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Analog Devices Inc. LTC3859AHFE#TRPBF
- Part No.:
- LTC3859AHFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859AHFE#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOP 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,681
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Product details
Overview
LTC3859AHFE#TRPBF from Analog Devices is a high-performance triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, featuring 55μA no-load quiescent current, 0.8V/1.2V precision references for buck/boost outputs, and operation from 4.5V–38V input with cold-crank support down to 2.5V after startup - used in automotive start-stop systems requiring stable multi-rail power delivery.
For engineers reviewing the LTC3859AHFE#TRPBF datasheet, LTC3859AHFE#TRPBF pinout, LTC3859AHFE#TRPBF application, or LTC3859AHFE#TRPBF equivalent, this page delivers verified technical context, package-validated pin functions, real-world application cards, and two confirmed alternative parts with documented functional and thermal differences.
Technical Context
The LTC3859AHFE#TRPBF implements three independent current-mode controllers: two buck channels with 0.8V reference and 99% dropout capability, and one boost channel with 1.2V reference and 100% duty-cycle support even in Burst Mode®. Its OPTI-LOOP compensation enables transient optimization across wide output capacitance and ESR ranges.
Phase-lockable switching frequency spans 75kHz–850kHz; programmable fixed-frequency range is 50kHz–900kHz. The PLLIN/MODE pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction - with improved boost-stage Burst Mode performance when VIN > VOUT, distinguishing it from the base LTC3859.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V main bias supply; supports cold-crank down to 2.5V after startup via boost output or auxiliary supply. |
| Buck Output Reference | 0.800V ±12mV (–40°C to 125°C), enabling precise regulation of 0.8V–24V outputs with tight load/line regulation. |
| Boost Output Reference | 1.200V ±12mV (–40°C to 125°C), supporting regulated boost outputs up to 60V with 100% duty cycle in Burst Mode. |
| No-Load Quiescent Current | 55μA (one channel active), extending battery runtime in always-on automotive and portable systems. |
| Switching Frequency Range | 75kHz–850kHz phase-lockable; programmable 50kHz–900kHz via FREQ pin resistor, enabling EMI optimization and inductor size reduction. |
| Operating Junction Temp | –40°C to +150°C (H-grade), validated for under-hood automotive applications with derated lifetime above 125°C. |
| Gate Driver Strength | TG3/BG3 pull-up/pull-down resistance ≤1.2Ω/1.0Ω, ensuring fast 120ns minimum on-time and robust N-MOSFET drive at high switching frequencies. |
Pinout & Package
Package: 38-pin plastic TSSOP (FE), 11.8mm × 4.4mm × 1.1mm body, exposed PGND pad (Pin 39) requiring PCB soldering for thermal and electrical performance. θJA = 25°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency control | Resistor-to-GND sets 50kHz–900kHz fixed frequency; tied to GND/INTVCC for 350kHz/535kHz default. |
| PLLIN/MODE (Pin 2) | Sync input / light-load mode select | Accepts external clock for synchronization; selects Burst Mode (GND), pulse-skipping (1.2V–INTVCC–1.3V), or forced CCM (INTVCC). |
| RUN1, RUN2, RUN3 (Pins 9–11) | Individual channel enable | Digital logic inputs; <1.17V (RUN1) or <1.20V (RUN2/3) disables respective channel; all <0.7V enters 14μA shutdown. |
| VFB1, VFB2, VFB3 (Pins 36, 14, 6) | Feedback voltage sense | High-impedance inputs monitoring resistive divider outputs; regulate to 0.8V (buck) or 1.2V (boost) with ±12mV tolerance. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– (Pins 37/38, 13/12, 4/5) | Differential current sensing | Support RSENSE or DCR sensing; SENSE3+ sources 170μA, enabling accurate current limit setting for boost stage. |
| TG1/TG2/TG3, BG1/BG2/BG3 (Pins 32/29, 18/21, 27/25) | N-MOSFET gate drivers | High-current floating (TG) and grounded (BG) drivers; TG3/BG3 RON ≤1.2Ω/1.0Ω ensures low-loss switching at high fSW. |
| PGOOD1 (Pin 33) | Power-good indicator | Open-drain output asserting low when VFB1 deviates >±10% from setpoint; enables system sequencing and fault reporting. |
| OV3 (Pin 17) | Boost overvoltage flag | Open-drain output pulled low when VFB3 exceeds 110% of setpoint; provides dedicated boost rail fault detection. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent controllers | Simultaneous buck/buck/boost regulation enables compact multi-rail power architecture without external sequencers. |
| OPTI-LOOP compensation | Allows single compensation network to optimize transient response across wide output capacitor types (ceramic, polymer, electrolytic) and ESR values. |
| 100% duty cycle in Burst Mode | Enables seamless low-noise, high-efficiency operation during VIN ≥ VOUT conditions in boost channel - critical for automotive cold-crank. |
| Low IQ sleep mode | 55μA quiescent current with one channel active meets ISO 26262 ASIL-B standby requirements for always-on vehicle networks. |
| Programmable soft-start/tracking | TRACK/SS1,2 pins allow buck outputs to follow external supplies; SS3 enables controlled ramp for boost output - preventing inrush and enabling safe power sequencing. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management in engine control units (ECUs) that must remain operational during cranking events where battery voltage dips to 2.5V. IC Role / Device Role / Timing Role: Triple-output controller delivering stable 5V, 8.5V, and dynamically regulated 10V rails from a 2.5V–38V automotive battery input. Use Value: Maintains regulation through cold crank via 2.5V startup capability and 99% buck dropout, eliminating need for backup LDOs or supercapacitors. | Use Scenario: Powering GPS, cellular modem, and microcontroller in fleet-tracking devices powered by 12V lead-acid or Li-ion batteries. IC Role / Device Role / Timing Role: Generates isolated 3.3V (buck), 5V (buck), and 12V (boost) rails while minimizing standby current draw between location updates. Use Value: 55μA sleep-mode IQ extends battery life beyond 3 months in low-duty-cycle telemetry applications. |
| Distributed DC Power Systems | Industrial IoT Edge Nodes |
Use Scenario: Centralized 24V bus powering multiple remote sensor nodes requiring different voltage rails (e.g., 3.3V, 5V, 12V). IC Role / Device Role / Timing Role: Local DC/DC controller at each node converting 24V bus to precise, independently regulated outputs with minimal board space. Use Value: Phase-lockable frequency allows synchronization across nodes to reduce conducted EMI in dense deployments. | Use Scenario: Powering ARM Cortex-M7 MCU, RS-485 transceiver, and analog front-end in factory-floor condition-monitoring sensors. IC Role / Device Role / Timing Role: Provides tightly regulated 1.2V core, 3.3V I/O, and 5V interface rails from a 12V industrial supply with high PSRR and low noise. Use Value: 0.8V/1.2V references with ±12mV tolerance ensure ADC accuracy and digital logic stability across –40°C to +150°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3859IFE#TRPBF | Same functionality and pinout, but rated for –40°C to +125°C junction temperature (I-grade vs H-grade). | Suitable for cabin electronics or non-under-hood applications; not qualified for under-hood placement where ambient exceeds 105°C. | Select when full 150°C operation is unnecessary and cost optimization is prioritized. |
| LTC3859AEFE#TRPBF | Same architecture and pinout, but specified for –40°C to +125°C with tighter initial VFB tolerance (±0.8% vs ±1.5% for H-grade). | Preferred for precision analog subsystems requiring tighter initial output accuracy; lacks extended high-temp validation. | Choose when initial output accuracy is more critical than extreme temperature resilience. |
Compared with LTC3859IFE#TRPBF and LTC3859AEFE#TRPBF, the LTC3859AHFE#TRPBF uniquely guarantees operation up to +150°C junction temperature - essential for direct mounting near engines or inverters - while maintaining identical control features, pinout, and 55μA sleep current.
Availability
LTC3859AHFE#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-operated telematics, and distributed DC power systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3859AHFE#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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3859A product line delivers high-efficiency, multi-output synchronous DC/DC controllers optimized for automotive, battery-powered, and industrial applications demanding ultra-low quiescent current and extended temperature operation.
FAQ
What is the maximum operating junction temperature for the LTC3859AHFE#TRPBF?
The LTC3859AHFE#TRPBF is guaranteed to operate over a junction temperature range of –40°C to +150°C, making it suitable for under-hood automotive applications where ambient temperatures exceed 105°C. This H-grade qualification is explicitly defined in the ordering information table and validated per Analog Devices' characterization protocols.
Does the LTC3859AHFE#TRPBF support synchronization to an external clock source?
Yes, the LTC3859AHFE#TRPBF supports external clock synchronization via the PLLIN/MODE pin (Pin 2). When an external clock is applied, the internal phase-locked loop aligns the rising edge of TG1 with the external clock's rising edge, enabling EMI reduction in multi-converter systems - a feature confirmed in the Functional Diagram and Electrical Characteristics tables.
How does the LTC3859AHFE#TRPBF achieve 2.5V cold-crank operation despite its 4.5V minimum VBIAS rating?
The LTC3859AHFE#TRPBF achieves 2.5V cold-crank operation by biasing from the boost converter's output or another auxiliary supply instead of the main VBIAS rail. Once started, it sustains operation down to 2.5V on that auxiliary input - a capability explicitly stated in the Description section and validated in Figure 12's test conditions.
Can the LTC3859AHFE#TRPBF drive both buck and boost channels simultaneously in Burst Mode?
Yes, the LTC3859AHFE#TRPBF supports simultaneous Burst Mode operation across all three channels. The PLLIN/MODE pin globally controls light-load behavior, and the datasheet confirms "Sleep Mode (All Three Channels On)" with 80–120μA IQ - verifying coordinated low-power operation without requiring separate mode configuration per channel.
What is the purpose of the OV3 pin on the LTC3859AHFE#TRPBF?
The OV3 pin on the LTC3859AHFE#TRPBF is an open-drain overvoltage indicator specific to the boost channel. It pulls low when VFB3 exceeds 110% of its regulated setpoint (1.2V), providing dedicated fault signaling for the boost output - distinct from PGOOD1, which monitors only the first buck channel. This is documented in the Pin Functions section and Absolute Maximum Ratings table.
LTC3859AHFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Buck-Boost, SEPIC
- Number of Outputs:
- 3
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 115kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99%, 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP-EP
LTC3859AHFE#TRPBF FAQ
1.How can I place an order for LTC3859AHFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AHFE#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 LTC3859AHFE#TRPBF reliable?
The price and inventory of LTC3859AHFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AHFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859AHFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AHFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AHFE#TRPBF?
LTC3859AHFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AHFE#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 LTC3859AHFE#TRPBF?
For technical support, including LTC3859AHFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AHFE#TRPBF requirements.
6.How does Aetrix verify that LTC3859AHFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AHFE#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 LTC3859AHFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859AHFE#TRPBF?
All LTC3859AHFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AHFE#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 LTC3859AHFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859AHFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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