Supervisory Circuits for Power-Supply Monitoring

Maxim Integrated Products introduces the MAX16033–MAX16040 low-power, microprocessor (µP) supervisory circuits with precision power-supply monitoring and battery control functions. Optimized for performance in space-saving 2mm x 2mm µDFN packages, these supervisory circuits offer a variety of features, including a µP reset, battery-backup switchover, power-fail warning, and chip-enable gating, thereby reducing the complexity and number of components for power-supply monitoring. The small size and high integration of the MAX16033–MAX16040 make them usefull for a wide variety of applications, including point-of sale equipment, industrial equipment, fax machines, computers, and set-top boxes. The MAX16033–MAX16040 automatically switch the RAM power source to the backup battery when VCC falls below the reset threshold and also VCC is below VBATT. These devices also assert a reset when VCC is below the reset-threshold voltage and for at least 150ms after VCC returns above its threshold.

 

The MAX16033/MAX16037 feature a manual-reset input, and the MAX16036/MAX16040 feature an auxiliary user-adjustable reset input for monitoring a second voltage. The MAX16034/MAX16038 include a watchdog function that triggers a reset pulse whenever WDI remains high or low for longer than the watchdog timeout period. The MAX16035/MAX16039 feature a battery-on output during battery-backup mode. The MAX16033–MAX16036 provide internal gating of the chip-enable signals to prevent erroneous data from corrupting the CMOS RAM. Each device offers either an active-low, push-pull reset or an active-low, open-drain reset, and includes a power-fail comparator that signals an interrupt when VPFI falls below 1.235V or when VCC falls below the reset threshold. The MAX16033–MAX16040 consume 13µA of quiescent current and operate from as low as 1.2V. Fully specified over the -40°C to +85°C extended temperature range, they are available in 8- or 10-pin µDFN packages. Pricing starts at $1.98 (1000-up, FOB USA).