Communications Power

Radiation-Tolerant PWM Controller and GaN FET Driver for DC-DCs in Small Satellites

Renesas Electronics Corporation announced what the company claims to be 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 suitable for half bridge power stages, isolated flyback, and motor control driver circuits in satellite buses and payloads.

Private ‘new space’ companies have started launching smallsats to form large constellations that operate in multiple low Earth orbit (LEO) planes.

Smallsat mega-constellations deliver global broadband Internet links, as well as high-resolution Earth observation imaging for air, sea, and land asset tracking.

The ISL71043M PWM controller delivers fast signal propagation and output switching in a 4mm x 5mm SOIC plastic package, thereby reducing PCB area up to 3x compared to competitive ceramic packages.

Also, the ISL71043’s 5.5mA max supply current reduces power loss more than 3x, and its adjustable operating frequency of up to 1MHz enables higher efficiency and the use of smaller passive filter components.

Features of the ISL71043M PWM controller include up to 13.2V operation, 2.9mA operating current, 90µA typical start-up current, adjustable operating frequency to 1MHz and 1A current drive capability with 50ns rise and fall times.

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

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

The ISL71040M precisely controls the gate driver voltage to +3/-5% over temperature and radiation to ensures reliable operation when driving GaN FETs. Floating protection circuitry eliminates unintentional switching.

“The ISL71043M and ISL71040M along with our GaN FETs and digital isolators give customers a size and cost optimized 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 provide the optimal cost and radiation performance new space customers demand for 5-year mission profiles in low Earth orbit.”

Key Features of ISL71043M PWM Controller
  • 1A MOSFET gate driver
  • 90µA typical start-up current, 125µA maximum
  • Moisture Sensitivity Level (MSL) rating is 1
  • 35ns propagation delay current sense to output
  • Fast transient response with Peak Current mode control
  • 9V to 13.2V operation
    • Rising UVLO: 8.4V
  • Maximum duty cycle: 100%
  • Adjustable switching frequency to 1MHz
  • 50ns rise and fall times with 1nF output load
  • Trimmed timing capacitor discharge current for accurate deadtime/maximum duty cycle control
  • 1.5MHz bandwidth error amplifier
  • Tight tolerance voltage reference over line, load, and temperature
  • ±3% current limit threshold
  • Ni/Pd/Au-Ag lead finish (Tin (Sn) free)
  • Characterized radiation levels
    • Low Lose Rate (LDR) (0.01rad(Si)/s) : 30krad(Si)
    • Single event burnout LET 43MeV•cm2/mg
Key Features of ISL71040M Low Side GaN FET Driver
  • Wide operating voltage range of 4.5V to 13.2V
  • Up to 14.7V logic inputs (regardless of VDD level)
    • Inverting and non-inverting inputs
  • Optimized to drive enhancement mode GaN FETs
    • Internal 4.5V regulated gate drive voltage
    • Independent outputs for adjustable turn-on/turn-off speeds
  • NiPdAu-Ag Lead finish (Sn-free, Pb-free)
  • Moisture Sensitivity Level (MSL) Rating: 1
  • Passes NASA Low Outgassing Specifications
  • Full military temperature range operation
    • TA = -55°C to +125°C
    • TJ = -55°C to +150°C
  • Characterized radiation levels
    • Low Dose Rate (LDR) <0.01rad(Si)/s : 30krad(Si)
    • No SEB/L, VDD = 16.5V : 43MeV•cm2/mg

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


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