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Analog Devices Inc. LTC3789IUFD#TRPBF
- Part No.:
- LTC3789IUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3789IUFD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK-BOOST 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,366
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Product details
Overview
LTC3789IUFD#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance, synchronous 4-switch buck-boost DC/DC controller IC that regulates output voltage across input voltages both above and below VOUT - supporting 4V to 38V input and 0.8V to 38V output with ±1% accuracy. It delivers up to 98% efficiency via synchronous N-channel MOSFET drive, features phase-lockable 200–600kHz fixed-frequency current-mode control, and includes input/output current sensing for battery charging applications in automotive and industrial power systems.
For engineers reviewing the LTC3789IUFD#TRPBF datasheet, LTC3789IUFD#TRPBF pinout, LTC3789IUFD#TRPBF application, or LTC3789IUFD#TRPBF equivalent, key selection criteria include seamless buck-boost transition behavior, programmable current limit via ILIM pin, dual-mode operation (pulse-skipping or forced continuous), PGOOD monitoring, and thermal performance enabled by its 28-pin 4mm × 5mm QFN package with exposed SGND pad.
Technical Context
The LTC3789IUFD#TRPBF implements a proprietary four-switch buck-boost topology with independent top- and bottom-gate drivers (TG1/BG1/TG2/BG2) enabling true single-inductor VIN-above/below/equal-to-VOUT regulation. Its current-mode architecture uses valley-current sensing in buck mode and peak-current sensing in boost mode, with ITH pin controlling loop gain and current threshold scaling.
Operation is determined by MODE/PLLIN pin state: grounded for forced continuous conduction (constant frequency, noise-sensitive designs), tied to INTVCC for pulse-skipping (high light-load efficiency), or driven externally for synchronization. The internal 5.5V LDO powers control circuitry from VIN or EXTVCC, and integrated charge pumps maintain BOOST1/BOOST2 bias during extended top-FET on-time in pure buck or boost regions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide automotive battery transients and industrial DC bus inputs without pre-regulation. |
| Output Voltage Range | 0.8V to 38V with ±1% feedback accuracy - enables precise regulation for diverse system rails including 3.3V, 5V, 12V, and 24V outputs. |
| Switching Frequency | 200kHz to 600kHz (phase-lockable) - balances EMI, inductor size, and efficiency across operating conditions. |
| Peak Efficiency | Up to 98% - achieved via synchronous rectification and low RDS(ON) gate drivers (2.6Ω pull-up / 1.5Ω pull-down). |
| Current Sensing | Programmable input/output average current limit via ILIM pin (SGND/INTVCC/floating); supports battery charge control and overcurrent protection. |
| Thermal Resistance | θJA = 34°C/W (QFN package) - enables higher power density than SSOP version (θJA = 80°C/W) with proper PCB copper area under exposed pad. |
| Operating Temperature | –40°C to +125°C junction - qualified for under-hood automotive and harsh industrial environments. |
Pinout & Package
The LTC3789IUFD#TRPBF is housed in a 28-lead (4mm × 5mm) plastic QFN package with exposed SGND pad (Pin 29), requiring soldering to PCB ground for thermal and electrical performance. Pin numbering follows top-view layout with Pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE– (Pin 1) | Current sense negative input | Connects to low-side of current-sense resistor; referenced to SGND for accurate valley/peak current detection. |
| ITH (Pin 2) | Error amplifier output & current threshold control | Sets per-cycle current limit; voltage directly scales sensed current trip point in buck (valley) and boost (peak) modes. |
| SGND (Pin 3) | Small-signal ground reference | Must be routed separately from PGND; connects to CIN– and forms reference for error amp, comparators, and analog blocks. |
| MODE/PLLIN (Pin 4) | Mode selection or external sync input | Determines operating mode: <0.8V → forced continuous; INTVCC → pulse-skipping; external clock → PLL sync with forced continuous. |
| FREQ (Pin 5) | Oscillator frequency programming | 10µA sink current; resistor to SGND sets nominal frequency (200–600kHz); DC voltage override also supported. |
| RUN (Pin 6) | Enable/disable control | Threshold = 1.22V (±150mV hysteresis); <0.5V forces shutdown with ~40µA quiescent current. |
| VINSNS (Pin 7) | VIN sense for buck-boost transition | Monitors input-side switch node (SW1) to detect VIN/VOUT relationship and enable seamless region transitions. |
| VOUTSNS (Pin 8) | VOUT sense for buck-boost transition | Monitors output-side switch node (SW2) to coordinate four-switch timing and prevent shoot-through during mode crossing. |
| ILIM (Pin 9) | Average current limit range select | SGND → 48mV; floating → 90mV; INTVCC → 130mV - configures maximum average inductor current for charge/discharge control. |
| IOSENSE+ (Pin 10) | Input/output average current sense + | Used with IOSENSE– to measure average current through RSENSE for battery charge regulation or load monitoring. |
| IOSENSE– (Pin 11) | Input/output average current sense – | Low-impedance return path for IOSENSE+; must connect to same node as SENSE– for accurate differential measurement. |
| TRIM (Pin 12) | Internal reference trim disable | Must be tied to SGND; floating causes undefined operation and potential regulation error. |
| VFB (Pin 26) | Feedback voltage input | Compares resistive divider output against 0.8V reference; regulates VOUT with ±1% accuracy over temperature and line/load. |
| SS (Pin 27) | Soft-start ramp control | Internal 3µA current charges external capacitor; ramps VFB setpoint from 0V to 0.8V for controlled VOUT rise and inrush limiting. |
| PGOOD (Pin 25) | Power-good open-drain output | Asserts low when VFB deviates >±10% from target for >20µs - signals stable regulation to downstream logic or sequencers. |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor buck-boost topology | Eliminates need for separate buck and boost converters; reduces BOM count, board space, and design complexity in wide-input-range systems. |
| Seamless region transition | No output disturbance or mode-hopping artifacts when VIN crosses VOUT - critical for stable power in automotive start-stop and battery backup systems. |
| True soft-start and short-circuit protection | Prevents inrush current during startup and limits fault current even in boost mode - protects MOSFETs and input sources during output shorts. |
| VOUT disconnection during shutdown | Isolates output from input when RUN = low - prevents backfeed and ensures zero-load leakage in standby or fault conditions. |
| Internal charge pump for bootstrap bias | Maintains BOOST1/BOOST2 voltage during 100% duty cycle in pure buck/boost, eliminating need for external charge pump circuits. |
Applications
| Automotive Start-Stop Systems | Industrial 24V DC Power Distribution |
|---|---|
Use Scenario: Regulating stable 12V rail from vehicle battery (6V–16V) during cranking and engine-off states. IC Role / Device Role / Timing Role: 4-switch buck-boost controller managing bidirectional power flow with seamless VIN/VOUT crossover. Use Value: Maintains uninterrupted MCU, sensor, and infotainment supply despite >50% battery sag during cold cranking. | Use Scenario: Converting unregulated 24V factory bus to clean 5V/3.3V for PLC I/O modules and fieldbus interfaces. IC Role / Device Role / Timing Role: High-efficiency synchronous controller delivering up to 10A with minimal heat rise in confined enclosures. Use Value: Achieves 96% efficiency at full load, reducing thermal management burden and enabling fanless industrial designs. |
| Battery-Powered Test Equipment | Telecom Remote Radio Units (RRUs) |
Use Scenario: Powering portable oscilloscopes and signal analyzers from Li-ion packs (9V–12.6V) while generating isolated ±15V analog rails. IC Role / Device Role / Timing Role: Primary buck-boost controller feeding secondary isolated DC/DC stages; supports programmable current limit for battery health monitoring. Use Value: Enables precise input current regulation during charging cycles and extends runtime via 98% peak efficiency. | Use Scenario: Providing stable 28V bias for GaN PA stages from fluctuating -48V telecom rectifier output (–36V to –72V). IC Role / Device Role / Timing Role: Negative-input buck-boost controller (using inverted topology) with robust EMI filtering and fast transient response. Use Value: Delivers <100µs load-step recovery and <1% output deviation - ensuring PA linearity and spectral purity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3780EUFD#TRPBF | Fixed 300kHz frequency; no FREQ pin; no PGOOD; lower max input (36V); no IOSENSE pins. | Lacks input/output current sensing and programmable frequency - unsuitable for battery charge control or EMI-sensitive designs. | Select only if cost sensitivity outweighs feature requirements and input range ≤36V suffices. |
| MP2918GL-Z | 3.5V–36V input; 0.6V–25V output; 500kHz max; no ILIM/IOSENSE; integrated MOSFETs (40V/6A). | Integrated power stage limits output current and thermal design flexibility; lacks average current sensing for charge control. | Choose for compact, lower-power (<100W) applications where board space is critical and discrete FET selection is unnecessary. |
Compared with LTC3780EUFD#TRPBF and MP2918GL-Z, the LTC3789IUFD#TRPBF provides superior flexibility in frequency tuning, comprehensive current monitoring (valley/peak/average), and seamless buck-boost transition - making it the preferred choice for high-reliability, wide-input industrial and automotive power systems requiring precise battery interface control.
Availability
LTC3789IUFD#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, industrial 24V DC distribution, battery-powered test equipment, and telecom remote radio units requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3789IUFD#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and automotive markets.
The LTC3789 belongs to Linear's high-efficiency synchronous controller product line, designed specifically for wide-input-range DC/DC conversion in mission-critical automotive, telecom, and industrial applications where reliability, efficiency, and seamless mode transitions are essential.
FAQ
What is the operating temperature range for the LTC3789IUFD#TRPBF?
The LTC3789IUFD#TRPBF is rated for a junction temperature range of –40°C to +125°C, meeting industrial and automotive under-hood requirements. Its 28-pin QFN package achieves θJA = 34°C/W with proper PCB thermal land design, enabling reliable operation at full load in high-ambient environments when mounted on ≥2 oz copper with thermal vias to inner layers.
How does the LTC3789IUFD#TRPBF handle transitions between buck, buck-boost, and boost modes?
The LTC3789IUFD#TRPBF uses dedicated VINSNS and VOUTSNS pins to monitor switch-node voltages and dynamically adjust gate timing without interruption. Its control logic coordinates TG1/BG1 and TG2/BG2 drivers to ensure zero-voltage switching and eliminate output glitches during VIN/VOUT crossovers - verified in typical application waveforms showing <10mV transient deviation during mode transitions.
Can the LTC3789IUFD#TRPBF be used for battery charging applications?
Yes - the LTC3789IUFD#TRPBF supports battery charging via its programmable input/output average current limit (ILIM pin) and dedicated IOSENSE+/IOSENSE– inputs. When configured with appropriate external sense resistors and feedback networks, it implements constant-current/constant-voltage (CC/CV) profiles for Li-ion, lead-acid, and other chemistries without additional ICs.
What is the purpose of the TRIM pin on the LTC3789IUFD#TRPBF?
The TRIM pin (Pin 12) on the LTC3789IUFD#TRPBF must be tied to SGND for normal operation. It disables internal reference trimming circuitry; leaving it floating may cause unpredictable feedback voltage accuracy and regulation instability. No external components are required - direct connection to signal ground is mandatory.
Does the LTC3789IUFD#TRPBF require external bootstrap diodes?
Yes - the LTC3789IUFD#TRPBF requires external Schottky diodes between BOOST1 and INTVCC, and BOOST2 and INTVCC, to recharge the bootstrap capacitors during top-FET off-time. Low-forward-voltage (≤0.3V), fast-recovery diodes such as PMEG3010CEH are recommended to minimize losses and ensure reliable high-side gate drive under all load conditions.
LTC3789IUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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):
- 4V ~ 38V
- Frequency - Switching:
- 200kHz ~ 640kHz
- Duty Cycle (Max):
- 90%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3789IUFD#TRPBF FAQ
1.How can I place an order for LTC3789IUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3789IUFD#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 LTC3789IUFD#TRPBF reliable?
The price and inventory of LTC3789IUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3789IUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3789IUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3789IUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3789IUFD#TRPBF?
LTC3789IUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3789IUFD#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 LTC3789IUFD#TRPBF?
For technical support, including LTC3789IUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3789IUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3789IUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3789IUFD#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 LTC3789IUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3789IUFD#TRPBF?
All LTC3789IUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3789IUFD#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 LTC3789IUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3789IUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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