First rad hard quad power supply sequencers

November 09, 2017 //By Nick Flaherty
Intersil, a subsidiary of Renesas Electronics, has launched two rad hard quad power supply sequencers to drive point-of load (POL) regulators for FPGAs and multi-rail designs in space systems.

The ISL70321SEH and ISL73321SEH allow up to four power supplies to be fully sequenced by a single device or multiple devices to be easily cascaded to sequence an unlimited number of power supplies. The sequencers ensure high reliability operation with fault monitoring to boost system health and performance, and they are the industry’s first space-grade sequencers backed by single event effects (SEE) mitigation tests and complete radiation assurance testing. 

The ISL70321SEH is radiation assurance tested to 100krad(Si) at high dose rate and 75krad(Si) at low dose rate, meeting radiation-hardened specs, while the ISL73321SEH is assurance tested to 75krad(Si) at low dose rate. Both sequencers provide an accurate and scalable method to achieve the proper power-up and power-down sequencing of DC-DC converters essential to powering FPGAs, DSPs, RF communications ICs, and high density distributed power systems. They simplify design by using minimal external components, only requiring two resistors per power supply for voltage monitoring, and a single resistor to program the rising and falling delay. 

The highly integrated sequencers provide critical reliability features, and reduce bill of materials cost by replacing discrete solutions that employ several comparators, resistors, and capacitors. To ensure accurate monitoring and reliable system operation, the ISL70321SEH and ISL73321SEH integrate precision input comparators with an input threshold voltage of 600mV ±1.5% to deliver the highest possible accuracy when monitoring power supply voltages. Both devices actively monitor seven different fault conditions to provide comprehensive fault detection, and a DONE indicator gives system feedback that power-up and power-down have completed successfully. 

The devices have a wide operating voltage range from 3V to 13.2V with an I/O fault pin that initiates a fault condition enabling simultaneous shut off all the power supplies before catastrophic damage. The 45mA drive capability of the high drive internal linear bias regulator allows the designer to connect the enable pull up resistors to this pin, eliminating the need for an external bias voltage and can power off POLs in