Battery back-up controller protects sensitive data

Dallas Semiconductor has introduced the DS3641 secure battery-backup controller, which offers comprehensive features for data protection in POS terminals and other applications containing sensitive data.

Tamper detection
Integrating a real-time clock (RTC), an automatic battery switch and a 4-wire interface in a CSBGA for added security, this controller provides active tamper detection and rapid erasure of key memory. Due to its high level of security, the DS3641 not only supports FIPS 140 security levels 3 and 4, but also meets the requirements of the Common Criteria, PCI-PED and EMV-4.1 certification entities.

An innovative feature of the DS3641 is the on-chip non-volatile SRAM it uses to store encryption keys. This memory architecture constantly complements the SRAM cells to eliminate the possibility of memory imprinting due to oxide stress. This technology prevents the passive detection of data remnants in stressed memory cells. Another innovation of this memory architecture is that the entire 1Kbyte array is immediately cleared in less than 100ns after a tamper alarm has been generated by the DS3641. This is enabled by the memory's high-speed hardwired clearing function and on-chip energy source, which ensures active erasure.

Continuous monitoring
The DS3641 controller provides tamper-detection inputs to interface with and provide low-power continuous monitoring of system voltages, resistive meshes, external sensors and digital interlocks. The RTC's crystal oscillator is also monitored and will invoke a tamper response if the frequency falls outside the set threshold. The internal digital temperature sensor integrates a programmable rate-of-change detector and protects the DS3641 internal encryption-key memory from thermal attacks. The device also constantly monitors primary power. In the event of a primary power failure, an external battery source automatically switches on to keep the SRAM, RTC and tamper-detection circuitry alive.

The DS3641 is specified over the -40°C to +85°C temperature range. Pricing information and product data sheet can be obtained from the factory.