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Analog Devices Inc. LT3570EFE#TRPBF
- Part No.:
- LT3570EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Regulators - Linear + Switching
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3570EFE#TRPBF.pdf
- Description:
- IC REG TRPL BUCK/BST/LNR 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,688
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Product details
Overview
LT3570EFE#TRPBF from Analog Devices (formerly Linear Technology) is a triple-output power management IC integrating a 1.5A buck converter, a 1.5A boost converter, and an LDO controller with external NPN transistor drive. It operates from 2.5V to 36V input, supports programmable switching frequency up to 2.1MHz, delivers regulated outputs down to 0.8V, and is used in automotive infotainment power rails requiring independent voltage sequencing.
For engineers reviewing the LT3570EFE#TRPBF datasheet, LT3570EFE#TRPBF pinout, LT3570EFE#TRPBF application, or LT3570EFE#TRPBF equivalent, key selection criteria include its dual independent soft-start, separate VIN supplies per converter, 788mV feedback reference accuracy, and 20-lead TSSOP package with exposed thermal pad for industrial temperature operation (–40°C to 125°C).
Technical Context
The LT3570EFE#TRPBF implements constant-frequency current-mode control for both buck and boost regulators, each with dedicated error amplifiers (VC1/VC2), soft-start pins (SS1/SS2), and feedback inputs (FB1/FB2) referenced to 788mV. The LDO controller uses FB3 to regulate an external NPN-based linear stage with up to 10mA base drive capability.
Its architecture supports independent shutdown (SHDN1/SHDN2/SHDN3), external frequency synchronization up to 2.75MHz via SYNC, and flexible biasing-BIAS pin available only on QFN variants, while TSSOP relies on VIN2 for internal circuitry supply. Switch current limit is 1.5A minimum (decreasing linearly to 1.2A at 80% duty cycle), with SW1/SW2 VCE(SAT) ≤240mV at 1A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 36V - supports wide-input industrial and automotive battery-supplied systems without pre-regulation. |
| Switch Current Limit | 1.5A min - ensures robust overload protection for both buck and boost stages under transient conditions. |
| Feedback Reference | 788mV ±16mV - enables precise output voltage setting with standard resistor dividers across full temperature range. |
| Switching Frequency | 500kHz to 2.1MHz - adjustable via RT resistor; allows optimization of size vs. efficiency and EMI performance. |
| Soft-Start Control | Independent SS1/SS2 pins - prevents output overshoot and limits inrush current during power-up of each converter. |
| LDO Base Drive | Up to 10mA - sufficient to bias external NPN transistors for low-noise auxiliary rails (e.g., analog sensor supplies). |
| Operating Temperature | –40°C to 125°C - qualified for under-hood automotive and industrial embedded applications. |
Pinout & Package
LT3570EFE#TRPBF is housed in a 20-lead plastic TSSOP package (FE) with exposed thermal pad (Pin 21) that must be soldered to PCB ground for thermal and electrical integrity. θJA = 38°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 (Pin 1) | Boost Output Feedback | Regulated to 788mV; sets VOUT1 via resistor divider; determines accuracy and loop stability of boost stage. |
| SHDN1 (Pin 2) | Boost Enable Control | ≥1.4V enables boost converter; <0.3V shuts down entire device; supports independent sequencing. |
| SHDN2 (Pin 3) | Buck Enable Control | ≥1.4V enables buck converter; allows staggered startup with boost or LDO stages. |
| SHDN3 (Pin 4) | LDO Enable Control | ≥1.5V enables NPN LDO controller; decouples LDO activation from switching regulators. |
| SYNC (Pin 5) | External Clock Input | Accepts 650kHz–2.75MHz clock for EMI reduction and multi-rail synchronization. |
| RT (Pin 6) | Oscillator Timing | Resistor-to-GND sets switching frequency; 44.2kΩ → ~500kHz, 7.87kΩ → ~2.1MHz. |
| SS2 (Pin 7) | Buck Soft-Start | Charged to 2V by 4.5μA current; ramps buck reference to prevent overshoot and inrush. |
| VC2 (Pin 8) | Buck Compensation | Connect RC network to GND for loop compensation; sets pole/zero placement for buck regulator stability. |
| FB2 (Pin 9) | Buck Output Feedback | Regulated to 788mV; sets VOUT2; identical reference as FB1 for consistent design methodology. |
| FB3 (Pin 10) | LDO Feedback | Regulated to 788mV; sets VOUT3 via external resistor; controls base current of external NPN. |
| NPN_DRV (Pin 11) | External NPN Base Drive | Sinks current from VIN3 to drive NPN base; max 10mA output enables low-dropout linear regulation. |
| VIN3 (Pin 12) | LDO Input Supply | Supplies current only to LDO controller and NPN_DRV; isolated from buck/boost power paths. |
| BOOST (Pin 13) | Buck NPN Bias Boost | Provides >VIN2 voltage via external Schottky diode/capacitor; ensures NPN saturation in buck stage. |
| VIN2 (Pin 14) | Buck Input & IC Bias | Primary supply for buck regulator and internal circuitry; requires local 10μF ceramic bypass. |
| SW2 (Pin 15) | Buck Switch Node | Emitter of internal NPN switch; connects to inductor, diode, and BOOST capacitor in buck topology. |
| SW1 (Pin 16) | Boost Switch Node | Collector of internal NPN switch; connects to inductor and diode in boost topology. |
| GND (Pins 17, 21) | Power & Thermal Ground | Multiple GND pins + exposed pad (Pin 21); mandatory soldering required for thermal dissipation and noise control. |
| VIN1 (Pin 18) | Boost Input Supply | Supplies current only to boost regulator; electrically isolated from VIN2/VIN3 for rail independence. |
| SS1 (Pin 19) | Boost Soft-Start | Charged to 2V by 4.5μA current; independently controls boost reference ramp rate. |
| VC1 (Pin 20) | Boost Compensation | Connect RC network to GND for boost loop compensation; matches VC2 function for design reuse. |
Key Features
| Feature | Design Value |
|---|---|
| Triple Independent Regulators | Separate VIN1/VIN2/VIN3 supplies, shutdown pins, soft-start, and feedback paths enable fully independent power rail generation and sequencing. |
| High-Frequency Operation | 2.1MHz max switching frequency reduces inductor and capacitor size-enables compact 5V/3.3V/2.5V power solutions for space-constrained STBs and displays. |
| Accurate 788mV Reference | ±16mV tolerance over –40°C to 125°C ensures stable output voltage across temperature without calibration. |
| Robust Switch Protection | 1.5A min current limit with duty-cycle-dependent derating (to 1.2A at 80%) prevents thermal runaway during overload or short-circuit events. |
| Thermal-Enhanced TSSOP | Exposed pad (Pin 21) tied to GND provides low-thermal-resistance path-supports 1.5A continuous operation at 125°C junction temperature. |
Applications
| Cable Set-Top Box Power | Automotive Infotainment |
|---|---|
|
Use Scenario: Generating 12V (tuner), 3.3V (SoC I/O), and 2.5V (memory) from 12V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Triple-output PMIC providing sequenced, independent DC/DC conversion with soft-start coordination. Use Value: Eliminates need for three discrete converters; reduces BOM count and layout area while maintaining rail isolation and fault containment. |
Use Scenario: Powering display backlight (boost), MCU core (buck), and audio codec (LDO) in head-unit with ESD-hardened 12V input. IC Role / Device Role / Timing Role: Integrated buck/boost/LDO controller delivering low-noise, thermally robust, and AEC-Q200-compatible power rails. Use Value: Meets automotive transient requirements (ISO 7637-2) via wide 2.5V–36V input range and independent shutdown for fail-safe behavior. |
| TFT LCD Display Bias | "Dying Gasp" Backup System |
|
Use Scenario: Generating high-voltage gate drive (e.g., 20V) and logic rails (3.3V, 1.8V) from single 5V supply in portable display modules. IC Role / Device Role / Timing Role: Boost converter (VOUT1) + buck (VOUT2) + LDO (VOUT3) delivering tightly regulated, low-ripple outputs with independent soft-start. Use Value: Enables fast, controlled startup of display panels without image artifacts; 788mV reference ensures <1% output error across temperature. |
Use Scenario: Maintaining critical communication (e.g., LTE modem) during AC power loss using supercapacitor backup charged from main 12V rail. IC Role / Device Role / Timing Role: Buck converter (main rail) + boost converter (supercap charging) + LDO (modem analog supply) with independent SHDN control. Use Value: Allows graceful shutdown and data preservation via programmable sequencing-SHDN3 disables LDO last to sustain analog functions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3570EUF#TRPBF | 24-lead QFN (4mm × 4mm); includes BIAS pin for lower-quiescent-current biasing; higher thermal performance (θJA = 37°C/W). | Preferred for space-constrained, high-density PCBs where thermal management is critical and BIAS pin utilization is needed. | Select when board layout allows QFN footprint and system benefits from reduced quiescent current via BIAS pin. |
| LT3570IFE#TRPBF | Same 20-lead TSSOP package as LT3570EFE#TRPBF but rated for –40°C to 125°C with full production testing and guaranteed specs across full range. | Required for automotive safety-critical subsystems demanding full-temperature-range validation and AEC-Q200 alignment. | Choose for production automotive programs where extended temperature assurance and test coverage are mandated. |
Compared with LT3570EFE#TRPBF, the LT3570EUF#TRPBF offers superior thermal dissipation and a BIAS pin for efficiency-sensitive designs, while the LT3570IFE#TRPBF provides guaranteed full-range performance for mission-critical automotive deployments-neither is pin-compatible without layout revision due to differing package types and pinouts.
Availability
LT3570EFE#TRPBF is available at Aetrix Electronics and suitable for cable set-top boxes, automotive infotainment systems, and TFT LCD display power supplies requiring stable component supply, long-term lifecycle support, and industrial temperature-grade reliability.
Supply support for LT3570EFE#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3570 product line was designed to consolidate multiple DC/DC functions into a single IC for space- and cost-sensitive applications requiring independent, sequenced power rails-targeting STB, telecom, and automotive display systems.
FAQ
What is the maximum switching frequency supported by the LT3570EFE#TRPBF?
The LT3570EFE#TRPBF supports a programmable switching frequency from 500kHz to 2.1MHz using the RT pin resistor. Its oscillator can also be synchronized to an external clock up to 2.75MHz via the SYNC pin-enabling EMI reduction and multi-rail timing coordination in complex systems.
Does the LT3570EFE#TRPBF include internal power switches?
Yes, the LT3570EFE#TRPBF integrates two internal NPN bipolar power switches-one for the buck converter (SW2, emitter-connected) and one for the boost converter (SW1, collector-connected). Each has a minimum 1.5A current limit and ≤240mV saturation voltage at 1A, eliminating need for external MOSFETs or drivers.
How does the LDO controller in the LT3570EFE#TRPBF operate?
The LT3570EFE#TRPBF's LDO controller uses FB3 (regulated to 788mV) and NPN_DRV to deliver up to 10mA base current to an external NPN transistor. VIN3 supplies this stage independently, enabling low-noise, post-regulated outputs-ideal for analog sensors or RF bias rails requiring ripple-free voltage.
What is the purpose of the BOOST pin on the LT3570EFE#TRPBF?
The BOOST pin on the LT3570EFE#TRPBF provides a voltage higher than VIN2 (via external Schottky diode and capacitor) to ensure full saturation of the internal NPN buck switch. This minimizes conduction losses and improves efficiency-especially critical at low input voltages or high load currents.
Is the LT3570EFE#TRPBF RoHS-compliant and lead-free?
Yes, the LT3570EFE#TRPBF is RoHS-compliant and features a lead-free finish. Its part marking "LT3570FE" and packaging designation "#TRPBF" confirm tape-and-reel delivery with Pb-free termination-fully aligned with IPC/JEDEC J-STD-020 moisture sensitivity level 3 requirements.
LT3570EFE#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), Step-Up (Boost) (1), Linear (LDO) (1)
- Number of Outputs:
- 3
- Frequency - Switching:
- 500kHz ~ 2.1MHz
- Voltage/Current - Output 1:
- Adj to 0.8V, 1.5A
- Voltage/Current - Output 2:
- Adj to 0.8V, 1.5A
- Voltage/Current - Output 3:
- Controller
- w/LED Driver:
- No
- w/Supervisor:
- No
- w/Sequencer:
- No
- Voltage - Supply:
- 2.5V ~ 36V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT3570EFE#TRPBF FAQ
1.How can I place an order for LT3570EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3570EFE#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 LT3570EFE#TRPBF reliable?
The price and inventory of LT3570EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3570EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3570EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3570EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3570EFE#TRPBF?
LT3570EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3570EFE#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 LT3570EFE#TRPBF?
For technical support, including LT3570EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3570EFE#TRPBF requirements.
6.How does Aetrix verify that LT3570EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3570EFE#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 LT3570EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3570EFE#TRPBF?
All LT3570EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3570EFE#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 LT3570EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3570EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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