Infineon’s LDO Regulator Uses “Flip-Chip” Technology to Diffuse Heat

January 27, 2020 by Gary Elinoff

The Optireg LS715B0NA V50 from Infineon supplies 5 VDC with ±2% precision at 150 mA and accepts inputs voltages of up to 40 V.

Infineon’s Optireg TLS715BONAV50 is a low dropout voltage (LDO) regulator featuring a quiescent current of 36 µA and a dropout voltage as low as 180 mV.

The TLS715BONAV50’s leadless package and thermal performance make it suitable for automated optical inspection.


3D package drawing of TLS715BONAV50

3D package drawing of the Optireg LS715B0NAV50. Image used courtesy of Infineon


The new device is said to use flip-chip technology, which enhances the ability of the TLS715BONAV50 to transfer heat away from itself and onto the PCB instead, where it can be dealt with more easily. 


What are Flip-Chips?

According to Infineon, flip-chip technology requires the IC to be mounted upside down within the package. This places the hottest part of the IC facing the bottom part of the IC, where the IC will be attached to the PCB during assembly.

Infineon estimates that this will more than double the thermal inductance between the IC and the board.

The obvious result of this arrangement is that heat will flow away from the IC into cooler parts of the PCB. This will allow a power supply IC, for example, to dissipate more energy without overheating.


Low Dropout Voltage

The TLS715BONAV50 features a dropout voltage of 180 mV at output currents below 100 mA. Importantly, the device’s dropout region only begins at an input voltage of 4.0 V.


Performance characteristics of TLS715B0NAV50

(Left) Output voltage VQ versus junction temperature Tj. (Right) Output current IQ versus input voltage VI. Image used courtesy of Infineon

This makes the TLS715B0NAV50 an appropriate choice to supply automotive systems with their unavoidable bus voltage fluctuations due to start-stop conditions.


Operating Characteristics

The device is switched on at the enable (EN) pin. The output voltage is divided by the illustrated two resistor network and compared to the bandgap reference, which determines the proper input to the pass transistor.

As illustrated, there are also limitations on current and internal temperatures that are taken into account.

The capacitor at the input isn’t strictly necessary, but it is useful to mitigate the effects of line voltage variations in the electrically noisy automotive environment.


Block diagram voltage regulation of the TLS715B0NAV50

Block diagram voltage regulation of the TLS715B0NAV50. Image used courtesy of Infineon


The TLS715BONAV50 is not internally protected against reverse polarity faults. For that reason, the inclusion of an external reverse polarity diode at the input (not illustrated) is needed.


Device Applications

While this device is expressly useful for automotive applications, like advanced driver assistance systems (ADAS), automotive infotainment, and dashboards, Infineon also recommends TLS715BONAV50 for any controller area network (CAN) power supplies and applications subject to tight space limitations.


Application diagram of TLS715B0NAV50.

Application diagram of TLS715B0NAV50. Image used courtesy of Infineon

Physical Considerations

The TLS715BONAV50 is offered in a tiny 2.0 mm x 2.0 mm TSNP-7-8 package, which makes it suitable for applications where space is at a premium. The junction temperature of the device can range from -40°C to +150°C.

The unit is RoHS compliant and qualified for the tough AEC-Q100/101 automotive standard.


Around the Industry

While the era of the electrically-powered vehicle won’t occur until an adequate battery is developed, the electrification of gasoline-powered cars is an ongoing reality. That being said, it’s no surprise that Infineon competes with several companies in this exploding market segment.

The TLE4275 from Texas Instruments is a monolithic LDO regulator that accepts inputs of up to 45 volts and provides an output voltage of 5 V ± 2% with an output current of up to 450 mA. The device protects against short-circuit and overtemperature.

ST’s L4925 operates from an of up to 28 volts. Designed with automotive applications in mind, the unit provides an output of 5 volts at up to 500 mA.