DS1218S+ Maxim Integrated Products, DS1218S+ Datasheet

IC CONTROLLER NV 8-SOIC

DS1218S+

Manufacturer Part Number
DS1218S+
Description
IC CONTROLLER NV 8-SOIC
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of DS1218S+

Controller Type
Nonvolatile RAM
Voltage - Supply
4.5 V ~ 5.5 V
Operating Temperature
0°C ~ 70°C
Package / Case
8-SOIC (3.9mm Width)
Manual Reset
No
Watchdog
No
Battery Backup Switching
Yes
Supply Voltage (max)
5.5 V
Supply Voltage (min)
4.5 V
Supply Current (typ)
70 mA
Mounting Style
SMD/SMT
Maximum Operating Temperature
+ 70 C
Chip Enable Signals
Yes
Minimum Operating Temperature
0 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
FEATURES
DESCRIPTION
The DS1218 is a CMOS circuit which solves the application problems of converting CMOS RAM into
nonvolatile memory. Incoming power is monitored for an out-of-tolerance condition. When such a
condition is detected, the chip enable output is inhibited to accomplish write protection and the battery is
switched on to supply 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 mini-
DIP package keeps PC board real estate requirements to a minimum. By combining the DS1218
nonvolatile controller chip with a full CMOS memory and lithium batteries, 10 years of nonvolatile RAM
operation can be achieved.
OPERATION
The DS1218 Nonvolatile Controller performs the circuit functions required to battery back-up a RAM.
First, a switch is provided to direct power from the battery or V
This switch has a voltage drop of less than 0.2V. The second function which the nonvolatile controller
provides is power-fail detection. The DS1218 constantly monitors the V
1.26 times the battery voltage, a precision comparator outputs a power-fail detect signal to the chip enable
logic. The third function of write protection is accomplished by holding the chip enable output signal to
within 0.2V of the V
During nominal supply conditions, the chip enable output will follow chip enable input with a maximum
propagation delay of 10 ns.
www.dalsemi.com
Converts CMOS RAM into nonvolatile
memories
Unconditionally write protects when V
out of tolerance
Automatically switches to battery when
power fail occurs
Space saving 8-pin mini-DIP/8-pin 150 mil
SOIC
Consumes less than 100 na of battery current
CCI
or battery supply, when a power-fail condition is detected.
CC
is
1 of 4
PIN ASSIGNMENT
PIN DESCRIPTION
V
V
NC
V
GND
CEI
CEO
CCI
CCO
BAT
GND
V
CCO
NC
NC
CCI
3
1
2
4
Nonvolatile Controller
supply, depending on which is greater.
- Input +5 Volt Supply
- RAM Power (V
- Chip Enable Input
- No Connection
- Chip Enable Output
- + Battery
- Ground
CC
8
7
6
5
supply. When V
V
V
CEO
CEI
CCI
BAT
CC
) Supply
DS1218
CCI
111899
falls to

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DS1218S+ Summary of contents

Page 1

FEATURES Converts CMOS RAM into nonvolatile memories Unconditionally write protects when V out of tolerance Automatically switches to battery when power fail occurs Space saving 8-pin mini-DIP/8-pin 150 mil SOIC Consumes less than 100 na of battery current DESCRIPTION ...

Page 2

ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the ...

Page 3

TIMING DIAGRAM: POWER-UP TIMING DIAGRAM: POWER-DOWN DS1218 ...

Page 4

NOTES: 1. All voltages referenced to ground. 2. Measured with a load as shown in Figure 1. 3. Outputs open. 4. Drain from battery when V 5. Maximum amount of current which can be drawn through pin 1 of the ...

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