CHALLENGE
Applications supporting plug-and-play connections require (accurate) current limitation and over-current protection, preferably implemented in a low-cost solid-state IC. For a division of a large semiconductor company the accurate current control was a design challenge that was tackled by involving SystematIC in the circuit design. The area, cost-of-silicon and on-resistance of the integrated power switch are relevant parameters for the technology choice, but in any case dictate preference for an NMOS power switch. Using an NMOS switch however complicates the design of driver and sensing circuits. After IC definition and process selection SystematIC was involved to do the challenging circuit design of the product.
SOLUTION
SystematIC did the challenging full-chip circuit design, including current sensing circuits using low-offset chopped amplifiers, adjustable over-current current control, over-temperature protection, and push-pull chargepumps to drive the area-optimized NMOS switch, and several other features. SystematIC also guided layout activities and supported evaluation of the silicon with measurement assistance and verification of the specifications. This included investigation and adjustment of the behavior over temperature and support for characterization in the final test.
TIME
From feasibility to final test support we were involved in a timespan of approximately 18 months.
WE ARE PROUD
We conquered the circuit design challenge for full-range current sensing and limiting, and verified robust operation over a range of environmental condition such as temperature, supply and output voltage, with minimum impact on on-resistance and chip area. We are proud having supported IC design and evaluation up to final testing, and that the product had several derivitives in different current ranges (up to 3A), including our involvement in the Lightning™ interface switch development.
BENEFITS FOR CUSTOMER
Our customer’s product line of switches was extended with a robust and feature-rich current-limited power switch. The development also was followed-up with several derivative products.
KEY TECHNICAL STATISTICS
- Input voltage 2.5 V to 6 V
- Total pin-to-pin on resistance < 100 mOhm
- Adjustable current limit, Max. 1.7 A (3 A in derivatives)
- Low off-current (1 uA), low-bias current (10 uA)
- Fast and accurate current limiting
- Internal charge pump driver
- Short-circuit protection
- Reverse-voltage protection
- Fault output with deglitch filters
- Under-voltage and Over-temperature protection
OUR OTHER SUCCESS STORIES
Successful achievement of your company’s goals will require IC solutions that are tailor made for your business needs. SystematIC was founded to help businesses imagine, plan, and develop these IC solutions.