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Analog Devices Inc. LTC3870EUFD#PBF
- Part No.:
- LTC3870EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3870EUFD#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,874
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Product details
Overview
LTC3870EUFD#PBF 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 two phases per device, operates across 4.5V–60V input, regulates output from 0.5V–14V via master coordination, and enables accurate inter-chip current sharing in high-current telecom and industrial power supplies.
For engineers reviewing the LTC3870EUFD#PBF datasheet, LTC3870EUFD#PBF pinout, LTC3870EUFD#PBF application, or LTC3870EUFD#PBF equivalent, key selection criteria include its role as a non-voltage-regulating slave controller, phase-shift programmability via PHASMD, dual-channel peak-current-mode architecture, EXTVCC support (5V–14V), and compatibility only with LTC3880/3883/3886/3887 master controllers.
Technical Context
The LTC3870EUFD#PBF implements a constant-frequency, peak-current-mode control architecture synchronized to an external master's SYNC signal (100kHz–1MHz), with independent ITH-based current command tracking per channel. Its internal PLL locks to the falling edge of the SYNC input, eliminating need for separate I²C addressing while preserving full programmability of fault protection and current limits.
It features dual N-channel MOSFET gate drivers (TG/BG) with matched 30ns rise/fall times, integrated 5V INTVCC regulator (VIN- or EXTVCC-powered), and pin-selectable CCM/DCM operation per channel via MODE0/MODE1. Current sensing uses external DCR or RSENSE networks referenced to ISENSE0±/ISENSE1±, with ILIM pin selecting low-range (45–55mV) or high-range (70–80mV) current threshold scaling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 60V - supports wide-input industrial and telecom rails without external pre-regulation |
| Output Voltage Range | 0.5V to 14V - set and regulated solely by master controller; LTC3870EUFD#PBF provides only current command following |
| SYNC Frequency Range | 100kHz to 1MHz - enables system-level EMI reduction and capacitor RMS current optimization across multi-phase designs |
| Gate Driver Strength | TG RUP/RDOWN: 2.5Ω/1.5Ω; BG RUP/RDOWN: 2.4Ω/1.1Ω - drives high-side and low-side N-MOSFETs with fast 30ns transitions under 3.3nF load |
| Current Sense Threshold | Low range: 45–55mV; High range: 70–80mV - selectable per device via ILIM pin to match master controller's MFR_PWM_MODE register setting |
| Operating Junction Temp | –40°C to 125°C - qualified for harsh industrial and telecom environments with thermal pad soldered to PCB |
| Package | 28-pin (4mm × 5mm) QFN with exposed SGND pad - enables compact layout and efficient thermal dissipation |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN with exposed SGND pad (Pin 29), requiring soldering to PCB for thermal and signal integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MODE0 / MODE1 (Pins 1, 8) | DCM/CCM mode select input | Logic high enables forced continuous conduction mode per channel; 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 bias current minimizes sensing error |
| ISENSE0−/ISENSE1− (Pins 3, 6) | Current sense comparator negative input | Connects to DCR network or RSENSE low-side node; matches ISENSE+ for accurate differential sensing |
| RUN0 / RUN1 (Pins 4, 5) | Channel enable input | Logic high >2.0V enables corresponding channel; tied to master RUN pins in multiphase systems |
| ITH0 / ITH1 (Pins 28, 9) | Current command threshold input | Driven by master controller to set per-channel peak inductor current; determines real-time load current allocation |
| ILIM (Pin 10) | Current range select input | GND = low range (50mV max); INTVCC = high range (75mV max); resistor divider enables asymmetric channel ranges |
| SYNC (Pin 11) | External clock synchronization input | Falling-edge triggered; synchronizes switching frequency to master controller's clock; must not be left floating |
| PHASMD (Pin 12) | Phase offset programming input | Four discrete phase relationships vs SYNC: GND=180°/0°, 1/3INTVCC=60°/300°, 2/3INTVCC=120°/240°, INTVCC=90°/270° |
| TG0 / TG1 (Pins 24, 13) | Top gate driver output | Floating N-MOSFET gate drive referenced to SW node; swing = INTVCC above SW voltage |
| BG0 / BG1 (Pins 21, 16) | Bottom gate driver output | Ground-referenced N-MOSFET gate drive; swing = 0V to INTVCC |
| BOOST0 / BOOST1 (Pins 22, 15) | Bootstrap supply connection | Connects to (+) terminal of bootstrap capacitors; swings from ~INTVCC–0.7V to VIN+INTVCC |
| SW0 / SW1 (Pins 23, 14) | Switch node connection | Drives external inductors; voltage swings from ~–0.3V (Schottky drop) to VIN |
| FAULT0 / FAULT1 (Pins 26, 25) | Master-initiated fault response input | Pulled low by master GPIO to disable corresponding TG/BG outputs; internal 500kΩ pull-down ensures safe default state |
| FREQ (Pin 27) | Internal oscillator frequency set | 10µA current sink; resistor to SGND sets default frequency (100–1000kHz) before SYNC lock |
| VIN (Pin 20) | Main input supply | Primary power source for INTVCC LDO; bypass with 0.1µF–1µF ceramic capacitor to PGND |
| EXTVCC (Pin 18) | External auxiliary supply input | Enables alternate INTVCC LDO when >4.8V; reduces IC temperature in high-VIN applications (e.g., 48V telecom) |
| INTVCC (Pin 17) | Internal 5V regulator output | Powers internal logic and gate drivers; requires ≥4.7µF low-ESR capacitor to PGND |
| PGND (Pin 19) | Power ground | Return path for high-current MOSFET sources and input capacitors; separate from SGND |
| SGND (Pin 29, Exposed Pad) | Signal ground | Reference for all small-signal pins (ISENSE, ITH, MODE, etc.); must be soldered and connected to PGND at single point |
Key Features
| Feature | Design Value |
|---|---|
| Dual-channel PolyPhase® slave control | Enables scalable high-current solutions (e.g., 2-phase LTC3880 + 2×LTC3870 = 6-phase) without additional I²C addresses or firmware changes |
| Pin-programmable phase offset (PHASMD) | Four discrete phase alignments relative to SYNC clock allow optimal interleaving for input/output capacitor RMS current reduction |
| EXTVCC-capable 5V regulator | Reduces power dissipation and junction temperature in high-input-voltage applications (e.g., 48V telecom) by sourcing INTVCC from external 5–14V supply |
| Independent CCM/DCM mode per channel | Optimizes light-load efficiency (DCM) or output ripple/noise performance (CCM) on a per-phase basis without affecting other channels |
| Matched gate drivers with anti-shoot-through logic | Ensures robust dead-time control between TG/BG outputs, preventing cross-conduction losses in high-frequency, high-current operation |
| Integrated current limit range selection (ILIM) | Supports asymmetric current capability per channel (e.g., Channel 0 high-range, Channel 1 low-range) to match heterogeneous power stage layouts |
Applications
| Telecom Rectifier Modules | Industrial PLC Power Supplies |
|---|---|
Use Scenario: 48V input to 12V/30A intermediate bus in carrier-grade telecom rectifier with strict efficiency and thermal requirements. IC Role / Device Role / Timing Role: LTC3870EUFD#PBF acts as slave controller in 4-phase configuration with LTC3880 master, providing per-phase current regulation and phase interleaving. Use Value: Reduces input capacitor RMS current by 75% vs single-phase, enabling smaller, lower-cost bulk capacitance while maintaining <10mV output ripple. |
Use Scenario: Distributed 24V-to-5V/20A power for modular I/O backplanes in factory automation PLCs with wide ambient temperature range. IC Role / Device Role / Timing Role: LTC3870EUFD#PBF extends LTC3883 master into dual-phase operation, delivering tight current matching (<3%) across channels under dynamic load steps. Use Value: Enables stable 5V rail during 10A/µs transients without output droop, meeting IEC 61000-4-4 immunity requirements for industrial environments. |
| High-Density Server VRMs | Test Equipment Power Rails |
Use Scenario: 12V input to 1.8V/120A CPU core supply using 6-phase topology (1×LTC3880 + 2×LTC3870) with digital PMBus monitoring. IC Role / Device Role / Timing Role: LTC3870EUFD#PBF serves as phase extender, accepting ITH commands and fault signals from LTC3880 master while executing local gate drive timing. Use Value: Achieves <±1.5% inter-phase current balance across full load range, minimizing thermal hotspots and extending MOSFET lifetime. |
Use Scenario: Programmable 3.3V/15A and 5V/10A dual-rail supply for automated test equipment requiring rapid voltage sequencing and overcurrent shutdown. IC Role / Device Role / Timing Role: LTC3870EUFD#PBF controls secondary phase in 3.3V rail while LTC3886 manages primary 5V rail, coordinated via shared SYNC and RUN signals. Use Value: Enables independent enable/disable and fault isolation per rail, supporting test sequence safety interlocks and reducing false-triggered shutdowns. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiphase slave controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3871IUFD#PBF | Single-channel, wider VIN (4.5V–60V), identical SYNC/ITH/ILIM interface but no PHASMD or MODE pins | Used where only one additional phase is needed; lacks per-channel CCM/DCM control and phase offset programming | Select LTC3871IUFD#PBF for cost-sensitive single-phase extension where phase alignment and light-load mode flexibility are not required |
| MP2960GQ-10 | Monolithic dual-phase controller (no master/slave separation); integrates MOSFET drivers, PWM logic, and PMBus interface in single chip | Replaces entire master+slave system with single IC; lacks LTC3870EUFD#PBF's scalability beyond 2 phases and direct LTC3880 compatibility | Select MP2960GQ-10 for space-constrained, fixed 2-phase designs needing integrated telemetry, not for expanding existing LTC3880-based platforms |
Compared with LTC3871IUFD#PBF and MP2960GQ-10, the LTC3870EUFD#PBF uniquely supports dual-channel expansion with programmable phase offset and per-channel conduction mode control-critical for optimizing EMI, thermal distribution, and light-load efficiency in scalable LTC3880-family systems.
Availability
LTC3870EUFD#PBF is available at Aetrix Electronics and suitable for telecom rectifier modules, industrial PLC power supplies, high-density server VRMs, and test equipment power rails requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3870EUFD#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, serving precision instrumentation, industrial automation, and communications infrastructure markets.
The LTC3870EUFD#PBF belongs to the PolyPhase® digital power system management product line, engineered specifically to extend LTC3880-family master controllers into higher-current, multi-phase DC/DC converters while preserving full PMBus programmability and fault coordination.
FAQ
Does the LTC3870EUFD#PBF regulate output voltage independently?
No, the LTC3870EUFD#PBF does not regulate output voltage. It functions exclusively as a current-mode slave controller that follows voltage setpoints and current commands issued by an LTC3880/3883/3886/3887 master controller. Output voltage regulation is performed entirely by the master's feedback loop; the LTC3870EUFD#PBF only adjusts per-phase inductor current to maintain precise current sharing across all phases in the system.
What is the purpose of the PHASMD pin on the LTC3870EUFD#PBF?
The PHASMD pin on the LTC3870EUFD#PBF sets the relative phase relationship between the device's internal switching edges and the external SYNC clock signal. By applying GND, 1/3 INTVCC, 2/3 INTVCC (or floating), or INTVCC, users select four discrete phase offsets-enabling optimal interleaving (e.g., 0°/180°, 60°/300°) to minimize input/output capacitor RMS current and improve thermal distribution in multiphase designs using the LTC3870EUFD#PBF.
Can the LTC3870EUFD#PBF operate without a master controller?
No, the LTC3870EUFD#PBF cannot operate autonomously. It requires coordination from an LTC3880-family master controller for critical functions including output voltage regulation, ITH current command generation, RUN enable signaling, fault response, and SYNC clock distribution. The LTC3870EUFD#PBF lacks internal voltage reference, error amplifier, and PWM oscillator independence-its design assumes tightly coupled operation within a master-slave architecture.
How does EXTVCC improve thermal performance of the LTC3870EUFD#PBF?
EXTVCC improves thermal performance by powering the internal 5V INTVCC regulator from an external 5–14V source instead of VIN, bypassing the VIN-to-INTVCC linear regulator. This eliminates power dissipation associated with dropping high input voltages (e.g., 48V) down to 5V, reducing junction temperature by up to 25°C in telecom applications. The LTC3870EUFD#PBF automatically switches to EXTVCC when its voltage exceeds 4.8V and VIN >6.5V.
What current sensing methods are supported by the LTC3870EUFD#PBF?
The LTC3870EUFD#PBF supports both inductor DCR sensing and discrete current-sense resistors (RSENSE). DCR sensing connects ISENSE0±/ISENSE1± across the inductor's parasitic resistance for lossless measurement, while RSENSE uses a dedicated shunt resistor. For accurate current sharing, the sensing method and component values must match those used in the master controller; mismatch causes imbalance and potential overcurrent faults in the LTC3870EUFD#PBF channels.
LTC3870EUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 28-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 ~ 60V
- Frequency - Switching:
- 500kHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Phase Control
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3870EUFD#PBF FAQ
1.How can I place an order for LTC3870EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3870EUFD#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 LTC3870EUFD#PBF reliable?
The price and inventory of LTC3870EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3870EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3870EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3870EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3870EUFD#PBF?
LTC3870EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3870EUFD#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 LTC3870EUFD#PBF?
For technical support, including LTC3870EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3870EUFD#PBF requirements.
6.How does Aetrix verify that LTC3870EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3870EUFD#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 LTC3870EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3870EUFD#PBF?
All LTC3870EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3870EUFD#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 LTC3870EUFD#PBF part is unused and in its original packaging.
Return procedure for LTC3870EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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