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Analog Devices Inc. LTC1437AIG#PBF
- Part No.:
- LTC1437AIG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1437AIG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,820
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Product details
Overview
LTC1437AIG#PBF from Analog Devices (formerly Linear Technology) is a phase-lockable, fixed-frequency synchronous step-down switching regulator controller driving external N-channel MOSFETs. It operates from 3.5V to 36V input, delivers up to 5A output via adaptive dual-MOSFET drive, supports pin-selectable 1.19V–9V outputs, and integrates a 0.5A low-noise linear regulator for CPU I/O or audio rails.
For engineers reviewing the LTC1437AIG#PBF datasheet, LTC1437AIG#PBF pinout, LTC1437AIG#PBF application, or LTC1437AIG#PBF equivalent, key selection criteria include its PLL-synchronizable 112–240kHz oscillator, ≤300ns minimum on-time for high-frequency/low-duty-cycle designs, remote voltage sensing capability, and dual-mode low-load operation (Adaptive Power™ or Burst Mode®).
Technical Context
The LTC1437AIG#PBF implements a constant-frequency current-mode control architecture with an error amplifier (ITH pin), programmable soft-start (RUN/SS), and built-in dropout detection that forces periodic top-FET off-time to recharge the bootstrap capacitor during low-VIN operation. Its Adaptive Power™ stage selectively drives large (TGL/BG) or small (TGS) external N-MOSFETs based on load current, maintaining fixed-frequency operation down to ~1% of full load.
It features a secondary feedback input (SFB) enabling regulation independent of main output loading, a dedicated auxiliary regulator/comparator block (AUXON/AUXDR/AUXFB) supporting 12V PNP-based linear supplies or low-battery detection, and a phase-locked loop (PLLIN/PLL LPF) allowing synchronization to external clocks with ±30% frequency tuning range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 36V - supports wide industrial and battery-powered systems including 24V DC distribution and automotive cold-crank conditions. |
| Switching Frequency | 112–240kHz (PLL-synchronizable) - enables EMI-controlled layout and predictable thermal behavior across load conditions. |
| Min On-Time | ≤300ns - allows stable 5V→1.2V conversion at 400kHz, critical for high-step-down ratio, high-frequency power supplies. |
| Output Voltage Range | 1.19V to 9V (pin-selectable or resistor-programmable) - supports core logic, I/O, and analog rail generation without external DAC or reference. |
| Shutdown Current | <25µA - enables ultra-low-power standby in portable devices with logic-controlled enable (RUN/SS). |
| Current Sense Threshold | 130–180mV - sets peak inductor current limit; combined with RSENSE, determines maximum output current and ripple control. |
| INTVCC Regulator | 5.0V ±2%, 50mA - powers internal logic and gate drivers; switchover to EXTVCC ≥4.7V improves efficiency by bypassing internal LDO. |
Pinout & Package
Package: 28-Lead Plastic SSOP (G Package), 150-mil width, θJA = 110°C/W. RoHS-compliant, lead-free (Pb-free) finish per #PBF suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply connection | Accepts 3.5V–36V; requires local decoupling to PGND to minimize noise coupling into control circuitry. |
| SW | Switch node | Connects to inductor and external high-side MOSFET source; swings from near ground to VIN + INTVCC. |
| TGL / BG / TGS | Gate drivers | TGL drives large top N-MOSFET; BG drives bottom N-MOSFET; TGS drives small top N-MOSFET for Adaptive Power™ mode. |
| SENSE+ / SENSE– | Current sense differential inputs | Measure voltage across RSENSE; built-in offset enables accurate peak-current limiting without external amplification. |
| VOSENSE / VPROG | Feedback and output voltage selection | VOSENSE receives remote output voltage; VPROG selects 1.19V (open), 3.3V (0V), or 5V (INTVCC) output configuration. |
| PLLIN / PLL LPF | Phase-locked loop interface | PLLIN accepts external sync clock; PLL LPF sets oscillator frequency (0–2.4V = ±30% fOSC) and serves as phase detector output. |
| AUXON / AUXDR / AUXFB | Auxiliary regulator control | AUXON enables 0.5A PNP-based linear regulator; AUXDR sinks base current; AUXFB senses 12V (internal divider) or custom voltage. |
| RUN/SS | Enable and soft-start control | Pull low to shut down; capacitor to ground sets ramp time (~0.5s/µF); clamps ITH during startup to prevent overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Power™ Architecture | Automatically switches between large (TGL/BG) and small (TGS) top-FET drive to maintain fixed-frequency operation down to ~1% load - eliminates audible noise and improves light-load efficiency vs Burst Mode®. |
| Programmable Fixed-Frequency PLL | Enables precise EMI management and multi-rail synchronization; frequency tunable ±30% via PLL LPF voltage without changing COSC capacitor. |
| Dual-Regulator Integration | Combines synchronous buck controller (5A capable) with 0.5A low-noise linear regulator - reduces BOM count and PCB area for mixed-signal systems requiring clean auxiliary rails. |
| Remote Output Sensing | VOSENSE pin accepts feedback directly from load point, compensating for IR drop in PCB traces - ensures tight regulation at FPGA/CPU VDD pins. |
| Low-Dropout Operation | Supports 99% duty cycle and dropout detection with forced off-time - maintains regulation during deep input undervoltage (e.g., 5V input → 4.95V output). |
Applications
| Portable Computing Power | Battery-Powered Instrumentation |
|---|---|
Use Scenario: Notebook motherboard supplying CPU core (1.2V/3A) and I/O (3.3V/1A) from single-cell Li-ion (3.0–4.2V) or 12V adapter input. IC Role / Device Role / Timing Role: Primary buck controller managing high-efficiency DC/DC conversion; auxiliary LDO provides low-noise 3.3V for USB PHY and PCIe reference clocks. Use Value: Adaptive Power™ avoids Burst Mode® noise during light-load sleep states; remote sensing maintains ±1% regulation at SoC package ball. | Use Scenario: Handheld multimeter with 24-bit ADC, microcontroller, and LCD backlight powered from two AA cells (1.8–3.2V). IC Role / Device Role / Timing Role: Step-down controller generating stable 3.3V system rail; auxiliary regulator supplies clean 12V for op-amp front-end and LCD bias. Use Value: 300ns min-on-time enables 3.2V→3.3V boostless operation; low shutdown IQ (<25µA) extends battery life beyond 100 hours. |
| Industrial DC Distribution | Wireless Modem Power Management |
Use Scenario: DIN-rail mounted 24V-to-5V/3.3V converter powering PLC I/O modules and fieldbus transceivers. IC Role / Device Role / Timing Role: Main controller for isolated or non-isolated 24V bus conversion; SFB pin used for secondary winding feedback in flyback-derived auxiliary supplies. Use Value: Wide 3.5–36V input handles brownouts and surges; PLL synchronization aligns switching edges with communication timing to reduce conducted EMI. | Use Scenario: LTE Cat-M1 module requiring 1.8V RF core, 3.3V digital, and 5V PA bias from 3.6–4.2V Li-Po battery. IC Role / Device Role / Timing Role: Multi-rail controller delivering three regulated outputs; low-battery comparator (LBI/LBO) triggers graceful shutdown before cell depletion. Use Value: Pin-selectable outputs eliminate external resistors; integrated POR ensures reliable boot after cold reset; foldback current limiting protects against antenna mismatch faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1436AIGN#PBF | 24-lead SSOP package; no PLLIN/PLL LPF pins; fixed 112–138kHz oscillator (no synchronization capability) | Suitable for cost-sensitive, single-rail designs where EMI control via frequency tuning is unnecessary | Select when board space is constrained and PLL functionality is unused - same control loop, reduced pin count. |
| MP2451DT-LF-Z | Integrated power MOSFETs (no external FETs); 2A max output; fixed 500kHz frequency; no auxiliary LDO or PLL | Targeted at compact, lower-current applications where integration outweighs flexibility and multi-rail support | Choose for simplified design with fewer external components - but cannot replace LTC1437AIG#PBF in >2A or auxiliary-regulator-dependent systems. |
Compared with LTC1436AIGN#PBF, LTC1437AIG#PBF adds PLL synchronization and SFB regulation for multi-output systems; versus MP2451DT-LF-Z, it offers higher current capability, external FET control for thermal optimization, and integrated auxiliary LDO - making it suitable for complex, high-reliability power architectures.
Availability
LTC1437AIG#PBF is available at Aetrix Electronics and suitable for notebook computing power, battery-powered instrumentation, industrial DC distribution, and wireless modem power management requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1437AIG#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC1437AIG#PBF belongs to Linear's legacy high-efficiency DC/DC controller family, designed specifically for demanding portable and industrial applications requiring precision regulation, low-noise auxiliary supplies, and robust transient response under wide input and load variations.
FAQ
What is the operating temperature range for the LTC1437AIG#PBF?
The LTC1437AIG#PBF is specified for –40°C to 85°C ambient operation (I-grade). This is confirmed in the Absolute Maximum Ratings table and Electrical Characteristics notes, where parameters marked with ● apply across this full range. The 28-lead SSOP package has θJA = 110°C/W, enabling reliable thermal performance in enclosed industrial enclosures without forced air.
Does the LTC1437AIG#PBF require external MOSFETs, and what type are supported?
Yes, the LTC1437AIG#PBF is a controller-only IC and requires external N-channel MOSFETs. It drives dual N-MOSFETs synchronously: large devices via TGL (top) and BG (bottom), and a smaller device via TGS for Adaptive Power™ mode. The datasheet explicitly references Si4412DY and IRLML2803 as validated devices, confirming compatibility with logic-level and standard-threshold N-channel FETs rated for ≥36V drain-source voltage.
How does the auxiliary regulator in the LTC1437AIG#PBF function, and what output voltages can it generate?
The auxiliary regulator in the LTC1437AIG#PBF controls an external PNP pass transistor to deliver up to 0.5A. When AUXDR exceeds 9.5V, it auto-selects an internal 12V resistive divider at AUXFB; below 8.5V, an external divider sets custom voltages (e.g., 5V or 3.3V). The LTC1437AIG#PBF's AUXON pin enables/disables this block with logic-level control, and the block can alternatively operate as a low-battery comparator using the same 1.19V reference.
Can the LTC1437AIG#PBF be synchronized to an external clock, and how is this configured?
Yes, the LTC1437AIG#PBF supports external clock synchronization via its PLLIN and PLL LPF pins. Applying a square wave to PLLIN locks the internal oscillator to the external frequency; the PLL LPF pin then serves as both phase detector output and oscillator control voltage (0–2.4V = ±30% fOSC). This capability is exclusive to the LTC1437AIG#PBF and LTC1436A-PLL variants - standard LTC1436A parts lack these pins and cannot be synchronized.
What is the purpose of the SFB (Secondary Feedback) pin on the LTC1437AIG#PBF?
The SFB pin on the LTC1437AIG#PBF enables regulation of a secondary winding in transformer-coupled topologies (e.g., flyback or forward converters). When SFB is tied to a resistive divider from the secondary, it forces continuous conduction mode regardless of main output loading - ensuring stable auxiliary rail regulation even under light or no load on the primary output. If unused, SFB must be tied to INTVCC or ground per the Pin Functions section.
LTC1437AIG#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:
- 1
- 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
LTC1437AIG#PBF FAQ
1.How can I place an order for LTC1437AIG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1437AIG#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 LTC1437AIG#PBF reliable?
The price and inventory of LTC1437AIG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1437AIG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1437AIG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1437AIG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1437AIG#PBF?
LTC1437AIG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1437AIG#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 LTC1437AIG#PBF?
For technical support, including LTC1437AIG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1437AIG#PBF requirements.
6.How does Aetrix verify that LTC1437AIG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1437AIG#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 LTC1437AIG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1437AIG#PBF?
All LTC1437AIG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1437AIG#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 LTC1437AIG#PBF part is unused and in its original packaging.
Return procedure for LTC1437AIG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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