My Inquiry
My Account
Analog Devices Inc. LTC1538CG-AUX#PBF
- Part No.:
- LTC1538CG-AUX#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1538CG-AUX#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,349
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC1538CG-AUX#PBF 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 5V/3.3V outputs up to 3.5A each, supports 3.5V–36V input, features adaptive power mode for ultrahigh efficiency down to 1% load, and integrates a 5V/20mA standby regulator active during shutdown. Used in notebook DC-DC power rails requiring high efficiency and low-noise auxiliary supplies.
For engineers reviewing the LTC1538CG-AUX#PBF datasheet, LTC1538CG-AUX#PBF pinout, LTC1538CG-AUX#PBF application, or LTC1538CG-AUX#PBF equivalent, key selection criteria include dual-channel programmable output voltage (3.3V/5V/adjustable), 28-pin SSOP package with remote sense on Channel 2, adaptive power vs. burst mode trade-offs, and compatibility with external PNP-based 12V auxiliary linear regulation.
Technical Context
The LTC1538CG-AUX#PBF implements two independent current-mode control loops with programmable ITH pins, fixed-frequency oscillator (112–138 kHz) set by COSC, and dropout detection enabling 99% duty cycle operation. Its Adaptive Power™ architecture dynamically selects between large (TGL/BG) and small (TGS) top-side MOSFET drivers based on load current to maintain constant frequency down to ~35mA per channel.
It integrates an always-on 5V/20mA INTVCC regulator, internal 1.19V reference, uncommitted comparator, and power-on reset timer (65536 cycles). Unlike the LTC1539, it lacks PLLIN, PLL LPF, POR1, LBI/LBO, and SFB1 functionality - confirmed by package pinout and functional diagram exclusions marked "NOT AVAILABLE ON LTC1538-AUX".
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 36V - supports wide industrial and battery-input systems without external pre-regulation. |
| Output Voltage Options | Channel 1: 3.3V or 5V only (VPROG1-controlled); Channel 2: 1.19V–9V adjustable via VOSENSE2 and VPROG2 - enables flexible dual-rail design. |
| Max Output Current | 3.5A per channel - determined by external MOSFETs and RSENSE; peak current limit threshold is 150mV across sense resistor. |
| Switching Frequency | 112–138 kHz (typ 125 kHz) - set by COSC capacitor; fixed-frequency operation simplifies EMI filtering. |
| Standby Quiescent Current | <200µA (shutdown mode) - enables ultra-low-power retention of 5V standby rail during system sleep. |
| Package | 28-lead plastic SSOP (G package) - surface-mount, thermally enhanced layout with separate PGND/SGND pins. |
| Operating Temperature | 0°C to +70°C - commercial-grade rating suitable for notebooks, portable instruments, and embedded industrial controls. |
Pinout & Package
Package: 28-lead plastic SSOP (G package), 0.025" pitch, exposed pad not specified. Thermal resistance θJA = 95°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| BOOST 1 | Top-side driver supply for Channel 1 | Connects to bootstrap capacitor for high-side N-MOSFET gate drive; swings from INTVCC to VIN + INTVCC. |
| RUN/SS1 | Channel 1 enable & soft-start control | Pulling below 1.3V disables Channel 1; capacitor to ground sets ramp time (~0.5s/µF) for controlled startup. |
| SENSE+ 1 / SENSE– 1 | Current sense inputs (Channel 1) | Differential pair measuring voltage across RSENSE1; built-in offset sets trip threshold at 150mV max. |
| VPROG1 | Channel 1 output voltage select | Open = 5V; 0V = 3.3V - configures internal attenuator; no adjustable mode on Channel 1. |
| ITH1 | Error amplifier compensation node | Controls peak inductor current; voltage increases with load to maintain regulation; used for loop compensation. |
| COSC | Oscillator timing input | External capacitor to ground sets switching frequency (125 kHz typ with 56pF). |
| SGND | Small-signal reference ground | Must be routed separately from PGND to avoid noise coupling into feedback and sense paths. |
| SFB1 | Secondary winding feedback input | Forces continuous operation on Channel 1 when pulled below 1.19V; tied to INTVCC if unused. |
| ITH2 | Error amplifier compensation node (Ch2) | Same function as ITH1 but for Channel 2; supports remote sensing via VOSENSE2. |
| VOSENSE2 | Remote output voltage sense (Ch2) | Connects directly to output or external divider; enables true remote sensing for Channel 2 only. |
| SENSE– 2 / SENSE+ 2 | Current sense inputs (Channel 2) | Same function as Ch1 sense pins; supports full adjustable output range on Channel 2. |
| RUN/SS2 | Channel 2 enable & soft-start control | Independent control of Channel 2; both RUN/SS pins low disables main controllers but retains 5V standby. |
| TGL1 / TGL2 | High-current top-gate drivers | Drive large external N-MOSFETs; active in Adaptive Power mode at medium-to-high loads. |
| SW1 / SW2 | Switch node connections | Connect to inductor high-side terminals; swing from Schottky diode drop below GND to VIN. |
| VIN | Main input supply | 3.5V–36V input; must be decoupled near PGND with ≥22µF ceramic + bulk capacitance. |
| BG1 / BG2 | Bottom-gate drivers | Drive synchronous N-MOSFETs; voltage swing from 0V to INTVCC (5V). |
| INTVCC/5V | Internal 5V regulator output | Supplies all internal circuitry and gate drivers; remains active in shutdown; requires ≥2.2µF tantalum to PGND. |
| PGND | Power ground | Return path for bottom MOSFET sources and CIN negative terminal; separate from SGND. |
| BG2 / EXTVCC | External VCC switch input | When >4.8V, bypasses internal LDO to power INTVCC directly - improves efficiency in high-current designs. |
| SW2 / TGL2 | Switch node & top-gate driver (Ch2) | Same as SW1/TGL1 but for second channel; independent control and layout required. |
| BOOST 2 | Top-side driver supply (Ch2) | Same function as BOOST 1; dedicated bootstrap supply for Channel 2 high-side driver. |
| AUXON / AUXFB / AUXDR | Auxiliary regulator control | AUXON enables 0.5A PNP-based linear regulator; AUXFB/AUXDR support 12V VPP or comparator use. |
| TGS1 / TGS2 | Small top-gate drivers | Drive smaller N-MOSFETs in Adaptive Power mode at light loads; open = Burst Mode fallback. |
Key Features
| Feature | Design Value |
|---|---|
| Dual synchronous buck controllers | Enables compact, high-efficiency dual-rail DC-DC conversion without external PWM ICs or discrete logic. |
| Adaptive Power™ mode | Maintains fixed-frequency operation down to ~1% rated load (vs. ~10% in Burst Mode), reducing audible noise and EMI variability. |
| Programmable output voltages | Channel 1 fixed at 3.3V/5V; Channel 2 adjustable 1.19V–9V with remote sensing - supports mixed-voltage SoC power domains. |
| Always-on 5V/20mA standby regulator | Provides low-quiescent backup power during full system shutdown - essential for RTC, wake-on-LAN, and fast boot circuits. |
| Integrated power-on reset timer | Generates 300ms (typ) delay after first output reaches regulation - ensures reliable microcontroller initialization without external RC networks. |
| Low-battery detection & foldback limiting | Configurable via external resistors; LBO/LBI pins omitted on LTC1538-AUX, but current-limiting remains active via ITH clamping. |
Applications
| Portable Computing Power | Industrial DC Distribution |
|---|---|
Use Scenario: Dual-rail power for CPU core (3.3V) and I/O (5V) in notebook motherboards with battery input (7–24V). IC Role / Device Role / Timing Role: Primary synchronous buck controller pair managing high-current, low-noise conversion with adaptive load optimization. Use Value: Achieves >90% efficiency at 1A–3.5A loads while maintaining stable 5V/3.3V rails under dynamic CPU load transitions. | Use Scenario: Centralized 5V/3.3V generation for PLC I/O modules powered from 24V industrial bus. IC Role / Device Role / Timing Role: Dual-channel DC-DC controller enabling single-board multi-voltage distribution with thermal separation. Use Value: Eliminates need for multiple isolated DC-DC bricks; 28-pin SSOP footprint allows dense, cost-effective PCB layout. |
| Low-Noise Audio Supply | Battery-Operated Test Equipment |
Use Scenario: Clean 5V analog supply for audio DACs and op-amps in portable audio recorders using Li-ion battery (3.0–4.2V). IC Role / Device Role / Timing Role: High-efficiency buck controller operating in Adaptive Power mode to suppress switching noise in sensitive analog sections. Use Value: Delivers ultralow ripple (<10mVpp) and <200µA shutdown IQ - preserves battery life and prevents audible artifacts. | Use Scenario: Dual-output power for microcontroller (3.3V) and sensor interface (5V) in handheld multimeters with alkaline battery input (4×AA = 6V). IC Role / Device Role / Timing Role: Main power management IC providing regulated rails with programmable soft-start to prevent inrush-induced brownouts. Use Value: Soft-start capacitor on RUN/SS pins ensures controlled ramp-up; 3.5V min VIN supports operation until battery depletion. |
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#PBF | 36-pin SSOP; adds PLL synchronization, POR1, LBI/LBO, SFB1, and full feature set - includes all LTC1538-AUX functions plus extras. | Required where phase-locking to system clock or low-battery monitoring is needed; larger footprint and higher BOM cost. | Select LTC1539CGW#PBF only if PLL sync, power-good signaling, or secondary feedback is mandatory - otherwise LTC1538CG-AUX#PBF offers lower cost and smaller size. |
| TPS54290RGTR | Single-channel, integrated FET; 4.5–20V input; 0.76–14V output; no auxiliary linear regulator or standby rail. | Not a functional replacement - lacks dual-channel capability, 5V standby, and PNP auxiliary control; requires two devices for dual-rail. | Use TPS54290RGTR only for single-rail designs where integration and footprint are prioritized over dual control and auxiliary features. |
Compared with LTC1539CGW#PBF, LTC1538CG-AUX#PBF sacrifices PLL sync and monitoring features for reduced pin count and cost, while retaining identical dual-buck control, Adaptive Power mode, and 5V standby functionality. Compared with TPS54290RGTR, it provides true dual-channel coordination and auxiliary regulation - critical for space-constrained multi-rail systems.
Availability
LTC1538CG-AUX#PBF is available at Aetrix Electronics and suitable for notebook computing power, portable instrumentation, and battery-operated medical devices requiring stable component supply with long-term industrial availability.
Supply support for LTC1538CG-AUX#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 notes for legacy Linear parts including the LTC series.
The LTC1538-AUX belongs to Linear's high-efficiency DC-DC controller family designed for portable and battery-powered systems requiring dual regulated outputs, adaptive light-load efficiency, and integrated auxiliary regulation.
FAQ
What is the maximum supported input voltage for the LTC1538CG-AUX#PBF?
The LTC1538CG-AUX#PBF supports an absolute maximum input voltage of 36V on the VIN pin. Continuous operation is rated from 3.5V to 30V, with transient tolerance up to 36V for ≤100ms. Exceeding 36V risks permanent damage to internal circuitry and gate drivers.
Can the LTC1538CG-AUX#PBF generate adjustable output voltages on both channels?
No. The LTC1538CG-AUX#PBF supports fixed 3.3V or 5V output on Channel 1 (selected via VPROG1), while Channel 2 supports fully adjustable output from 1.19V to 9V using VOSENSE2 and external resistive dividers. This asymmetry is inherent to the LTC1538-AUX variant and confirmed in Table 1 of the datasheet.
Does the LTC1538CG-AUX#PBF include a phase-locked loop (PLL) for frequency synchronization?
No. The LTC1538CG-AUX#PBF does not include PLLIN or PLL LPF pins - these are exclusive to the LTC1539. The LTC1538CG-AUX#PBF uses a standalone fixed-frequency oscillator set by the COSC capacitor, with no provision for external clock synchronization.
How does the Adaptive Power™ mode improve light-load efficiency in the LTC1538CG-AUX#PBF?
The Adaptive Power™ mode in the LTC1538CG-AUX#PBF reduces switching losses at light loads by automatically routing gate drive to smaller top-side MOSFETs (via TGS1/TGS2) instead of the main drivers (TGL1/TGL2). This maintains constant-frequency operation down to ~1% of full load (~35mA), avoiding the variable-frequency noise and EMI of Burst Mode.
Is remote output voltage sensing supported on both channels of the LTC1538CG-AUX#PBF?
Remote sensing is supported only on Channel 2 via the VOSENSE2 pin. Channel 1's SENSE–1 is internally connected to its output node, preventing true remote sensing - this limitation is explicitly stated in the PIN FUNCTIONS section and Table 1 of the datasheet.
LTC1538CG-AUX#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
LTC1538CG-AUX#PBF FAQ
1.How can I place an order for LTC1538CG-AUX#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1538CG-AUX#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 LTC1538CG-AUX#PBF reliable?
The price and inventory of LTC1538CG-AUX#PBF 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#PBF is usually 5 days.
3.What payment methods are accepted for LTC1538CG-AUX#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1538CG-AUX#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1538CG-AUX#PBF?
LTC1538CG-AUX#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1538CG-AUX#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 LTC1538CG-AUX#PBF?
For technical support, including LTC1538CG-AUX#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1538CG-AUX#PBF requirements.
6.How does Aetrix verify that LTC1538CG-AUX#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1538CG-AUX#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 LTC1538CG-AUX#PBF meets industry standards.
7.What is the process for return or replacement of LTC1538CG-AUX#PBF?
All LTC1538CG-AUX#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1538CG-AUX#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 LTC1538CG-AUX#PBF part is unused and in its original packaging.
Return procedure for LTC1538CG-AUX#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC1538CG-AUX#PBF Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
