Detailed Description
The MAX40000/MAX40001 feature an on-board voltage reference with ±1% initial accuracy. This family of comparators with internal references are available in multiple voltage reference options. The Ordering Information table provides exact part numbers associated with a particular voltage reference option. The common-mode voltage range of this family extends 200mV beyond the rails, allowing signals slightly beyond the rails to trigger the comparator. The 2.5mV internal hysteresis ensures clean output switching even with slow moving input signals. Large internal output drivers allow rail-to-rail output swing with up to ±2mA loads.
The output stage employs a unique design that minimizes supply current surges while switching, virtually eliminating supply glitches typical of many other comparators. The MAX40000 has a push-pull output stage that sinks as well as sources current. The MAX40001 has an open-drain output stage that can be pulled beyond VDD to a maximum of 5.5V above GND. Multiple comparators with open-drain outputs (OUT) can be connected together in parallel and share a single pullup resistor. This enables user to detect if there is any fault if at least one comparator trips different to other comparators.
The input common-mode voltage range extends from - 0.2V to VDD + 0.2V. These comparators operate at any differential input voltage within these limits. Input bias current is typically ±1nA if the input voltage is between the supply rails.
Output Stage Structure
The devices contain a unique break-before-make output stage capable of rail-to-rail operation with up to ±2mA loads. Many comparators consume orders of magnitude more current during switching than during steady-state operation. In the
Typical Operating Characteristics, the Supply Current graphs show the minimal supply-current increase as the output switching frequency approaches 1kHz. This characteristic reduces the need for power-supply filter capacitors to reduce glitches created by comparator switching currents. In battery-powered applications, this characteristic results in a substantial increase in battery life.
The MAX40000/MAX40001 come with different internal voltage reference options that has initial accuracy of ±1%. 1.252V, 1.6V, 1.9V, and 2.2V options of internal voltage references are available. The devices’ internal reference has a typical temperature coefficient of 15ppm/°C over the full -40°C to +125°C temperature range. The reference is a very-low-power bandgap cell, with a maximum 10kΩ output impedance. REF pin can source and sink up to 100nA to external circuitry. For applications that need increased drive, buffer REF with a low input-bias current op amp such as the MAX44265. Most applications require no bypass capacitor on REF pin.