Texas Instruments UCC39002D

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 power shelves to balance output current across multiple modules.

For engineers reviewing the UCC39002 datasheet, UCC39002 pinout, UCC39002 application, or UCC39002 equivalent, key selection criteria include its single-wire load-share bus architecture, ±0.375 V UVLO hysteresis, 75–90 dB CMRR, 2 MHz gain-bandwidth product, and support for both SOIC and VSSOP packages - critical for thermal management and board space constraints in high-density power systems.

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 0 V to V_DD common-mode range. Its load-share bus driver operates as a unity-gain buffer with ideal-diode behavior, enabling dynamic leadership assignment among parallel modules without fixed master designation.

Start-up mode forces ADJ pin sink current to maximum (3.95 mA typical) until V_CSO exceeds 80% of V_LS, ensuring rapid current engagement. LS bus protection includes window comparator fault detection (V_LS < 2/3 × V_CSO or V_LS > V_VDD − 0.7 V), triggering automatic disconnect from the bus.

Key Specifications

Pinout & Package

UCC39002 is available in 8-pin VSSOP (DGK) package (3.00 mm × 4.90 mm) and 8-pin SOIC (D) package (4.90 mm × 6.00 mm), both RoHS-compliant and lead-free assembly ready.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC29002, UCC39002 trades extended temperature rating for lower unit cost and tighter commercial qualification; compared with UC3907, it integrates sensing, protection, and bus driving into a single 8-pin package - reducing layout complexity and improving current-match repeatability across production batches.

Availability

UCC39002 is available at Aetrix Electronics and suitable for telecom rectifier systems, server power shelves, and industrial PLC backplanes requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.

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 company specializing in analog, embedded processing, and power management technologies, with decades of leadership in power conversion ICs.

The UCC39002 belongs to TI's advanced load-share controller product line, designed specifically for high-reliability N+1 redundant power systems in datacenter, telecom, and industrial infrastructure where precise current balancing and bus fault resilience are mandatory.

FAQ

What is the primary function of the UCC39002 in a multi-module power system?

The UCC39002 serves as a load-share controller that dynamically balances output current across two or more parallel DC-DC modules or AC-DC power supplies. It achieves this by measuring each module's output current via an external shunt resistor, amplifying the signal, and using a single-wire load-share bus to coordinate adjustments through the ADJ pin - ensuring <1% current imbalance at full load in systems like telecom rectifiers and server power shelves.

Does the UCC39002 support both high-side and low-side current sensing configurations?

Yes, the UCC39002 supports both high-side and low-side current sensing thanks to its current-sense amplifier's 0 V to V_DD common-mode input range. When placed in the GND return path (low-side), CS− connects to shunt ground and CS+ to shunt output; for high-side placement, CS+ connects to V_OUT and CS− to shunt output - with design constraints limiting CS− to ≤0.3 V above V_DD in that configuration.

How does the UCC39002 handle load-share bus faults such as short-to-rail conditions?

The UCC39002 continuously monitors the LS bus voltage using an internal window comparator. If V_LS falls below 2/3 × V_CSO or rises above V_VDD − 0.7 V, the device asserts a fault condition, disables the LS bus driver, and forces the ADJ pin current to zero - effectively isolating the module from the bus and preventing erroneous voltage adjustment. This protection is active during normal operation and start-up.

What is the difference between UCC39002 and UCC29002 beyond temperature rating?

UCC39002 and UCC29002 share identical electrical specifications, pinout, functional behavior, and start-up logic. The only differences are operating temperature range (UCC39002: 0°C to 70°C; UCC29002: –40°C to 105°C) and orderable part numbering. Both comply with Intel® SSI and deliver <1% current-share accuracy - making UCC39002 the commercial-grade variant optimized for cost-sensitive server and telecom applications.

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

No - the UCC39002 requires remote-sense capability to inject correction current via the ADJ pin into the feedback network of the controlled power supply. It sinks current proportional to the error voltage (VEAO) and applies it across the adjust resistor (RADJ) and remote-sense resistor (RSENSE), thereby modulating the output voltage setpoint. Without a remote-sense path, the ADJ signal cannot influence regulation accuracy, rendering UCC39002 nonfunctional in such configurations.