Analog Devices Inc. LT8708IUHG-1#TRPBF

Overview

LT8708IUHG-1#TRPBF from Analog Devices is a high-voltage synchronous 4-switch buck-boost DC/DC slave controller designed to parallel with the LT8708 master in multiphase systems. It operates as a synchronized slave, supports bidirectional conduction (forward/reverse VIN current), delivers up to 80V input/output capability, and enables scalable power delivery in automotive 48V and dual-battery systems.

For engineers reviewing the LT8708IUHG-1#TRPBF datasheet, LT8708IUHG-1#TRPBF pinout, LT8708IUHG-1#TRPBF application, or LT8708IUHG-1#TRPBF equivalent, this page provides verified pin functions, conduction-mode control thresholds (CCM/HCM/DCM), slave-specific current monitoring (IMON_INP/IMON_INN), and AEC-Q100-compliant thermal performance for automotive-grade design validation.

Technical Context

The LT8708IUHG-1#TRPBF implements identical conduction modes (CCM, HCM, DCM, Burst) as the LT8708 master and uses shared timing (SYNC/CLKOUT) and current command signals (ICP/ICN) to enforce proportional current sharing. Its DIR pin selects forward (VIN→VOUT) or reverse (VOUT→VIN) power flow under HCM/DCM operation, while MODE pin configures regulation mode via voltage thresholds (0.4V CCM, 0.8–1.2V HCM, 1.6–2.0V DCM).

It features dual independent VIN current limiting via IMON_INP (positive current) and IMON_INN (negative current), each with programmable thresholds (235–280mV rising, 185–235mV falling), and integrates gate drivers with 20ns rise/fall times, 80–90ns dead-time control, and 200ns minimum on/off times for M2/M3 switches - all validated across –40°C to 125°C junction temperature.

Key Specifications

Pinout & Package

LT8708IUHG-1#TRPBF is housed in a 40-lead (5mm × 8mm) plastic QFN package (UHG) with exposed GND pad (Pin 41) requiring PCB soldering for thermal and electrical integrity. Pin pitch is optimized for high-voltage spacing (≥0.3mm creepage/clearance).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8708EUHG-1#TRPBF, the LT8708IUHG-1#TRPBF adds AEC-Q100 compliance and automotive reliability data, while LT8708HUHG-1#TRPBF extends thermal margin to 150°C - both retain identical pinout, feature set, and slave-control architecture.

Availability

LT8708IUHG-1#TRPBF is available at Aetrix Electronics and suitable for automotive 48V systems, bidirectional battery chargers, and industrial DC UPS applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.

Supply support for LT8708IUHG-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.

The LT8708 product line delivers scalable, high-voltage buck-boost controllers for demanding power conversion applications - specifically engineered for automotive 48V architectures, bidirectional energy transfer, and multiphase power system expansion.

FAQ

What is the primary function of the LT8708IUHG-1#TRPBF in a power system?

The LT8708IUHG-1#TRPBF functions exclusively as a synchronized slave controller that parallels with the LT8708 master to increase total system power and current capability. It does not operate independently - it relies on the master for voltage regulation, frequency control, and current command signals (ICP/ICN). Its role is to replicate the master's behavior in an additional phase while maintaining precise current matching and bidirectional conduction capability.

How does the LT8708IUHG-1#TRPBF achieve current matching with the master LT8708?

The LT8708IUHG-1#TRPBF achieves current matching through analog current command signals: ICP and ICN pins receive voltage commands from the master LT8708 to set positive and negative output current limits. Combined with matched RT resistors, synchronized CLKOUT/SYNC timing, and identical conduction mode settings (via MODE and DIR pins), the LT8708IUHG-1#TRPBF regulates its phase current to track the master's average output current within tight tolerances across load and temperature.

Can the LT8708IUHG-1#TRPBF operate as a standalone controller without the LT8708 master?

No, the LT8708IUHG-1#TRPBF cannot operate as a standalone controller. It lacks autonomous voltage regulation circuitry - FBIN and FBOUT are intended to be disabled (tied to LDO33 and GND respectively), and VC is driven by the master. All critical control loops (voltage, current, timing) depend on signals from the master LT8708. Attempting standalone operation results in undefined behavior and no regulated output.

What are the key differences between the UHG (QFN) and LWE (eLQFP) packages for the LT8708-1 family?

The LT8708IUHG-1#TRPBF uses the 40-lead UHG QFN package (5mm × 8mm), offering θJA = 36°C/W and requiring soldered exposed pad for thermal management. The LWE eLQFP variant is 64-lead (10mm × 10mm) with lower θJA = 17°C/W but larger footprint and different pinout - incompatible with UHG PCB layouts. Both share identical electrical functionality, but UHG is optimized for space-constrained automotive modules, while LWE suits high-power industrial designs needing enhanced thermal dissipation.

Does the LT8708IUHG-1#TRPBF support burst mode operation, and how is it enabled?

Yes, the LT8708IUHG-1#TRPBF supports burst mode operation. It is enabled by setting the MODE pin voltage to ≥2.4V (typical threshold), which places the device in low-quiescent-current discontinuous mode during light loads. This feature reduces standby power consumption and improves light-load efficiency - particularly valuable in always-on automotive subsystems where battery drain must be minimized.