Some more expensive chips have laser-trimmed resistors, where a laser burns away part of the resistor before the chip is packaged, providing more control than a fuse. The die photo below shows one of the fuse circuits. There is a small resistor (actually two parallel resistors) in parallel...
1812L010R: RESISTOR, TEMPERATURE DEPENDENT, PTC RESETTABLE FUSE, 7 ohm, SURFACE MOUNT. s: Category / Application: General Use ; Mounting / Packaging: Surface Mount Technology (SMT / SMD), ROHS COMPLIANT ; Resistance Range: 7 ohms ; Operating Temperature: -40 to 85 C (-40 to 185 F) ;...