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Analog Devices Inc. LTC1538CG-AUX#TRPBF
- Part No.:
- LTC1538CG-AUX#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1538CG-AUX#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,369
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Product details
Overview
LTC1538CG-AUX#TRPBF from Analog Devices (formerly Linear Technology) is a dual synchronous step-down switching regulator controller driving external N-channel MOSFETs in fixed-frequency, current-mode architecture. It delivers two independent regulated outputs - one fixed 3.3V/5V (Controller 1), one adjustable 1.19V–9V (Controller 2) - with up to 3.5A per channel, 99% duty cycle low-dropout operation, and integrated 5V/20mA standby regulator. It targets high-efficiency power conversion in portable computing and battery-powered instrumentation.
For engineers reviewing the LTC1538CG-AUX#TRPBF datasheet, LTC1538CG-AUX#TRPBF pinout, LTC1538CG-AUX#TRPBF application, or LTC1538CG-AUX#TRPBF equivalent, key selection criteria include dual-channel programmable output voltage, adaptive power mode for ultralow-load efficiency, remote sensing on Channel 2, and 28-lead SSOP package compatibility with thermal management requirements.
Technical Context
The LTC1538CG-AUX#TRPBF implements a constant-frequency current-mode control loop per channel, using internal error amplifiers (ITH1/ITH2), peak-current sensing via SENSE+/SENSE− pairs, and adaptive gate drive (TGL1/TGS1/BG1 for Channel 1; TGL2/TGS2/BG2 for Channel 2). Its Adaptive Power™ architecture dynamically selects between large- and small-MOSFET drive paths to sustain >100kHz operation down to ~1% load without Burst Mode.
It integrates auxiliary functions including a shutdown-persistent 5V INTVCC regulator, programmable soft-start (RUN/SS1/RUN/SS2), power-on reset timer (65536 cycles), low-battery detection (LBI/LBO), and secondary feedback (SFB1) for transformer-coupled regulation. The device lacks PLLIN and PLL LPF pins - distinguishing it from the LTC1539 - and supports only fixed-frequency operation via COSC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Channels | Dual independent controllers: Channel 1 fixed 3.3V/5V only; Channel 2 adjustable 1.19V–9V with VOSENSE2 remote sense |
| Input Voltage Range | 3.5V to 36V - enables direct operation from 12V/24V industrial rails or multi-cell Li-ion batteries |
| Switching Frequency | Programmable 112–138kHz via COSC capacitor - fixed-frequency operation without PLL synchronization capability |
| Peak Efficiency | Up to 95% at 1A load (VOUT=3.3V, VIN=10V) - achieved via synchronous N-MOSFET drive and Adaptive Power mode |
| Standby Quiescent Current | <200µA with both controllers shut down - sustained by always-on 5V INTVCC regulator for system wake-up readiness |
| Package & Thermal | 28-lead plastic SSOP (G package), θJA = 95°C/W - requires PCB copper area and thermal vias for 3.5A/channel continuous operation |
| Protection Features | Foldback current limiting (optional), overvoltage lockout (1.24–1.32V threshold), dropout detector, and POR with 300ms typical delay |
Pinout & Package
Package: 28-lead plastic SSOP (G package), 0.025" pitch, exposed pad not electrically connected. Thermal resistance θJA = 95°C/W. Requires SGND/PGND separation and local 2.2µF INTVCC decoupling.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| BOOST 1 | Topside driver supply for Channel 1 | Provides floating bias for TGL1 gate drive; connects to bootstrap capacitor between SW1 and BOOST 1 |
| RUN/SS1 | Channel 1 enable & soft-start control | Pulling below 1.3V disables Channel 1; capacitor to ground sets ramp time (~0.5s/µF) |
| SENSE+ 1 / SENSE– 1 | Current sense differential inputs (Channel 1) | Fixed internal connection prevents true remote sensing on Channel 1; sets current limit via RSENSE1 (e.g., 0.03Ω → 5A peak) |
| VPROG1 | Channel 1 output voltage select | Open = 5V; 0V = 3.3V - no adjustable mode supported on Channel 1 per datasheet Table 1 |
| ITH1 | Error amplifier compensation node (Channel 1) | DC voltage controls peak inductor current; clamped during soft-start; used for loop compensation |
| COSC | Oscillator timing capacitor connection | 100pF sets ~125kHz; frequency varies inversely with COSC value per fOSC = 8.4×10⁸/(COSC + 11) × (1/ICHG + 1/IDISC)⁻¹ |
| SGND | Small-signal reference ground | Must be routed separately from PGND to avoid noise coupling into SENSE+/VOSENSE2 paths |
| SFB1 | Secondary winding feedback input | Pulling below 1.19V forces continuous synchronous operation on Channel 1 - critical for transformer-isolated designs |
| VOSENSE2 | Remote output voltage sense (Channel 2) | Accepts feedback directly from VOUT2 or external divider; enables true remote sensing and load regulation for Channel 2 |
| VPROG2 | Channel 2 output voltage select | Open = adjustable mode (via VOSENSE2); 0V = 3.3V; INTVCC = 5V - full flexibility for Channel 2 output programming |
| TGL1 / BG1 | High-side / low-side gate drivers (Channel 1) | TGL1 drives large top N-MOSFET; BG1 drives bottom N-MOSFET - both active in Adaptive Power high-current mode |
| TGS1 | Small top MOSFET gate driver (Channel 1) | Drives auxiliary small N-MOSFET + Schottky diode in low-current Adaptive Power mode; open = Burst Mode fallback |
| VIN | Main input supply | 3.5V–36V range powers internal circuitry and switch nodes; requires ≥22µF/35V local ceramic+electrolytic decoupling |
| INTVCC/5V | Internal 5V LDO output | Supplies gate drivers and logic; remains active in shutdown; requires ≥2.2µF tantalum to PGND |
| PGND | Power ground return | Connects to sources of bottom MOSFETs and (–) terminals of CIN/COUT - must tie to power plane, not SGND |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Power™ mode | Maintains fixed-frequency operation down to ~1% rated load by switching between large- and small-MOSFET drive paths - avoids audible noise and EMI spikes from Burst Mode |
| Dual independent control loops | Channel 1 supports only 3.3V/5V outputs with no remote sense; Channel 2 supports 1.19V–9V with VOSENSE2 remote sensing and VPROG2 programmability |
| Always-on 5V standby regulator | Delivers 5V/20mA from INTVCC pin even when both controllers are shut down - enables microcontroller wake-up circuitry without external LDO |
| Programmable soft-start & shutdown | RUN/SS1 and RUN/SS2 pins provide independent channel enable/disable with capacitor-programmable ramp time and <200µA shutdown IQ |
| Secondary feedback support (SFB1) | SFB1 pin forces continuous operation on Channel 1 when pulled below 1.19V - ensures regulation stability in flyback-derived auxiliary supplies |
| Integrated protection suite | Includes overvoltage lockout (1.24–1.32V), power-on reset (65536-cycle timer), low-battery detection (LBI/LBO), and dropout recovery circuitry |
Applications
| Portable Medical Instrumentation | Industrial Handheld Terminals |
|---|---|
|
Use Scenario: Battery-powered ultrasound probe with dual rail requirements (5V analog front-end, 3.3V digital core). IC Role / Device Role / Timing Role: LTC1538CG-AUX#TRPBF provides tightly regulated, low-noise 5V and 3.3V outputs from single Li-ion cell stack (8.4V–12.6V), with Adaptive Power sustaining efficiency during intermittent signal acquisition. Use Value: Eliminates need for discrete LDOs while maintaining <0.8% load regulation and <200µA shutdown current - extending battery life beyond 8 hours per charge. |
Use Scenario: Ruggedized warehouse scanner requiring stable 3.3V logic and 5V imager supply across wide temperature (-20°C to 70°C) and input (9V–30V) ranges. IC Role / Device Role / Timing Role: LTC1538CG-AUX#TRPBF serves as primary DC-DC controller, leveraging SFB1 for secondary-winding feedback to maintain 3.3V regulation despite varying imager load transients. Use Value: Achieves 94% peak efficiency at 2A load and maintains <1.2% line regulation across 9V–30V input - reducing thermal stress in sealed enclosure. |
| Test & Measurement Data Loggers | Avionics Cabin Control Units |
|
Use Scenario: Low-power environmental sensor node logging data every 10 seconds, spending >99% time in deep sleep with periodic 5V/3.3V wake-up bursts. IC Role / Device Role / Timing Role: LTC1538CG-AUX#TRPBF delivers precise 5V and 3.3V rails with <200µA quiescent current in shutdown, enabling 5-year battery life on AA cells. Use Value: Adaptive Power mode sustains 125kHz switching down to 35mA load - avoiding Burst Mode EMI that would corrupt sensitive ADC measurements. |
Use Scenario: Aircraft cabin lighting controller requiring fault-tolerant 5V/3.3V supplies compliant with DO-160 lightning-induced transient standards. IC Role / Device Role / Timing Role: LTC1538CG-AUX#TRPBF operates as dual-output controller with foldback current limiting and overvoltage lockout, interfacing to external MOSFETs rated for 60V transients. Use Value: Integrated POR timer (300ms delay) ensures clean power sequencing after engine start-up transients, preventing microcontroller latch-up. |
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 |
|---|---|---|---|
| LTC1539CGW | 36-lead SSOP; adds PLLIN/PLL LPF pins for external clock synchronization; includes POR1, LBI, LBO, and PLL circuitry absent in LTC1538CG-AUX#TRPBF | Required where system-level clock domain alignment or deterministic phase relationship between multiple converters is needed | Select LTC1539CGW only if PLL synchronization is mandatory; otherwise LTC1538CG-AUX#TRPBF offers lower cost and smaller footprint |
| TPS54290RGTT | Single-channel 2A synchronous buck controller (not dual); integrates MOSFET drivers but lacks auxiliary linear regulator, SFB1, and standalone 5V standby rail | Suitable for space-constrained designs needing only one regulated output and no auxiliary 12V/5V generation | Use TPS54290RGTT when dual-channel operation and auxiliary regulator functionality are unnecessary - reduces BOM count but sacrifices integration |
Compared with LTC1539CGW, the LTC1538CG-AUX#TRPBF trades PLL synchronization capability for smaller 28-pin SSOP packaging and lower system cost, while retaining identical dual-channel control architecture and Adaptive Power efficiency benefits; versus TPS54290RGTT, it provides true dual independent outputs plus always-on 5V standby - essential for systems requiring coordinated power sequencing and ultra-low-quiescent backup rails.
Availability
LTC1538CG-AUX#TRPBF is available at Aetrix Electronics and suitable for portable medical instrumentation, industrial handheld terminals, and test & measurement data loggers requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance across temperature.
Supply support for LTC1538CG-AUX#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 precision instrumentation, industrial automation, and aerospace markets.
The LTC1538-AUX product line was designed specifically for dual-rail, battery-efficient power conversion in portable computing and instrumentation - emphasizing adaptive low-load efficiency, integrated standby regulation, and robust protection without external complexity.
FAQ
What output voltages does the LTC1538CG-AUX#TRPBF support on each channel?
The LTC1538CG-AUX#TRPBF supports fixed 3.3V or 5V on Channel 1 (selected via VPROG1 pin), and adjustable 1.19V–9V on Channel 2 (selected via VPROG2 pin and VOSENSE2 feedback). Channel 1 cannot operate in adjustable mode per datasheet Table 1, and its SENSE–1 pin is internally tied to prevent true remote sensing - unlike Channel 2 which fully supports remote sense via VOSENSE2.
Does the LTC1538CG-AUX#TRPBF support external clock synchronization?
No, the LTC1538CG-AUX#TRPBF does not support external clock synchronization. It lacks PLLIN and PLL LPF pins - features present only on the pin-compatible LTC1539 variant. The LTC1538CG-AUX#TRPBF operates exclusively in fixed-frequency mode set by the COSC capacitor, with typical oscillator frequency of 125kHz (range 112–138kHz).
How does the Adaptive Power™ mode function in the LTC1538CG-AUX#TRPBF?
Adaptive Power™ mode in the LTC1538CG-AUX#TRPBF automatically switches gate drive from large-MOSFET outputs (TGLx/BGx) to small-MOSFET outputs (TGSx) as load decreases, sustaining fixed-frequency operation down to ~1% of rated current. This avoids efficiency collapse and EMI from Burst Mode. If TGSx pins are left open, the device defaults to Burst Mode instead.
What is the purpose of the SFB1 pin on the LTC1538CG-AUX#TRPBF?
The SFB1 pin on the LTC1538CG-AUX#TRPBF provides secondary winding feedback for Channel 1. Pulling SFB1 below 1.19V forces continuous synchronous operation - critical for maintaining regulation in flyback-derived auxiliary supplies where main output loading may cause instability. When unused, SFB1 should be tied to INTVCC.
Can the LTC1538CG-AUX#TRPBF operate with only one channel enabled?
Yes, the LTC1538CG-AUX#TRPBF supports independent channel control: pulling RUN/SS1 low disables only Channel 1 while Channel 2 remains active, and vice versa. Both channels can be disabled simultaneously to enter ultra-low-IQ shutdown (<200µA), leaving only the 5V INTVCC standby regulator, 1.19V reference, and uncommitted comparator operational.
LTC1538CG-AUX#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:
- 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
LTC1538CG-AUX#TRPBF FAQ
1.How can I place an order for LTC1538CG-AUX#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1538CG-AUX#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 LTC1538CG-AUX#TRPBF reliable?
The price and inventory of LTC1538CG-AUX#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1538CG-AUX#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1538CG-AUX#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1538CG-AUX#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1538CG-AUX#TRPBF?
LTC1538CG-AUX#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1538CG-AUX#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 LTC1538CG-AUX#TRPBF?
For technical support, including LTC1538CG-AUX#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1538CG-AUX#TRPBF requirements.
6.How does Aetrix verify that LTC1538CG-AUX#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1538CG-AUX#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 LTC1538CG-AUX#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1538CG-AUX#TRPBF?
All LTC1538CG-AUX#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1538CG-AUX#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 LTC1538CG-AUX#TRPBF part is unused and in its original packaging.
Return procedure for LTC1538CG-AUX#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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