Engineering 101

Radiation-Tolerant PWM Controller for Small Satellites

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Supplier of advanced semiconductor solutions, Renesas Electronics, has announced the space industry’s first plastic-packaged, radiation-tolerant PWM controller and Gallium Nitride (GaN) FET driver for DC/DC power supplies in small satellites (smallsats) and launch vehicles.

The ISL71043M single-ended current mode PWM controller and ISL71040M low-side GaN FET driver are ideal for isolated flyback and half-bridge power stages, and motor control driver circuits in satellite buses and payloads.

Private ‘new space’ companies have begun launching smallsats to form large constellations operating in multiple low Earth orbit (LEO) planes. Smallsat mega-constellations provide global broadband Internet links, as well as high-resolution Earth observation imaging for sea, air, and land asset tracking.

The ISL71043M PWM controller provides fast signal propagation and output switching in a small four by five millimetres SOIC plastic package, reducing PCB area up to three times compared to competitive ceramic packages. In addition, the ISL71043’s 5.5mA max supply current reduces power loss more than three times, and its adjustable operating frequency, up to one megahertz, enables higher efficiency and the use of smaller passive filter components.

The ISL71043M and ISL71040M are characterisation tested at a total ionising doze (TID) of up to 30krads(Si), and for single event effects (SEE) at a linear energy transfer (LET) of 43MeV•cm2/mg. Both devices operate over an extended temperature range of -55 to +125°C.

The ISL71040M low-side GaN FET driver safely drives Renesas’ rad-hard GaN FETs in isolated topologies and boost type configurations. The ISL71040M operates with a supply voltage between 4.5 and 13.2V, a gate drive voltage (VDRV) of 4.5V, and it includes both inverting and non-inverting inputs. The device’s split outputs adjust the turn-on and turn-off speeds, and its high current source and sink capability enables high frequency operation.

The ISL71040M ensures reliable operation when driving GaN FETs by precisely controlling the gate driver voltage to +3/-5% over temperature and radiation. It also includes floating protection circuitry to eliminate unintentional switching.

“The ISL71043M and ISL71040M along with our GaN FETs and digital isolators give customers a size and cost optimised power supply solution for large constellations of smallsats,” said Philip Chesley, Vice President, Industrial Analog and Power Business Division, Renesas Electronics Corporation. “Renesas’ radiation-tolerant plastic package flow and cutting-edge IC technology provides the optimal cost and radiation performance new space customers demand for five year mission profiles in low Earth orbit.”

Features of ISL71043M PWM Controller:

  • Operating supply range of nine to 13.2V
  • 5.5mA (max) operating supply current
  • ±3% current limit threshold
  • Integrated 1A MOSFET gate driver: 35ns rise and fall times with 1nF output load
  • 1.5MHz bandwidth error amplifier

Features of ISL71040M Low Side GaN FET Driver:

  • Operating supply range of 4.5 to 13.2V
  • Internal 4.5V regulated gate drive voltage
  • Independent outputs to adjust rise and fall time
  • High 3A/2.8A sink/source capability: 4.3ns rise/3.7ns fall times with 1nF output load
  • Internal undervoltage lockout (UVLO) on the gate driver

The ISL71043M PWM controller and ISL71040M GaN FET driver can be combined with the ISL73024SEH 200V GaN FET or ISL73023SEH 100V GaN FET, and ISL71610M passive-input digital isolator to create a variety of power stage configurations.

The ISL71043M radiation-tolerant PWM controller is available now in an 8-lead 4mm x 5mm SOIC package, and the ISL71040M radiation-tolerant low-side GaN FET driver is available in an eight-lead four by four millimetres TDFN package.

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