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Analog Devices Inc. LTC1873EG#TRPBF
- Part No.:
- LTC1873EG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1873EG#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,514
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Product details
Overview
LTC1873EG#TRPBF from Analog Devices (formerly Linear Technology) is a dual-phase synchronous buck controller optimized for microprocessor core and I/O voltage regulation. It integrates two independent 550kHz voltage-mode PWM controllers, supports Intel Desktop VRM 8.4-compliant 5-bit VID programming on Channel 1 (1.3V–3.5V in 50/100mV steps), delivers up to 25A per channel, and features an internal 0.8V ±1% reference with better than ±1.5% total output regulation over line, load, and temperature.
For engineers reviewing the LTC1873EG#TRPBF datasheet, LTC1873EG#TRPBF pinout, LTC1873EG#TRPBF application, or LTC1873EG#TRPBF equivalent, key selection criteria include dual-phase interleaved operation for reduced input RMS current, VID-controlled dynamic voltage scaling for CPU power states, MOSFET VDS-based current limiting without sense resistors, and Burst Mode™ operation for light-load efficiency.
Technical Context
The LTC1873EG#TRPBF implements two independent voltage-mode feedback loops with 25MHz gain-bandwidth error amplifiers, enabling high-loop crossover frequencies and fast transient response. Each channel drives external N-channel MOSFET pairs using floating top-gate drivers powered by charge-pumped BOOST supplies and low-impedance bottom-gate drivers referenced to PGND.
Phase alignment is fixed at 180° between channels to minimize input capacitor ripple current; FCB (Force Continuous Bar) pin allows forced continuous conduction mode across both regulators. Current limiting is implemented via IMAX pins sensing VDS of bottom MOSFETs, eliminating external sense resistors while maintaining accuracy over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 550kHz typical - enables use of small-value inductors (e.g., 1µH) and low-ESR ceramic output capacitors without compromising stability or transient performance. |
| Output Voltage Range (Ch1) | 1.3V to 3.5V in 50mV/100mV steps via 5-bit VID - directly supports Intel Desktop VRM 8.4 CPU voltage scaling requirements including sleep/standby states. |
| Output Voltage Range (Ch2) | 0.8V to 5.5V via external resistor divider - independent of VID, supports logic supplies, chipset rails, or auxiliary voltages. |
| Max Output Current | 25A per channel - achievable with appropriate external MOSFET selection (e.g., FDS6670A, Si4966) and thermal design; limited by gate drive strength and PCB layout. |
| Reference Accuracy | 0.8V ±1% (initial), ±1.5% over line/load/temperature - ensures tight DC regulation critical for sub-1.5V microprocessor cores. |
| Shutdown Current | <100µA - achieved when both RUN/SS pins pulled low; essential for system-level power gating and standby compliance. |
| Operating Temp Range | –40°C to +85°C - qualified for industrial and embedded computing environments; full specifications guaranteed over this range. |
Pinout & Package
Package: 28-pin plastic SSOP (G package), 0.025" pitch, body size 10.2mm × 5.3mm. RoHS-compliant, lead-free, moisture sensitivity level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVCC (1) | Driver Power Supply Input | Supplies power to BG1/BG2 bottom-gate drivers; must be ≥ VGS(ON) of QB1/QB2; typically tied to VIN. |
| BOOST1 (2), BOOST2 (27) | Floating Top-Gate Driver Supply | Provides gate drive voltage referenced to SW1/SW2; requires 1µF capacitor to respective SW pin and optional Schottky diode from VIN for charge pump. |
| BG1 (3), BG2 (26) | Bottom Gate Drive Output | Drives source-grounded N-MOSFETs (QB1/QB2); capable of driving ≥10,000pF gate capacitance directly; goes high during FAULT latch. |
| TG1 (4), TG2 (25) | Top Gate Drive Output | Drives drain-connected N-MOSFETs (QT1/QT2); floating driver referenced to SW1/SW2; shuts down low in fault/shutdown. |
| SW1 (5), SW2 (24) | Switching Node | Connection point between QT drain, QB drain, and inductor; used as return for TG drivers and current limit sensing (IMAX). |
| IMAX1 (6), IMAX2 (28) | Current Limit Threshold Input | Sets overcurrent trip point via external resistor to PGND; uses internal –10µA current source; senses VDS of QB1/QB2. |
| FCB (7) | Force Continuous Bar | Pull to SGND to disable Burst Mode™ and enforce continuous conduction on both channels; normally tied to VCC. |
| RUN/SS1 (8), RUN/SS2 (21) | Run/Soft-Start Control | Pull low to disable respective channel; internal 3.5µA current source enables soft-start timing with external capacitor (≈50ms/µF). |
| COMP1 (9), COMP2 (20) | Loop Compensation Node | Connects to output of error amplifier and input of PWM comparator; RC network here sets loop stability and transient response. |
| SGND (10) | Signal Ground | Return for low-power analog circuitry (FB, COMP, VID, RUN/SS); must be separated from PGND except at single-point tie near CIN. |
| FB1 (11), FB2 (19) | Feedback Input | FB1 internally connected to VID resistor network for Ch1; FB2 accepts external divider for Ch2; both referenced to 0.8V internal reference. |
| SENSE (12) | Channel 1 Output Sense | Connected to VOUT1 to complete VID feedback path; ties to FB1 through internal 20kΩ resistor (R1). |
| VID0–VID4 (13–17) | 5-Bit VID Programming Inputs | Digital inputs defining Ch1 output voltage per Intel VRM 8.4 Table 1; each has 40kΩ pull-up to VCC via diode for overvoltage tolerance. |
| VCC (18) | Analog Core Supply | Powers internal bias, references, and error amplifiers; 3V–7V range; bypass with ≥1µF capacitor to SGND. |
| FAULT (22) | Latched Overvoltage Fault Output | Open-drain output asserting high if either VOUT exceeds programmed value by >15% for >25µs; internal 10µA pull-up; latches until power cycle unless tied to SGND. |
| PGND (23) | Power Ground | Return for BG drivers and high-current paths; connect to high-current ground plane near QB sources and CIN/COUT. |
Key Features
| Feature | Design Value |
|---|---|
| Interleaved 2-phase operation | 180° phase shift reduces input capacitor RMS current by ~48% (e.g., 9.3A → 4.8A), lowering EMI, input ripple, and required capacitance. |
| VID-compliant digital voltage control | Direct support for Intel Desktop VRM 8.4 codes (Table 1) enables dynamic CPU voltage scaling without external DAC or logic. |
| VDS-based current limiting | Eliminates external current-sense resistors and associated power loss in high-current paths; maintains accuracy via MOSFET RDS(on) tracking. |
| Burst Mode™ operation | Automatically transitions to discontinuous conduction then burst mode under light loads, sustaining >85% efficiency at 100mA output. |
| High-speed 25MHz GBW error amplifier | Enables complex pole-zero compensation networks for stable loop response with fast load transients (<1% deviation at 0→10A step). |
Applications
| Microprocessor Core Supply | Chipset Power Supply |
|---|---|
|
Use Scenario: Regulating VCORE for Pentium III/IV-class desktop CPUs requiring dynamic VID-based voltage scaling across P-states. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller providing tightly regulated 1.3V–2.05V outputs with <±1.5% total error and sub-25µs overvoltage fault response. Use Value: Enables compliant VRM 8.4 operation with no external VID DAC, reduces input capacitor count by 50%, and sustains >90% efficiency at full 20A load. |
Use Scenario: Generating stable 2.5V/7A and 2.45V/100mA standby rails for Intel 8xx-series chipsets with RDRAM keepalive. IC Role / Device Role / Timing Role: Independent Channel 2 regulates non-VID rail; Channel 1 handles main core supply; FCB pin synchronizes burst behavior across both outputs. Use Value: Eliminates need for separate regulators, reduces BOM count by 3+ ICs, and ensures coordinated shutdown via shared RUN/SS control. |
| Multiple Logic Supply Generator | Low-Cost Desktop CPU Supply |
|
Use Scenario: Consolidating 1.8V I/O, 2.5V memory, and 3.3V peripheral rails in space-constrained embedded systems. IC Role / Device Role / Timing Role: Channel 2 configured with precision resistor divider for fixed 1.8V/2.5V; Channel 1 provides VID-programmable primary rail. Use Value: Achieves full dual-output functionality in 1.5in² PCB area using SSOP-28 package and low-profile passives. |
Use Scenario: Cost-sensitive OEM desktop motherboards requiring VRM-compliant CPU power with minimal external components. IC Role / Device Role / Timing Role: Replaces discrete op-amp + comparator + logic solutions with single-chip controller supporting all VRM 8.4 timing and sequencing requirements. Use Value: Reduces component count by 12+ parts, eliminates manual calibration, and guarantees ±1.5% regulation without trimming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL6522CRZ-T | Single-channel 5-bit VID controller; requires external second controller for dual-phase; lower max frequency (300kHz). | Lacks integrated dual-channel architecture; cannot achieve true interleaving without additional timing coordination circuitry. | Select only if redesigning for modular control or legacy platform compatibility where split control is preferred. |
| TPS54620RGYT | Single-channel 2.95–17V input, 500kHz sync buck controller; no VID interface; integrated MOSFETs (3A). | Not VID-compliant; unsuitable for CPU core regulation; intended for general-purpose point-of-load conversion. | Choose only for non-CPU applications requiring integrated FETs and wider input range, not as functional replacement. |
Compared with ISL6522CRZ-T and TPS54620RGYT, the LTC1873EG#TRPBF uniquely integrates dual independent 550kHz VID-compliant controllers in one SSOP-28 package, enabling true 180° interleaved operation, eliminating external current-sense resistors via VDS sensing, and delivering guaranteed ±1.5% regulation - capabilities neither alternative matches in a single device.
Availability
LTC1873EG#TRPBF is available at Aetrix Electronics and suitable for microprocessor core supplies, chipset power delivery, and multi-rail logic generation requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LTC1873EG#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and computing markets.
The LTC1873EG#TRPBF belongs to Linear's high-efficiency power controller product line, designed specifically for advanced microprocessor and digital logic power delivery where tight regulation, dynamic voltage scaling, and compact dual-phase integration are critical.
FAQ
What is the maximum supported output current per channel for the LTC1873EG#TRPBF?
The LTC1873EG#TRPBF supports up to 25A per channel when paired with appropriately rated external N-channel MOSFETs (e.g., FDS6670A for high-side, Si4966 for low-side), proper thermal management, and adequate PCB copper area. The actual achievable current depends on MOSFET RDS(on), gate drive strength, inductor saturation rating, and ambient temperature. The controller itself does not limit current - the IMAX pins set the overcurrent threshold based on VDS of the bottom FET.
Does the LTC1873EG#TRPBF require external current-sense resistors?
No, the LTC1873EG#TRPBF does not require external current-sense resistors. It implements MOSFET VDS-based current limiting by monitoring the voltage drop across the bottom N-channel MOSFET (QB1/QB2) via the IMAX1/IMAX2 pins. An internal –10µA current source pulls the IMAX pin, allowing a single Kelvin-connected resistor from IMAX to PGND to set the current limit threshold accurately and efficiently.
How does the 5-bit VID interface on the LTC1873EG#TRPBF work?
The LTC1873EG#TRPBF implements a fully compliant Intel Desktop VRM 8.4 5-bit VID interface on Channel 1 using VID0–VID4 pins (pins 13–17). Each pin has an internal 40kΩ pull-up to VCC via a diode, allowing direct connection to CPU VID signals without level-shifting. The internal resistor network (20kΩ from SENSE to FB1 plus programmable RB) sets VOUT1 from 1.3V to 3.5V in precise 50/100mV steps per Table 1 in the datasheet. Channel 2 operates independently with standard resistor-divider feedback.
What is the purpose of the FCB (Force Continuous Bar) pin on the LTC1873EG#TRPBF?
The FCB pin (pin 7) on the LTC1873EG#TRPBF forces both converter channels into continuous conduction mode regardless of load current. When FCB voltage drops below 0.8V (e.g., tied to SGND), Burst Mode™ and discontinuous operation are disabled. This is useful in noise-sensitive applications where switching frequency must remain constant, or when output ripple must be minimized at light loads. FCB is normally tied to VCC to enable automatic Burst Mode™ efficiency optimization.
Can the LTC1873EG#TRPBF operate with input voltages below 5V?
Yes, the LTC1873EG#TRPBF operates with input voltages as low as 4.5V (per typical application schematic) and supports VCC supply from 3V to 7V. Its PVCC pin must be supplied at a voltage sufficient to fully enhance the external bottom MOSFETs (typically ≥4.5V for logic-level FETs), and BOOST pins require ≥2.7V above respective SW node. The controller is explicitly optimized for low-input-voltage, high-efficiency applications such as 5V-input CPU core supplies, making it suitable for modern low-voltage computing platforms.
LTC1873EG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- 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):
- 3V ~ 7V
- Frequency - Switching:
- 550kHz
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC1873EG#TRPBF FAQ
1.How can I place an order for LTC1873EG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1873EG#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 LTC1873EG#TRPBF reliable?
The price and inventory of LTC1873EG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1873EG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1873EG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1873EG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1873EG#TRPBF?
LTC1873EG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1873EG#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 LTC1873EG#TRPBF?
For technical support, including LTC1873EG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1873EG#TRPBF requirements.
6.How does Aetrix verify that LTC1873EG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1873EG#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 LTC1873EG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1873EG#TRPBF?
All LTC1873EG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1873EG#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 LTC1873EG#TRPBF part is unused and in its original packaging.
Return procedure for LTC1873EG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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