Radiation-Tolerant PWM Controller and GaN FET Driver


Renesas announced the space industry’s first plastic-packaged, radiation-tolerant PWM controller and GaN FET driver for DC/DC power supplies in smallsats.

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 4mm x 5mm SOIC plastic package, reducing PCB area up to 3x compared to competitive ceramic packages. In addition, the ISL71043’s 5.5mA max supply current reduces power loss more than 3x, and its adjustable operating frequency -- up to 1 MHz -- enables higher efficiency and the use of smaller passive filter components. The ISL71043M and ISL71040M are characterization tested at a total ionizing 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°C 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 4.5V 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.


Key Features of ISL71043M PWM Controller


Operating supply range of 9V 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


Key Features of ISL71040M Low Side GaN FET Driver


Operating supply range of 4.5V 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.