Texas Instruments TPS65235RUKT

Overview

TPS65235RUKT from Texas Instruments is a monolithic LNB voltage regulator with integrated I²C interface, boost converter, low-dropout linear regulator, and 22-kHz tone generator - designed specifically to power satellite LNBs and support DiSEqC 1.x/2.x communication. It delivers 13.4 V or 18.2 V output at up to 650 mA (±10% accuracy), features 1-MHz/500-kHz selectable switching frequency, 140-mΩ internal boost FET, and 0.44–1.2 V dropout across load and tone modes.

For engineers reviewing the TPS65235RUKT datasheet, TPS65235RUKT pinout, TPS65235RUKT application, or TPS65235RUKT equivalent, key selection considerations include DiSEqC-compliant tone generation (22 kHz or 44 kHz), programmable current limit via ISET resistor, dual-voltage output selection (VCTRL), thermal shutdown at 160°C, and fault diagnostics accessible over I²C including cable detection, tone status, and output voltage monitoring.

Technical Context

The TPS65235RUKT integrates a current-mode boost converter with cycle-by-cycle peak current limiting and a push-pull LDO stage that superimposes tone onto VLNB without external components. Its tone generation supports both internal 22-kHz oscillation and external 22/44-kHz input via EXTM, with configurable amplitude (650 mV or 750 mV) and duty cycle (45–55%).

DiSEqC compliance is implemented through dedicated circuitry: DIN/DOUT for tone detection, GDR for external MOSFET control in DiSEqC 2.x, and register-accessible diagnostics for cable integrity, tone presence, and output voltage validity. The device operates in either I²C-controlled or EN-pin direct mode, with I²C registers accessible even when EN = low.

Key Specifications

Pinout & Package

TPS65235RUKT uses a 20-lead WQFN package (3.0 mm × 3.0 mm, RUK suffix) with exposed thermal pad requiring PCB soldering and thermal vias for optimal junction temperature management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS65235RUKT, TPS65233RUKT removes tone generation and diagnostics to reduce cost and complexity, while MAX2105ETL+ offers a non-I²C, fixed-output alternative with no programmability - making TPS65235RUKT the only option supporting full DiSEqC 2.x, dual-voltage selection, and real-time cable/fault monitoring.

Availability

TPS65235RUKT is available at Aetrix Electronics and suitable for satellite set-top boxes, TV satellite receivers, PC card tuners, and multi-switch distribution systems requiring stable component supply, long-term lifecycle support, and DiSEqC-compliant LNB power delivery.

Supply support for TPS65235RUKT 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 ICs, with leadership in high-reliability, application-optimized solutions for industrial, automotive, and communications markets.

The TPS65235RUKT belongs to TI's satellite receiver power management product line, engineered specifically to consolidate LNB power, DiSEqC tone generation, and diagnostics into a single WQFN package for space-constrained, standards-compliant satellite front-end designs.

FAQ

What output voltages does the TPS65235RUKT support, and how are they selected?

The TPS65235RUKT supports two regulated output voltages: 13.4 V and 18.2 V. Selection is achieved either by logic level on the VCTRL pin (low = 13.4 V, high = 18.2 V) or via I²C register configuration. Both methods are valid simultaneously, with VCTRL taking precedence at power-up. The output remains stable across 0–650 mA load with ≤18.4 V maximum and ≥13.25 V minimum under all operating conditions specified in the datasheet.

How is the 22-kHz tone generated and controlled on the TPS65235RUKT?

The TPS65235RUKT generates the 22-kHz tone internally using a dedicated oscillator, which is superimposed onto the VLNB output via its push-pull LDO stage - ensuring clean waveform fidelity even at zero load. Tone activation is controlled by the EXTM pin: logic high enables internal tone, logic low disables it. Additionally, an external 22-kHz or 44-kHz signal applied to EXTM can be gated through, and the tone frequency (22 kHz or 44 kHz) is selected via I²C Control Register 1.

Can the TPS65235RUKT be used without I²C, and what functionality remains available?

Yes, the TPS65235RUKT operates fully in standalone mode using only the EN, VCTRL, and ISET pins. In this configuration, output voltage is set by VCTRL, current limit by ISET resistor, and tone enabled/disabled by EXTM. All protection features - thermal shutdown, overcurrent hiccup mode, UVLO, and fault indication via FAULT pin - remain active. I²C is optional and used only for diagnostics, fine-grained configuration, and overriding default behavior.

What is the purpose of the TCAP pin on the TPS65235RUKT, and how does it affect system performance?

TCAP sets the slew rate for voltage transitions between 13.4 V and 18.2 V on VLNB. A capacitor (e.g., 22 nF) connected to TCAP establishes a ~2-ms transition time, preventing abrupt steps that could cause LNB lock loss or DiSEqC command corruption. This controlled ramp ensures the boost converter tracks the LDO reference smoothly, avoids output droop during switching, and maintains tone integrity throughout the transition - critical for reliable DiSEqC 2.x burst signaling.

How does the TPS65235RUKT handle fault conditions such as overcurrent or thermal overload?

On overcurrent, the TPS65235RUKT clamps output current at the programmed ISET limit for 4 ms, then enters hiccup mode (off for 128 ms, then retry) unless reconfigured via I²C. Thermal shutdown triggers at 160°C junction temperature, disabling VLNB until die cools to ~140°C. During either fault, the FAULT pin pulls low and I²C registers remain readable - allowing host processors to identify root cause (e.g., cable short, overheating) without resetting the TPS65235RUKT.