5G921C

The 5G921C is a high-performance micropower single comparator from 5G Semiconductor, featuring an integrated precision voltage reference and programmable hysteresis for versatile low-power system monitoring and signal detection applications. This device is designed for ultra-low-power operation, drawing only 2.5µA of quiescent current typical while operating from a single 2.5V to 11V supply (or ±1.25V to ±5.5V dual supply), making it ideal for battery-powered and energy-harvesting applications. The integrated 1.182V bandgap voltage reference provides ±1% accuracy, eliminating the need for an external reference in many threshold detection applications. The unique programmable hysteresis feature, accessed through the dedicated HYST pin, allows designers to easily set the hysteresis voltage with just two external resistors, eliminating the need for complex feedback networks and calculations. The push-pull output stage is capable of sourcing up to 40mA and sinking 5mA, providing direct drive capability for LEDs, relays, and logic circuits without requiring additional buffer stages. The output is compatible with both TTL and CMOS logic levels. The input common-mode voltage range extends all the way to the negative supply rail (V-), enabling ground-referenced signal detection, while the upper limit extends to within 1.3V of the positive supply. The 5G921C provides a propagation delay of 12µs maximum at 10mV input overdrive, offering a good balance between speed and power consumption. With 80dB typical common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR), the comparator maintains stable performance in noisy environments. Pin-compatible with industry-standard MAX921 and TSM921 series devices, the 5G921C provides a drop-in alternative for cost-sensitive applications. This comparator is widely used in battery-powered systems, threshold detectors, window comparators, oscillator circuits, power supply monitoring, under-voltage/over-voltage detection, zero-crossing detection, level translation, and industrial sensor interfaces where minimal power consumption is essential.

The 5G921C is a voltage comparator that compares two analog input voltages and outputs a digital signal indicating which input is higher. It contains a high-gain differential amplifier that amplifies the difference between the non-inverting (IN+) and inverting (IN-) inputs. When the voltage at IN+ exceeds the voltage at IN-, the output goes high; when IN+ is below IN-, the output goes low. The internal architecture includes several key functional blocks. The input stage is a differential amplifier that provides the initial gain and common-mode rejection. This is followed by additional gain stages that amplify the difference signal to drive the output stage. The push-pull output stage is designed to source and sink significant current (40mA source, 5mA sink) without drawing excessive supply current during transitions, eliminating the crowbar current typical of many comparator output stages. The integrated 1.182V bandgap reference uses the bandgap voltage principle, where the negative temperature coefficient of a diode’s forward voltage is compensated by the positive temperature coefficient of the thermal voltage (VT), producing a temperature-stable reference voltage of approximately 1.2V. This reference is available at the REF output pin for use by external circuits. The programmable hysteresis feature operates by using the HYST pin, which is connected to an internal resistive network. By connecting external resistors between HYST, REF, and either V+ or V-, the user can set the amount of hysteresis (the difference between the rising and falling threshold voltages). This eliminates the need for external positive feedback resistors typically required to implement hysteresis in comparator circuits. The device’s micropower operation is achieved through careful design optimization, including low-bias-current input stages and efficient output stage architecture, making it suitable for the most power-constrained applications.

• Battery voltage monitoring and low-battery detection in portable devices
• Under-voltage lockout (UVLO) and over-voltage protection circuits
• Window comparators for acceptable range detection
• Low-power relaxation oscillators and timer circuits
• Zero-crossing detectors for AC line monitoring
• Power supply supervisory and sequencer circuits
• Level translation between different voltage domains
• Sensor threshold detection (temperature, light, pressure)
• Energy harvesting power management systems
• Automotive electronics – low-power wake-up and monitoring