DS1238S-5 Maxim Integrated Products, DS1238S-5 Datasheet
DS1238S-5
Specifications of DS1238S-5
Available stocks
Related parts for DS1238S-5
DS1238S-5 Summary of contents
Page 1
FEATURES Holds microprocessor in check during power transients Halts and restarts an out-of-control microprocessor Warns microprocessor of an impending power failure Converts CMOS SRAM into nonvolatile memory Unconditionally write-protects memory when power supply is out of tolerance Delays write ...
Page 2
Oscillator control pins OSCSEL and OSCIN provide either external or internal clock timing for both the reset pulse width and ...
Page 3
DS1238 FUNCTIONAL BLOCK DIAGRAM Figure 1 WATCHDOG TIMER The DS1238 provides a watchdog timer function which forces the active state when the strobe input ( is described below in Table 1. The watchdog timeout period begins as soon as RST ...
Page 4
Table 1. The pin will remain low until one of three operations occurs. The first is to strobe the WDS pin with a falling edge, which will both set the to leave the pin open, which disables the watchdog. Lastly, ...
Page 5
OSCILLATOR CONTROLS Table 1 OSCIN OSCSEL Ext Clk Low External Ext Cap Low Low Hi/Open Internal Hi/Open Hi/Open Note that the OSCIN and OSCSEL pins are tri-stated when V POWER MONITOR, WATCHDOG TIMER, AND PUSHBUTTON RESET Figure 3 PUSHBUTTON RESET ...
Page 6
NON-MASKABLE INTERRUPT Figure 1.27 SENSE R2 V SENSE MAXVOLTAGE = 1.27 Example 1: 5 Volt Supply 10k Ohms 4.8 Volts SENSE R1 10k 4 1. 27.8k ...
Page 7
MEMORY BACKUP The DS1238 provides all of the necessary functions required to battery back a static RAM. First, an internal switch is provided to supply SRAM power from the primary 5-volt supply (V external battery (V ), whichever is greater. ...
Page 8
NONVOLATILE SRAM Figure 7 FRESHNESS SEAL Figure 8 Note: This series of pulses must be applied during normal +5 volt operation DS1238 ...
Page 9
POWER SWITCHING Figure 9 Note: If freshness on the DS1238 is not used, and V for system use. BAT01 TIMING DIAGRAMS This section provides a description of the timing diagrams shown in Figure 10 and Figure 11. Figure 10 illustrates ...
Page 10
POWER-DOWN TIMING Figure DS1238 ...
Page 11
POWER-UP TIMING Figure DS1238 ...
Page 12
ABSOLUTE MAXIMUM RATINGS* Voltage on V Pin Relative to Ground CC Voltage on I/O Relative to Ground Voltage on IN Pin Relative to Ground Operating Temperature Operating Temperature (Industrial Version) Storage Temperature Soldering Temperature * This is a stress rating ...
Page 13
AC ELECTRICAL CHARACTERISTICS PARAMETER V Fail Detect to RST, RST NMI TP RESET Active OSCSEL=High Pulse Width ST PBRST @ Slew Rate 4.75 to 4.25 CC Chip Enable Prop Delay V Fail to Chip ...
Page 14
NOTES: 1. All voltages referenced to ground. 2. Measured with PF, CEO CCO the maximum average load which the DS1238 can supply at V CCO1 during normal 5-volt operation the maximum ...