DS1210

DS1210_03 DALLAS | Alldatasheet

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Technical content

FEATURES

/g167 Converts CMOS RAMs into Nonvolatile Memories /g167 Unconditionally Write Protects when VCC is Out-of-Tolerance /g167 Automatically Switches to Battery when Power-Fail Occurs /g167 Space-Saving 8-Pin DIP /g167 Consumes <100nA of Battery Current /g167 Tests Battery Condition on Power up /g167 Provides for Redundant Batteries /g167 Optional 5% or 10% Power-Fail Detection /g167 Low Forward Voltage Drop on the VCC Switch /g167 Optional 16-Pin SOIC Surface Mount Package /g167 Optional Industrial (N) Temperature Range of -40°C to +85°C PIN ASSIGNMENT PIN DESCRIPTION VCCO - RAM Supply VBAT1 - + Battery 1 TOL - Power Supply Tolerance GND - Ground CE - Chip Enable Input CEO - Chip Enable Output VBAT2 - + Battery 2 VCCI - + Supply NC - No Connect

DESCRIPTION

The DS1210 Nonvolatile Controller Chip is a CMOS ci rcuit which solves the application problem of converting CMOS RAM into nonvolatile memory. Incoming power is monitored for an out-of-tolerance condition. When such a condition is detected, chip en able is inhibited to accomplish write protection and the battery is switched on to suppl y the RAM with uninterrupted power . Special circuitry uses a low- leakage CMOS process which affords precise voltage detection at extremely low battery consumption. The 8-pin DIP package keeps PC board real estate requirements to a minimum. By combining the DS1210 Nonvolatile Controller Chip with a CMOS memory and batteries, nonvolatile RAM operation can be achieved. DS1210 Nonvolatile Controller Chip www.maxim-ic.com VCCO VBAT1 TOL GND VCCI VBAT2 CEO CE DS1210 8-pin DIP (300-mil) See Mech. Drawings Section NC VCCO NC VBAT1 NC TOL NC GND NC VCCI NC VBAT2 NC CEO NC CE DS1210S 16-pin SOIC (300-mil) See Mech. Drawings Section

The DS1210 nonvolatile controller perform s five circuit functions required to battery back up a RAM. First, a switch is provided to direct power from the battery or the incoming supply (V CCI) depending on which is greater. This switch has a voltage drop of less than 0.3V. The second function which the nonvolatile controller provide s is power-fail detection. The DS1210 constantly monitors the incoming supply. When the supply goes out of tolerance a precision comparator detects power-fail and inhibits chip enable ( CEO ). The third function of write protection is accomplished by holding the CEO output signal to within 0.2 volts of the V CCI or battery supply. If CE input is low at the time power-fail detection occurs, the CEO output is kept in its present state until CE is returned high. The de lay of write protection until the current memory cycle is completed prevents the corruption of data. Power-fail detection occurs in the range of 4.75 volts to 4.5 volts with the toleranc e Pin 3 grounded. If Pin 3 in connected to V CCO, then power-fail detection occurs in the range of 4.5 vo lts to 4.25 volts. During nominal supply conditions CEO will follow CE with a maximum propagation delay of 20ns. The fourth function the DS1210 performs is a battery status warning so that potential data loss is avoided. Each time that the circuit is powered up the battery voltage is checked with a precision comparator. If the battery voltage is less than 2.0 volts, the second memory cycle is inhibited. Ba ttery status can, therefore, be determined by performing a read cycle after power-up to any location in memory, verifying that memory location content. A subsequent write cycle can then be executed to the same memory location altering the data. If the next read cycle fails to verify the written data, then the batteries are less than 2.0V and data is in danger of being corrupted. The fifth function of the nonvolatile contro ller provides for battery redundancy. In many applications, data integrity is paramount. In these applications it is often desirable to use two batteries to ensure reliability. The DS1210 c ontroller provides an intern al isolation switch which allows the connection of two batteries. During ba ttery backup operation the battery with the highest voltage is selected for use. If one battery should fa il, the other will take over the load. The switch to a redundant battery is transparent to circuit operation and to the user. A battery status warning will occur when the battery in use falls below 2.0 volts. A grounded V BAT2 pin will not activate a battery-fail warning. In applications where battery redundancy is not required, a single battery should be connected to the BAT1 pin. The BAT2 battery pin must be ground ed. The nonvolatile controlle r contains circuitry to turn off the battery backup. This is to maintain the battery(s) at its highest capacity until the equipment is powered up and valid data is written to the SRAM. While in the freshness seal mode the CEO and VCCO will be forced to VOL. When the batteries are first attached to one or both of the V BAT pins, VCCO will not provide battery back-up until VCCI exceeds VCCTP, as set by the TOL pin, and then falls below VBAT. Figure 1 shows a typical application incorporating the DS1210 in a microprocessor-based system. Section A shows the connections necessary to write protect the RAM when VCC is less than 4.75 volts and to back up the supply with batteries. Section B shows the use of the DS1210 to halt the processor when V CC is less than 4.75 volts and to delay its restart on power-up to prevent spurious writes.

SECTION A - BATTERY BACKUP Figure 1 BATTERY BACKUP CURRENT DRAIN EXAMPLE CONSUMPTION DS1210 IBAT 100 nA RAM ICC02 10 /g109A Total Drain 10.1 /g109A SECTION B - PROCESSOR RESET

ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground -0.3V to +7.0V Operating Temperature 0 /g176C to +70/g176C, -40/g176C to +85/g176C for N parts Storage Temperature -55 /g176C to +125/g176C Soldering Temperature See IPC/JEDEC J-STD-020A * 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. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. RECOMMENDED DC OPERATING CONDITIONS (See Note 9) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Pin 3 = GND Supply Voltage V CCI 4.75 5.0 5.5 V 1 Pin 3 = VCCO Supply Voltage V CCI 4.5 5.0 5.5 V 1 Logic 1 Input V IH 2.2 V CC+0.3 V 1 Logic 0 Input V IL -0.3 +0.8 V 1 Battery Input V BAT1, VBAT2 2.0 4.0 V 1, 2 DC ELECTRICAL CHARACTERISTICS (See Note 9; VCCI = 4.75 to 5.5V PIN 3 = GND) (VCCI = 4.5 to 5.5V, PIN 3 = VCCO) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Supply Current I CCI 5m A3 Supply Voltage V CCO VCC-0.2 V 1 Supply Current I CCO1 80 mA 4 Input Leakage I IL -1.0 +1.0 µA Output Leakage I LO -1.0 +1.0 µA CEO Output @ 2.4V IOH -1.0 mA 5 CEO Output @ 0.4V IOL 4.0 mA 5 VCC Trip Point (TOL=GND) V CCTP 4.50 4.62 4.74 V 1 VCC Trip Point (TOL=VCCO)V CCTP 4.25 4.37 4.49 V 1 (See Note 9; VCCI = < VBAT) CEO Output VOHL VBAT-0.2 V 7 VBAT1 or VBAT2 Battery Current IBAT 100 nA 2, 3 Battery Backup Current @ VCCO = VBAT – 0.3V ICCO2 50 µA 6, 7

CAPACITANCE (TA = 25°C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Capacitance C IN 5p F Output Capacitance C OUT 7p F AC ELECTRICAL CHARACTERISTICS (See Note 9; VCCI = 4.75V to 5.5V, PIN 3 = GND) (VCCI = 4.75V to 5.5V, PIN 3 = GND) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES CE Propagation Delay tPD 51 0 2 0 n s5 CE High to Power-Fail tPF 0n s (See Note 9; VCCI = 4.75V, PIN 3 = GND; VCCI < 4.5, PIN 3 = VCCO) Recovery at Power Up t REC 2 80 125 ms VCC Slew Rate Power-Down t F 300 µs VCC Slew Rate Power-Down t FB 10 µs VCC Slew Rate Power-Down t R 0µ s CE Pulse Width tCE 1.5 µs 8 NOTES: 1. All voltages are referenced to ground. 2. Only one battery input is required. Unused battery inputs must be grounded. 3. Measured with VCCO and CEO open. 4. ICC01 is the maximum average load which the DS1210 can supply to the memories. 5. Measured with a load as shown in Figure 2. 6. ICC02 is the maximum average load current which the DS1210 can supply to the memories in the battery backup mode. 7. tCE max. must be met to ensure data integrity on power loss. 8. CEO can only sustain leakage current in the battery backup mode. 9. All AC and DC electrical characteristics are valid for the full temperature range. For commercial products, this range is 0 to +70/g176C. For industrial products (N), this range is -40/g176C to +85/g176C. 10. DS1210 is recognized by Underwriters Laboratory (U.L.®) under file E99151.

TIMING DIAGRAM: POWER-UP TIMING DIAGRAM: POWER-DOWN OUTPUT LOAD Figure 2