Texas Instruments TPS61042DRBRG4

Overview

TPS61042DRBRG4 from Texas Instruments is a constant-current, high-frequency boost LED driver IC with integrated 30 V/500 mA main switch (Q1) and 60 mA LED switch (Q2), regulating LED current via external sense resistor RS to 252 mV (typ) at FB pin; supports 1.8 V–6 V input, up to 27.5 V output, and PWM brightness control (100 Hz–50 kHz) for white LED backlighting in portable displays.

For engineers reviewing the TPS61042DRBRG4 datasheet, TPS61042DRBRG4 pinout, TPS61042DRBRG4 application, or TPS61042DRBRG4 equivalent, key selection considerations include its dual-switch architecture (SW + LED pins), OVP-triggered shutdown at 27.5–30 V, 38 µA no-load quiescent current, 85% typical efficiency at 4-LED load, and QFN-8 (3 mm × 3 mm) thermal-pad package requiring GND-connected exposed die pad.

Technical Context

The TPS61042DRBRG4 implements pulse-frequency modulation (PFM) with peak-current control (500 mA typ ILIM) and discontinuous conduction mode (DCM) operation, where switching frequency varies with LED current, input voltage, and inductor value-enabling stable regulation without external compensation. Its feedback loop regulates voltage across RS to 252 mV (244–260 mV over temp), not output voltage, making LED current independent of VIN and LED count.

Two internal MOSFETs operate independently: Q1 (SW pin) handles boost conversion with 300–600 mΩ rds(on); Q2 (LED pin) acts as series current-path switch with 1–2 Ω rds(on), disconnecting LEDs from GND during shutdown (CTRL = GND ≥32 ms) to eliminate leakage. Overvoltage protection triggers at 27.5–30 V (OVP pin), disabling Q1 until voltage falls below hysteresis threshold (5–7 V).

Key Specifications

Pinout & Package

TPS61042DRBRG4 uses an 8-pin SON (DRB) package with 3.00 mm × 3.00 mm body and exposed thermal die pad connected to GND per datasheet Figure 6. Pin numbering follows top-view layout with pin 1 at top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with TPS61042DRBRG4, TPS61040DRBR sacrifices OVP protection and output headroom for cost reduction, while MAX1910EUT+T trades integrated dimming simplicity for higher current capacity and fixed OVP-making TPS61042DRBRG4 optimal for compact, safety-aware, multi-mode dimming designs.

Availability

TPS61042DRBRG4 is available at Aetrix Electronics and suitable for smartphone backlighting, handheld medical display illumination, PDA sidelite systems, and industrial HMI panels requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for TPS61042DRBRG4 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-efficiency DC/DC conversion and LED lighting solutions.

The TPS6104x family was designed specifically for space-constrained portable backlight applications, emphasizing ultra-low quiescent current, integrated safety features, and flexible dimming-targeting battery-powered consumer and industrial displays.

FAQ

What is the maximum number of white LEDs the TPS61042DRBRG4 can drive in series?

The TPS61042DRBRG4 supports up to 27.5 V output, sufficient for eight standard white LEDs (3.4 V forward voltage each) in series. Real-world count depends on actual LED V_F variation and minimum input voltage; at 1.8 V input and 3.3 V average V_F, it reliably drives 6–7 LEDs. The device's OVP protection activates at 27.5–30 V to prevent damage if fewer LEDs are connected or an open-circuit fault occurs.

How does the TPS61042DRBRG4 achieve LED current regulation without a current-sense amplifier?

The TPS61042DRBRG4 uses direct feedback regulation: the FB pin senses voltage across the external sense resistor R_S and compares it to an internal 252 mV reference. When V_FB falls below 252 mV, the boost converter increases duty cycle to raise LED current until V_FB = 252 mV, yielding I_LED = 0.252 V / R_S. This eliminates external amplifiers, reduces BOM count, and maintains ±1% accuracy over temperature and line.

Can the TPS61042DRBRG4 operate with a 100 nF output capacitor, and what is the trade-off?

Yes, the TPS61042DRBRG4 is specified to operate with output capacitors as low as 100 nF, enabling ultra-compact designs. However, smaller CO increases LED ripple current and degrades line regulation. Using 1 µF or larger CO (as in Figure 17) reduces ripple by >50% and improves regulation-so 100 nF is optimal for size-constrained apps where ripple <10% is acceptable, while ≥1 µF is preferred for high-fidelity lighting.

What happens to the LEDs during shutdown of the TPS61042DRBRG4?

When CTRL is pulled low for ≥32 ms, the TPS61042DRBRG4 disables both Q1 (SW) and Q2 (LED switch), physically disconnecting the LED string from GND via Q2's open state. This eliminates leakage current through the LEDs-critical for battery-powered devices where even nanoamp-level leakage could drain the battery over weeks. Unlike basic enable-only drivers, this dual-switch architecture ensures true zero-current off-state.

Is the TPS61042DRBRG4 compatible with analog brightness control, and how is it implemented?

Yes, the TPS61042DRBRG4 supports analog dimming via the CTRL pin: applying a DC voltage between 0 V and 3.3 V (with appropriate R1/R2 divider per Figure 13) linearly adjusts LED current from 0% to 100%. This avoids PWM-induced EMI and flicker, making it ideal for sensitive medical or test equipment displays. The analog mode uses the same FB/RS regulation loop-only the CTRL bias point changes the effective current setpoint.