Colorado Springs, Colo. - EM Microelectronic says its 615x/625x family of microprocessor supervisory ICs is especially suited to automotive applications. It features programmable voltage reset monitoring, special watchdog timer with programmable time window, system enable output, optional low-dropout (LDO) +5-volt regulator and a power saving function compatible with the CANbus sleep mode that, together, eliminate the need for redundant microprocessors to supervise each other. The family includes the V6150 and V6155 windowed watchdog ICs, and the A6150, A6155 and A6250 windowed watchdog ICs with the LDO regulator. The A6150 and A6250 will operate over -40 to +125°C, and are thus compatible with the demanding temperature extremes in automotive and industrial environments. All microprocessor supervisory ICs in the 615x/625x family are TTL/CMOS compatible.
The chips' highly functional watchdog section features voltage-and time-windowed circuitry to keep tabs on supply voltages, which are especially critical during power-up and power-down. The circuitry is apart from common watchdogs that depend on CPU hardware and software to generate a counter reset signal and therefore do not reliably prevent hardware and software errors. In contrast, the 615x/625x windowed watchdog ensures that the timer "clear" signal occurs within the correct time window; otherwise it activates a system reset or other error handling. It's programmed with an external resistor to set the power-on reset delay, watchdog time and the close/open window time. Watchdog function and timing is dependent on reset voltage monitoring of the power supply, which is also programmable using an external two-resistor voltage divider.
The 615x/625x family use an open drain reset output, which allows direct interface to shared control buses, and wired-OR connections to suit automotive applications with multiple CPU subsystems spread throughout the chassis. The chip also provides an independent system enable output, which prevents critical control functions from being activated until software has successfully cleared the watchdog three times.
In addition to the windowed watchdog and voltage monitoring functions, the A6150 offers a 5-volt LDO (dropout is 380 mV) regulator rated at 100 mA. The device's unregulated DC input can withstand -20 volt reverse- battery and +60-volt power transients, such as the "jump start" spike encountered in automotive applications. It is fully operational for unregulated DC input voltages up to 26 volts and delivers a regulated output voltage down to 3 volts, with guaranteed valid enable and reset logic states for regulated output voltage down to 1.2 volts.
Basically a higher power version of the A6150, the A6250 features an internal 5-volt LDO regulator and a special PSOP2-16 power package that allows it to deliver up
to 250 mA for higher power applications. The A6250 can deliver 150 mA at 85°C, and 70 mA at 125°C for a 15-volt input.
The V6155 and A6155 offer a windowed watchdog with a CANbus sleep mode detector. In a typical automotive or industrial application, a central processor can issue a general "sleep" instruction to all V6155/A6155-equipped peripheral modules.
The A6150, V6150, A6155 and V6155 are available in a SO-8 package. The A6250, in the aforementioned PSOP2-16 power package, may be directly soldered to a printed circuit board using a bottom slug for better heat sinking. Pricing for the 615x/625x family of microprocessor supervisory ICs starts at $1.20 each in 1k pieces. Contact Rick Mintle.