Texas Instruments TPS65121RGTT

Overview

TPS65121RGTT from Texas Instruments is a single-inductor quadruple-output DC-DC converter for amorphous-silicon and LTPS TFT-LCD displays. It delivers 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, with post-regulated <5 mV_P-P ripple on VMAIN and ±0.8% typical accuracy. It serves as the core power supply in compact portable LCD systems.

For engineers reviewing the TPS65121RGTT datasheet, TPS65121RGTT pinout, TPS65121RGTT application, or TPS65121RGTT equivalent, key selection criteria include its 4.0 MHz switching frequency, integrated automatic power sequencing, QFN-16 (3 × 3 × 0.9 mm) package, −40°C to +85°C operating range, and compatibility with low-profile 8.2–10 µH inductors in space-constrained handheld designs.

Technical Context

The TPS65121RGTT employs a free-running variable peak-current PWM control scheme that time-multiplexes a single inductor between BOOT, VGH, and VGL outputs using pseudo-fixed-frequency operation. This architecture enables fast transient response while maintaining high efficiency (up to 83%) across 2.7–5.5 V input and wide output voltage ranges.

VMAIN is post-regulated via an integrated LDO stage to achieve low ripple (<5 mV_P-P) and tight regulation (±0.8% typical), while VGH and VGL are independently regulated through feedback pins FBH (1.213 V reference) and FBL (0 V reference). The device includes internal current limiting (150 mA typical P-MOS1 limit), UVLO (2.15 V falling threshold), and fault detection with latched shutdown.

Key Specifications

Pinout & Package

The TPS65121RGTT is housed in a 3 mm × 3 mm × 0.9 mm QFN-16 package with an exposed thermal die pad. Pin 1 is marked by a dot; pins are numbered counterclockwise starting from top-left corner when viewed from top.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS65120RGTT and TPS65123RGTT, the TPS65121RGTT uniquely provides both adjustable VMAIN (3.0–5.3 V) and integrated 1.8 V LDO output-making it optimal for new designs requiring flexibility in source driver voltage and self-contained logic power without external regulators.

Availability

TPS65121RGTT is available at Aetrix Electronics and suitable for smartphone LCD power management, portable GPS display supply, digital still camera backlight panels, and handheld medical instrument displays requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for TPS65121RGTT 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 for industrial, automotive, and consumer applications.

The TPS65121RGTT belongs to TI's TFT-LCD power supply product line, engineered specifically to consolidate multiple display rail generators into a single compact IC for space-constrained portable electronics.

FAQ

What is the maximum output current capability of the TPS65121RGTT on its VMAIN rail?

The TPS65121RGTT delivers up to 25 mA on VMAIN when VMAIN ≤ 5.3 V, and 7.5 mA when VMAIN ≥ 5.3 V. This is specified under conditions of VIN = 2.7–5.5 V and TA = −40°C to +85°C. The post-regulated LDO stage ensures <5 mV_P-P ripple at full load, making TPS65121RGTT suitable for noise-sensitive LCD source drivers in portable devices.

Does the TPS65121RGTT support programmable power sequencing like the TPS65124RGTT?

No, the TPS65121RGTT implements fixed automatic power sequencing-not programmable sequencing. It powers VGL first, then VGH after VGL reaches 90% of target, and finally enables VMAIN after VGH stabilizes. In contrast, TPS65124RGTT uses dedicated ENVGL/ENVGH pins for user-defined sequencing. TPS65121RGTT is optimized for standard a-Si/LTPS panels requiring this specific order.

What is the purpose of the GATE pin on the TPS65121RGTT, and how is it used?

The GATE pin on the TPS65121RGTT is an open-drain output that drives the gate of an external P-channel MOSFET (e.g., in Figure 18). When RUN is high, GATE is pulled low via an internal 100 kΩ resistor to turn on the MOSFET and initiate converter startup. During shutdown, GATE is pulled to VIN to ensure clean turn-off. Leaving GATE floating is prohibited-it must be terminated.

Can the TPS65121RGTT generate a 3.3 V VMAIN output, and what is its regulation accuracy?

Yes, the TPS65121RGTT supports VMAIN from 3.0 V to 5.3 V via external resistor divider on FBM. At 3.3 V output, regulation accuracy is ±0.8% typical (±1.5% max over temperature and line/load), based on the 1.213 V internal reference and feedback network tolerance. This meets stringent requirements for LCD source driver bias stability.

How does the TPS65121RGTT handle short-circuit conditions on VGH or VGL outputs?

The TPS65121RGTT monitors VGH and VGL continuously. If either output drops below its fault threshold for >100 µs (typical fault timer), the device simultaneously disables all outputs (VMAIN, VGH, VGL, LDOOUT) and enters a latched shutdown state. Recovery requires toggling EN/RUN below 0.4 V or cycling VIN below the 2.15 V UVLO threshold-ensuring robust protection in field deployments.