The AD5171 is a 64-position， one-time programmable （OTP） digital potentiometer2 that uses fuse link technology to achieve the memory retention of the resistance setting function. OTP is a cost-effective alternative over the EEMEM approach for users who do not need to reprogram new memory settings in the digital potentiometer. This device performs the same electronic adjustment function as most mechanical trimmers and variable resistors. The AD5171 is programmed using a 2-wire， I2 C?- compatible digital control. It allows unlimited adjustments before permanently setting the resistance value. During the OTP activation， a permanent fuse blown command is sent after the final value is determined， freezing the wiper position at a given setting （analogous to placing epoxy on a mechanical trimmer）.When this permanent setting is achieved， the value does not change regardless of supply variations or environmental stresses under normal operating conditions. To verify the success of permanent programming， Analog Devices， Inc.， patterned the OTP validation such that the fuse status can be discerned from two validation bits in read mode. For applications that program the AD5171 in factories， Analog Devices offers device programming software that operates across Windows? 95 to XP platforms， including Windows NT. This software application effectively replaces the need for external I 2 C controllers or host processors and， therefore， significantly reduces the development time of the users. An AD5171 evaluation kit includes the software， connector， and cable that can be converted for factory programming applications. The AD5171 is available in a compact 8-lead SOT-23 package. All parts are guaranteed to operate over the automotive temperature range of ?40°C to +125°C. Besides its unique OTP feature， the AD5171 lends itself well to other general-purpose digital potentiometer applications due to its temperature performance， small form factor， and low cost.