| Number of supplies monitored | 1 |
| Threshold voltage 1 (Typ) (V) | 4.63 |
| Features | Ease-of-use |
| Reset threshold accuracy (%) | 5 |
| Output driver type/reset output | Active-high, Push-pull |
| Time delay (ms) | 240 |
| Rating | Catalog |
| Watchdog timer WDI (sec) | None |
| Operating temperature range (C) | -40 to 105 |
- Precision Monitoring of Supply Voltages
- Available Threshold Options:
2.63 V, 2.93 V, 3.08 V, 4.38 V, 4.63 V
- Available Threshold Options:
- Superior Upgrade to MAX809 and MAX810
- Fully Specified Over Temperature
- 140-ms Minimum Power-On Reset Pulse Width,
240-ms Typical- Active-Low RESET Output (LM809)
- Active-High RESET Output (LM810)
- Ensured RESET Output Valid for VCC ≥ 1 V
- Low Supply Current, 15-μA Typical
- Power Supply Transient Immunity
The LM809 and LM810 microprocessors supervisory circuits can be used to monitor the power supplies in microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-down and brown-out conditions.
The function of the LM809 and LM810 are to monitor the VCC supply voltage, and assert a reset signal whenever this voltage declines below the factory-programmed reset threshold. The reset signal remains asserted for 240 ms after VCC rises above the threshold. The LM809 has an active-low RESET output, while the LM810 has an active-high RESET output.
Seven standard reset voltage options are available, suitable for monitoring 5-V, 3.3-V, and 3-V supply voltages.
With a low supply current of only 15 μA, the LM809 and LM810 are ideal for use in portable equipment.
