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GENERAL DESCRIPTION

The DS1677 portable system controller is a

circuit that incorporates many of the functions

necessary for low-power portable products

integrated into one chip. The device provides a

real-time clock (RTC), NV RAM controller,

microprocessor monitor, power-fail warning, and

a 3-channel, 8-bit analog-to-digital converter

(ADC). Communication with the DS1677 is

established through a simple 3-wire interface.

The RTC provides seconds, minutes, hours, day,

date, month, and year information with leap year

compensation. The RTC also provides an alarm

interrupt. This interrupt works when the DS1677

is powered by the system power supply or when

in battery-backup operation so the alarm can be

used to wake up a system that is powered down.

Automatic backup and write protection of an

external SRAM is provided through the V

CCO

and

CEO pins. The backup energy source used to

power the RTC is also used to retain RAM data in

the absence of V

through the V

CCO

pin. CEO,

the chip-enable output to SRAM, is controlled

during power transients to prevent data

corruption.

ORDERING INFORMATION

PART*

VOLTAGE

(V)

PIN-

PACKAGE

TOP MARK†

DS1677E 5.0 20 TSSOP DS1677-5

DS1677E+ 5.0 20 TSSOP DS1677-5

* All devices are specified over the 0°C to +70°C operating range.

† A “‘+” anywhere on the top mark denotes a lead(Pb)-free device.

+ Denotes a lead(Pb)-free/RoHS-compliant device.

FEATURES

 Provides Real-Time Clock

Counts Seconds, Minutes, Hours, Date of the

Month, Month, Day of the Week, and Year

with Leap Year Compensation Valid Up to

2100

Power Control Circuitry Supports System

Power-On from Day/Time Alarm

 Microprocessor Monitor

Halts Microprocessor During Power-Fail

Automatically Restarts Microprocessor After

Power Failure

Monitors Pushbutton for External Override

Halts and Resets an Out-of-Control

Microprocessor

 NV RAM Control

Automatic Battery Backup and Write

Protection to External SRAM

 3-Channel, 8-Bit ADC

 Simple 3-Wire Interface

 +5.0V Operation

 1.25V Threshold Detector for Power-Fail

Warning

 UL Recognized

PIN CONFIGURATION

DS1677

Portable System Controlle

www.maxim-ic.com

TSSOP

4.4mm

BAT

CCO

SCLK

I/O

N.C.

INT

GND

AIN0

AIN1

AIN2

TOP VIEW

DS1677

Summary of content (18 pages)

PAGE 1
DS1677 Portable System Controller www.maxim-ic.com GENERAL DESCRIPTION FEATURES The DS1677 portable system controller is a circuit that incorporates many of the functions necessary for low-power portable products integrated into one chip. The device provides a real-time clock (RTC), NV RAM controller, microprocessor monitor, power-fail warning, and a 3-channel, 8-bit analog-to-digital converter (ADC). Communication with the DS1677 is established through a simple 3-wire interface.
PAGE 2
DS1677 DETAILED DESCRIPTION The microprocessor monitor circuitry of the DS1677 provides three basic functions. First, a precision temperature-compensated reference and comparator circuit monitors the status of VCC. When an out-oftolerance condition occurs, an internal power-fail signal is generated which forces the to RST the active state. When VCC returns to an in-tolerance condition, the RST signal is kept in the active state for 250ms to allow the power supply and processor to stabilize.
PAGE 3
DS1677 PIN DESCRIPTION PIN NAME 1 VBAT 2 VCCO 3 4 SCLK I/O 5 CS 6 7 8 CEI CEO N.C. 9 INT 10 GND 11 PFO 12 PFI 13 RST 14, 15, 16 AIN2, AIN1, AIN0 17, 18 X2, X1 19 VCC 20 ST FUNCTION Battery Input for Standard 3V Lithium Cell or Other Energy Source. UL recognized to ensure against reverse charging when used with a lithium battery. Go to www.maximic.com/qa/info/ul/. External SRAM Power Supply Output. This pin is internally connected to VCC when VCC is within nominal limits.
PAGE 4
DS1677 POWER-UP/POWER-DOWN CONSIDERATIONS When VCC is applied to the DS1677 and reaches a level greater than VCCTP (power-fail trip point), the device becomes fully accessible after tRPU (250ms typical). Before tRPU elapses, all inputs are disabled. When VCC drops below VCCSW, the device is switched over to the VBAT supply. During power-up, when VCC returns to an in-tolerance condition, the RST pin is kept in the active state for 250ms (typical) to allow the power supply and microprocessor to stabilize.
PAGE 5
DS1677 DS1677 ADDRESS MAP Figure 3 BIT7 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 0 0 0 0 0 0 M M M M BIT0 10 SECONDS SECONDS 10 MINUTES MINUTES 10 HR 12 10 HR HOURS 24 A/P 0 0 0 0 DAY 0 10 DATE DATE 0 0 10 MO.
PAGE 6
DS1677 TIME OF DAY ALARM BITS Table 1 ALARM REGISTER MASK BITS (BIT 7) SECONDS MINUTES HOURS DAYS 1 1 1 1 0 1 1 1 0 0 1 1 0 0 0 1 0 0 0 0 DESCRIPTION Alarm once per second. Alarm when seconds match. Alarm when minutes and seconds match. Alarm when hours, minutes and seconds match. Alarm when day, hours, minutes and seconds match. SPECIAL PURPOSE REGISTERS The DS1677 has two additional registers (control register and status register) that control the RTC and interrupts.
PAGE 7
DS1677 STATUS REGISTER BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 CU LOBAT 0 0 0 0 0 IRQF CU (Conversion Update In Progress). When this bit is a one, an update to the ADC Register (register 0Eh) will occur within 488 μs. When this bit is a zero, an update to the ADC Register will not occur for at least 244 μs. LOBAT (Low Battery Flag). This bit reflects the status of the backup power source connected to the VBAT pin. When VBAT is greater than 2.5V, LOBAT is set to a logic 0.
PAGE 8
DS1677 MICROPROCESSOR MONITOR The DS1677 monitors three vital conditions for a microprocessor: power supply, software execution, and external override. First, a precision temperature-compensated reference and comparator circuit monitors the status of VCC. When an out-of-tolerance condition occurs, an internal power-fail signal is generated which forces the RST pin to the active state thus warning a processor-based system of impending power failure.
PAGE 9
DS1677 ANALOG-TO-DIGITAL CONVERTER The DS1677 provides a 3-channel 8-bit analog-to-digital converter. The A/D reference voltage (2.55V typical) is derived from an on-chip band-gap circuit. Three multiplexed analog inputs are provided through the AIN0, AIN1, and AIN2 pins. The ADC is monotonic (no missing codes) and uses a successive approximation technique to convert the analog signal into a digital code. An A/D conversion is the process of assigning a digital code to an analog input voltage.
PAGE 10
DS1677 CU BIT TIMING Figure 5 3-WIRE SERIAL INTERFACE Communication with the DS1677 is accomplished through a simple 3-wire interface consisting of the Chip Select (CS), Serial Clock (SCLK) and Input/Output (I/O) pins. All data transfers are initiated by driving the CS input high. The CS input serves two functions. First, CS turns on the control logic, which allows access to the shift register for the address/command sequence.
PAGE 11
DS1677 SINGLE BYTE DATA TRANSFER Figure 6 MULTIPLE BYTE BURST TRANSFER Figure 7 11 of 18
PAGE 12
DS1677 POWER-FAIL COMPARATOR Figure 8 = 12 of 18
PAGE 13
DS1677 ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground……………………………………………..-0.3V to +7.0V Operating Temperature Range………………………………………………………………..0C to +70C Storage Temperature Range………………………………………………………………-55C to +125C Soldering Temperature………………………………………….See IPC/JEDEC J-STD-020 Specification This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied.
PAGE 14
DS1677 (TA = +25C) CAPACITANCE PARAMETER Input Capacitance I/O Capacitance Crystal Capacitance SYMBOL CI CI/O CX MIN AC ELECTRICAL CHARACTERISTICS PARAMETER Data to Clock Setup CLK to Data Hold CLK to Data Delay CLK to Low Time CLK to High Time CLK Frequency CLK Rise and Fall CS to CLK Setup CLK to CS Hold CS Inactive Time CS to I/O High-Z VCC Slew Rate (4.5V to 2.3V) VCC Slew Rate (2.3V to 4.
PAGE 15
DS1677 TIMING DIAGRAM: READ DATA Figure 9 TIMING DIAGRAM: WRITE DATA Figure 10 PUSHBUTTON RESET Figure 11 15 of 18
PAGE 16
DS1677 POWER-UP Figure 12 POWER-DOWN Figure 13 16 of 18
PAGE 17
DS1677 POWER-FAIL WARNING Figure 14 NOTES: 1. All voltages are referenced to ground. 2. ICCA is specified with outputs open, CS set to a logic 1, SCLK = 500kHz, oscillator enabled, and ADC enabled. 3. IADC is specified with CS, VCCO open and I/O, SCLK at logic 0. ADC is enabled. 4. ICCS is specified with CS, VCCO open and I/O, SCLK at logic 0. ADC is disabled. 5. CS has a 40k pulldown resistor to ground. 6. Measured at VIH = 2.0V or VIL = 0.8V and 10ns maximum rise and fall time. 7. Measured at VOH = 2.
PAGE 18
DS1677 PACKAGE INFORMATION For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 20 TSSOP U20+1 21-0066 18 of 18 Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product. No circuit patent licenses are implied.