Texas Instruments UCD9081RHBR

Overview

UCD9081 from Texas Instruments is an 8-channel digital power supply sequencer and monitor IC with integrated 10-bit SAR ADC, I²C interface, on-chip flash memory, and error logging capability. It sequences up to eight voltage rails using programmable timing or rail-regulation dependencies, monitors each rail with 3.2-mV resolution, and supports four configurable general-purpose outputs (GPOs). It operates from a single 3.3-V supply and is used in telecom switches, servers, and networking equipment for reliable multi-rail power-up/down control.

For engineers reviewing the UCD9081 datasheet, UCD9081 pinout, UCD9081 application, or UCD9081 equivalent, key selection considerations include rail sequencing flexibility (timeline/parent-rail-triggered), per-rail undervoltage/overvoltage thresholds with glitch filtering, flash-based configuration persistence, I²C-configurable alarm response (log/retry/sequence/shutdown), and integrated 10-bit analog monitoring without external reference dependency.

Technical Context

The UCD9081 implements a deterministic, event-driven sequencing engine that supports four sequencing modes: fixed delay after reset, delay after parent rail regulation, delay after parent rail voltage threshold, or no sequencing. Each of its eight MONx inputs feeds a 10-bit SAR ADC with selectable internal (2.5 V ±100 ppm/°C) or external (VCC-derived) reference, enabling rail voltage measurement with ±12.2 mV total unadjusted error.

Its eight ENx outputs and four GPOs (multiplexed with I²C address pins) are fully configurable for active-high/active-low polarity and support independent shutdown timing (0–4095 ms). Alarm processing per rail includes ignore, log-only, retry (0–4×), continuous retry, immediate sequence, or sequence-after-shutdown - all stored in nonvolatile flash with timestamped error logging for failure analysis.

Key Specifications

Pinout & Package

VQFN-32 (RHB) package, 5.0 mm × 5.0 mm body size, with exposed PowerPAD™ thermally connected to VSS. Pin count and layout optimized for compact multi-rail power management in space-constrained telecom and server PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power supply sequencing applications.

Compared with UCD9081, UCD90160RGZR offers greater channel density and precision at the cost of footprint and complexity, while TPS65400RGER trades configurability and diagnostics for integration and cost-making UCD9081 optimal for mid-complexity, field-serviceable systems requiring traceable power health data.

Availability

UCD9081 is available at Aetrix Electronics and suitable for telecom switches, servers, and networking equipment requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for UCD9081 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 high-reliability power control ICs.

The UCD9081 belongs to TI's digital power sequencer product line, designed specifically for complex, multi-rail systems in communications infrastructure and enterprise computing where deterministic sequencing, fault resilience, and field-diagnostic capability are critical.

FAQ

What is the primary function of the UCD9081 in a power management system?

The UCD9081 serves as a dedicated 8-channel digital power supply sequencer and monitor. It controls the timing and order of voltage rail enablement, continuously monitors rail voltages via its 10-bit SAR ADC, detects undervoltage/overvoltage faults, logs errors to on-chip flash, and executes configurable responses-including shutdown propagation and retry sequences. Its role is to ensure safe, repeatable, and diagnosable power-up/down behavior in complex electronic systems.

Does the UCD9081 require an external crystal or clock source to operate?

No, the UCD9081 does not require an external crystal or clock source. It contains an internal oscillator whose frequency is adjusted via the ROSC pin, which must be pulled up to VCC with a 100-kΩ resistor for minimum drift and maximum sampling accuracy. The XIN pin is internally tied to VCC and is not used for external clock input-eliminating BOM cost and layout complexity associated with external timing components.

How many independent voltage rails can the UCD9081 monitor and sequence, and what is the resolution?

The UCD9081 can monitor and sequence exactly eight independent voltage rails using its MON1–MON8 analog inputs and EN1–EN8 digital outputs. Voltage measurement resolution is 3.2 mV per LSB, achieved through its integrated 10-bit SAR ADC with selectable internal (2.5 V) or external (VCC-derived) reference-providing sufficient accuracy to validate ±1% tolerances on common 1.2-V to 5-V rails.

Can the UCD9081 store its configuration permanently, and how is it updated?

Yes, the UCD9081 stores its full configuration-including rail thresholds, sequencing delays, alarm actions, and GPO settings-in on-chip nonvolatile flash memory. Configuration is updated via the I²C interface using TI's Windows-based GUI tool, which generates and downloads register maps. Flash retention is rated for 100 years at 25°C, ensuring configuration integrity across power cycles and long-term deployment without battery backup.

What are the key differences between the ENx pins and the GPOx pins on the UCD9081?

The UCD9081 has eight ENx pins (EN1–EN8) dedicated to controlling power supply enable inputs, and four GPOx pins (GPO1–GPO4) usable for general-purpose digital signaling. EN8 is multiplexed with GPO1 and ADDR1; ADDR2–ADDR4 are similarly multiplexed with GPO2–GPO4. All eight ENx outputs support independent polarity configuration and high-impedance state during reset, while GPOs share the same sequencing engine and timing logic-allowing them to be synchronized with rail enables for functions like processor reset assertion or status flag generation.