Texas Instruments UCC39002DGKR

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 implements Intel® SSI-compliant single-wire load-share bus with short-circuit protection. It is used in telecom rectifiers and server VRMs requiring precise current balancing.

For engineers reviewing the UCC39002 datasheet, UCC39002 pinout, UCC39002 application, or UCC39002 equivalent, key selection criteria include its ±100 µV current-sense offset, 75–90 dB CMRR, 4.175 V UVLO threshold, 8-pin VSSOP package (3.00 mm × 4.90 mm), and leader/follower auto-assignment architecture - all critical for stable multi-module current sharing in high-reliability distributed power systems.

Technical Context

The UCC39002 uses a transconductance error amplifier (g_M = 14 mS) to compare follower module current (via CSO) against leader module current (via LS bus), generating VEAO to drive the ADJ buffer. Its current-sense amplifier features rail-to-rail common-mode input (0 V to V_DD) and programmable gain ≥3, enabling shunt placement in either GND-return or positive output rail.

Load-share bus operation relies on a unity-gain LS driver with ideal-diode behavior inside the feedback loop, ensuring automatic leader election and isolation of follower modules. LS bus fault protection monitors V_LS against windows defined by V_CSO and V_VDD, disabling the controller if V_LS < (2/3 × V_CSO) or V_LS > (V_VDD − 0.7 V).

Key Specifications

Pinout & Package

UCC39002 is housed in an 8-pin VSSOP (DGK) package measuring 3.00 mm × 4.90 mm, with exposed pad optional per TI mechanical drawings. Pin functions are validated per SLUS495J Rev J (Dec 2023) Figure 4-1.

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 capability for lower cost and optimized commercial-server qualification; compared with UC3907, it adds fault protection, 5× lower offset, and SSI compliance - directly improving system reliability and reducing design validation effort.

Availability

UCC39002 is available at Aetrix Electronics and suitable for telecom rectifier systems, server VRM current sharing, industrial PLC power backplanes, and modular test equipment supplies requiring stable component supply and long-term production continuity.

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 servers, telecom infrastructure, and industrial distributed power architectures.

FAQ

What is the key functional difference between UCC39002 and UCC29002?

The UCC39002 and UCC29002 share identical electrical specifications, pinout, and functional behavior. The sole documented difference is operating temperature range: UCC39002 is rated for 0°C to 70°C, while UCC29002 extends to –40°C to 105°C. Both comply with Intel® SSI and use the same VSSOP-8 (DGK) package. UCC39002 is optimized for commercial-server applications where extended temperature is unnecessary.

Does UCC39002 support high-side current sensing, and what are the layout constraints?

Yes, UCC39002 supports high-side current sensing via CS+ and CS− inputs, which feature a rail-to-rail common-mode range (0 V to V_DD). When placing R_SHUNT in the positive output rail, ensure CS− does not exceed V_DD + 0.3 V. To disable the device in high-side configuration, pull CS+ at least 0.5 V below CS− - not vice versa - to avoid violating absolute maximum ratings on CS−.

How many modules can be connected to the UCC39002 load-share bus?

The UCC39002 LS bus supports up to approximately 10 modules under typical conditions. This limit derives from the LS driver's minimum output current (–1.5 mA) and the 100 kΩ input impedance of each follower's LS pin, per Equation 1 in the datasheet. Reducing full-scale LS voltage (e.g., via lower current-sense gain) increases node count but degrades current-sharing accuracy; verify system-level performance with worst-case gain and offset tolerances.

What happens to the UCC39002 during a load-share bus short circuit?

When the UCC39002 detects a short on the LS bus - defined as V_LS < (2/3 × V_CSO) or V_LS > (V_VDD − 0.7 V) - the internal fault comparator asserts, triggering the Start-Up and Adjust Logic block to disable the LS bus driver and force ADJ sink current to zero. This isolates the faulty bus, prevents erroneous voltage adjustment, and maintains safe operation of the local power module.

Is UCC39002 pin-compatible with UC3907, and can it be used as a direct replacement?

UCC39002 is not pin-compatible with UC3907. Although both are 8-pin load-share controllers, UC3907 uses SOIC-8 (D) packaging with different pin assignments (e.g., UC3907 pin 1 is V_REF, while UCC39002 pin 1 is CS−). Electrical differences - including ±500 µV vs ±100 µV current-sense offset, absence of LS bus protection, and no integrated UVLO hysteresis in UC3907 - require PCB redesign and loop compensation revalidation. UCC39002 is a next-generation upgrade, not a drop-in replacement.