What this supervisor does
The MAX6326XR30 from Maxim Integrated is a single-channel voltage supervisor that monitors a 3V rail and holds the microprocessor in reset for a minimum of 100ms after the supply rises above the threshold. The active-low, push-pull output drives the reset line directly without an external pull-up resistor. It comes in a compact SC-70-3 package, sized for space-constrained boards in industrial control, telecom, and embedded systems where a clean power-on reset sequence is required.
3V threshold and 100ms timeout — what they mean for the BOM
The 3V threshold is the trip point at which the reset asserts when the monitored supply drops below that level. For a 3.3V rail, this gives roughly 300mV of margin before a brownout triggers a reset — enough headroom for most linear regulators but tight if the rail is heavily loaded. The 100ms minimum reset timeout ensures the core supply and oscillator have stabilised before the processor starts executing code. If your design uses a fast-starting oscillator or a regulator with a slow ramp, verify that 100ms covers the full power-up sequence; otherwise, an external capacitor on the MR pin (if available on a sibling) extends the delay.
Active-low push-pull output
The push-pull output eliminates the need for an external pull-up resistor to the supply rail, saving one component and one PCB trace. It drives the reset input of the monitored IC directly, sourcing or sinking current as needed. The active-low polarity is standard for most MCUs and DSPs — confirm the processor's reset input is active low before committing the BOM.
Package and mounting
The SC-70-3 (SOT-323) footprint is one of the smallest for a voltage supervisor, occupying roughly 2mm × 2mm of board area. Surface-mount assembly is straightforward for standard reflow profiles. The three-pin layout — VCC, GND, and RESET — keeps routing simple: place it close to the monitored IC's supply pin to minimise noise pickup on the sense line.
Lifecycle and sourcing
It is RoHS non-compliant as listed, so verify your assembly house's exemption policy if you require RoHS compliance.