Design of the first radiationtolerant buck converter ASIC
Design of the first radiation-tolerant buck converter ASIC prototype Power Working Group S. Michelis – PH/ESE/ME 1
DC-DC Development DC-DC working plan: • • Choice of an architecture : Buck Choice of the inductor Choice of a rad-hard technology Design of the converter with the control loop Planar Solenoid 19 mm Specification: Input Voltage=12 -24 V Output Voltage=1. 5 -3 V Output current=1 -2 A 14 mm Chosen for Toroid different reasons: -High possible conversion ratio -High possible 35 mm output current 19 mm -Only one magnetic component Presented at Twepp 07 -On chip control th 6 September 2007 -Simplicity Rad hard high voltage technology used to create low resistance power transistor. Radiation tolerance demonstrated Simulation for the emitted magnetic field shows best performance of toroid inductor Use of solenoid in prototype for reason of commercial availability 2
Design of the converter with the control loop In view of a fully integrated DC/DC converter a prototype was developed in order to leave some degree of freedom for testing purpose. Input Voltage=12 -24 V Output Voltage=1. 5 -3 V Output current=1 -2 A Switching frequency=1 -2 Mhz This choice implies the presence of some external components 3
CHIP Design: schematics Bootstrap capacitor in order to drive the floating upper MOS Line BTSTR D 2 Saw-tooth Vin VRAMP Output + - IND Vo GND_D On chip component Vss Vdd SUB Rg VF Rf 2 3. 3 V VI Reference Ci 2 VREF Ri 1 S 2 + - Off chip component Ri 2 jumper Cf 2 Cf 1 Compensation network Voltage divider 4
CHIP DESIGN: layout GND_D 4. 5 mm D 2 IND S 2 2. 5 mm Vdd Vss VREF VRAMP VI VF BTSTR SUB 5
Conclusions The ASIC was submitted in a MPW in Marc 3 th 2008 Expected return date around end June 2008 Functional and irradiations tests will be then performed 6
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