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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > DC DC Switching Controllers

Analog Devices Inc. LTC3785EUF#PBF

Name: LTC3785EUF#PBF
Brand: Analog Devices Inc.
SKU: LTC3785EUF#PBF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LTC3785EUF#PBF

Manufacturer:: Analog Devices Inc.

Category:: DC DC Switching Controllers

Package:: 24-WFQFN Exposed Pad

Datasheet:: LTC3785EUF#PBF.pdf

Description:: IC REG CTRLR BUCK-BOOST 24QFN

Quantity:: RFQ Add To RFQ list

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Product details

Overview

LTC3785EUF#PBF from Analog Devices (formerly Linear Technology) is a high-efficiency, synchronous, no-RSENSE buck-boost DC/DC controller IC that regulates output voltage across input voltages both above and below VOUT using four external N-channel MOSFETs. It operates from 2.7V to 10V input, delivers up to 10A output current, achieves up to 96% efficiency, and supports programmable switching frequency from 100kHz to 1MHz - ideal for single/dual-cell Li-ion portable power systems.

For engineers reviewing the LTC3785EUF#PBF datasheet, LTC3785EUF#PBF pinout, LTC3785EUF#PBF application, or LTC3785EUF#PBF equivalent, key selection considerations include its single-inductor buck-boost topology, true output disconnect during shutdown, programmable current limit and soft-start, Burst Mode® operation for light-load efficiency, and integrated overvoltage/undervoltage protection with ±6.5% UV/OV thresholds referenced to 1.225V FB.

Technical Context

The LTC3785EUF#PBF implements a voltage-mode, four-switch buck-boost architecture with drain-to-source current sensing (No RSENSE™) for both forward and reverse current limiting. Its control loop uses an internal 1.225V reference and error amplifier output (VC) to modulate duty cycles across three operational regions: buck (VIN > VOUT), buck-boost (VIN ≈ VOUT), and boost (VIN < VOUT), with seamless mode transitions.

It integrates dual floating gate drivers (VBST1/VBST2) for top-side N-MOSFETs A and D, ground-referenced drivers (VDRV) for bottom switches B and C, and independent current limit comparators with programmable thresholds via ILSET and CCM pins. Protection includes foldback current limiting below 1.8V VOUT, thermal shutdown, and latch-off or auto-recycle fault response configurable via RUN/SS discharge timing.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	2.7V to 10V - supports single/dual Li-ion, multicell alkaline/NiMH battery inputs without level-shifting.
Output Current Capability	Up to 10A - determined by external MOSFETs and inductor; enables high-power portable rail generation.
Switching Frequency	100kHz to 1MHz - set by RT resistor; higher frequencies allow smaller magnetics and faster transient response.
Feedback Reference Voltage	1.225V ±25mV - precise internal bandgap reference enabling accurate output regulation from 2.7V to 10V.
Efficiency	Up to 96% - achieved with all-N-MOSFET synchronous rectification and low-loss No RSENSE current sensing.
Operating Temperature	–40°C to +85°C - industrial-grade junction temperature range for reliable deployment in handheld and telecom equipment.
Quiescent Current (Burst)	86µA typical - enables ultra-low standby power in battery-powered applications with Burst Mode enabled.

Pinout & Package

Package: 24-lead (4mm × 4mm) plastic QFN with exposed pad (Pin 25 = GND). Thermal performance requires soldering the exposed pad to PCB ground plane.

Pin/Terminal	Circuit Role	Design Meaning
RUN/SS (1)	Enable & soft-start control	Internal 1µA charge current; clamps VC during startup; discharges on current fault to trigger latch-off or recycle.
VC (2)	Error amplifier output	Loop compensation node; connects to FB via RC network; clamped by RUN/SS during soft-start.
FB (3)	Feedback input	Connects to resistor divider; compares against 1.225V reference to regulate VOUT.
VSENSE (4)	OV/UV sense input	Monitors VOUT via dedicated divider; triggers shutdown at +10% OV or –6.5% UV relative to FB.
ILSET (5)	Current limit programming	Resistor to GND sets forward current limit threshold (20–155mV range) for ISVIN–ISSW1 sensing.
CCM (6)	Conduction mode control	Low = –15mV reverse limit; high = symmetric forward/reverse limit - enables true bidirectional current control.
RT (7)	Oscillator frequency set	Resistor to GND programs f_SW ≈ 25 MHz / R_T(kΩ); e.g., 49.9kΩ → ~500kHz.
MODE (8)	Burst Mode enable	High = variable-frequency Burst Mode; low = fixed-frequency PWM - selectable for noise vs. efficiency trade-off.
NC (9)	No connect	No internal connection; leave unconnected or tie to GND per layout best practice.
ISVOUT (10)	Reverse current sense (+)	Connects to drain of boost-side MOSFET D (TG2); used with ISSW2 for reverse current detection.
VBST2 (11)	Boost supply for TG2	Floating supply for top boost switch D; swings up to VOUT + VCC – V_diode.
TG2 (12)	Top gate driver D	Drives gate of N-MOSFET D; referenced to SW2; requires external bootstrap capacitor on VBST2.
SW2 (13)	Switch node D/C	Common source node for boost switches C and D; reference for TG2/BG2 drivers.
ISSW2 (14)	Reverse current sense (–)	Connects to source of MOSFET D; differential pair with ISVOUT detects reverse conduction.
BG2 (15)	Bottom gate driver C	Drives gate of N-MOSFET C; referenced to SW2; complements TG2 in synchronous boost phase.
VDRV (16)	Driver supply	Connects to VCC; powers ground-referenced drivers BG1/BG2 and logic circuits.
VG1 (17)	Bottom gate driver B	Drives gate of N-MOSFET B; referenced to SW1; complements TG1 in synchronous buck phase.
ISSW1 (18)	Forward current sense (–)	Connects to source of buck-side MOSFET A (TG1); differential pair with ISVIN senses input current.
SW1 (19)	Switch node A/B	Common source node for buck switches A and B; reference for TG1/BG1 drivers.
TG1 (20)	Top gate driver A	Drives gate of N-MOSFET A; referenced to SW1; requires external bootstrap capacitor on VBST1.
VBST1 (21)	Boost supply for TG1	Floating supply for top buck switch A; swings up to VIN + VCC – V_diode.
ISVIN (22)	Forward current sense (+)	Connects to drain of MOSFET A; differential pair with ISSW1 enables R_{DS(on)-based input current monitoring.}
VCC (23)	Internal LDO output	4.35V regulated supply (100mA peak); powers gate drivers and internal circuitry; bypass with ≥4.7µF ceramic.
VIN (24)	Input supply	Primary input for VCC LDO; requires ≥10µF ceramic decoupling close to pin and GND.
GND (25)	Ground / Exposed Pad	Electrical and thermal ground; exposed pad must be soldered to PCB ground plane for θ_JA = 30°C/W (4-layer).

Key Features

Feature	Design Value
Single-inductor buck-boost topology	Enables VIN > VOUT, VIN = VOUT, and VIN < VOUT operation without transformer or multiple inductors - reduces BOM count and board area.
No RSENSE™ current sensing	Uses MOSFET R_{DS(on) as current sense element - eliminates power loss and accuracy drift of discrete sense resistors.}
True output disconnect	Shuts off all four switches during shutdown - prevents backfeed from VOUT to VIN, critical for battery isolation.
Programmable burst mode	Reduces quiescent current to 86µA at light loads while maintaining regulation - extends battery runtime in standby modes.
Independent forward/reverse current limits	Configurable via ILSET and CCM pins - supports bidirectional power flow and prevents reverse conduction in boost mode.
Integrated OV/UV protection	±6.5% undervoltage and +10% overvoltage thresholds referenced to 1.225V FB - protects downstream circuitry without external comparators.

Applications

Palmtop Computers	Handheld Instruments
Use Scenario: Power management in compact, battery-operated palmtop PCs requiring stable 3.3V or 5V rails from varying Li-ion cell voltages (2.7V–4.2V). IC Role / Device Role / Timing Role: Primary buck-boost controller managing single-inductor conversion with seamless transition between buck and boost phases. Use Value: Eliminates need for separate buck and boost ICs; maintains >90% efficiency across full battery discharge curve.	Use Scenario: Precision power supply for portable test equipment (e.g., multimeters, oscilloscope probes) needing low-noise, regulated outputs from 2-cell alkaline or NiMH batteries. IC Role / Device Role / Timing Role: Synchronous controller delivering clean, ripple-controlled output with Burst Mode disabled for fixed-frequency low-noise operation. Use Value: Achieves <50mV_PP output ripple at full load and 86µA quiescent current in sleep - extends operating time between battery changes.
Wireless Modems	Cellular Telephones
Use Scenario: Power conversion in LTE/5G USB modems where input voltage varies widely (3.0V–10V) due to host USB port or external adapter sourcing. IC Role / Device Role / Timing Role: Adaptive buck-boost regulator supporting dynamic load steps up to 10A during RF transmission bursts. Use Value: Delivers fast transient response (<100µs settling) and 96% peak efficiency - minimizes thermal stress and improves modem uptime.	Use Scenario: Main system power rail generation in smartphones using dual Li-ion cells (up to 8.4V) to supply 3.3V core logic and 5V USB OTG. IC Role / Device Role / Timing Role: High-density, thermally optimized controller driving low-R_DS(on) MOSFETs in 4mm × 4mm QFN package. Use Value: Enables true output disconnect during deep sleep - prevents battery drain from peripheral leakage currents.

Palmtop Computers

Handheld Instruments

Use Scenario: Power management in compact, battery-operated palmtop PCs requiring stable 3.3V or 5V rails from varying Li-ion cell voltages (2.7V–4.2V).

IC Role / Device Role / Timing Role: Primary buck-boost controller managing single-inductor conversion with seamless transition between buck and boost phases.

Use Value: Eliminates need for separate buck and boost ICs; maintains >90% efficiency across full battery discharge curve.

Use Scenario: Precision power supply for portable test equipment (e.g., multimeters, oscilloscope probes) needing low-noise, regulated outputs from 2-cell alkaline or NiMH batteries.

IC Role / Device Role / Timing Role: Synchronous controller delivering clean, ripple-controlled output with Burst Mode disabled for fixed-frequency low-noise operation.

Use Value: Achieves <50mV_PP output ripple at full load and 86µA quiescent current in sleep - extends operating time between battery changes.

Wireless Modems

Cellular Telephones

Use Scenario: Power conversion in LTE/5G USB modems where input voltage varies widely (3.0V–10V) due to host USB port or external adapter sourcing.

IC Role / Device Role / Timing Role: Adaptive buck-boost regulator supporting dynamic load steps up to 10A during RF transmission bursts.

Use Value: Delivers fast transient response (<100µs settling) and 96% peak efficiency - minimizes thermal stress and improves modem uptime.

Use Scenario: Main system power rail generation in smartphones using dual Li-ion cells (up to 8.4V) to supply 3.3V core logic and 5V USB OTG.

IC Role / Device Role / Timing Role: High-density, thermally optimized controller driving low-R_DS(on) MOSFETs in 4mm × 4mm QFN package.

Use Value: Enables true output disconnect during deep sleep - prevents battery drain from peripheral leakage currents.

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck-boost controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LTC3786EUF#PBF	Enhanced version with improved current limit accuracy (±3% vs ±5%), lower 55µA Burst Mode IQ, and extended –40°C to 125°C temp grade (I-grade).	Preferred for automotive-adjacent or extended-temperature industrial designs requiring tighter current regulation and lower standby power.	Select LTC3786EUF#PBF when higher precision current limiting and wider temperature support are required; pin-compatible but requires validation of new ILSET resistor value.
MP2918GL-Z	Monolithic 4-switch buck-boost converter (integrated MOSFETs); 3.3V–36V input; fixed 500kHz f_SW; no programmable current limit or Burst Mode.	Suitable for space-constrained designs where 5A max output suffices and external MOSFET flexibility is not needed.	Choose MP2918GL-Z for simplified layout and reduced component count in ≤5A applications; not pin- or function-compatible with LTC3785EUF#PBF.

Compared with LTC3786EUF#PBF, the LTC3785EUF#PBF offers identical topology and pinout but trades off tighter current limit tolerance and lower quiescent current for cost-sensitive industrial use; versus MP2918GL-Z, it provides design flexibility with external MOSFETs, programmable frequency/current limit, and true output disconnect - essential for high-current, battery-isolation-critical systems.

Availability

LTC3785EUF#PBF is available at Aetrix Electronics and suitable for palmtop computers, handheld instruments, and wireless modems requiring stable component supply, long-lifecycle availability, and guaranteed industrial-temperature performance.

Supply support for LTC3785EUF#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 engineering for legacy Linear parts including the LTC3785 series.

The LTC3785 belongs to Linear's high-efficiency, no-RSENSE synchronous controller family designed specifically for single-inductor buck-boost power conversion in portable and battery-powered systems with wide input voltage ranges.

FAQ

What is the maximum output current supported by the LTC3785EUF#PBF?

The LTC3785EUF#PBF itself does not deliver current - it controls external N-channel MOSFETs to achieve up to 10A output current. Actual capability depends on selected MOSFETs (R_{DS(on), Q_g), inductor saturation rating, thermal design, and PCB copper area. The controller's current limit threshold is programmable from 20mV to 155mV via ILSET, corresponding to typical 5A–10A ranges with common 5mΩ–10mΩ R_DS(on) devices.}

Does the LTC3785EUF#PBF require external sense resistors for current limiting?

No - the LTC3785EUF#PBF uses No RSENSE™ technology, sensing current via the R_DS(on) of external N-channel MOSFETs (e.g., ISVIN–ISSW1 for forward current, ISVOUT–ISSW2 for reverse). An optional external sense resistor can be added for higher accuracy, but it is not required. This eliminates power loss and board space associated with traditional shunt resistors.

How does the LTC3785EUF#PBF handle input voltages both above and below the output voltage?

The LTC3785EUF#PBF implements a four-switch synchronous buck-boost topology that automatically transitions between buck (VIN > VOUT), buck-boost (VIN ≈ VOUT), and boost (VIN < VOUT) modes based on the error amplifier output (VC) voltage. Its control logic ensures continuous, seamless mode transitions without output disruption - enabling stable regulation across the full 2.7V–10V input range into a fixed 3.3V, 5V, or other user-defined output.

What protection features are integrated into the LTC3785EUF#PBF?

The LTC3785EUF#PBF integrates foldback current limiting (reducing limit to 50% when VOUT < 1.8V), overvoltage protection (+10% above FB reference), undervoltage protection (–6.5% below FB), thermal shutdown, and programmable fault response (latch-off or auto-recycle). All protections act independently and do not require external components - simplifying design while ensuring robust system-level safety.

Can the LTC3785EUF#PBF be used in applications requiring true output disconnect during shutdown?

Yes - the LTC3785EUF#PBF provides true output disconnect by turning off all four external N-channel MOSFETs during shutdown (RUN/SS < 0.35V). This prevents reverse current flow from VOUT to VIN, eliminating battery backfeed and protecting upstream sources. Unlike controllers with body-diode conduction paths, this feature ensures complete isolation - critical for battery-powered systems with multiple power domains.

LTC3785EUF#PBF Specifications

Product attributes: Attribute value

Manufacturer:: Analog Devices Inc.

Series:: -

Package/Case:: 24-WFQFN Exposed Pad

Packaging:: Tube

Product Status:: Active

Output Type:: Transistor Driver

Function:: Step-Up/Step-Down

Output Configuration:: Positive

Topology:: Buck-Boost

Number of Outputs:: 2

Output Phases:: 1

Voltage - Supply (Vcc/Vdd):: 2.7V ~ 10V

Frequency - Switching:: 100kHz ~ 1MHz

Duty Cycle (Max):: 99%

Synchronous Rectifier:: Yes

Clock Sync:: No

Serial Interfaces:: -

Control Features:: Current Limit, Enable, Soft Start

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 24-QFN (4x4)

LTC3785EUF#PBF FAQ

1.How can I place an order for LTC3785EUF#PBF through Aetrix?

Please submit a Request for Quotation (RFQ) for LTC3785EUF#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 LTC3785EUF#PBF reliable?

The price and inventory of LTC3785EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3785EUF#PBF is usually 5 days.

3.What payment methods are accepted for LTC3785EUF#PBF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3785EUF#PBF transactions.

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4.How is shipping managed for LTC3785EUF#PBF?

LTC3785EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LTC3785EUF#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 LTC3785EUF#PBF?

For technical support, including LTC3785EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3785EUF#PBF requirements.

6.How does Aetrix verify that LTC3785EUF#PBF is sourced from the original manufacturer or authorized distributors?

All LTC3785EUF#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 LTC3785EUF#PBF meets industry standards.

7.What is the process for return or replacement of LTC3785EUF#PBF?

All LTC3785EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3785EUF#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 LTC3785EUF#PBF part is unused and in its original packaging.

Return procedure for LTC3785EUF#PBF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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