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Analog Devices Inc. LTC1439IG#PBF
- Part No.:
- LTC1439IG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1439IG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,588
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Product details
Overview
LTC1439IG#PBF from Analog Devices (formerly Linear Technology) is a dual, synchronous step-down switching regulator controller driving external N-channel MOSFETs in a phase-lockable fixed-frequency architecture. It delivers two regulated outputs (1.19V–9V), supports 3.5V–30V input, maintains constant frequency down to ~1% load via Adaptive Power™ mode, and integrates a 0.5A auxiliary linear regulator for low-noise VPP or audio supply - used in notebook computers and portable instrumentation.
For engineers reviewing the LTC1439IG#PBF datasheet, LTC1439IG#PBF pinout, LTC1439IG#PBF application, or LTC1439IG#PBF equivalent, key selection criteria include programmable output voltage (via VPROG pins), remote sense capability on VOSENSE2, PLL synchronization support, foldback current limiting option, and 36-lead SSOP package thermal performance (θJA = 85°C/W).
Technical Context
The LTC1439IG#PBF implements a current-mode, dual-channel DC/DC control architecture with independent error amplifiers, ITH1/ITH2 compensation nodes, and adaptive gate drive routing between TGL/TGS and BG outputs. Its Adaptive Power™ stage dynamically switches between high-current synchronous (TGL/BG) and low-current diode-assisted (TGS) operation based on inductor current reversal detection and RSENSE voltage hysteresis.
It features a phase-locked loop (PLLIN/PLL LPF) enabling external clock synchronization up to ±30% frequency shift, a secondary feedback input (SFB1) forcing continuous operation for transformer-coupled regulation, and integrated power-on reset (POR2) with 65536-cycle delay timed to fCLK (~300ms at 125kHz). The auxiliary regulator uses AUXFB/AUXON/AUXDR to control an external PNP for 12V or adjustable low-noise output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 30V (absolute max 36V); enables direct battery or industrial rail operation without pre-regulation. |
| Output Voltage Range | 1.19V to 9V per channel; set by VPROG1/VPROG2 pin states or external resistive divider on VOSENSE2. |
| Switching Frequency | 112–138kHz (typ), extendable to 240kHz via PLL; COSC pin sets base frequency with 100pF yielding 125kHz. |
| Efficiency Mode | Adaptive Power™ maintains fixed frequency down to ~1% rated load; eliminates audible noise and EMI variation at light loads. |
| Auxiliary Regulator | 0.5A linear regulator controlled by AUXFB/AUXON; supports 12V (internal divider) or adjustable output via external PNP pass device. |
| Thermal Performance | θJA = 85°C/W in 36-lead SSOP (GW package); junction limit 125°C; supports sustained 3.5A per channel with proper layout. |
| Shutdown Current | <30µA (IQ = 16–30µA typ); logic-controlled via RUN/SS1 & RUN/SS2 pins; enables long battery life in portable systems. |
Pinout & Package
Package: 36-lead plastic SSOP (GW), 0.025" pitch, exposed pad not specified; thermal resistance θJA = 85°C/W. Pinout validated per Linear Technology LTC1438/LTC1439 datasheet Rev. fb (14389fb), Figure 3 (top view).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS1, RUN/SS2 | Soft-start & enable control | Capacitor-to-ground sets ramp time (~0.5s/µF); <1.3V forces shutdown of respective channel; both low disables entire IC. |
| SENSE+1/2, SENSE−1/2 | Current-sense differential inputs | Measure voltage across external RSENSE; built-in offset sets trip threshold (130–180mV); enables cycle-by-cycle current limiting. |
| VPROG1, VPROG2 | Output voltage programming | Selects internal attenuator ratio: open = adjustable; |
| VOSENSE2 | Remote output voltage sense (CH2) | Connects to external resistive divider for precise regulation; required for adjustable output on second channel; not present on CH1 for LTC1439. |
| SFB1 | Secondary winding feedback | Forces continuous operation on CH1 when pulled <1.19V; ensures regulation under light/no load on main output via transformer auxiliary winding. |
| PLLIN, PLL LPF | Phase-locked loop interface | PLLIN accepts external sync clock; PLL LPF is phase detector output and oscillator control voltage (0–2.4V = ±30% fOSC shift). |
| AUXFB, AUXON, AUXDR | Auxiliary regulator control | AUXFB = feedback node (12V internal divider or external); AUXON = logic-enable (1.19V threshold); AUXDR = open-drain PNP base drive. |
| TGL1/2, BG1/2, TGS1/2 | Gate drive outputs | TGL/BG drive large N-MOSFETs (high-current mode); TGS drives small N-MOSFET + Schottky (low-current Adaptive Power™ mode). |
Key Features
| Feature | Design Value |
|---|---|
| Dual synchronous buck control | Independent CH1/CH2 with separate ITH, SENSE, and RUN/SS pins enables asymmetric 5V/3.3V or dual 3.3V rails with no cross-talk. |
| Adaptive Power™ topology | Automatically toggles between TGL/BG (full sync) and TGS (diode-assisted) drive to sustain 125kHz operation down to 1% load - avoids Burst Mode noise. |
| PLL synchronization | External clock locking via PLLIN allows EMI reduction through frequency alignment with system master clock or adjacent converters. |
| Secondary feedback (SFB1) | Guarantees CH1 regulation under zero-load conditions using transformer auxiliary winding - critical for isolated multi-output supplies. |
| Integrated POR2 timer | Generates 300ms (65536 cycles) reset pulse after VOUT2 reaches ±5% regulation - provides deterministic power sequencing for downstream logic. |
| Logic-controlled auxiliary regulator | AUXON pin enables/disables 0.5A PNP-based linear supply with <1% load regulation - ideal for low-noise analog/audio bias or VPP generation. |
Applications
| Portable Instrumentation | Notebook Computing |
|---|---|
Use Scenario: Handheld multimeter with dual isolated analog front-ends requiring clean 3.3V ADC reference and 5V digital core supply. IC Role / Device Role / Timing Role: LTC1439IG#PBF acts as dual synchronous buck controller managing independent 3.3V/5V rails with remote sensing and SFB1-enforced regulation during sleep mode. Use Value: Adaptive Power™ eliminates light-load efficiency drop and audible coil whine; SFB1 ensures stable 3.3V rail even when digital core is powered off. | Use Scenario: Ultrabook motherboard needing tightly regulated 1.8V DDR3 memory rail and 5V USB peripheral bus from shared 12V battery input. IC Role / Device Role / Timing Role: LTC1439IG#PBF configures CH1 as 1.8V adjustable output (via VOSENSE2 + divider) and CH2 as 5V fixed output, both with remote sense and soft-start coordination. Use Value: Programmable VPROG2 and VOSENSE2 enable precise 1.8V tolerance (<±0.8%); RUN/SS1/SS2 sequencing prevents bus contention during boot. |
| Battery-Powered Medical Devices | DC Power Distribution Systems |
Use Scenario: Portable ECG monitor requiring ultra-low-noise 2.5V analog sensor supply and 3.3V microcontroller rail from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: LTC1439IG#PBF operates CH1 as 2.5V adjustable buck (VPROG1 open + VOSENSE2 divider) and CH2 as 3.3V buck; auxiliary regulator powers op-amp bias. Use Value: Auxiliary linear regulator delivers 0.5A @ 2.5V with <1% load regulation and 60dB PSRR at 10kHz - suppresses switching noise coupling into analog path. | Use Scenario: Industrial PoE-powered access point with 48V input, needing 12V PoE PD interface, 5V FPGA core, and 3.3V PHY rails. IC Role / Device Role / Timing Role: LTC1439IG#PBF controls CH1 (12V) and CH2 (5V) via external MOSFETs; EXTVCC tied to CH1 output improves efficiency; PLL synchronized to system clock reduces EMI. Use Value: EXTVCC switchover cuts INTVCC losses by bypassing internal LDO; PLL lock aligns switching edges across multiple converters - simplifies EMI filter design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3728CUH#PBF | Single-channel, higher current (20A), supports MOSFET RDS(on) current sensing; no auxiliary regulator or SFB1. | Best for high-power single-rail designs; lacks dual-channel coordination and secondary feedback for isolated supplies. | Choose LTC3728CUH#PBF only when scaling output current beyond 3.5A per rail and auxiliary regulation is unnecessary. |
| MP2918GL-Z | Dual-channel, 5V/3.3V fixed outputs only; no VPROG/VOSENSE adjustability; no PLL or SFB1; lower IQ (12µA). | Targeted at cost-sensitive consumer notebooks; lacks remote sense, programmability, and transformer-coupled regulation support. | Choose MP2918GL-Z only for fixed-voltage, non-isolated, high-volume applications where design flexibility and precision are secondary. |
Compared with LTC3728CUH#PBF and MP2918GL-Z, the LTC1439IG#PBF uniquely combines dual-channel programmability, Adaptive Power™ light-load optimization, SFB1 for transformer regulation, and integrated auxiliary linear control - making it irreplaceable in precision portable and isolated multi-rail systems.
Availability
LTC1439IG#PBF is available at Aetrix Electronics and suitable for notebook computing, portable instrumentation, battery-operated medical devices, and DC power distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed extended temperature performance (–40°C to 85°C).
Supply support for LTC1439IG#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. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1439IG#PBF belongs to Linear's legacy high-efficiency DC/DC controller family, designed specifically for space-constrained, battery-sensitive applications demanding dual regulated outputs, adaptive light-load operation, and auxiliary low-noise bias generation.
FAQ
What is the maximum supported switching frequency for the LTC1439IG#PBF?
The LTC1439IG#PBF supports a base oscillator frequency of 112–138kHz (typical), extendable to 240kHz using the PLL function with VPLLLPF = 2.4V. The datasheet specifies 400kHz as the maximum recommended switching frequency to maintain ultrahigh efficiency and manage MOSFET gate charge losses. Operation above 240kHz requires external PLL injection and careful layout to avoid instability.
Does the LTC1439IG#PBF support remote voltage sensing on both output channels?
The LTC1439IG#PBF supports remote voltage sensing only on the second channel via the VOSENSE2 pin. Channel 1 does not have a dedicated VOSENSE1 pin in the LTC1439 variant (unlike the LTC1438-ADJ); its feedback is internally routed through SENSE−1. Remote sensing on CH2 enables precise regulation at the load point for sensitive applications like FPGA core supplies.
How does the Adaptive Power™ mode in the LTC1439IG#PBF differ from standard Burst Mode operation?
Adaptive Power™ mode in the LTC1439IG#PBF maintains constant 125kHz switching down to ~1% of rated load by dynamically routing gate drive to TGS (small MOSFET + Schottky) instead of disabling pulses entirely. Standard Burst Mode interrupts full switching cycles, causing variable frequency and potential EMI/audible noise. Adaptive Power™ eliminates both, preserving EMI profile and measurement integrity in portable instrumentation.
Can the auxiliary regulator in the LTC1439IG#PBF be used as a comparator?
Yes - the auxiliary block in the LTC1439IG#PBF can operate as a comparator by connecting AUXFB to the signal to monitor and leaving AUXON unconnected or grounded. The internal 1.19V reference serves as the inverting input; AUXDR becomes an open-drain output requiring an external pull-up. This configuration is used for low-battery detection or overvoltage monitoring without adding discrete components.
What thermal derating applies to the LTC1439IG#PBF in its 36-lead SSOP (GW) package?
The LTC1439IG#PBF in the 36-lead SSOP (GW) package has a junction-to-ambient thermal resistance θJA of 85°C/W. At 25°C ambient and 125°C max junction temperature, this allows ~1.18W of total power dissipation before thermal shutdown. Derating is linear: for 70°C ambient, max allowable power drops to ~0.65W. Proper PCB copper area and airflow are essential to sustain 3.5A per channel continuously.
LTC1439IG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.5V ~ 30V
- Frequency - Switching:
- Up to 400kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power on Reset, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
LTC1439IG#PBF FAQ
1.How can I place an order for LTC1439IG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1439IG#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 LTC1439IG#PBF reliable?
The price and inventory of LTC1439IG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1439IG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1439IG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1439IG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1439IG#PBF?
LTC1439IG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1439IG#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 LTC1439IG#PBF?
For technical support, including LTC1439IG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1439IG#PBF requirements.
6.How does Aetrix verify that LTC1439IG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1439IG#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 LTC1439IG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1439IG#PBF?
All LTC1439IG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1439IG#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 LTC1439IG#PBF part is unused and in its original packaging.
Return procedure for LTC1439IG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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