Texas Instruments UCD3138RHAR

Overview

UCD3138RHAR from Texas Instruments is a highly integrated digital power controller for isolated DC-DC and AC-DC applications, featuring three independent PID-based digital control loops, 8 high-resolution DPWM outputs with 250-ps pulse width resolution, and a 31.25 MHz ARM7TDMI-S processor with 32 KB flash and 4 KB RAM. It supports voltage, peak/average current, constant current, and constant power modes for telecom rectifiers and PFC stages.

For engineers reviewing the UCD3138RHAR datasheet, UCD3138RHAR pinout, UCD3138RHAR application, or UCD3138RHAR equivalent, key selection criteria include DPWM timing resolution (4 ns frequency/phase), EADC resolution (as low as 1 mV/LSB), burst mode and ideal diode emulation for light-load efficiency, and support for phase-shifted full-bridge, LLC, and dual-phase PFC topologies.

Technical Context

The UCD3138RHAR implements three dedicated Digital Power Peripherals (DPPs), each integrating an error ADC, configurable 2-pole/2-zero digital compensator, and hardware-accelerated loop execution - enabling sub-microsecond closed-loop response. Its DPWM module delivers cycle-by-cycle duty matching and adjustable dead-band between complementary pairs, critical for ZVS/ZCS soft-switching in resonant converters.

It integrates a 12-bit, 267-ksps general-purpose ADC with programmable averaging filters and dual sample-and-hold, plus seven high-speed analog comparators with blanking and fault counting - all synchronized to the ARM core's real-time firmware for adaptive protection and dynamic mode switching between PWM, phase-shift, and frequency modulation.

Key Specifications

Pinout & Package

VQFN-40 package (6.00 mm × 6.00 mm) with exposed thermal pad; RoHS-compliant, lead-free finish; 0.5-mm pitch; designed for high-power density layouts with optimized thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital power controller applications.

Compared with UCD3138RGC, the UCD3138RHAR offers identical control loop performance and DPWM resolution in a smaller 40-pin package but trades off UART count and ADC channel count - making it optimal for space-constrained, cost-sensitive isolated DC-DC modules. Against UCD3138A64PFC, it provides broader topology support and full firmware programmability at the expense of PFC-specific analog enhancements.

Availability

UCD3138RHAR is available at Aetrix Electronics and suitable for telecom rectifiers, server PSUs, and isolated DC-DC modules requiring stable component supply, long-term lifecycle assurance, and production-ready qualification for industrial temperature operation.

Supply support for UCD3138RHAR 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 technologies, with decades of expertise in digital power control and energy-efficient system solutions.

The UCD3138 family was developed to replace analog controllers in high-performance isolated power supplies, delivering programmable flexibility, hardware-accelerated control loops, and integrated PMBus telemetry for next-generation data center and telecom infrastructure.

FAQ

What is the maximum DPWM switching frequency supported by the UCD3138RHAR?

The UCD3138RHAR supports DPWM operation up to 2 MHz. This specification is validated across the full –40°C to 125°C operating temperature range and enables compatibility with GaN and high-frequency SiC MOSFETs in resonant and hard-switched topologies. The 4-ns frequency resolution ensures precise timing control even at maximum switching rates, and the hardware-based cycle-by-cycle duty matching maintains symmetry under dynamic load conditions. All UCD3138RHAR units shipped meet this spec per TI's production test flow.

Does the UCD3138RHAR support peak current mode control?

Yes, the UCD3138RHAR supports peak current mode control using its dedicated EADC2 front-end, which is optimized for fast current sensing with adaptive blanking and comparator-based cycle-by-cycle limiting. Unlike generic ADC channels, EADC2 provides hardware-triggered sampling aligned to DPWM edges, enabling stable operation at >200 kHz with minimal external components. This capability is explicitly documented in the UCD3138RHAR datasheet Section 9.5 and confirmed in TI Application Report SLUA902.

How many independent feedback loops does the UCD3138RHAR implement, and are they fully configurable?

The UCD3138RHAR implements three independent, hardware-accelerated digital feedback loops - each with a dedicated EADC, configurable 2-pole/2-zero PID filter, and associated DPWM outputs. All loops support voltage mode, peak/average current mode, constant current, and constant power configurations via firmware registers. Loop parameters (gain, zero/pole locations, sample rate) are fully programmable in real time without CPU intervention, and nonlinear control features like burst mode and soft-start are applied per-loop. This architecture is detailed in the UCD3138RHAR Technical Reference Manual (SPRUH17).

What communication interfaces are available on the UCD3138RHAR?

UCD3138RHAR provides one PMBus/I²C interface and one UART (SCI) interface. The PMBus interface supports full v1.2 command set for telemetry, configuration, and fault logging; the UART supports asynchronous serial communication for firmware updates and debug. Unlike the 64-pin RGC variant, the 40-pin RHAR does not include a second UART. Both interfaces operate at 3.3-V logic levels and are electrically isolated from DPWM domains per TI's layout recommendations in SLUU375.

Is the UCD3138RHAR pin-compatible with other members of the UCD3138 family?

No, the UCD3138RHAR is not pin-compatible with UCD3138RGC (64-pin) or UCD3138RJA (40-pin with corner anchors). While all share the same functional blocks and register map, the RHAR uses a 40-pin VQFN package with specific pin assignments - including consolidated fault inputs and shared PMBus/UART pins - that differ from RGC's expanded I/O and RJA's mechanical anchor layout. Migration requires PCB redesign; however, firmware is binary-compatible across the family when using TI's Fusion Digital Power Designer software.