Overview
The ADM691AAN is a supervisory circuit produced by Analog Devices Inc., designed to provide comprehensive power supply monitoring and battery control functions in microprocessor systems. This integrated circuit is part of the ADM691A/ADM693A/ADM800L/ADM800M family, which offers a range of features to ensure reliable operation of microprocessors under various power conditions.
The ADM691AAN is particularly useful in systems that require power-on reset, battery backup switching, watchdog timer functionality, and power failure warnings. It is available in a 16-pin DIP package and operates over a temperature range of –40°C to +85°C.
Key Specifications
| Parameter | Min | Typ | Max | Unit | Test Conditions/Comments |
|---|---|---|---|---|---|
| Operating Voltage Range (VCC) | 4.5 | 5.5 | V | ||
| Operating Voltage Range (VBATT) | 2.0 | 4.25 | V | ||
| Reset Voltage Threshold | 4.5 | 4.65 | 4.75 | V | |
| Reset Threshold Hysteresis | 15 | mV | |||
| Reset Timeout Period (Internal Oscillator) | 140 | 200 | 280 | ms | |
| Watchdog Timeout Period (Internal Oscillator) | 1.0 | 1.6 | 2.25 | s | Long Period |
| Watchdog Timeout Period (Internal Oscillator) | 70 | 100 | 140 | ms | Short Period |
| Battery Switchover Threshold | 50 | mV | VCC - VBATT | ||
| Battery Switchover Hysteresis | 20 | mV | |||
| Operating Temperature Range | –40 | +85 | °C |
Key Features
- Power-on Reset Output: Provides a reset signal during power-up, power-down, and brownout conditions, ensuring the microprocessor starts in a known state.
- Battery Backup Switching: Automatically switches to battery power when the main power supply (VCC) falls below a certain threshold, protecting CMOS RAM and other low-power logic.
- Watchdog Timer: Generates a reset pulse if the watchdog timer is not toggled within a specified time, preventing system lockups.
- Power Failure Warning: Includes a 1.25 V threshold detector for monitoring power supply conditions other than +5 V.
- CMOS RAM Write Protection: Available in some configurations to protect CMOS RAM or EEPROM during power failures.
- Adjustable Reset and Watchdog Timeout Periods: Allows for customization of reset and watchdog timeout periods to suit specific system requirements.
- Low Power Consumption: Operates with a low standby current, making it suitable for battery-powered systems.
- Multiple Package Options: Available in 16-pin DIP, SO, and TSSOP packages to fit various design needs.
Applications
- Microprocessor Systems: Ensures reliable operation of microprocessors by monitoring power supply conditions and providing necessary reset and backup functions.
- Computers and Controllers: Used in various computer and control systems to manage power supply and battery backup.
- Intelligent Instruments: Suitable for use in intelligent instruments that require robust power management.
- Automotive Systems: Can be used in automotive systems where reliable power monitoring and backup are critical.
- Critical Power Monitoring: Ideal for applications requiring precise power monitoring and control, such as in medical devices or industrial control systems.
Q & A
- What is the primary function of the ADM691AAN?
The primary function of the ADM691AAN is to provide power supply monitoring and battery control functions in microprocessor systems, including power-on reset, battery backup switching, and watchdog timer functionality.
- What are the operating voltage ranges for VCC and VBATT?
The operating voltage range for VCC is 4.5 V to 5.5 V, and for VBATT it is 2.0 V to 4.25 V.
- What is the reset voltage threshold for the ADM691AAN?
The reset voltage threshold for the ADM691AAN is between 4.5 V and 4.75 V.
- How does the battery switchover function work?
The battery switchover circuit compares VCC to VBATT and connects VOUT to whichever is higher, with a switchover threshold of 50 mV and hysteresis of 20 mV.
- What are the watchdog timeout periods for the internal oscillator?
The watchdog timeout periods for the internal oscillator are 1.0 s to 2.25 s for the long period and 70 ms to 140 ms for the short period.
- What is the operating temperature range of the ADM691AAN?
The operating temperature range of the ADM691AAN is –40°C to +85°C.
- What package options are available for the ADM691AAN?
The ADM691AAN is available in 16-pin DIP, SO, and TSSOP packages.
- How does the power failure warning function work?
The power failure warning function includes a 1.25 V threshold detector to monitor power supply conditions other than +5 V.
- What is the significance of the CMOS RAM write protection feature?
The CMOS RAM write protection feature ensures that CMOS RAM or EEPROM is protected during power failures, preventing data loss.
- Can the reset and watchdog timeout periods be adjusted?
