The ADM705ARZ is a low-power microprocessor supervisory IC from Analog Devices' ADM705/706/707/708 series, integrating power supply monitoring, reset, watchdog timer, manual reset, and power-fail detection functions.
What Is ADM705ARZ?
The ADM705ARZ is designed to monitor 5V power supplies and microprocessor activity. It belongs to the ADM705 series.
Its power monitoring circuit generates a reset signal during power-up, power-down, and brownout conditions, with the reset output remaining operational down to 1V VCC. The built-in watchdog monitors microprocessor activity and can trigger an output when the watchdog input is not toggled within 1.60 seconds. A 1.25V threshold detector is also included for power-fail warning, low-battery detection, or monitoring an additional supply rail.
In the ADM705 family, the main difference between ADM705 and ADM706 is the reset threshold, at 4.65V and 4.40V, respectively. The ADM705ARZ comes in an 8-lead SOIC package and is suitable for microprocessor systems, embedded controllers, and other applications requiring power and system monitoring.
ADM705ARZ Specifications
This section lists the key specifications of the ADM705ARZ under defined operating conditions.
Parameter | Value |
Part Number | ADM705ARZ |
Manufacturer | ADI (Analog Devices, Inc.) |
Voltage - Threshold | 4.65V |
Reset | Active Low |
Type | Simple Reset/Power-On Reset |
Operating Temperature | -40°C ~ 85°C (TA) |
Mounting Type | Surface Mount |
Output | Push-Pull, Totem Pole |
Reset Timeout | 160 ms Minimum |
Number of Voltages Monitored | 1 |
Packaging | Tube |
Package | 8-SOIC |
Base Part Number | ADM705 |
ADM705ARZ Pin Configuration
1. MR (Manual Reset Input): Manual reset input. Pulling this pin low triggers a reset.
2. VCC (Supply Voltage): Power supply input for the ADM705ARZ.
3. GND (Ground): Ground connection for the device.
4. PFI (Power-Fail Input): Power-fail input used to monitor an additional power supply or low-battery condition.
5. PFO (Power-Fail Output): Power-fail output that indicates the status of the PFI input.
6. WDI (Watchdog Input): Watchdog input that monitors activity from the microprocessor.
7. RESET (Active-Low Reset Output): Active-low reset output that is triggered during power supply faults or watchdog timeout conditions.
8. WDO (Watchdog Output): Watchdog output that indicates a watchdog timeout when the WDI signal is not toggled within the specified period.
How Does ADM705ARZ Work?
The ADM705ARZ continuously monitors the VCC supply voltage. When the voltage falls below the specified threshold during power-up, power-down, or brownout conditions, the RESET output is pulled low, keeping the microprocessor in or placing it into reset. Once the supply returns to a normal level, the system resumes operation after the specified reset delay.
The ADM705ARZ also features an independent watchdog timer that monitors microprocessor activity through the WDI pin. If the WDI signal is not toggled within 1.60 seconds, the watchdog triggers the corresponding WDO output.
ADM705ARZ Functional Block Diagram
ADM705ARZ Features
l Guaranteed RESET valid with VCC = 1 V
l 190 μA quiescent current
l Precision supply voltage monitor 4.65 V
l 200 ms reset pulse width
l Debounced TTL/CMOS manual reset input (MR)
l Independent watchdog timer
l 1.60 sec timeout
l Voltage monitor for power fail or low battery warning
l Superior upgrade for MAX705 to MAX708
ADM705ARZ Applications
The ADM705ARZ provides power and operating status monitoring for various microprocessor-based systems and is suitable for the following applications:
1. Microprocessor Systems
The ADM705ARZ monitors supply voltage and processor activity, providing reset control during power-up, power-down, or brownout conditions and watchdog monitoring during operation.
2. Computers
It monitors critical power conditions and uses RESET and watchdog functions to help maintain stable operation during power or processor faults.
3. Controllers
The ADM705ARZ is suitable for controllers and embedded systems, providing power monitoring, manual reset, and watchdog functions for system management.
4. Intelligent Instruments
It monitors system power and microprocessor activity, providing reliable operation for data acquisition, control, and communication tasks.
5. Critical Microprocessor Supply Monitoring
The ADM705ARZ continuously monitors critical supply rails and provides signals when undervoltage or power-fail conditions occur, helping maintain system stability.
ADM705 vs. ADM706 vs. ADM707 vs. ADM708
The ADM705, ADM706, ADM707, and ADM708 are microprocessor supervisory circuits with similar power monitoring functions, but they differ mainly in reset threshold and watchdog functionality.
l ADM705: 4.65 V reset threshold, with watchdog timer and active-low RESET output.
l ADM706: 4.40 V reset threshold, with watchdog timer and active-low RESET output.
l ADM707: 4.65 V reset threshold, without watchdog timer, but with both active-low and active-high reset outputs.
l ADM708: 4.40 V reset threshold, without watchdog timer, but with both active-low and active-high reset outputs.
In simple terms, ADM705 and ADM706 are the watchdog versions, while ADM707 and ADM708 replace the watchdog function with an additional active-high RESET output. The main difference between each pair is the reset threshold: 4.65 V for ADM705/ADM707 and 4.40 V for ADM706/ADM708.
Which ADM70x Device Should You Choose?
When choosing an ADM70x device, the main factors are the reset threshold and watchdog requirements. For systems that need watchdog monitoring, choose the ADM705 or ADM706. The ADM705 has a 4.65 V reset threshold, while the ADM706 has a 4.40 V threshold. If a watchdog is not required but both active-high and active-low reset outputs are needed, the ADM707 or ADM708 can be considered, with reset thresholds of 4.65 V and 4.40 V, respectively.
For common 5 V microprocessor systems that require power monitoring, reset control, and watchdog functions, the ADM705 is a suitable choice. The ADM706 may be preferred when a lower reset threshold is needed. Final selection should also consider the system supply voltage, reset logic, and MCU interface requirements.
ADM705ARZ Package
This part shows the package outlines of the ADM705ARZ microprocessor supervisory IC.
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