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DS1212 Nonvolatile Controller x 16 Chip
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FEATURES
Converts full CMOS RAM into nonvolatile memory Unconditionally write protects when VCC is out of tolerance Automatically switches to battery when power-fail occurs 4 to 16 decoder provides control for up to 16 CMOS RAMs Consumes less than 100 nA of battery current Tests battery condition on power-up Provides for redundant batteries Power fail signal can be used to interrupt processor on power failure Optional 5% or 10% power-fail detection Optional 28-pin PLCC surface mount package Optional industrial temperature range of -40C to +85C
PIN ASSIGNMENT
VBAT1 VCCO TOL PF CE15 CE14 CE13 CE12 CE11 D C B A GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 VCCI VBAT2 CE CE0 CE1 CE2 CE3 CE4 CE5 CE6 CE7 CE8 CE9 CE10
28-Pin DIP (600-mil) See Mech. Drawings Section PF TOL VCCO VBAT1 VCCI VBAT2 CE
4 3 2 1 28 27 26 25 24 23 22 21 20 19 12 13 14 15 16 17 18
PIN DESCRIPTION
A, B, C, D
CE CE0 - CE15
GND VBAT1 VBAT2 TOL VCCI VCCO
PF
- Address Inputs - Chip Enable - Chip Enable Outputs - Ground - + Battery 1 - + Battery 2 - Power Supply Tolerance - +5V Supply - RAM Supply - Power Fail
CE15 CE14 CE13 CE12 CE11 D C
5 6 7 8 9 10 11
CE0 CE1 CE2 CE3 CE4 CE5 CE6
28-Pin PLCC See Mech. Drawings Section
DESCRIPTION
The DS1212 Nonvolatile Controller x16 Chip is a CMOS circuit that solves the application problem of converting CMOS RAMs into nonvolatile memories. Incoming power is monitored for an out-oftolerance condition. When such a condition is detected, the chip enables are inhibited to accomplish write protection and the battery is switched on to supply the RAMs with uninterrupted power. Special circuitry uses a low-leakage CMOS process that affords precise voltage detection at extremely low battery consumption. 1 of 7 111899
B A GND CE10 CE9 CE8 CE7
DS1212
By combining the DS1212 Nonvolatile Controller chip and lithium batteries, nonvolatile RAM operation can be achieved for up to 16 CMOS memories.
OPERATION
The DS1212 performs six circuit functions required to decode and battery back up a bank of up to 16 RAMs. First, the 4-to-16 decoder provides selection of one of 16 RAMs. Second, a switch is provided to direct power from the battery or VCCI supply, depending on which is greater. This switch has a voltage drop of less than 0.2V. The third function the DS1212 provides is power-fail detection. It constantly monitors the VCCI supply. When VCCI falls below 4.75 volts or 4.5 volts, depending on the level of tolerance Pin 3, a precision comparator outputs a power-fail detect signal to the decoder/chip enable logic and the PF signal is driven low. The PF signal will remain low until VCCI is back in normal limits. The fourth function of write protection is accomplished by holding all chip enable outputs ( CE0 - CE15 ) to within 0.2 volts of VCCI or battery supply. If CE is low at the time power fail detection occurs, the chip enable outputs are kept in their present state until CE is driven high. The delay of write protection until the current memory cycle is completed prevents corruption of data. Power-fail detection occurs in the range of 4.75 volts to 4.5 volts with tolerance Pin 3 grounded. If Pin 3 is connected to VCCO, then powerfail occurs in the range of 4.5 volts to 4.25 volts. During nominal supply conditions the chip enable outputs follow the logic of a 4-to-16 decoder, shown in Figure 1. The fifth function the DS1212 performs is a battery status warning so that data loss is avoided. Each time the circuit is powered up, the battery voltage is checked with a precision comparator. If the battery voltage is less than 2 volts, the second memory cycle is inhibited. Battery 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 2.0 volts and data is in danger of being corrupted. The sixth function of the DS1212 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 DS1212 provides an internal isolation switch which allows the connection of two batteries during battery backup operation. The battery with the highest voltage is selected for use. If one battery should fail, the other will then assume the load. The switch to a redundant battery is transparent to circuit operation and the user. A battery status warning will only occur if both batteries are less than 2.0 volts. For single battery applications the unused battery input must be grounded.
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DS1212
NONVOLATILE CONTROLLER/DECODER Figure 1
CE
D X X L L L L L L L L H H H H H H H H
INPUTS C B X X L L L L H H H H L L L L H H H H X X L L H H L L H H L L H H L L H H
OUTPUTS A X X L H L H L H L H L H L H L H L H
CE0 CE1 CE2 CE3 CE4 CE5 CE6 CE7 CE8 CE9 CE10 CE11 CE12 CE13 CE14 CE15
PF
H X L L L L L L L L L L L L L L L L
H H L H H H H H H H H H H H H H H H
H H H L H H H H H H H H H H H H H H
H H H H L H H H H H H H H H H H H H
H H H H H L H H H H H H H H H H H H
H H H H H H L H H H H H H H H H H H
H H H H H H H L H H H H H H H H H H
H H H H H H H H L H H H H H H H H H
H H H H H H H H H L H H H H H H H H
H H H H H H H H H H L H H H H H H H
H H H H H H H H H H H L H H H H H H
H H H H H H H H H H H H L H H H H H
H H H H H H H H H H H H H L H H H H
H H H H H H H H H H H H H H L H H H
H H H H H H H H H H H H H H H L H H
H H H H H H H H H H H H H H H H L H
H H H H H H H H H H H H H H H H H L
H L H H H H H H H H H H H H H H H H
H = High Level L = Low Level X = Irrelevant Note: VCCI input is 250 mV lower when TOL PIN3 = VCCO.
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DS1212
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * -0.3V to +7.0V 0C to 70C -55C to +125C 260C for 10 seconds
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
PARAMETER Pin 3 = GND Supply Voltage Pin 3 = VCCO Supply Voltage Logic 1 Input Logic 0 Input Battery Input SYMBOL VCCI VCCO VIH VIL VBAT1, VBAT2 MIN 4.75 4.5 2.2 -0.3 2.0 TYP 5.0 5.0 MAX 5.5 5.5 VCC+0.3 +0.8 4.0
(0C to 70C)
UNITS V V V V V NOTES 1 1 1 1 1, 2
(0C to 70C; VCCI = 4.75 to 5.5V PIN 3 = GND) (0C to 70C; VCCI = 4.5 to 5.5V, PIN 3 = VCCO) DC ELECTRICAL CHARACTERISTICS
PARAMETER Supply Current Supply Current @ VCCO= VCCI-0.2 Input Leakage Output Leakage CE0 - CE15 , PF Output @ 2.4V CE0 - CE15 , PF Output @ 0.4V VCC Trip Point (TOL=GND) VCC Trip Point (TOL=VCCO) SYMBOL ICCI ICCO1 IIL ILO IOH IOL VCCTP VCCTP MIN TYP MAX 5 80 +1.0 +1.0 4.0 4.74 4.49 UNITS mA mA A A mA mA V V NOTES 3 1, 4 ,10
-1.0 -1.0 -1.0 4.50 4.25 4.62 4.37
5 5 1 1
(0C to 70C; VCCI < VBAT)
PARAMETER CE0 -CE15 Output Battery Current Battery Backup Current @ VCCO = VBAT1 - 0.5V SYMBOL VOHL IBAT ICC2 MIN VBAT-0.2 TYP MAX 0.1 100 UNITS V A A NOTES 3, 7 2, 3 6, 10, 11
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DS1212
CAPACITANCE
PARAMETER Input Capacitance Output Capacitance SYMBOL CIN COUT MIN TYP MAX 5 7
(TA = 25C)
UNITS pF pF NOTES
(0C to 70C; VCCI = 4.75 to 5.5V, PIN 3 = GND) (0C to 70C; VCCI = 4.5 to 5.5V, PIN 3 = VCCO) AC ELECTRICAL CHARACTERISTICS
PARAMETER CE Propagation Delay CE High to Power-Fail Address Setup SYMBOL tPD tPF tAS MIN 5 20 TYP 10 MAX 20 0 UNITS ns ns ns NOTES 5 9
(0C to 70C; VCCI < 4.75V, PIN 3 = GND) (0C to 70C; VCCI < 4.5V, PIN 3 = VCCO)
PARAMETER Recovery at Power-Up VCC Slew Rate Power-Down VCC Slew Rate Power-Down VCC Slew Rate Power-Up CE Pulse Width Power Fail to PF Low SYMBOL tREC tF tFB tR tCE tPFL MIN 2 300 10 0 300 TYP 80 MAX 125 UNITS ms s s s s s NOTES
1.5
7, 8
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DS1212
TIMING DIAGRAM: DECODER
TIMING DIAGRAM: POWER-UP
TIMING DIAGRAM: POWER-DOWN
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DS1212
TYPICAL APPLICATION Figure 2
OUTPUT LOAD Figure 3
NOTES:
1. All voltages referenced to ground. 2. Only one battery input is required. 3. Measured with VCCO and CE0 - CE15 open. 4. ICC01 is the maximum average load which the DS1212 can supply to the memories. 5. Measured with a load as shown in Figure 3. 6. ICC02 is the maximum average load current which the DS1212 can supply to the memories in the battery backup mode. 7. Chip enable outputs CE0 - CE15 can only sustain leakage current in the battery backup mode. 8. tCE max. must be met to ensure data integrity on power loss. 9. tAS is only required to keep the decoder outputs glitch-free. While CE is low, the outputs ( CE0 - CE15 ) will be defined by inputs A through D with a propagation delay of tPD from an A through D input change. 10. For applications where higher currents are required, please see the Battery Manager chip data sheet (DS1259). 11. The DS1212 has a 5 kohm resistor in series with the battery input. As current from the battery increases over 100 A, the voltage drop will increase proportionately. The device cannot be damaged by higher currents in the battery path.
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