This is the datasheet of DS1231/S power monitor chip. This chip can warn the processor of an impending power failure, provide an orderly shutdown time, and prevent the processor from destroying nonvolatile memory during power transients. It will also automatically restart the processor after power is restored. This chip is suitable for linear or switching power supplies and can adjust to the hold time of the power supply. It also supplies necessary signals for processor interface. This chip can accurately monitor 5% or 10% VCC and can replace power-up reset circuitry. It does not require external capacitors and is available in an optional 16-pin SOIC surface mount package.
The DS1231/S is a power‑monitoring IC that warns a processor of an impending power failure, provides an orderly shutdown, and automatically restarts the processor when power is restored. It supports both linear and switching supplies, offers selectable 5 % or 10 % VCC detection thresholds, and requires no external capacitors.
The datasheet details pin assignments for the 16‑pin SOIC and 8‑pin DIP packages, operation modes (high‑impedance or current‑source input), absolute maximum ratings, recommended operating conditions, electrical characteristics, and timing diagrams for power‑up and power‑down sequences.
| Supply Voltage VCC (min‑typ‑max) | 4.5 V – 5.0 V – 5.5 V |
|---|---|
| Input Pin 1 VIN VCC | 1 V |
| Low Level @ RST VOL | 0.4 V |
| Output Current @2.4 V IOH | 1.0 mA – 2.0 mA |
| Input Leakage IIL | -10 µA – +10 µA |
| Input Capacitance CIN | 5 pF |
| VCC Trip Point (TOL=GND) | 4.50 V – 4.62 V – 4.74 V |
| VCC Trip Point (TOL=VCC) | 4.25 V – 4.37 V – 4.49 V |
In this configuration the input pin is a high‑impedance input, allowing a simple resistor divider to sense high‑voltage signals.
The processor shutdown time is proportional to the supply’s hold‑up time; the DS1231 keeps the processor inactive until the power supply stabilizes after the threshold is crossed.
No external capacitors are required for the DS1231 to function.