Renesas ISL88021IU8FAZ

Overview

ISL88021IU8FAZ from Intersil is a triple voltage monitor IC with adjustable power-on-reset, undervoltage monitoring on VDD (3.09V threshold), V2MON (1.69V fixed), and V3MON (UV detection referenced to 0.605V), designed for reliable system reset assertion in multi-rail embedded systems. It delivers active-low open-drain RST and active-high push-pull RST outputs, operates from 2.0V to 5.5V supply, consumes only 15µA typical, and supports manual reset with internal 20kΩ pull-up.

For engineers reviewing the ISL88021IU8FAZ datasheet, ISL88021IU8FAZ pinout, ISL88021IU8FAZ application, or ISL88021IU8FAZ equivalent, key selection considerations include its 8-lead MSOP package, UV-only V3MON configuration, 140–200ms POR timeout (adjustable via CPOR capacitor), ±6mV VTH1 accuracy over –40°C to +85°C, and dual-reset output architecture for flexible microcontroller interface.

Technical Context

The ISL88021IU8FAZ implements independent comparator-based monitoring of three rails: VDD (fixed 3.09V trip), V2MON (fixed 1.69V trip), and V3MON (undervoltage detection against 0.605V internal reference). Reset assertion occurs when any monitored voltage falls below its threshold, and remains asserted until all voltages stabilize for the full tPOR delay period.

Its POR circuit activates at VDD > 1V and holds RST low for a minimum 140ms timeout-extendable up to ~390ms using an external capacitor on CPOR-while MR provides debounced active-low manual reset with 550ns minimum pulse width. Both RST and RST outputs are guaranteed functional down to VDD = 1V.

Key Specifications

Pinout & Package

ISL88021IU8FAZ is housed in an 8-lead MSOP package (JEDEC MO-187AA), measuring 3.0mm × 3.0mm × 0.85mm, with exposed pad not electrically connected. The package is RoHS-compliant (Pb-free plus anneal) and rated for reflow per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple-voltage monitor applications.

Compared with MAX6361KA29+T and TPS3808G12DBVR, the ISL88021IU8FAZ uniquely integrates three independent voltage monitors, dual-reset outputs, and capacitor-adjustable POR in an 8-pin MSOP-enabling compact, self-contained system supervision without external components or secondary supervisors.

Availability

ISL88021IU8FAZ is available at Aetrix Electronics and suitable for industrial process controllers, embedded medical instruments, multi-voltage server management cards, portable test equipment, and intelligent instrumentation requiring stable component supply and long-term lifecycle support.

Supply support for ISL88021IU8FAZ 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

Intersil Corporation (now part of Renesas Electronics) is a U.S.-based analog and mixed-signal semiconductor company founded in 1967, specializing in power management, precision analog, and interface solutions.

The ISL88021IU8FAZ belongs to Intersil's voltage supervisor product line, engineered specifically for robust, multi-rail system reset control in industrial and embedded applications where reliability, small footprint, and configurable timing are essential.

FAQ

What is the VDD undervoltage threshold for ISL88021IU8FAZ?

The ISL88021IU8FAZ has a fixed VDD undervoltage threshold of 3.09V, with ±6mV accuracy over the full –40°C to +85°C operating temperature range. This value is factory-trimmed and specified in the ordering information table of the FN8226 datasheet. The threshold is used to detect brownout conditions on the primary supply rail, and reset remains asserted until VDD rises above 3.09V + hysteresis (37mV) and stabilizes for the full tPOR period.

Does ISL88021IU8FAZ support overvoltage monitoring on V3MON?

No, ISL88021IU8FAZ supports undervoltage (UV) monitoring only on the V3MON pin. The datasheet explicitly states that ISL88021 devices monitor V3MON for undervoltage conditions, whereas ISL88022 variants support overvoltage (OV) detection on V3MON. This distinction is encoded in the part number suffix and confirmed in the Ordering Information table, where ISL88021IU8FAZ is marked "UV" under V3MON TYPE.

How is the Power-On-Reset timeout adjusted on ISL88021IU8FAZ?

The Power-On-Reset timeout (tPOR) of ISL88021IU8FAZ is adjusted by connecting an external capacitor between the CPOR pin and GND. With CPOR open, tPOR is 140–200ms; adding capacitance extends it-e.g., 10pF yields ~390ms. The maximum recommended CPOR capacitance is 50pF. Stray capacitance must be minimized during layout, as it directly impacts timing accuracy and can cause premature or delayed reset release.

What are the electrical characteristics of the RST and RST outputs on ISL88021IU8FAZ?

The ISL88021IU8FAZ provides two reset outputs: RST is an active-low open-drain output capable of sinking 2.5mA at VDD ≥3.3V (VOL ≤0.4V), requiring an external pull-up; RST is an active-high push-pull output that drives to VDD–0.4V when high and actively pulls low during reset, eliminating external components. Both outputs remain valid down to VDD = 1V, ensuring functionality during deep brownout recovery.

Can ISL88021IU8FAZ monitor a 5V rail using the V3MON input?

Yes, ISL88021IU8FAZ can monitor a 5V rail via V3MON by using a resistor divider to scale the voltage down to ≤0.616V (the max VTH3 specification), enabling precise undervoltage detection at any desired threshold above 0.6V. For example, a 5V rail with a 10:1 divider presents 0.5V to V3MON-well within the 0.594–0.616V reference window-allowing detection of drops below 4.9V with high accuracy.