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Analog Devices Inc. LT3694EFE-1#TRPBF
- Part No.:
- LT3694EFE-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3694EFE-1#TRPBF.pdf
- Description:
- IC REG TRIPLE BUCK/LNR 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,490
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Product details
Overview
LT3694EFE-1#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 36V, 2.6A step-down DC/DC converter with dual LDO linear regulator controllers in a 20-lead TSSOP package. It delivers three regulated outputs (buck + two LDOs), supports 4V–36V input, features adjustable 250kHz–2.5MHz switching frequency, and includes PGOOD, TRK/SS, and CLKOUT for power sequencing and synchronization in industrial power systems.
For engineers reviewing the LT3694EFE-1#TRPBF datasheet, LT3694EFE-1#TRPBF pinout, LT3694EFE-1#TRPBF application, or LT3694EFE-1#TRPBF equivalent, key selection criteria include its triple-output architecture, CLKOUT-enabled multi-regulator synchronization, -40°C to 125°C operating junction temperature, 0.75V feedback reference, and thermal shutdown with overvoltage protection up to 70V transients.
Technical Context
The LT3694EFE-1#TRPBF integrates a constant-frequency current-mode buck regulator with internal 2.6A bipolar switch and two independent LDO controllers driving external NPN pass transistors. Its VC1 error amplifier output controls peak switch current with 0.75V threshold and 2V clamp, while DA pin senses catch diode current for overload protection.
It uses a master oscillator set by RT resistor or external clock (not applicable - this is LT3694-1 variant with CLKOUT, not SYNC), provides independent TRK/SS inputs per regulator for ratiometric start-up or soft-start, and derives bias current from BIAS pin (≥3V) to reduce dissipation. Overvoltage shutdown activates at 38V, surviving 70V non-repetitive transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 36V continuous; survives 70V non-repetitive transients - enables use with lead-acid batteries, wall adapters, and unregulated 24V/36V rails. |
| Switching Regulator Output | Up to 2.6A at adjustable VOUT ≥0.75V - supports high-current digital loads like FPGAs or processors. |
| LDO Controllers | Dual independent controllers with programmable current limit - drives external NPN transistors for low-noise, post-regulated outputs. |
| Switching Frequency | 250kHz to 2.5MHz via RT resistor - allows optimization of size (high fSW → small L/C) vs. efficiency (low fSW → lower losses). |
| Feedback Reference | 0.75V ±15mV over temperature - ensures accurate output regulation across -40°C to 125°C. |
| CLKOUT Pin | Logic-level clock output (1.6V–2.6V VOH, 0.3V VOL) - synchronizes other switching regulators without external timing ICs. |
| Thermal Protection | Thermal shutdown with automatic recovery - prevents permanent damage during sustained overload or poor PCB heatsinking. |
Pinout & Package
LT3694EFE-1#TRPBF is housed in a thermally enhanced 20-lead plastic TSSOP package (4.4mm × 6.5mm) with exposed pad (Pin 21) soldered to PCB ground for thermal and electrical integrity (θJA = 38°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Main input power supply | Supplies internal switch, reference, and startup circuitry; must be locally bypassed with ceramic capacitor. |
| EN/UVLO (Pin 2) | Enable and undervoltage lockout input | Shuts down device below 0.5V (typ); enables at >1.2V (typ); supports resistor-divider UVLO configuration. |
| CLKOUT (Pin 3) | Digital clock output | Provides synchronized clock signal (fSW) to other DC/DC converters; exclusive to LT3694-1 variants. |
| PGOOD (Pin 4) | Open-collector power-good indicator | Pulls low when any FB pin voltage drops below 90% of nominal - signals fault across all three outputs. |
| RT (Pin 4) | Frequency-setting resistor connection | Resistor to GND sets switching frequency (250kHz–2.5MHz); 40.2kΩ yields ~1MHz typical. |
| TRK/SS1–3 (Pins 5,6,17) | Tracking/soft-start inputs | Override 0.75V reference when <0.75V - enables controlled ramp-up and supply sequencing with microcontrollers. |
| FB1–3 (Pins 18,7,16) | Feedback inputs for buck and LDOs | Each regulates to min(0.75V, TRK/SSx voltage); connects to resistor divider taps for output programming. |
| DRV2/DRV3 (Pins 8,15) | LDO base drive outputs | Provide up to 6V base drive for external NPN pass transistors - determines LDO current capability and dropout. |
| LIM2/LIM3 (Pins 9,14) | LDO current limit sense inputs | Monitor voltage across external sense resistors tied to BIAS - enable foldback current limiting for transistor protection. |
| BIAS (Pin 20) | Bias supply input | Must be ≥3V (typically connected to VOUT1); supplies internal regulator and LDO base current if ≥1.8V above LDO output. |
| BST (Pin 21) | Bootstrap supply for switch driver | Capacitor between BST and SW generates >VIN voltage to saturate internal bipolar switch - critical for low VCESAT. |
| DA (Pin 22) | Diode current sense input | Detects catch diode conduction to prevent excessive inductor current during overload or short-circuit events. |
| SW (Pins 23,24) | Switch node output | Connects to inductor and Schottky catch diode; carries high di/dt pulsed current - requires tight layout and ground plane. |
| GND (Pin 21 Exposed Pad) | Power and signal ground | Exposed thermal pad must be soldered to large PCB ground plane - essential for thermal performance and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output power management | Single IC delivers one high-current buck (2.6A) plus two independently programmable LDOs - reduces component count and board space in multi-rail systems. |
| CLKOUT synchronization | On-chip clock output eliminates need for external timing ICs when coordinating multiple switching regulators - simplifies system-level EMI control and reduces BOM cost. |
| Independent TRK/SS inputs | Three dedicated tracking/soft-start pins allow precise power-up sequencing (e.g., core before I/O) and eliminate external RC networks for controlled ramp rates. |
| Overvoltage transient protection | Shuts down at 38V input and withstands 70V non-repetitive transients - protects downstream circuitry in automotive, industrial, and battery-powered applications. |
| Thermally enhanced TSSOP | 20-lead TSSOP with exposed ground pad achieves θJA = 38°C/W - enables reliable 2.6A operation without heatsinks in compact industrial designs. |
Applications
| Industrial PLC Power Supply | DSL/Cable Modem Multi-Rail System |
|---|---|
Use Scenario: Powering FPGA, microcontroller, and analog front-end from a single 24V industrial bus with strict sequencing and ripple requirements. IC Role / Device Role / Timing Role: Primary triple-output PMIC providing [email protected] (buck), 2.5V@450mA (LDO1), and 1.8V@450mA (LDO2) with CLKOUT-synchronized auxiliary converters. Use Value: Eliminates discrete regulators and timing ICs; TRK/SS pins enforce safe power-up order; PGOOD confirms all rails before system boot. | Use Scenario: Generating clean, low-noise 3.3V, 2.5V, and 1.8V rails for DSL PHY, Ethernet MAC, and memory in broadband access equipment. IC Role / Device Role / Timing Role: Buck regulator supplies high-current digital core; LDOs deliver quiet analog/IO supplies; CLKOUT minimizes beat frequencies between converters. Use Value: Reduces conducted EMI through synchronized switching; LDOs suppress switching noise on sensitive analog paths; 0.75V reference ensures stable DDR termination. |
| Automotive Body Control Module | Distributed Telecom Power |
Use Scenario: Powering MCU, CAN transceiver, and sensor interface from 12V battery with cold-crank (4.5V) and load-dump (40V+) resilience. IC Role / Device Role / Timing Role: Main regulator handling wide VIN range; overvoltage shutdown protects against 70V transients; EN/UVLO implements battery undervoltage cutoff. Use Value: Single-chip solution meets AEC-Q100 stress requirements; thermal shutdown prevents latch-up during extended high-temp operation; PGOOD validates rail stability pre-wakeup. | Use Scenario: Providing isolated 5V, 3.3V, and 1.2V outputs in remote radio units powered from 48V telecom rectifiers. IC Role / Device Role / Timing Role: Buck stage steps 48V to intermediate 5V; LDOs generate precise low-noise sub-rails; CLKOUT aligns switching edges across distributed boards. Use Value: Enables deterministic EMI filtering across rack; eliminates inter-board jitter from unsynchronized clocks; BIAS pin reduces power loss in high-VIN conversion. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output buck+LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3375EFE#PBF | 8-channel configurable buck (up to 4A total), no integrated LDOs; requires external LDOs for low-noise rails; 4mm × 5mm QFN-28. | Higher integration for multi-output digital systems but lacks native LDO controllers - adds complexity for analog-sensitive designs. | Select LTC3375EFE#PBF only when needing >2 buck outputs or fine-grained channel enable/disable; not drop-in for LDO-dependent noise specs. |
| TPS546D24RSAR | Single 6A buck with PMBus interface; no LDOs; 5V–16V input; 3.5mm × 4.5mm QFN-24; requires external LDOs and sequencing logic. | Designed for server VR13/IMVP8 compliance; lacks TRK/SS and CLKOUT - unsuitable for standalone multi-rail sequencing without FPGA/MCU coordination. | Choose TPS546D24RSAR for digitally managed high-efficiency CPU cores; avoid when analog subsystems require integrated LDO control and hardware sequencing. |
Compared with LTC3375EFE#PBF and TPS546D24RSAR, LT3694EFE-1#TRPBF uniquely combines high-current buck, dual LDO controllers, hardware-based sequencing (TRK/SS), and clock distribution (CLKOUT) in one 20-pin TSSOP - making it optimal for cost-sensitive, space-constrained industrial and telecom systems requiring analog-clean, self-contained triple-rail generation.
Availability
LT3694EFE-1#TRPBF is available at Aetrix Electronics and suitable for industrial PLC power supplies, DSL/cable modem multi-rail systems, and automotive body control modules requiring stable component supply, long-term lifecycle support, and guaranteed -40°C to 125°C operation.
Supply support for LT3694EFE-1#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. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3694 product line was designed by Linear Technology specifically for high-voltage, multi-output power management in harsh environments - targeting industrial automation, telecom infrastructure, and automotive electronics where reliability, wide VIN, and hardware-controlled sequencing are critical.
FAQ
What is the maximum continuous output current of the buck regulator in LT3694EFE-1#TRPBF?
The LT3694EFE-1#TRPBF buck regulator delivers up to 2.6A continuous output current under typical thermal conditions (θJA = 38°C/W, 20-lead TSSOP). Actual achievable current depends on input/output voltage, ambient temperature, PCB copper area, and airflow. Switch current limit is guaranteed ≥3.5A at low duty cycles and decreases linearly to ~2.8A at 80% duty cycle per datasheet Figure G05.
Does LT3694EFE-1#TRPBF support synchronization with external clock sources?
No - LT3694EFE-1#TRPBF is the LT3694-1 variant, which features CLKOUT (Pin 3) for driving other regulators' SYNC inputs, but does not include a SYNC pin for accepting external clocks. Only the LT3694 (non-"-1") variants have SYNC functionality. For external clock synchronization, use LT3694EFE#TRPBF instead.
How does the TRK/SS function work on LT3694EFE-1#TRPBF?
Each TRK/SS pin (TRK/SS1–3) on LT3694EFE-1#TRPBF overrides the 0.75V internal reference when pulled below 0.75V. If a capacitor is connected from TRK/SS to ground, it ramps up slowly, causing the corresponding FB pin to track that voltage - enabling soft-start. If connected to another regulator's output, it forces ratiometric tracking. Pins left open default to 0.75V regulation.
What is the purpose of the BIAS pin on LT3694EFE-1#TRPBF?
The BIAS pin on LT3694EFE-1#TRPBF supplies current to internal regulators and boost circuits. It must be connected to a ≥3V source (typically VOUT1) to reduce power dissipation. When BIAS ≥1.8V above an LDO output, it supplies base drive current to DRV2/DRV3; otherwise, base current draws from VIN - impacting efficiency and thermal performance.
Can LT3694EFE-1#TRPBF survive automotive load dump transients?
Yes - LT3694EFE-1#TRPBF includes overvoltage shutdown that activates at 38V and is rated to survive non-repetitive 70V transients for up to 1 second (per Absolute Maximum Ratings). This meets common automotive load dump requirements (ISO 7637-2 Pulse 5a), provided input capacitance and layout minimize voltage overshoot at the VIN pin.
LT3694EFE-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Topology:
- Step-Down (Buck) (1), Linear (LDO) (2)
- Number of Outputs:
- 3
- Frequency - Switching:
- 250kHz ~ 2.5MHz
- Voltage/Current - Output 1:
- 0.75V ~ 16V, 2.6A
- Voltage/Current - Output 2:
- Controller
- Voltage/Current - Output 3:
- Controller
- w/LED Driver:
- No
- w/Supervisor:
- No
- w/Sequencer:
- Yes
- Voltage - Supply:
- 4V ~ 36V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT3694EFE-1#TRPBF FAQ
1.How can I place an order for LT3694EFE-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3694EFE-1#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 LT3694EFE-1#TRPBF reliable?
The price and inventory of LT3694EFE-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3694EFE-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3694EFE-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3694EFE-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3694EFE-1#TRPBF?
LT3694EFE-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3694EFE-1#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 LT3694EFE-1#TRPBF?
For technical support, including LT3694EFE-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3694EFE-1#TRPBF requirements.
6.How does Aetrix verify that LT3694EFE-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3694EFE-1#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 LT3694EFE-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3694EFE-1#TRPBF?
All LT3694EFE-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3694EFE-1#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 LT3694EFE-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3694EFE-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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