Mini Power Supply: Linear Voltage Regulator in a Flip-Chip Package

Reductions in power-supply solution size and cost, which is critical to furthering development of automotive systems, also presents the challenge of reduced thermal performance. Simply put, using smaller ICs in a design can significantly increase temperature.

With flip-chip technology, however, the ICs are installed face down so that the copper bumps are upside down and soldered directly to the lead frame (Fig. 1). As a result, the heated part of the IC is closer to the package bottom, and in a PCB, thermal inductance can improve by a factor between 2 and 3.

Taking advantage of the flip-chip configuration, Infineon Technologies is laying claim as the first chipmaker to set up a dedicated production process for flip-chip packages that’s also aligned with the quality requirements of the automotive market. The company’s new low-dropout linear voltage regulator Optireg TLS715B0NAV50 can handle load current up to 150 mA (Fig. 2).

An input voltage of up to 40 V is regulated to VQ,nom = 5 V with ±2% precision, according to the company. With a typical quiescent current of 36 μA, the TLS715B0 is applicable to systems requiring very low operating current, such as those permanently connected to the battery.

The footprint of Infineon's new linear voltage regulator (TSNP-7-8 package, 2.0 × 2.0 mm) is more than 60% smaller than that of an established reference product (TSON-10 package, 3.3 × 3.3 mm), while the thermal resistance stays the same. This makes the new device particularly well-suited to applications with very limited board space, such as radar and cameras.

The part features a low dropout voltage of 180 mV, when the output current is less than 100 mA. In addition, the dropout region begins at input voltages of 4.0 V (extended operating range). This makes the TLS715B0NAV50 suitable to supply automotive systems with start-stop requirements.

In addition, the TLS715B0NAV50 requires only a single 1-µF output capacitor to maintain stable regulation. 

Flip-chip technology has been used in consumer and industrial markets for several years. Infineon noted that it doesn’t rely on a subsequent qualification of existing consumer and industrial products. Rather, it has created a dedicated production process for automotive devices to offer what’s claimed to be best-in-class flip-chip quality.

The device is designed for the harsh environment of automotive applications. Thus, it implements standard features like output-current limitation, over-temperature shutdown, and output short circuit to GND.

Infineon plans to use flip-chip technology to strengthen its portfolio of automotive power-supply products in the OPTIREG family. The chipmaker also expects to apply it to switch-mode voltage regulators and power-management ICs.

The OPTIREG TLS715B0NAV50 is currently available.