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Analog Devices Inc. LTC3870IUFD#TRPBF
- Part No.:
- LTC3870IUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3870IUFD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,921
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Product details
Overview
LTC3870IUFD#TRPBF from Analog Devices (formerly Linear Technology) is a PolyPhase® step-down slave controller designed for multiphase DC/DC systems with LTC3880-family master controllers. It delivers precise per-phase current regulation, supports up to 2-phase extension, operates from 4.5V to 60V input, provides 0.5V–14V output range, and features pin-programmable CCM/DCM mode - used in high-current telecom power supplies.
For engineers reviewing the LTC3870IUFD#TRPBF datasheet, LTC3870IUFD#TRPBF pinout, LTC3870IUFD#TRPBF application, or LTC3870IUFD#TRPBF equivalent, key selection criteria include phase synchronization capability (100kHz–1MHz SYNC), dual-channel gate drive (TG0/BG0 & TG1/BG1), ILIM-selectable current sense thresholds (50mV/75mV), EXTVCC support (5V–14V), and 28-pin 4mm × 5mm QFN package thermal performance.
Technical Context
The LTC3870IUFD#TRPBF implements peak current mode control with synchronized switching via external SYNC input, enabling coherent multiphase operation without additional I²C addresses. Its dual-channel architecture uses independent ITH0/ITH1 inputs tied to the master controller for real-time current sharing and dynamic load balancing across phases.
It integrates high-speed N-channel MOSFET gate drivers (TG/BG) with <30ns rise/fall times, programmable phase-shift via PHASMD pin (0°–300° relative offsets), and dual-mode operation (CCM/DCM) selected by MODE0/MODE1 pins. The device does not regulate output voltage - that function resides entirely in the master controller - and relies on shared ITH voltage for current matching.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 60V - supports wide-input industrial and telecom rails; EXTVCC enables efficient biasing above 6.5V VIN. |
| Output Voltage Range | 0.5V to 14V - set and regulated solely by master controller; LTC3870IUFD#TRPBF only regulates per-phase current. |
| SYNC Frequency Range | 100kHz to 1MHz - enables precise frequency alignment with LTC3880-family masters; PLL locks to falling edge of SYNC signal. |
| Current Sense Threshold | 50mV (low range) or 75mV (high range) - selected via ILIM pin; matches MFR_PWM_MODE register setting in master for balanced sharing. |
| Gate Driver Strength | TG RUP = 2.5Ω, BG RDOWN = 1.1Ω - drives high-side and low-side N-MOSFETs directly; supports fast transitions with 30ns tr/tf (CLOAD = 3300pF). |
| Operating Temperature | –40°C to +125°C - specified and guaranteed for industrial-grade operation; θJA = 43°C/W with exposed pad soldered. |
| Package | 28-pin (4mm × 5mm) QFN - exposes thermal pad (Pin 29 = SGND) requiring PCB soldering for thermal and signal integrity. |
Pinout & Package
Package: 28-lead plastic QFN (4mm × 5mm), exposed thermal pad (Pin 29 = SGND), RoHS-compliant, tape-and-reel (TRPBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE0 / MODE1 (Pins 1, 8) | DCM/CCM mode select | Logic high → forced continuous conduction; internal 500kΩ pull-down defaults to DCM if floating. |
| ISENSE0+/ISENSE1+ (Pins 2, 7) | Current sense comparator positive input | Connects to DCR network or RSENSE high-side node; ±0.1µA input bias enables accurate sensing. |
| ISENSE0−/ISENSE1− (Pins 3, 6) | Current sense comparator negative input | Connects to DCR network or RSENSE low-side node; matched to ISENSE+ for differential sensing. |
| RUN0 / RUN1 (Pins 4, 5) | Channel enable input | Logic high (>2V) enables channel; internal 500kΩ pull-down ensures safe shutdown if unconnected. |
| ITH0 / ITH1 (Pins 28, 9) | Current threshold control input | Tied to master's ITH outputs; voltage sets per-phase peak current limit; no internal clamping - protection handled by master. |
| ILIM (Pin 10) | Current range select | GND = both channels low range (50mV max); INTVCC = both high range (75mV max); resistor divider enables asymmetric setup. |
| SYNC (Pin 11) | External clock input | Falling-edge triggered; synchronizes switching frequency to master; must not be left floating. |
| PHASMD (Pin 12) | Phase offset programming | Voltage level selects 0°–300° relative phase shift between channels and SYNC; GND = 180°/0°, INTVCC = 90°/270°. |
| TG0 / TG1 (Pins 24, 13) | Top gate driver output | Floating N-MOS driver; swing = INTVCC referenced to SW node; drives high-side FET gate. |
| BG0 / BG1 (Pins 21, 16) | Bottom gate driver output | Ground-referenced N-MOS driver; swing = 0V to INTVCC; drives low-side FET gate. |
| SW0 / SW1 (Pins 23, 14) | Switch node connection | Connects to inductor and external Schottky diode or synchronous rectifier; voltage swings from ~–0.3V to VIN. |
| BOOST0 / BOOST1 (Pins 22, 15) | Bootstrap supply terminal | Connects to (+) terminal of bootstrap capacitor; swings from ~INTVCC–0.7V to VIN+INTVCC. |
| INTVCC (Pin 17) | Internal 5V regulator output | Supplies internal logic and gate drivers; bypass with ≥4.7µF ceramic/tantalum to PGND. |
| EXTVCC (Pin 18) | External bias input | Enables alternate LDO path for INTVCC when >4.8V applied; active only if VIN >6.5V; max 14V rating. |
| PGND (Pin 19) | Power ground | Low-impedance return for high-current paths; connect to bottom FET sources and CIN (–) terminal. |
| VIN (Pin 20) | Main input supply | 4.5V–60V input; bypass with 0.1µF–1µF ceramic capacitor close to pin. |
| FAULT0 / FAULT1 (Pins 26, 25) | Fault response input | Driven low by master GPIO during fault; pulls TG/BG low to disable channel; internal 500kΩ pull-down. |
| FREQ (Pin 27) | Frequency set input | 10µA sink current; resistor to SGND sets default frequency (100kHz–1MHz) before SYNC lock. |
| SGND (Pin 29) | Signal ground (exposed pad) | Mandatory PCB solder connection; reference for all small-signal components; ties to PGND at single point. |
Key Features
| Feature | Design Value |
|---|---|
| PolyPhase® slave architecture | Coherent 2-phase extension with LTC3880-family masters; zero additional I²C address required. |
| Dual independent gate drivers | Integrated TG/BG drivers per channel with <30ns transition times and anti-shoot-through logic. |
| Programmable phase alignment | Four discrete phase offsets (0°–300°) via PHASMD pin voltage; enables optimal ripple cancellation. |
| Flexible current sensing interface | Supports DCR or RSENSE methods; matched ITH/ILIM setup ensures identical current sharing with master. |
| Robust thermal design | 4mm × 5mm QFN with exposed SGND pad; θJC_BOT = 3.4°C/W enables high-power density layouts. |
Applications
| Telecom Power Supply | Industrial CPU Core Power |
|---|---|
|
Use Scenario: 48V input distributed power system delivering 1.8V/60A to baseband processor in 5G radio unit. IC Role / Device Role / Timing Role: LTC3870IUFD#TRPBF acts as 2-phase slave, extending LTC3880 master to meet high-current demand while maintaining tight current balance. Use Value: Enables 75% reduction in input capacitor RMS current vs. single-phase design, lowering EMI and component count. |
Use Scenario: High-efficiency 12V-to-0.85V VRM for industrial FPGA with dynamic load steps up to 30A/µs. IC Role / Device Role / Timing Role: LTC3870IUFD#TRPBF provides synchronized, phase-shifted current regulation under LTC3887 master control. Use Value: Achieves <±3% inter-phase current mismatch across temperature and line/load variations. |
| Data Center ASIC Power | High-Power PoL Converter |
|
Use Scenario: Dual-output 3.3V/12A and 1.0V/40A supply for AI accelerator card using cascaded LTC3880 + LTC3870 configuration. IC Role / Device Role / Timing Role: LTC3870IUFD#TRPBF serves as dedicated slave for 1.0V rail, handling 20A per phase with DCM/CCM mode selection. Use Value: Pin-programmable MODE0/MODE1 allows light-load efficiency optimization without firmware changes. |
Use Scenario: 24V input, 5V/30A point-of-load converter in factory automation PLC with strict thermal limits. IC Role / Device Role / Timing Role: LTC3870IUFD#TRPBF operates as 2-phase slave driving paralleled MOSFETs, coordinated via SYNC and ITH from LTC3886 master. Use Value: EXTVCC support (up to 14V) reduces IC self-heating at high VIN, improving long-term reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PolyPhase slave controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3871IUFD#TRPBF | 3-phase slave (vs. 2-phase); adds third channel, higher pin count (32-QFN); identical SYNC/ITH/ILIM architecture. | Suitable for >60A applications requiring three-phase current sharing; requires layout revision for extra phase loop. | Select LTC3871IUFD#TRPBF when scaling beyond 2-phase current capacity while retaining same master compatibility. |
| ISL68224IRAZ-T7A | 3+1 phase digital slave with PMBus interface; includes integrated telemetry, no external ITH dependency. | Requires full PMBus system integration; lacks analog ITH-based current sharing simplicity of LTC3870IUFD#TRPBF. | Choose ISL68224IRAZ-T7A for telemetry-rich designs where digital monitoring outweighs analog simplicity. |
Compared with LTC3870IUFD#TRPBF, LTC3871IUFD#TRPBF extends phase count but increases complexity and footprint, while ISL68224IRAZ-T7A shifts to digital control with added overhead - making LTC3870IUFD#TRPBF optimal for cost-sensitive, analog-synchronized 2-phase extensions.
Availability
LTC3870IUFD#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, industrial CPU core power, data center ASIC power, and high-power PoL converters requiring stable component supply across extended temperature ranges.
Supply support for LTC3870IUFD#TRPBF 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 power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3870IUFD#TRPBF belongs to the PolyPhase® slave controller product line, engineered specifically to extend LTC3880-family digital power managers in high-current, multi-phase DC/DC applications where analog current sharing and minimal communication overhead are critical.
FAQ
What is the primary function of the LTC3870IUFD#TRPBF in a power system?
The LTC3870IUFD#TRPBF functions exclusively as a 2-phase PolyPhase® slave controller - it does not regulate output voltage. Instead, it precisely controls per-phase inductor current by tracking the ITH voltage from an LTC3880-family master controller, enabling accurate current sharing and phase synchronization without additional I²C addressing. Its role is strictly current regulation within a coordinated multiphase architecture.
Can the LTC3870IUFD#TRPBF operate independently without a master controller?
No, the LTC3870IUFD#TRPBF cannot operate as a standalone DC/DC controller. It lacks voltage feedback, error amplification, and PWM generation circuitry - all voltage regulation and command functions reside in the master (e.g., LTC3880). The LTC3870IUFD#TRPBF requires continuous ITH, RUN, SYNC, and FAULT signals from the master to enable switching, set current limits, synchronize timing, and respond to faults.
How does the ILIM pin affect current sharing between LTC3870IUFD#TRPBF and the master controller?
The ILIM pin on the LTC3870IUFD#TRPBF must match the MFR_PWM_MODE register's current range setting in the master controller (e.g., LTC3880). If ILIM is grounded (low range = 50mV max), the master must also be configured for low-range sensing; mismatch causes unequal current sharing. This alignment ensures identical gain between ITH voltage and current sense threshold across all phases.
What are the absolute maximum ratings for EXTVCC and why is voltage sequencing important?
The EXTVCC pin on the LTC3870IUFD#TRPBF has an absolute maximum rating of 14V and is only enabled when VIN exceeds 6.5V. Although EXTVCC may be present before VIN, the internal LDO remains inactive until that threshold is crossed - preventing unintended biasing. Exceeding 14V risks permanent damage; proper sequencing avoids overstress during power-up and ensures reliable INTVCC regulation.
Does the LTC3870IUFD#TRPBF support both DCR and resistor-based current sensing?
Yes, the LTC3870IUFD#TRPBF supports both methods: ISENSE0+/ISENSE0− and ISENSE1+/ISENSE1− accept differential inputs from either copper inductor DCR networks or precision current-sense resistors (RSENSE). For accurate current sharing, the sensing method and component values must be identical between the LTC3870IUFD#TRPBF and its master controller - including trace resistance and filter pole placement.
LTC3870IUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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 ~ 60V
- Frequency - Switching:
- 500kHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Phase Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3870IUFD#TRPBF FAQ
1.How can I place an order for LTC3870IUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3870IUFD#TRPBF 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 LTC3870IUFD#TRPBF reliable?
The price and inventory of LTC3870IUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3870IUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3870IUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3870IUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3870IUFD#TRPBF?
LTC3870IUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3870IUFD#TRPBF 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 LTC3870IUFD#TRPBF?
For technical support, including LTC3870IUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3870IUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3870IUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3870IUFD#TRPBF 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 LTC3870IUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3870IUFD#TRPBF?
All LTC3870IUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3870IUFD#TRPBF, 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 LTC3870IUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3870IUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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