Texas Instruments TPS75105DSKT

Overview

TPS75105DSKT from Texas Instruments is a low-dropout linear LED current driver IC optimized for keypad and navigation pad backlighting in Li-ion–powered portable devices. It delivers matched, constant current (up to 25 mA per channel) across four LEDs organized in two independent 2-LED banks (D1A/D2A and D1B/D2B) using common-cathode topology, with 2% LED-to-LED current matching and 28-mV typical dropout voltage at 5 mA.

For engineers reviewing the TPS75105DSKT datasheet, TPS75105DSKT pinout, TPS75105DSKT application, or TPS75105DSKT equivalent, key selection considerations include factory-programmable default current (±0.5% typical accuracy), independent PWM brightness control per bank via ENA/ENB, absence of internal switching (EMI-free operation), ISET-based current programming, and WSON-10 package thermal performance (R_θJA = 65.3°C/W).

Technical Context

The TPS75105DSKT implements four matched NMOS-based linear current sources sharing a single precision 1.225-V internal reference and 420:1 current mirror ratio. Each output operates in LDO mode with ultra-low dropout (28 mV typ. @ 5 mA), enabling stable regulation down to 1.5 V LED forward voltage while maintaining tight line regulation (2.0 %/V) and load regulation (0.8 %/V).

It supports dual-bank independent control: ENA and ENB accept active-high logic or PWM signals (min. 33 µs on-time) to enable/disable or dim each 2-LED bank; unused enables may be left open or grounded. Current setting is auto-detected-internal EEPROM preset (3–10 mA in 1-mA steps) when ISET is open, or external resistor (e.g., 32.4 kΩ for 15.9 mA) when ISET current exceeds 3 µA.

Key Specifications

Pinout & Package

TPS75105DSKT is packaged in a 2.50-mm × 2.50-mm, 10-pin WSON (DSK) thermally enhanced leadless package with exposed thermal pad (Pin 5). The package supports high-density PCB layouts and provides R_θJA = 65.3°C/W for reliable thermal management in compact handheld designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED current source applications.

Compared with TPS75103DSKT and TPS75100DSKT, the TPS75105DSKT offers the highest factory-preset current (5 mA per channel), enabling immediate deployment in mid-brightness keypad/display applications without resistor calculation or placement-reducing design cycle time and test validation scope.

Availability

TPS75105DSKT is available at Aetrix Electronics and suitable for keypad backlighting, navigation pad illumination, and white LED display backlighting requiring stable component supply, long-term production continuity, and RoHS-compliant packaging.

Supply support for TPS75105DSKT 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 digital signal processing technologies, with leadership in power management and precision analog ICs.

The TPS7510x product line was designed specifically for low-power, EMI-sensitive LED backlighting in space-constrained portable electronics, emphasizing factory-programmable current, dual-bank independent control, and ultra-low dropout performance.

FAQ

What is the factory-preset current value for TPS75105DSKT?

The TPS75105DSKT is factory-programmed to deliver 5 mA per LED channel when the ISET pin is left unconnected. This preset is accurate to ±0.5% typical and eliminates the need for external current-setting resistors in standard backlighting applications. The TPS75105DSKT supports eight factory presets (3–10 mA in 1-mA steps); 5 mA is the nominal value assigned to the "05" suffix variant.

Can TPS75105DSKT drive LEDs with forward voltages below 1.5 V?

No. The TPS75105DSKT uses NMOS-based current sources requiring a minimum output voltage of approximately 1.5 V to maintain high accuracy. Driving red LEDs with V_F < 1.5 V may cause current regulation errors or instability. The TPS75105DSKT is optimized for white LEDs (V_F ≈ 3.0–3.6 V) and higher-V_F color LEDs (e.g., green, blue), all of which exceed this threshold.

How does PWM dimming work on TPS75105DSKT, and what is the minimum pulse width?

PWM dimming on the TPS75105DSKT is implemented by applying a logic-level square wave to ENA or ENB: high = LED bank ON at full programmed current, low = OFF. The perceived brightness scales linearly with duty cycle. The device requires a minimum on-time of 33 µs to reach full current; shorter pulses reduce effective current. If one bank is already active, the second bank's minimum on-time drops to ~23 µs due to faster turn-on dynamics.

Is an external capacitor required for stable operation of TPS75105DSKT?

No external capacitor is required for stability with the TPS75105DSKT. The device is internally compensated and operates reliably with only standard PCB decoupling capacitance (e.g., 0.1 µF ceramic near VIN). Adding output capacitors is not recommended, as they can degrade transient response and are unnecessary for regulation integrity.

What thermal considerations apply to TPS75105DSKT in the WSON-10 package?

The TPS75105DSKT in the DSK (WSON-10) package has R_θJA = 65.3°C/W and requires its exposed thermal pad (Pin 5) to be soldered to a solid PCB ground plane for effective heat dissipation. At 25 mA per channel (100 mA total), power dissipation reaches ~100 mW; with ambient at 60°C, junction temperature rises to ~125°C - within the –40°C to +85°C operating limit only with adequate copper area and airflow.