Microprocessor Supervisory Circuit

The ADM8690 / ADM8691 / ADM8695 supervisory circuits offer complete single-chip solutions for power supply monitoring and battery control functions in microprocessor systems. These functions include microprocessor reset, backup battery switchover, watchdog timer, CMOS RAM write protection, and power failure warning. The complete family provides a variety of configurations to satisfy most microprocessor system requirements.

The ADM8690 / ADM8691 / ADM8695 are fabricated using an advanced epitaxial CMOS process that combines low power consumption (0.7 mW), extremely fast chip enable gating (3 ns), and high reliability. RESET assertion is guaranteed with VCC as low as 1 V. In addition, the power switching circuitry is designed for minimal voltage drop, thereby permitting increased output current drive of up to 100 mA without the need for an external pass transistor

PRODUCT HIGHLIGHTS

The ADM8690 is available in 8-lead PDIP and SOIC packages and provides the following functions:

* Power-on reset output during power-up, power-down and brownout conditions. The RESET output remains operational with VCC as low as 1 V.

* Battery backup switching for CMOS RAM, CMOS microprocessor or other low power logic.

* A reset pulse if the optional watchdog timer has not been toggled within a specified time.

* A 1.3 V threshold detector for power fail warning, low battery detection or to monitor a power supply other than +5 V.

The ADM8691 and ADM8695 are available in 16-lead PDIP and small outline packages (including TSSOP) and provide three additional functions:

* Write protection of CMOS RAM or EEPROM.

* Adjustable reset and watchdog timeout periods.

* Separate watchdog timeout, backup battery switchover, and low VCC status outputs.

APPLICATIONS

* Microprocessor systems

* Computers

* Controllers

* Intelligent instruments

* Automotive systems

* Upgrade for the ADM690, ADM691, ADM695 and for the MAX690, MAX691, MAX695

* Specified over temperature

* Low power consumption: 0.7 mW

* Precision voltage monitor

* Reset assertion down to 1 V VCC

* Low switch on resistance: 0.7 Ω normal, 7 Ω in backup