DS1670

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CS (Chip Select) - The Chip Select signal must be asserted high during a read or a write for

communication over the 3-wire serial interface. CS had an internal 40k ohm pull down resistor.

INT (Interrupt Output) - The INT pin is an active high output of the DS1670 that can be used as an

interrupt input to a microprocessor. The INT output remains high as long as the status bit causing the

interrupt is present and the corresponding interrupt-enable bit is set. The INT pin operates when the

CEI

BLE

driven low.

BHE

driven low.

CEOL

(RAM Chip Enable Out Low) - Chip enable output for low order SRAM byte.

CEOH

(RAM Chip Enable Out High) - Chip enable output for high order SRAM byte.

ST

RST

least 250 ms is generated. This pin has an open drain output with an internal 47 k

Ω pull-up resistor.

AIN0, AIN1, AIN2 (Analog Inputs) - These pins are the three analog inputs for the 3-channel analog-to-

digital converter.

X1, X2 - Connections for a standard 32.768 kHz quartz crystal. For greatest accuracy, the DS1670 must

be used with a crystal that has a specified load capacitance of 6 pF. There is no need for external

capacitors or resistors. Note: X1 and X2 are very high impedance nodes. It is recommended that they

and the crystal be guard-ringed with ground and that high frequency signals be kept away from the crystal

area.

For more information on crystal selection and crystal layout considerations, please consult

Application Note 58, “Crystal Considerations with Dallas Real Time Clocks.”

The DS1670 will not function without a crystal.