DS1677(2000) View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS1677
(Rev.:2000)

Portable System Controller

Dallas Semiconductor -> Maxim Integrated 

SIGNAL DESCRIPTIONS

VCC, GND – DC power is provided to the device on these pins. VCC is the +5.0 volt input.

DS1677

VBAT (Backup Power Supply) – Battery input for standard 3 volt lithium cell or other energy source.

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.

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.

VCCO (External SRAM Power Supply Output) – This pin is internally connected to VCC when VCC is

within nominal limits. However, during power–fail VCCO is internally connected to the VBAT pin.

Switchover occurs when VCC drops below VCCSW.

INT (Interrupt Output) – The INT pin is an active high output of the DS1677 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

DS1677 is powered by VCC or VBAT.

CEI (SRAM Chip Enable In) – CEI must be driven low to enable the external SRAM.

CEO (SRAM Chip Enable Output) – Chip enable output for SRAM.

PFI (Power–Fail Input) – Power–Fail comparator input. When PFI is less than 1.25V, PFO goes low;

otherwise PFO remains high. Connect PFI to GND or VCC when not used.

PFO (Power–Fail Output) – Power–Fail output goes low and sinks current when PFI is less than 1.25V;

otherwise PFO remains high.

ST (Strobe Input) – The Strobe input pin is used in conjunction with the watchdog timer. If the ST pin

is not driven low within the watchdog time period, the RST pin is driven low.

RST (Reset) – The RST pin functions as a microprocessor reset signal. This pin is driven low

1) when VCC is outside of nominal limits; 2) when the watchdog timer has “timed out”; 3) during the

power–up reset period; and 4) in response to a push–button reset. The RST pin also functions as a push–

button reset input. When the RST pin is driven low, the signal is debounced and timed such that a RST

signal of at least 250 ms is generated. This pin has an internal 47 kΩ pull up resistor.

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

to–digital converter.

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