DS1670

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The microprocessor monitor circuitry of the DS1670 provides three basic functions. First, a precision

tolerance condition occurs, an internal power-fail signal is generated which forces the reset to the active

250 ms to allow the power supply and processor to stabilize. The second microprocessor monitor

function is pushbutton reset control. The DS1670 debounces a pushbutton input and guarantees an active

reset pulse width of 250 ms. The third function is a watchdog timer. The DS1670 has an internal timer

that forces the reset signals to the active state if the strobe input is not driven low prior to watchdog

time-out.

The DS1670 also provides a 3-channel, 8-bit successive approximation analog-to-digital converter. The

converter has an internal 2.55-volt (typical) reference voltage generated by an on-board band-gap circuit.

The A/D converter is monotonic (no missing codes) and has an internal analog filter to reduce high

frequency noise.

OPERATION

The block diagram in Figure 1 shows the main elements of the DS1670. The following paragraphs

describe the function of each pin.

DS1670 BLOCK DIAGRAM Figure 1

SIGNAL DESCRIPTIONS

3.3 volts are applied within nominal limits, the device is fully accessible and data can be written and read.

SCLK (Serial Clock Input) - SCLK is used to synchronize data movement on the serial interface.

I/O (Data Input/Output) - The I/O pin is the bi-directional data pin for the 3-wire interface.