Texas Instruments TPS65121RGTTG4

Overview

TPS65121RGTTG4 from Texas Instruments is a single-inductor quadruple-output DC-DC converter for a-Si and LTPS TFT-LCD displays, delivering independently regulated VMAIN (3.0–5.3 V/25 mA), VGH (up to 20 V/2 mA), VGL (down to −18 V/2 mA), and a fixed 1.8 V auxiliary LDO output. It operates from 2.7–5.5 V input, features automatic power sequencing, and achieves up to 83% core converter efficiency.

For engineers reviewing the TPS65121RGTTG4 datasheet, TPS65121RGTTG4 pinout, TPS65121RGTTG4 application, or TPS65121RGTTG4 equivalent, key selection criteria include its integrated power sequencing logic, post-regulated low-ripple VMAIN (5 mV_P-P), ±0.8% VMAIN accuracy, and QFN-16 (3 × 3 × 0.9 mm) package with exposed thermal pad.

Technical Context

The TPS65121RGTTG4 uses a free-running variable peak-current PWM control scheme to time-multiplex a single inductor across BOOT, VGH, and VGL outputs at ~4 MHz pseudo-fixed frequency. Its architecture enables fast transient response while maintaining high efficiency across wide input/output voltage ranges.

VMAIN is post-regulated via an integrated LDO stage with 130 mV dropout at 10 mA, minimizing ripple to 5 mV_P-P. Fault protection includes cycle-by-cycle current limiting (150 mA typ), UVLO (2.15 V falling), and latched shutdown on sustained output faults (>100 µs).

Key Specifications

Pinout & Package

TPS65121RGTTG4 is housed in a thermally enhanced 3 × 3 × 0.9 mm QFN-16 package with exposed thermal die pad (Pin 14). The package supports high-power-density layout and efficient PCB heat dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TFT LCD power management applications.

Compared with TPS65121RGTTG4, TPS65120RGT provides identical functionality but targets 3.3 V logic systems, while TPS65123RGT removes the 1.8 V LDO entirely-offering lower cost and thermal density when that rail is externally supplied.

Availability

TPS65121RGTTG4 is available at Aetrix Electronics and suitable for smartphone LCD power management, portable GPS display supply, digital still camera viewfinder, and handheld medical instrument display requiring stable component supply and long-term production continuity.

Supply support for TPS65121RGTTG4 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 ICs with broad automotive, industrial, and consumer design expertise.

The TPS6512x product line was designed specifically for compact, high-efficiency power solutions in portable a-Si and LTPS TFT-LCD displays-integrating sequencing, regulation, and protection in a single QFN package.

FAQ

What is the primary function of the TPS65121RGTTG4 in a TFT-LCD system?

The TPS65121RGTTG4 serves as a complete single-chip power supply for a-Si and LTPS TFT-LCD panels, generating four regulated rails: VMAIN (3.0–5.3 V) for source drivers, VGH (up to 20 V) and VGL (down to −18 V) for gate drivers, and a fixed 1.8 V auxiliary LDO for timing controller logic-all with automatic power sequencing. Its integrated architecture eliminates discrete DC-DC converters and linear regulators in space-sensitive portable displays.

How does the TPS65121RGTTG4 achieve low output ripple on the VMAIN rail?

The TPS65121RGTTG4 achieves 5 mV_P-P VMAIN ripple through post-regulation: the main switching stage generates a BOOST voltage, which is then fed into an integrated low-dropout linear regulator (LDO) stage. This LDO provides tight regulation (±0.8% accuracy) and filters high-frequency switching noise, making it suitable for noise-sensitive TFT source driver biasing.

What are the absolute maximum ratings for the VGH and VGL outputs of the TPS65121RGTTG4?

The absolute maximum rating for VGH is +21 V, and for VGL it is −18 V. These limits are defined relative to network ground and must not be exceeded under any condition-including transients-to prevent permanent device damage. Operating specifications recommend VGH ≤20 V and VGL ≥−18 V for reliable performance across −40°C to +85°C ambient.

Does the TPS65121RGTTG4 support programmable power sequencing like the TPS65124?

No-the TPS65121RGTTG4 implements fixed automatic power sequencing (VGL → VGH → VMAIN) controlled internally by EN and RUN pins. Unlike the TPS65124, it lacks separate ENVGH and ENVGL enable inputs and cannot be reconfigured for custom sequencing order or independent output control. Its sequencing behavior is hardwired per TI SLVS531A specification.

What thermal management considerations apply to the TPS65121RGTTG4 in high-power operation?

The TPS65121RGTTG4 uses a QFN-16 package with an exposed thermal die pad (Pin 14) and has a junction-to-ambient thermal resistance (R_θJA) of 68°C/W. For continuous 120 mW total output power, PCB layout must include adequate copper area under the pad, multiple thermal vias to inner ground planes, and airflow or heatsinking if ambient exceeds 60°C-ensuring junction temperature stays below the 135°C maximum.