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Analog Devices Inc. LTC1438IG-ADJ#PBF
- Part No.:
- LTC1438IG-ADJ#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1438IG-ADJ#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,411
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Product details
Overview
LTC1438IG-ADJ#PBF from Analog Devices (formerly Linear Technology) is a dual synchronous step-down switching regulator controller driving external N-channel MOSFETs in a fixed-frequency, phase-lockable architecture. It delivers two independently programmable outputs (1.19V–9V), supports adaptive power mode up to 400kHz, maintains constant frequency down to ~1% load, and integrates a 0.5A auxiliary linear regulator for low-noise VPP or audio supply - used in notebook computers and portable instrumentation requiring high efficiency and remote sensing.
For engineers reviewing the LTC1438IG-ADJ#PBF datasheet, LTC1438IG-ADJ#PBF pinout, LTC1438IG-ADJ#PBF application, or LTC1438IG-ADJ#PBF equivalent, key selection criteria include dual adjustable output voltage programming via VPROG pins, SFB1-enabled secondary winding regulation, ultralow shutdown current (<30µA), 3.5V–30V input range, and 28-lead SSOP package with verified thermal performance (θJA = 95°C/W).
Technical Context
The LTC1438IG-ADJ#PBF implements a current-mode, constant-frequency PWM control architecture with independent error amplifiers per channel, where ITH1/ITH2 set peak current thresholds via external sense resistors. Its Adaptive Power™ topology dynamically routes gate drive between TGL/TGS outputs to sustain fixed-frequency operation at light loads by engaging a small top-side MOSFET with Schottky diode instead of large synchronous switches.
It features dual independent feedback paths: Controller 1 uses VOSENSE1 (available only on -ADJ variant) with external resistive divider for fully adjustable remote-sense output; Controller 2 uses VOSENSE2 with VPROG2-selectable 3.3V/5V/adjustable configuration. Secondary feedback via SFB1 forces continuous conduction mode regardless of main output loading - critical for multi-winding transformer designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 30V (36V absolute max) - supports wide-input battery and DC distribution systems without pre-regulation. |
| Output Voltage Range | 1.19V to 9V (adjustable via external resistor dividers on VOSENSE1/VOSENSE2) - enables precise rail generation for mixed-signal SoCs and FPGAs. |
| Switching Frequency | Programmable 112–138kHz (COSC-dependent); up to 400kHz with Adaptive Power - balances efficiency vs. component size in space-constrained portable designs. |
| Shutdown Current | <30µA (IQ) - preserves battery life in always-on subsystems during deep sleep modes. |
| Current Sense Threshold | 130–180mV (ΔVSENSE(MAX)) - sets accurate overcurrent protection with minimal power loss across RSENSE. |
| Thermal Resistance | θJA = 95°C/W (28-lead SSOP) - defines maximum power dissipation capability under natural convection cooling. |
| Auxiliary Regulator Output | 0.5A linear regulator (AUXDR/AUXFB) with 12V or 1.19V options - supplies low-noise analog rails or VPP programming voltage without additional LDOs. |
Pinout & Package
Package: 28-lead plastic SSOP (G package), RoHS-compliant, moisture-sensitive level 3. Thermal pad not present; requires standard reflow profile for SSOP.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS1, RUN/SS2 | Soft-start and enable inputs | Capacitor-to-ground sets ramp time (~0.5s/µF); <1.3V forces shutdown of respective channel; both low disables entire IC. |
| VOSENSE1 | Remote feedback input (Controller 1) | Required only on -ADJ variant; connects to external resistor divider to set fully adjustable output voltage with remote sensing. |
| VPROG1, VPROG2 | Output voltage select inputs | VPROG1 open → Controller 1 adjustable; VPROG2 open → Controller 2 adjustable; grounded/INTVCC selects 3.3V/5V fixed outputs. |
| SFB1 | Secondary winding feedback | Pulling below 1.19V forces continuous conduction on Controller 1 - ensures regulation when secondary winding supplies auxiliary bias. |
| ITH1, ITH2 | Error amplifier compensation nodes | Set peak current limit and loop stability; voltage increases with load to maintain regulation - used for slope compensation and current limiting. |
| TGL1/TGL2, BG1/BG2 | Main top/bottom gate drivers | TGL drives large N-MOSFETs (high-current mode); BG drives bottom N-MOSFETs; both swing 0V to INTVCC (≈5V). |
| TGS1/TGS2 | Small top-side gate drivers | Enable Adaptive Power mode: engaged at light load to drive small N-MOSFET + Schottky, reducing gate charge losses while maintaining fixed frequency. |
| SENSE+1/SENSE−1, SENSE+2/SENSE−2 | Current sense differential inputs | Measure voltage drop across external RSENSE; built-in offset enables accurate current limiting without external op-amps. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent adjustable outputs | Controller 1: VOSENSE1-based remote sensing (LTC1438IG-ADJ#PBF only); Controller 2: VPROG2-selectable 3.3V/5V/adjustable - eliminates need for external DACs or trimming. |
| Adaptive Power™ topology | Maintains fixed-frequency operation down to ~1% rated load by switching gate drive from TGL to TGS outputs - avoids audible noise and EMI spikes from Burst Mode. |
| Secondary feedback enforcement (SFB1) | Guarantees continuous conduction on Controller 1 when secondary winding voltage drops - essential for flyback-derived bias in isolated DC/DC converters. |
| Integrated 0.5A auxiliary linear regulator | Generates low-noise 12V (via internal 12V divider) or 1.19V (direct reference) from AUXDR/AUXFB - replaces discrete PNP-based LDOs in VPP/audio supply chains. |
| Logic-controlled micropower shutdown | IQ < 30µA with both RUN/SS pins low - enables system-level power gating without external supervisors or sequencers. |
Applications
| Notebook Computer Power Management | Portable Instrumentation Supply |
|---|---|
Use Scenario: Dual-rail CPU core (1.2V) and I/O (3.3V) supply in space-constrained clamshell design with battery backup. IC Role / Device Role / Timing Role: Primary dual-output synchronous buck controller managing dynamic load transients and enabling adaptive frequency scaling. Use Value: Remote sensing on VOSENSE1 compensates for PCB trace IR drop; Adaptive Power sustains 200kHz switching at standby current, avoiding Burst Mode noise in audio subsystems. |
Use Scenario: Battery-powered handheld multimeter requiring ultra-stable analog reference (±0.1%) and isolated digital logic supply. IC Role / Device Role / Timing Role: Main DC/DC controller with SFB1-driven secondary winding feedback ensuring regulation during battery sag. Use Value: SFB1 pin forces continuous operation on Controller 1 even under light load, preventing output droop that would corrupt ADC reference accuracy. |
| Battery-Operated Medical Sensor Node | DC Power Distribution System |
Use Scenario: Wearable ECG monitor with low-power MCU, analog front-end, and BLE radio sharing single Li-ion cell. IC Role / Device Role / Timing Role: Dual-output regulator delivering 1.8V (digital) and 3.3V (RF/analog) with coordinated soft-start and shutdown sequencing. Use Value: RUN/SS1/RUN/SS2 pins allow independent enable/disable timing; <30µA shutdown current extends battery runtime beyond 6 months in sleep mode. |
Use Scenario: Industrial 24V DC bus powering multiple distributed modules (IO, comms, actuator drivers) with centralized supervision. IC Role / Device Role / Timing Role: High-efficiency dual buck controller feeding local point-of-load regulators, with POR2 providing reset signal synchronized to 3.3V rail stabilization. Use Value: POR2 delay (65536 oscillator cycles ≈300ms at 125kHz) ensures reliable microcontroller reset after full rail establishment - no external RC timer needed. |
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 |
|---|---|---|---|
| LTC1439IG | Fixed 3.3V/5V outputs on Controller 1; no VOSENSE1 pin; includes PLLIN/PLL LPF for synchronization - lacks full adjustability of LTC1438IG-ADJ#PBF. | Used where dual fixed outputs suffice and clock synchronization across multiple rails is required - e.g., FPGA power trees with deterministic timing. | Select LTC1439IG if system does not require adjustable Controller 1 output and benefits from external clock locking. |
| MP2451DT-LF-Z | Single-channel 2A buck controller (not dual); no auxiliary LDO; no SFB1 or Adaptive Power; 36V max VIN; 0.8V–15V adjustable output. | Applicable only for single-rail systems needing compact footprint and lower BOM cost - cannot replace dual-output functionality of LTC1438IG-ADJ#PBF. | Consider MP2451DT-LF-Z only for non-dual, non-remote-sense, cost-sensitive applications where auxiliary regulation is handled externally. |
Compared with LTC1439IG, LTC1438IG-ADJ#PBF provides full VOSENSE1-based adjustability and remote sensing on Channel 1 but omits PLL synchronization; versus MP2451DT-LF-Z, it offers true dual independent outputs, integrated auxiliary LDO, and Adaptive Power - making it uniquely suited for precision dual-rail portable systems.
Availability
LTC1438IG-ADJ#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, battery-operated medical devices, and industrial DC power distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.
Supply support for LTC1438IG-ADJ#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 digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1438/LTC1439 family was designed by Linear Technology specifically for high-efficiency, low-noise dual-output DC/DC conversion in portable and battery-critical applications - emphasizing adaptive light-load behavior, remote sensing, and integrated auxiliary regulation.
FAQ
What output voltage options does the LTC1438IG-ADJ#PBF support on its two channels?
The LTC1438IG-ADJ#PBF supports fully adjustable output voltages from 1.19V to 9V on both channels via external resistor dividers: Controller 1 uses VOSENSE1 (exclusive to -ADJ variants), while Controller 2 uses VOSENSE2 with VPROG2 pin selection. Unlike non-ADJ versions, LTC1438IG-ADJ#PBF does not restrict Controller 1 to fixed 3.3V/5V outputs - enabling custom rail generation for ASICs or specialized sensors.
How does the Adaptive Power™ mode in the LTC1438IG-ADJ#PBF improve light-load efficiency?
The LTC1438IG-ADJ#PBF's Adaptive Power™ mode reduces switching losses at light loads by routing gate drive from TGL1/TGL2 (large MOSFETs) to TGS1/TGS2 (small MOSFETs + Schottky diode), sustaining fixed-frequency operation down to ~1% of full load. This avoids efficiency collapse and audible noise associated with Burst Mode - a key advantage of LTC1438IG-ADJ#PBF over standard current-mode controllers.
Can the LTC1438IG-ADJ#PBF be used with secondary winding feedback, and how is it implemented?
Yes - the LTC1438IG-ADJ#PBF supports secondary winding regulation via the SFB1 pin, which connects to a resistive divider from an auxiliary transformer winding. Pulling SFB1 below 1.19V forces Controller 1 into continuous conduction mode regardless of main output loading, ensuring stable regulation when primary-side feedback is compromised - a documented function of LTC1438IG-ADJ#PBF confirmed in the functional diagram and Applications Information section.
What is the role of the VOSENSE1 pin, and why is it unique to the LTC1438IG-ADJ#PBF variant?
The VOSENSE1 pin is exclusive to LTC1438IG-ADJ#PBF and serves as the remote feedback input for Controller 1, enabling fully adjustable output voltage via external resistor divider. Non-ADJ variants (e.g., LTC1438IG) tie SENSE−1 internally and only support fixed 3.3V/5V outputs - making VOSENSE1 a defining feature that differentiates LTC1438IG-ADJ#PBF for precision dual-rail applications requiring custom voltage levels.
Does the LTC1438IG-ADJ#PBF include an integrated power-on reset function, and how is it configured?
The LTC1438IG-ADJ#PBF does not include a POR function on Controller 1; however, its POR2 pin provides a power-on reset signal tied to Controller 2's output, asserting low when VOUT2 drops >7.5% below regulation and releasing after 65536 oscillator cycles (~300ms at 125kHz) once regulation is restored. This POR2 functionality is active and verified for LTC1438IG-ADJ#PBF per the Absolute Maximum Ratings and Electrical Characteristics tables.
LTC1438IG-ADJ#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-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:
- 28-SSOP
LTC1438IG-ADJ#PBF FAQ
1.How can I place an order for LTC1438IG-ADJ#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1438IG-ADJ#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 LTC1438IG-ADJ#PBF reliable?
The price and inventory of LTC1438IG-ADJ#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1438IG-ADJ#PBF is usually 5 days.
3.What payment methods are accepted for LTC1438IG-ADJ#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1438IG-ADJ#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1438IG-ADJ#PBF?
LTC1438IG-ADJ#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1438IG-ADJ#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 LTC1438IG-ADJ#PBF?
For technical support, including LTC1438IG-ADJ#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1438IG-ADJ#PBF requirements.
6.How does Aetrix verify that LTC1438IG-ADJ#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1438IG-ADJ#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 LTC1438IG-ADJ#PBF meets industry standards.
7.What is the process for return or replacement of LTC1438IG-ADJ#PBF?
All LTC1438IG-ADJ#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1438IG-ADJ#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 LTC1438IG-ADJ#PBF part is unused and in its original packaging.
Return procedure for LTC1438IG-ADJ#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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