DS1673 Portable System Controller www .maxim-ic.com GENERAL DESCRIPTION FEATURES The DS1673 portable system controller is a circuit Provides Real-Time Clock that incorporates many of the functions necessary for Counts Seconds, Minutes, Hours, Date of the low-power portable products integrated into one chip. Month, Month, Day of the Week, and Year The device provides a real-time clock (RTC), NV with Leap Year Compensation Valid Up to RAM controller, microprocessor monitor, and a 2100 3-channel, 8-bit analog-to-digital converter (ADC). Power-Control Circuitry Supports System Communication with the DS1673 is established Power-On from Day/Time Alarm through a simple 3-wire interface. Microprocessor Monitor Halts Microprocessor During Power Fail The RTC provides seconds, minutes, hours, day, Automatically Restarts Microprocessor after date, month, and year information with leap year Power Failure compensation. The RTC also provides an alarm Monitors Pushbutton for External Override interrupt. This interrupt works when the DS1673 is Halts and Resets an Out-of-Control powered by the system power supply or when in Microprocessor battery-backup operation, so the alarm can be used to NV RAM Control wake up a system that is powered down. Automatic Battery Backup and Write Protection to External SRAM Automatic backup and write protection of an external 3-Channel, 8-Bit ADC SRAM is provided through the V , CEOL, and CCO Simple 3-Wire Interface CEOH pins. The backup energy source used to power +3.0V or +5.0V Operation the RTC is also used to retain RAM data in the absence of V through the V pin. The chip- CC CCO PIN CONFIGURATION enable outputs to RAM (CEOL and CEOH) are controlled during power transients to prevent data TOP VIEW corruption. V BAT ST 1 20 DS1673 2 V 19 V CCO CC ORDERING INFORMATION SCLK 3 18 X1 VOLTAGE PIN- PART* TOP MARK I/O 4 X2 17 (V) PACKAGE AIN0 CS 16 5 DS1673E-3 3.0 20 TSSOP DS1673-3 AIN1 CEI 6 15 DS1673E-3+ 3.0 20 TSSOP DS1673-3 CEOL 7 AIN2 DS1673E-5 5.0 20 TSSOP DS1673-5 14 RST CEOH DS1673E-3/ 8 13 3.0 20 TSSOP DS1673-3 T&R 12 INT 9 BLE DS1673E-3+ 11 GND 10 BHE 3.0 20 TSSOP DS1673-3 T&R DS1673E-5/ TSSOP (4.4mm) 5.0 20 TSSOP DS1673-5 T&R SO (300 mils) DS1673S-3 3.0 20 SO DS1673S-3 DS1673S-5 5.0 20 SO DS1673S-5 * All devices are specified over the 0C to +70C operating range. A + anywhere on the top mark denotes a lead-free device. + Denotes a lead(Pb)-free/RoHS-compliant device. 1 of 18 REV: 080805 DS1673 DETAILED DESCRIPTION The microprocessor monitor circuitry of the DS1673 provides three basic functions. First, a precision temperature-compensated reference and comparator circuit monitors the status of V . When an out-of- CC tolerance condition occurs, an internal power-fail signal is generated which forces the reset to the active state. When V returns to an in-tolerance condition, the reset signals are kept in the active state for CC 250 ms to allow the power supply and processor to stabilize. The second microprocessor monitor function is pushbutton reset control. The DS1673 debounces a pushbutton input and guarantees an active reset pulse width of 250 ms. The third function is a watchdog timer. The DS1673 has an internal timer that forces the reset signals to the active state if the strobe input is not driven low prior to watchdog timeout. The DS1673 also provides a 3-channel, 8-bit successive approximation analog-to-digital converter. The converter has an internal 2.55V (typical) reference voltage generated by an on-board band-gap circuit. The ADC 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 DS1673. The following paragraphs describe the function of each pin. DS1673 BLOCK DIAGRAM Figure 1 2 of 18