Texas Instruments UCC39002DR

Overview

UCC39002 from Texas Instruments is an advanced 8-pin BiCMOS load-share controller for paralleling DC-DC modules and power supplies in N+1 redundant systems. It delivers <1% current-share error at full load, supports high-side or low-side current sensing via ultra-low-offset amplifier (±100 µV), and complies with Intel® SSI load-share specification. Used in telecom rectifiers and server VRMs to balance output current across multiple converters.

For engineers reviewing the UCC39002 datasheet, UCC39002 pinout, UCC39002 application, or UCC39002 equivalent, key selection criteria include its single-wire load-share bus architecture, ±100 µV current-sense offset, 4.575–13.5 V operating supply range, and VSSOP-8 package compatibility with space-constrained distributed power designs.

Technical Context

The UCC39002 implements automatic leader/follower architecture using a transconductance error amplifier (g_M = 14 mS) and a post-package-trimmed current-sense amplifier with 75–90 dB CMRR and 2 MHz GBW. Its differential CSA inputs support common-mode range from 0 V to V_DD, enabling shunt placement in either GND-return or positive output rail-provided V_OUT ≤ V_DD.

Load-share bus operation relies on a unity-gain LS driver with ideal-diode behavior inside the feedback loop, allowing dynamic leadership assignment. The LS receiver includes a 15 kHz filter and 100 kΩ input impedance to prevent bus loading, while fault protection monitors V_LS against windows defined by V_VDD − 0.7 V and (2/3) × V_CSO.

Key Specifications

Pinout & Package

UCC39002 is packaged in an 8-pin VSSOP (DGK) measuring 3.00 mm × 4.90 mm, optimized for high-density PCB layouts in telecom and server power systems.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar load-share controller applications.

Compared with UCC29002, the UCC39002 trades extended temperature rating for lower cost and commercial-grade qualification, while UC3907 requires additional components to achieve basic LS bus robustness - making UCC39002 optimal for new 0°C–70°C telecom and server designs prioritizing integration and accuracy.

Availability

UCC39002 is available at Aetrix Electronics and suitable for telecom rectifiers, server VRMs, and industrial PLC power supplies requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for UCC39002 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of heritage in high-reliability power control solutions.

The UCC39002 belongs to TI's advanced load-share controller product line, designed specifically for N+1 redundant DC-DC systems in telecom infrastructure and enterprise computing where precision current balancing and bus fault resilience are mandatory.

FAQ

What is the maximum number of UCC39002 devices that can share a single load-share bus?

The UCC39002 load-share bus supports up to approximately 10 modules when using standard 100 kΩ input impedance and full-scale LS voltage of 10 V, based on its minimum LS driver output current of –1.5 mA. This assumes identical gain settings and matched current-sense amplifiers across all modules. For higher counts, reduce current-sense amplifier gain - though this degrades current-share accuracy below 1%. Always verify bus voltage swing and noise margin in final layout.

Does UCC39002 support high-side current sensing in 48 V telecom systems?

Yes, UCC39002 supports high-side current sensing in 48 V systems, but the CS+ and CS− pins must remain within their absolute maximum rating of V_VDD + 0.3 V. Since V_VDD is limited to 13.5 V, direct connection to 48 V is unsafe. Instead, place the shunt in the GND-return path - which is explicitly supported and recommended in the datasheet for high-voltage applications to avoid level-shifting errors and maintain accuracy.

How does UCC39002 handle load-share bus faults such as short-to-ground?

UCC39002 continuously monitors the LS bus with an internal window comparator. If V_LS falls below (2/3) × V_CSO or rises above V_VDD − 0.7 V, the LS-bus FAULT signal triggers immediate disablement of the LS driver and forces ADJ current to zero. This prevents erroneous voltage adjustment and isolates the faulty node - a key requirement for Intel® SSI compliance and system-level fault containment in redundant power architectures.

What is the functional difference between UCC39002 and UCC29002-1?

The UCC39002 and UCC29002-1 differ only in start-up behavior: UCC39002 forces maximum ADJ current at startup to rapidly elevate output voltage and engage load sharing, while UCC29002-1 allows ADJ current to scale gradually with VEAO, resulting in slower, smoother current ramp-up. Both share identical pinout, electrical specs, temperature range (0°C–70°C), and fault response - making UCC39002 preferable for fast-turn-on systems and UCC29002-1 for noise-sensitive or soft-start-critical applications.

Can UCC39002 be used with power supplies lacking remote-sense capability?

UCC39002 requires remote-sense capability to function correctly, as its ADJ pin sinks current into the feedback network (typically across R_SENSE and R_ADJ) to adjust output voltage. Without remote-sense terminals, there is no dedicated path to inject the ADJ current without disrupting regulation. The datasheet explicitly states use "in conjunction with the internal feedback E/A of OEM power supply units" - confirming dependency on accessible error amplifier nodes or sense lines. Non-remote-sense PSUs are incompatible.