Exact device and ordering identity
UCD3138ARJAR is a programmable digital power controller in TI’s RJA 40-pin VQFN format, intended for isolated power supplies rather than a ready-to-use voltage regulator. Its digital feedback control, high-resolution PWM and fault handling can serve telecom rectifiers, server power conversion and other controlled isolated topologies. The RJA package and firmware requirements distinguish this orderable from 64-pin UCD3138A variants; an engineer cannot assume that a reference design for a 64-pin controller has identical external signals on the 40-pin board. The complete UCD3138ARJAR identity must be verified before PCB assembly.
Operating and control considerations
The manufacturer lists up to three independent digital feedback loops, up to eight DPWM outputs with 250-ps pulse-width resolution and a fast error-conversion path. Those are device peripheral capabilities, not a guarantee that each board can drive eight independent power phases with any topology. Hardware PID loops, fault comparators and dead-time controls reduce CPU intervention, while the programmable ARM core and PMBus/UART services still require verified firmware. Control resolution and switching frequency describe different timing dimensions. External current sensing, isolation barriers, synchronous-rectifier drivers and gate-drive topology determine real closed-loop performance and protection behavior.
Package, sourcing and engineering trade-offs
Compare exact package pin mapping, memory and firmware boot method, available DPWM/ADC pins, current-sense requirements, digital-loop compensation and fault response before using a UCD3138 or a generic digital PWM chip as a replacement. The A-suffix revision and RJA lead format are meaningful. A practical RFQ should identify UCD3138ARJAR, expected topology, switching frequency, power-stage drivers, firmware revision and approved package drawing. Without a verified firmware and interface migration plan, a related family controller is only a redesign candidate.
Manufacturer-verified selection specifications
| Selection parameter | TI-verified value | Engineering condition |
|---|---|---|
| Feedback | Digital Control of up to 3 Independent Feedback Loops | Refer to exact manufacturer operating conditions |
| Eadc | Up to 16 MHz Error Analog-to-Digital Converter (EADC) | Refer to exact manufacturer operating conditions |
| Dpwm | Up to 8 High-Resolution Digital Pulse Width Modulated (DPWM) Outputs | Output-pin and firmware mapping |
| Pwm resolution | 250-ps Pulse Width Resolution | Timing granularity, not ADC precision |
| Frequency | Up to 2-MHz Switching Frequency | Mode-dependent switching behavior |
| General adc | 14-Channel, 12-Bit, 267-ksps General-Purpose ADC | Refer to exact manufacturer operating conditions |
| Flash | 32 KB of Program Flash | Confirm firmware image layout |
| Catalog package | VQFN-40-EP(6×6) | Match exact TI mechanical drawing before footprint or replacement approval |
Procurement and datasheet
Request a quotation for UCD3138ARJAR using the complete orderable number, target quantity and package requirement. Stock, pricing and delivery timing require a direct RFQ confirmation; no on-page availability or price is promised. Source-listed alternative candidates, where present, are for engineering evaluation and do not establish drop-in compatibility.
