MAX1441: Single-chip proximity/touch sensor solution for passive RKE systems

The MAX1441 allows system designers to enjoy all the benefits of an integrated solution without sacrificing performance or programmability. It boasts advanced features such as low-power operation (< 100microamps at 14V), long-range detection, integrated power regulation, overvoltage and reverse-voltage protections, and spread-spectrum antijamming technology. Additionally, an embedded MAXQ(R) microcontroller offers ample memory to support user-customized algorithms, allowing designers to easily optimize system performance.

Adding capacitive touch/proximity sensing to automotive applications

Touch-enabled interfaces have emerged as a value-added feature in luxury and, more recently, economy automobiles. Applications such as passive-entry systems use capacitive sensing to deliver a new level of convenience, allowing the driver to lock/unlock the vehicle without removing the key from her pocket.

Designers of these systems face a number of challenges, from meeting tight power and cost budgets in automotive systems, to programming the microcontroller to fit their specific application environment.

Proximity/touch sensor systems typically employ 8-bit, general-purpose microcontrollers with ADCs and external discrete components to allow programming specialized functions like diagnostics, offset tracking, and communication protocols. Alternately, they use devices with proprietary sensing algorithms that are not user programmable, which prevents the inclusion of user-defined functionality.


MAX1441 delivers the most integrated capacitive sensing solution

The MAX1441 provides a complete proximity/touch sensor solution in a single IC. The device combines high-sensitivity detection circuits with an embedded MAXQ microcontroller, power and protection functions, and interface I/O. This integrated solution only requires five passive components to complete the capacitive sensing circuit. In contrast, the nearest competitive IC requires 16 passive components, as well as a costly high-voltage LDO regulator. Using Maxim's solution, system designers will save substantial board space and reduce solution cost by at least 30%.

In addition to these savings, the MAX1411 delivers better sensing performance and greater flexibility to customize system functions. End users will benefit from its longer range proximity sensing, immunity to rain and environmental variations, and reliable detection of gloved hands.

Meanwhile, system designers will appreciate the sophistication of Maxim's solution. Unique features include an active guard architecture to shield the sense electrodes from unwanted sources without adding parasitic capacitance; spread-spectrum modulation to reduce electromagnetic emissions and susceptibility; and ample memory resources to enable user-defined signal processing and discrimination algorithms for optimal system performance. Altogether, these capabilities give designers the most advanced capacitive sensing solution available on the market.