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Analog Devices Inc. LTC1438XCG#PBF
- Part No.:
- LTC1438XCG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1438XCG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,332
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Product details
Overview
LTC1438XCG#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 supports 3.5V–30V input, delivers two independently programmable outputs (1.19V–9V), and integrates Adaptive Power™ mode for ultrahigh efficiency down to ~1% load. Used in notebook computers and portable instrumentation requiring low-noise, high-efficiency dual-rail power.
For engineers reviewing the LTC1438XCG#PBF datasheet, LTC1438XCG#PBF pinout, LTC1438XCG#PBF application, or LTC1438XCG#PBF equivalent, key selection criteria include its dual-channel current-mode control, 28-lead SSOP package, 400kHz max switching frequency, remote sense capability on VOSENSE2, and absence of POR2 functionality compared to LTC1439 variants.
Technical Context
The LTC1438XCG#PBF implements a constant-frequency current-mode control architecture with separate error amplifiers and current-sense comparators per channel. Its Adaptive Power™ stage dynamically routes gate drive to either large (TGL/BG) or small (TGS) top-side MOSFETs based on load current, maintaining fixed-frequency operation down to ~1% of full scale without entering burst mode.
It features dual independent RUN/SS pins for soft-start and shutdown control, programmable output voltages via VPROG1/VPROG2, and secondary feedback support via SFB1 to enforce continuous conduction on Channel 1. Unlike the LTC1439, it lacks PLLIN, PLL LPF, and POR2 pins - confirming its role as the non-synchronizable, non-power-on-reset variant within the family.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 30V (absolute max 36V); enables direct operation from 5V, 12V, or 24V rails without pre-regulation. |
| Max Switching Frequency | 400kHz; set by COSC capacitor; higher frequencies reduce passive size but increase gate charge losses. |
| Output Voltage Range | 1.19V to 9V per channel; selected via VPROG1/VPROG2 pin states or external resistive divider on VOSENSE2. |
| Current Sense Threshold | 130–180mV (ΔVSENSEMAX); sets overcurrent trip point with external RSENSE, enabling precise peak-current limiting. |
| Quiescent Current | 320µA typical (normal mode); <30µA in shutdown; critical for battery-operated system standby efficiency. |
| Operating Temperature | 0°C to 70°C (Commercial grade); validated for notebook and portable instrument ambient conditions. |
| Package | 28-lead plastic SSOP (G package); 0.025" pitch; compatible with standard surface-mount reflow processes. |
Pinout & Package
Package: 28-lead plastic SSOP (G package), 0.300" wide body, 0.025" lead pitch.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS1, RUN/SS2 | Soft-start & enable inputs | Capacitor-to-ground sets ramp time (~0.5s/µF); <1.3V forces shutdown of respective channel. |
| SENSE+1, SENSE–1, SENSE+2, SENSE–2 | Differential current sense inputs | Measure voltage across external RSENSE; built-in offset sets trip threshold at 130–180mV. |
| VPROG1, VPROG2 | Output voltage programming inputs | DC voltage level selects internal resistor divider ratio: open = adjustable, 0V = 3.3V, INTVCC = 5V. |
| VOSENSE2 | Remote feedback input (Channel 2) | Accepts externally divided output voltage; enables precision regulation with PCB trace resistance compensation. |
| TGL1, TGL2, BG1, BG2, TGS1, TGS2 | Gate drive outputs | TGL/BG drive large N-MOSFETs; TGS drives small N-MOSFET for Adaptive Power™ low-load operation. |
| SW1, SW2 | Switch node connections | Connect to inductor high-side; swing from Schottky diode drop below GND to VIN. |
| VIN, PGND, SGND | Power and ground terminals | VIN supplies main logic/driver; PGND carries high pulsed currents; SGND is clean reference for analog circuitry. |
| INTVCC, EXTVCC | Internal supply & bypass inputs | INTVCC = 5V regulated output; EXTVCC >4.7V bypasses internal LDO to improve efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Power™ mode | Automatically switches between large and small top-side MOSFETs to sustain fixed-frequency operation down to ~1% load - avoiding efficiency collapse in burst mode. |
| Dual independent control loops | Separate RUN/SS, ITH, VPROG, and sensing paths per channel allow asymmetric configurations (e.g., 5V/3.3V or 3.3V/adjustable). |
| Remote output voltage sensing | VOSENSE2 pin accepts feedback from point-of-load, compensating for IR drop in PCB traces or connectors. |
| Programmable soft start | External capacitor on RUN/SS pins controls output voltage ramp rate, preventing inrush current and system reset glitches. |
| Low dropout operation | Supports 99% duty cycle; maintains regulation even when VIN approaches VOUT - essential for Li-ion battery discharge profiles. |
Applications
| Portable Instrumentation | Notebook Computing |
|---|---|
Use Scenario: High-precision data acquisition systems powered by single-cell Li-ion batteries (3.0–4.2V). IC Role / Device Role / Timing Role: Dual-channel DC/DC controller generating clean 3.3V for ADC/DAC and 1.8V for FPGA core from variable battery input. Use Value: Adaptive Power™ sustains >90% efficiency at microamp loads during sleep modes; remote sensing ensures ±0.5% output accuracy at sensor nodes. | Use Scenario: Mainboard power delivery in ultra-thin notebooks with thermal constraints. IC Role / Device Role / Timing Role: Primary controller for CPU I/O (5V) and memory interface (3.3V) rails, coordinating with system PMIC. Use Value: 28-lead SSOP footprint minimizes board area; 400kHz switching allows compact 10µH inductors and 220µF output caps. |
| Battery-Operated Medical Devices | Industrial Handheld Terminals |
Use Scenario: Portable ECG monitor requiring low-noise analog supply and reliable digital rail. IC Role / Device Role / Timing Role: Generates isolated 3.3V digital rail and low-noise 5V analog rail using external PNP linear post-regulator on AUXDR. Use Value: Integrated 0.5A auxiliary linear regulator path (via AUXON/AUXFB) eliminates need for discrete LDO, reducing BOM count and noise coupling. | Use Scenario: Ruggedized barcode scanner operating across –10°C to 60°C ambient. IC Role / Device Role / Timing Role: Dual-output controller powering 3.3V MCU and 5V laser driver from 7.4V Li-Po pack. Use Value: Wide 3.5–30V input range accommodates battery sag and surge transients; commercial-grade temp rating matches industrial handheld requirements. |
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 |
|---|---|---|---|
| LTC1439CG#PBF | Includes PLLIN, PLL LPF, and POR2 pins; supports external clock synchronization and power-on reset assertion. | Required where system-level timing alignment or sequenced power-up is mandatory (e.g., multi-rail FPGAs). | Select LTC1439CG#PBF only if PLL lock or POR2 signaling is needed; otherwise LTC1438XCG#PBF reduces pin count and layout complexity. |
| MP2491DS-LF-Z | Single-channel, integrated MOSFETs; no external gate drive; fixed 5V/3.3V outputs only; no Adaptive Power™ or remote sense. | Suitable for cost-sensitive, space-constrained designs where dual-rail flexibility and ultra-low-light-load efficiency are not required. | Choose MP2491DS-LF-Z for simplified design with lower component count; avoid when dual independent outputs or sub-1% load efficiency matters. |
Compared with LTC1439CG#PBF, LTC1438XCG#PBF removes synchronization and reset functions to reduce pin count and cost, while retaining identical core regulation, Adaptive Power™, and sensing capabilities. Versus MP2491DS-LF-Z, it offers greater design flexibility through external MOSFET control, programmable outputs, and superior light-load performance - at the expense of higher external component count.
Availability
LTC1438XCG#PBF is available at Aetrix Electronics and suitable for notebook computing, portable instrumentation, and battery-operated medical devices requiring stable component supply, long-term lifecycle support, and guaranteed commercial-temperature performance.
Supply support for LTC1438XCG#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 acquired Linear Technology in 2017 and maintains full product support, datasheets, and application engineering for legacy Linear parts including the LTC series.
The LTC1438/LTC1439 family was designed for high-efficiency, dual-output DC/DC conversion in portable and battery-powered systems - emphasizing adaptive light-load operation, remote sensing, and flexible voltage programming without external op-amps.
FAQ
What is the key functional difference between LTC1438XCG#PBF and LTC1439CG#PBF?
The LTC1438XCG#PBF omits the PLLIN, PLL LPF, and POR2 pins present on the LTC1439CG#PBF. This means LTC1438XCG#PBF cannot be synchronized to an external clock nor generate a power-on reset signal. All other regulation, Adaptive Power™, and sensing functions are identical. The LTC1438XCG#PBF is the streamlined variant for applications where those features are unnecessary.
Does LTC1438XCG#PBF support remote voltage sensing on both outputs?
No. LTC1438XCG#PBF supports remote sensing only on Channel 2 via the VOSENSE2 pin. Channel 1 uses internal sensing tied to SENSE–1 and does not expose VOSENSE1 - unlike the LTC1438-ADJ variant. This is confirmed by the pinout diagram and "Table 1. Output Voltage Table" in the datasheet, which lists VOSENSE1 as unavailable on LTC1438X.
What is the maximum recommended switching frequency for LTC1438XCG#PBF?
The maximum recommended switching frequency for LTC1438XCG#PBF is 400kHz, as explicitly stated in the datasheet's "Features" section and confirmed in the "Applications Information" section. Operating above this frequency increases MOSFET gate charge losses and degrades efficiency, especially at higher load currents.
Can LTC1438XCG#PBF be used to generate a 1.2V output?
Yes. LTC1438XCG#PBF supports adjustable outputs down to 1.19V. By leaving VPROG2 open and connecting VOSENSE2 to an external resistive divider from the output, the second channel can be configured for 1.2V (±1%). The first channel is limited to 3.3V or 5V only per the datasheet's Table 1, so 1.2V requires use of Channel 2 with external feedback.
Is the AUX linear regulator functional on LTC1438XCG#PBF?
No. The AUX regulator block (AUXON, AUXFB, AUXDR pins) is not present on LTC1438XCG#PBF - it is exclusive to the LTC1439 variants. The datasheet's "PIN FUNCTIONS" section explicitly notes "**NOT AVAILABLE ON LTC1438X", and the functional diagram shows these pins grayed out or absent for LTC1438X. Therefore, LTC1438XCG#PBF cannot generate auxiliary low-noise rails.
LTC1438XCG#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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC1438XCG#PBF FAQ
1.How can I place an order for LTC1438XCG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1438XCG#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 LTC1438XCG#PBF reliable?
The price and inventory of LTC1438XCG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1438XCG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1438XCG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1438XCG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1438XCG#PBF?
LTC1438XCG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1438XCG#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 LTC1438XCG#PBF?
For technical support, including LTC1438XCG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1438XCG#PBF requirements.
6.How does Aetrix verify that LTC1438XCG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1438XCG#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 LTC1438XCG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1438XCG#PBF?
All LTC1438XCG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1438XCG#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 LTC1438XCG#PBF part is unused and in its original packaging.
Return procedure for LTC1438XCG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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