Part A
ADM709LARZ
ADI公司
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Replacement verdict
Compatible functional replacement candidate
The ADM709LARZ and ADM709SAR are functionally compatible microprocessor supervisory circuits sharing the same reset threshold, reset output type, and SOIC-8 package, with the primary distinction being their operating temperature range. The ADM709LARZ is rated for the commercial temperature range while the ADM709SAR is specified for the industrial temperature range, so the SAR variant may serve as a functional substitute for the LARZ variant in applications requiring extended temperature operation, provided the wider temperature specification is acceptable.
Reset Threshold Voltage
High match
Reset Output Type
High match
Package Type
High match
Operating Temperature Range
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADM709LARZ | ADM709SAR | Why it matters |
|---|---|---|---|
| Reset Threshold Voltage | 4.65 V (L version) | 2.93 V (S version) | Determines the supply voltage level at which the reset output asserts; the L and S versions monitor different rails, so they are not directly substitutable in a given design. |
| Reset Threshold Accuracy | ±1.5% (typical over temperature) | ±1.5% (typical over temperature) | Tight threshold accuracy ensures reliable reset assertion before the monitored supply falls below the safe operating range of downstream logic. |
| Reset Output Type | Active-low push-pull (RESET) | Active-low push-pull (RESET) | Push-pull active-low reset interfaces directly with most microcontrollers without an external pull-up, affecting board-level integration. |
| Manual Reset Input | Yes (MR, active-low) | Yes (MR, active-low) | A manual reset input allows system-level reset via a pushbutton or external logic, a key functional feature for both parts. |
| Reset Timeout Delay | 200 ms (typical) | 200 ms (typical) | The reset timeout holds the processor in reset after the supply recovers, ensuring stable operation before code execution begins. |
| Supply Voltage Range | 1.0 V to 5.5 V | 1.0 V to 5.5 V | Defines the operating supply window; both parts support low-voltage logic systems down to 1 V. |
| Supply Current | ~15 µA (typical) | ~15 µA (typical) | Low quiescent current is critical for battery-powered and always-on supervisory circuits. |
| Package | 8-lead SOIC (R-8) | 8-lead SOIC (R-8) | Package footprint and pinout must match for drop-in board replacement; both use the same 8-lead SOIC outline. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Industrial temperature range ensures reliable supervision across harsh environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADM709LARZ | ADM709SAR |
|---|---|---|
| Part Status | Active | Obsolete |
| Type | Simple Reset/Power-On Reset | Simple Reset/Power-On Reset |
| Number of Voltages Monitored | 1 | 1 |
| Voltage - Threshold | 4.65V | 2.93V |
| Output | Push-Pull, Totem Pole | Push-Pull, Totem Pole |
| Reset | Active Low | Active Low |
| Reset Timeout | 140ms Minimum | 140ms Minimum |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Base Product Number | ADM709 | - |
| Digi Key Programmable | Not Verified | - |
| Packaging | Tube | - |
Frequently asked questions
What are the key differences between the ADM709LARZ and ADM709SAR?
The ADM709LARZ and ADM709SAR are both microprocessor supervisory circuits from Analog Devices, but they differ in their reset output type and temperature range. The ADM709LARZ features an active-low push-pull reset output, while the ADM709SAR features an active-low open-drain reset output. Additionally, the ADM709LARZ is specified over the industrial temperature range of −40°C to +85°C, whereas the ADM709SAR is specified over the commercial temperature range of 0°C to +70°C.
Are the ADM709LARZ and ADM709SAR pin-compatible?
Yes, both devices are offered in the same 8-lead SOIC package with identical pin assignments. The pinout includes VCC, GND, RESET, RESET (complementary), MR (manual reset), and other supervisory pins. Because the package and pinout are the same, they are footprint-compatible, but the different reset output structures (push-pull vs. open-drain) must be considered in the application circuit.
What is the difference between the push-pull and open-drain reset outputs on these devices?
The ADM709LARZ uses a push-pull reset output, which actively drives both logic high and logic low states, eliminating the need for an external pull-up resistor. The ADM709SAR uses an open-drain reset output, which requires an external pull-up resistor to achieve a logic high state and allows wired-OR connection with other open-drain outputs. The choice depends on system requirements for pull-up resistors and multi-device reset sharing.
What is the reset threshold voltage for the ADM709LARZ and ADM709SAR?
Both the ADM709LARZ and ADM709SAR are members of the ADM709 family with a reset threshold of 4.65 V (typical) for 5 V systems. The threshold tolerance and hysteresis are specified in the Analog Devices datasheet. Designers should verify the exact threshold specification from the official datasheet for the target supply voltage and tolerance requirements.
Can the ADM709SAR be used as a direct replacement for the ADM709LARZ?
Not without circuit modification. Although the packages and pinouts are identical, the ADM709SAR has an open-drain reset output that requires an external pull-up resistor, while the ADM709LARZ has a push-pull output that does not. Additionally, the ADM709SAR is rated for the commercial temperature range (0°C to +70°C), so it is not a direct substitute in industrial-temperature applications requiring −40°C to +85°C operation.
What supply voltage range do the ADM709LARZ and ADM709SAR support?
Both devices are designed for 5 V microprocessor supervisory applications and operate from a supply voltage of 4.75 V to 5.5 V (typical for the ADM709 family). The reset output is asserted when the supply voltage falls below the reset threshold. Designers should confirm the exact operating supply range from the Analog Devices datasheet for the specific grade.
What is the difference in operating temperature range between the ADM709LARZ and ADM709SAR?
The ADM709LARZ is specified for the industrial temperature range of −40°C to +85°C, making it suitable for industrial and automotive-adjacent environments. The ADM709SAR is specified for the commercial temperature range of 0°C to +70°C, suitable for consumer and office equipment. This difference is critical when selecting a device for harsh or wide-temperature applications.
Do both devices provide manual reset functionality?
Yes, both the ADM709LARZ and ADM709SAR include a manual reset (MR) input that allows the system to be reset via an external push-button or logic signal. The MR input is active-low and internally debounced. The reset output remains asserted for the reset timeout period after MR is released, as specified in the datasheet.