frequency operation across full VIN/VOUT/load range without compensation tuning. |
| Load-release transient detection (DTR) | Reduces output overshoot by dynamically disabling bottom FET during rapid load release - verified in 15A→0A steps. |
| Programmable current sense range | VRNG pins set max sense voltage (30/60/100mV) per channel - optimizes signal-to-noise ratio for RSENSE or DCR sensing topologies. |
| Integrated gate drivers with tight timing | TG/BG drivers feature <20ns dead-time control (tD(TG/BG)=20ns, tD(BG/TG)=15ns) and low RON (≤2.5Ω UP / ≤0.8Ω DOWN) for efficient MOSFET switching. |
Applications
| Server Point-of-Load Regulation | Telecom Intermediate Bus Converter |
|---|---|
Use Scenario: Regulating 1.2V/15A CPU core voltage from 12V intermediate bus in high-density server blades. IC Role / Device Role / Timing Role: Dual-channel controller managing two parallel 1.2V phases with interleaved timing to halve input ripple and improve thermal distribution. Use Value: Differential sensing maintains 1.2V accuracy despite PCB plane resistance; 30ns min on-time enables direct 12V→1.2V conversion at 500kHz. |
Use Scenario: Generating 3.3V/20A from 48V telecom rectified bus using two-phase interleaving with external clock sync. IC Role / Device Role / Timing Role: Controller synchronizing both channels to 333kHz external clock (via MODE/PLLIN) with 180° phase shift for optimal EMI filtering. Use Value: 2MHz max switching allows compact magnetics; DTR prevents overshoot during sudden load removal in hot-swap modules. |
| Industrial FPGA Power Supply | Networking ASIC Core Rail |
Use Scenario: Providing tightly regulated 0.85V/12A core voltage for Xilinx Kintex Ultrascale+ FPGA with pre-biased soft-start requirement. IC Role / Device Role / Timing Role: Uses TRACK/SS1 pin to track auxiliary 1.8V supply during startup, avoiding reverse current into partially powered FPGA I/O banks. Use Value: Soft-start into pre-biased output confirmed in Figure G10; ±0.67% accuracy ensures FPGA core voltage stays within 10mV spec. |
Use Scenario: Delivering 0.6V/18A to Broadcom Tomahawk ASIC in 1RU switch with strict thermal constraints. IC Role / Device Role / Timing Role: Dual-channel operation in forced continuous mode (MODE/PLLIN = INTVCC) with DCR current sensing for minimal component count. Use Value: QFN-38 package achieves 34°C/W θJA; 90ns min off-time supports 0.6V output at 2MHz for ultra-small output caps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3838-1IUHF#PBF | Both channels offer ±0.67%/±0.75% differential regulation; single-pin VRNG control (30mV/60mV); improved current limit accuracy. | Preferred where matched accuracy across both outputs is required (e.g., DDR memory VDDQ/VTT tracking), not just Ch1 precision. | Select LTC3838-1IUHF#PBF if dual-channel differential sensing and tighter current limit tolerance are needed; otherwise LTC3838IUHF#PBF suffices for Ch1-critical designs. |
| LTC3855IUFD#PBF | Single-channel, 4-phase capable controller; supports up to 60A per phase; no differential sensing; 45ns min on-time. | Used in higher-current, single-output applications (e.g., GPU VRMs); lacks Ch2 independence and remote-sense capability. | Choose LTC3855IUFD#PBF only for >30A single-rail needs; LTC3838IUHF#PBF remains superior for dual-rail, differential-sense, or lower-current (<20A/channel) systems. |
Compared with LTC3838-1IUHF#PBF and LTC3855IUFD#PBF, the LTC3838IUHF#PBF uniquely balances Ch1 precision (±0.67% diff-sense), Ch2 flexibility (independent or PolyPhase), and industrial-grade thermal performance in a compact QFN - making it optimal for dual-rail, space-constrained, and ground-noise-sensitive applications.
Availability
LTC3838IUHF#PBF is available at Aetrix Electronics and suitable for server point-of-load converters, telecom intermediate bus supplies, and industrial FPGA power systems requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to 125°C operation.
Supply support for LTC3838IUHF#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 high-performance analog and power management product lines with rigorous qualification and long-term support.
The LTC3838IUHF#PBF belongs to Linear's PolyPhase® synchronous buck controller family, designed specifically for high-efficiency, high-density, multi-phase DC/DC conversion in computing, datacom, and industrial infrastructure equipment.
FAQ
What is the operating temperature range for the LTC3838IUHF#PBF?
The LTC3838IUHF#PBF is specified for –40°C to 125°C junction temperature operation. Its UHF QFN package features an exposed PGND pad that must be soldered to the PCB for thermal and electrical performance. The "I" grade guarantees full electrical specifications across this extended industrial temperature range, unlike the "E" grade which is limited to 0°C–85°C.
Does the LTC3838IUHF#PBF support differential sensing on both channels?
No - only Channel 1 of the LTC3838IUHF#PBF supports differential output voltage sensing (VOUTSENSE1+/–) with ±0.67% accuracy. Channel 2 uses single-ended feedback (VFB2) with ±1% regulation. For dual-channel differential sensing, the pin-compatible LTC3838-1IUHF#PBF variant must be selected, as explicitly documented in Table 1 of the datasheet.
How does the DTR (Detect Transient) feature work on the LTC3838IUHF#PBF?
The DTR1/DTR2 pins on the LTC3838IUHF#PBF monitor load-release transients: when voltage on DTRx drops below half of INTVCC, the controller disables the bottom gate driver (BGx) to accelerate inductor current decay and suppress VOUT overshoot. An internal 2.5µA current source pulls DTRx toward INTVCC; tying DTRx to INTVCC disables the feature.
Can the LTC3838IUHF#PBF operate with inductor DCR current sensing?
Yes - the LTC3838IUHF#PBF supports both RSENSE and inductor DCR current sensing. SENSE+/– pins accept Kelvin connections for RSENSE or connect to RC networks across the inductor for DCR sensing. The VRNG pins configure the maximum sense voltage (30mV–100mV), and the internal 500kΩ resistor from SENSE– to SGND aids DCR network biasing.
What is the purpose of the PHASMD pin on the LTC3838IUHF#PBF?
The PHASMD pin (Pin 4) sets the relative phase relationship between Channel 1 and Channel 2, and determines CLKOUT phase. Pulling PHASMD to SGND configures 180° channel phase shift and 60° CLKOUT phase; floating yields 180°/90°; connecting to INTVCC gives 240°/120° - enabling flexible interleaving and clock distribution in multi-controller systems.
LTC3838IUHF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 200kHz ~ 2MHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Phase Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3838IUHF#PBF FAQ
1.How can I place an order for LTC3838IUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3838IUHF#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 LTC3838IUHF#PBF reliable?
The price and inventory of LTC3838IUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3838IUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3838IUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3838IUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3838IUHF#PBF?
LTC3838IUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3838IUHF#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 LTC3838IUHF#PBF?
For technical support, including LTC3838IUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3838IUHF#PBF requirements.
6.How does Aetrix verify that LTC3838IUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3838IUHF#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 LTC3838IUHF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3838IUHF#PBF?
All LTC3838IUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3838IUHF#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 LTC3838IUHF#PBF part is unused and in its original packaging.
Return procedure for LTC3838IUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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