Texas Instruments TPS61187RTJT

Overview

TPS61187 from Texas Instruments is a white-LED driver IC for notebook LCD backlight systems, integrating a 40-V/2-A boost regulator, six 30-mA current sinks, adaptive output voltage regulation up to 38 V, programmable switching frequency (300 kHz–1 MHz), and dual PWM dimming modes (phase-shift and direct). It delivers precise current matching (±1.5% typ) and supports up to 60 WLEDs in parallel strings.

For engineers reviewing the TPS61187 datasheet, TPS61187 pinout, TPS61187 application, or TPS61187 equivalent, key selection considerations include input voltage range (4.5–24 V), IFB current sink accuracy, RFPWM/MODE pin configuration for dimming mode selection, thermal performance (R_θJA = 39.9°C/W), and integrated open/short LED protection.

Technical Context

The TPS61187 employs current-mode control in its fixed-frequency boost regulator with integrated loop compensation and automatic output voltage adjustment to match the lowest IFB pin voltage (350 mV threshold). Its six independent current sinks are regulated using internal reference and feedback, enabling high-precision string current control across temperature (±2.3% max error).

Dimming is implemented via two distinct modes: phase-shift PWM (resistor-programmed FDIM from 100 Hz to 22 kHz) or direct PWM (100 Hz–50 kHz), selected by pulling RFPWM/MODE to VDDIO or grounding through a resistor. The device decodes external PWM duty cycle into an 8-bit register for reconstruction across all channels with ±1/256 duty resolution hysteresis.

Key Specifications

Pinout & Package

TPS61187 is housed in a 20-pin WQFN package (RTJ) with 4.0 mm × 4.0 mm body and exposed thermal pad. The package supports high-power dissipation (R_θJB = 9.9°C/W) when the thermal pad is soldered to a PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar WLED driver applications.

Compared with TPS61187, TPS61183RTWR provides pin-compatible scaling down for smaller panels, while LM3409QMH/NOPB trades integration for design flexibility - making TPS61187 optimal for mid-to-large notebook backlight systems prioritizing compactness and time-to-market.

Availability

TPS61187 is available at Aetrix Electronics and suitable for notebook backlight design, industrial HMI displays, and medical imaging equipment requiring stable component supply, long-lifecycle support, and guaranteed traceability.

Supply support for TPS61187 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 display power solutions.

The TPS61187 belongs to TI's WLED backlight driver product line, engineered specifically for high-efficiency, low-noise, and thermally robust notebook and portable display applications.

FAQ

What is the maximum number of white LEDs the TPS61187 can drive?

The TPS61187 supports up to 60 white LEDs arranged across six parallel strings (10 LEDs per string typical), assuming 3.2–3.6 V forward voltage per LED and 38 V maximum output. Total string count depends on forward voltage sum staying below 38 V - e.g., 11 LEDs × 3.4 V = 37.4 V is within limit. The TPS61187 regulates each string independently via its six IFB inputs, and the boost output adapts to the highest string voltage requirement.

How does the TPS61187 achieve 10000:1 dimming ratio?

The TPS61187 achieves 10000:1 dimming ratio in direct PWM mode at 200 Hz by precisely controlling the on/off timing of all six current sinks synchronously with the external PWM signal. This relies on fast turn-on/turn-off capability of the internal 2-A MOSFET and low-latency current sink response. The TPS61187 maintains regulation fidelity even at 0.01% duty cycle due to accurate ISET programming and stable IFB feedback loop - confirmed in datasheet Figure 2 across full dimming range.

Can the TPS61187 operate without connecting unused IFB pins?

Yes - the TPS61187 supports unused IFB pins left open or shorted to ground. During startup, it sources ~40 µA per IFB pin for 4 ms and measures voltage; any pin reading <600 mV is disabled from the boost control loop. TI recommends shorting unused IFB pins to ground for faster startup and improved noise immunity. Leaving them open is acceptable but may slightly increase start-up time or susceptibility to EMI on floating nodes - both configurations are validated in the TPS61187 datasheet Section 7.3.5.

What is the role of the RFPWM/MODE pin in TPS61187 operation?

The RFPWM/MODE pin selects between phase-shift PWM dimming (resistor-to-ground) and direct PWM dimming (tied to VDDIO). In phase-shift mode, it sets the dimming frequency (e.g., 9.09 kΩ → 20 kHz); in direct mode, it disables internal frequency generation and passes the external PWM signal unchanged to all sinks. The pin is noise-sensitive at high impedance, so TI recommends adding ≤33 pF bypass capacitance if routing is long or noisy - a detail specified in Section 7.4.3 of the TPS61187 datasheet.

Does the TPS61187 require external compensation components?

No - the TPS61187 integrates full loop compensation for its current-mode boost regulator. TI specifies stable operation with recommended external components: 10–22 µH inductor (for 600–1000 kHz), 2.2 µF input capacitor, and 4.7 µF output capacitor. No external compensation network (e.g., RCZ, pole-zero) is needed, simplifying design and reducing board space. This is explicitly stated in Section 7.3.2 and validated in the Typical Application schematic (Figure 2) of the TPS61187 datasheet.