Analog Devices Inc. ADM803RAKSZ-REEL7

Overview

ADM803RAKSZ-REEL7 from Analog Devices is a microprocessor supervisory circuit in 3-lead SC70 package, featuring open-drain active-low RESET output, 2.63 V reset threshold (±0.04 V over −40°C to +125°C), 17 μA supply current, and 240 ms typical reset timeout. It monitors VCC down to 1.0 V and ensures reliable power-on reset for embedded microcontrollers.

For engineers reviewing the ADM803RAKSZ-REEL7 datasheet, ADM803RAKSZ-REEL7 pinout, ADM803RAKSZ-REEL7 application, or ADM803RAKSZ-REEL7 equivalent, key selection criteria include reset threshold accuracy (±2.3% over temperature), open-drain output requiring external pull-up, SC70 footprint compatibility, and operation across industrial temperature range (−40°C to +125°C).

Technical Context

The ADM803RAKSZ-REEL7 integrates a precision voltage comparator with built-in glitch immunity and an internal 240 ms reset timer. Its reset assertion remains valid even as VCC drops to 1.0 V, enabling robust brownout detection in low-voltage systems.

Unlike push-pull variants (ADM809/ADM810), the ADM803RAKSZ-REEL7 uses an open-drain RESET output, mandating an external pull-up resistor for logic-level compatibility with diverse host interfaces including 1.8 V, 3.3 V, and 5 V microcontrollers.

Key Specifications

Pinout & Package

ADM803RAKSZ-REEL7 is housed in a 3-lead SC70 (KS-3) package with gull-wing leads, optimized for high-density layouts and reflow soldering. Pin 1 = GND, Pin 2 = RESET (open-drain), Pin 3 = VCC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX809RTRG+T, ADM803RAKSZ-REEL7 offers smaller SC70 footprint and open-drain flexibility but requires a pull-up; versus TPS3808G12DBVR, it delivers guaranteed 2.63 V accuracy without calibration overhead, at higher current cost.

Availability

ADM803RAKSZ-REEL7 is available at Aetrix Electronics and suitable for industrial control systems, automotive electronics, medical instrumentation, and smart metering applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM803RAKSZ-REEL7 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The ADM803 series belongs to Analog Devices' precision supervisory IC product line, designed specifically for deterministic power-on reset and brownout protection in resource-constrained embedded systems operating across harsh environmental conditions.

FAQ

What is the exact reset threshold voltage of ADM803RAKSZ-REEL7 and how does it vary with temperature?

The ADM803RAKSZ-REEL7 has a nominal reset threshold of 2.63 V at 25°C, with guaranteed limits of 2.55 V to 2.70 V over −40°C to +85°C and 2.52 V to 2.74 V over −40°C to +125°C. This corresponds to ±2.3% total variation across its full industrial temperature range, ensuring reliable supervision of 2.5 V rails without external calibration. The ADM803RAKSZ-REEL7 achieves this via a trimmed bandgap reference and low-drift comparator design.

Does ADM803RAKSZ-REEL7 require an external pull-up resistor on the RESET pin, and why?

Yes, ADM803RAKSZ-REEL7 requires an external pull-up resistor on the RESET pin because it features an open-drain output architecture. The internal transistor can only sink current (pull low); it cannot actively drive high. A typical 10 kΩ resistor to the target logic rail (e.g., 3.3 V or 1.8 V) ensures proper logic-high level when RESET is deasserted. This design enables voltage-level translation and wired-OR reset bus configurations not possible with push-pull outputs like those in ADM809/ADM810.

What is the minimum VCC voltage at which ADM803RAKSZ-REEL7 continues to assert RESET reliably?

The ADM803RAKSZ-REEL7 maintains valid RESET assertion down to VCC = 1.0 V, as specified in the Absolute Maximum Ratings and confirmed in the General Description. Below 1.0 V, the internal circuitry ceases to function reliably, and RESET may float or become indeterminate. For systems requiring reset assertion all the way to 0 V, a 100 kΩ pull-down resistor from RESET to GND is recommended per Analog Devices Application Note AN-805.

How does the 240 ms reset timeout of ADM803RAKSZ-REEL7 behave across temperature and supply voltage?

The ADM803RAKSZ-REEL7's reset timeout is specified as 140 ms minimum to 460 ms maximum over −40°C to +85°C, and 100 ms to 840 ms over +85°C to +125°C. This variation arises from process and temperature dependencies in the internal RC timer. At 25°C and nominal VCC, the typical value is 240 ms. Designers should use the worst-case minimum (140 ms) for timing margin calculations in safety-critical applications, as stated in Table 1 of the ADM803/ADM809/ADM810 datasheet Rev. I.

Can ADM803RAKSZ-REEL7 be used to monitor a 3.3 V supply, and what are the implications?

No, ADM803RAKSZ-REEL7 is not suitable for monitoring a 3.3 V supply because its fixed 2.63 V reset threshold is intended for 2.5 V rails. Using it on 3.3 V would cause immediate, permanent reset assertion. For 3.3 V supervision, select ADM803SAKSZ-REEL7 (2.93 V threshold) or ADM803TAKSZ-REEL7 (3.08 V threshold). Each ADM803 variant is laser-trimmed at wafer test for its specific threshold; cross-voltage usage violates the device's design intent and datasheet specifications.