DS1216B Maxim, DS1216B Datasheet - Page 5

• Manufacturer Part Number: DS1216B
• Description: The DS1216 SmartWatch RAM and SmartWatch ROM sockets are 600-mil-wide DIP sockets with a built-in CMOS watch function, an NV RAM controller circuit, and an embedded lithium energy source
• Manufacturer: Maxim

Figure 1. SmartWatch Comparison Register Definition
NONVOLATILE CONTROLLER OPERATION
The DS1216 SmartWatch performs circuit functions required to make a CMOS RAM nonvolatile. 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 that the SmartWatch provides is
power-fail detection, which occurs at V
goes out of tolerance, a comparator outputs a power-fail signal to the chip-enable logic. The third function
accomplishes write protection by holding the chip-enable signal to the memory within 0.2V of V
battery. During nominal power-supply conditions, the memory chip-enable signal will track the chip-
enable signal sent to the socket with a maximum propagation delay of 6ns.
FRESHNESS SEAL
Each DS1216 is shipped from Maxim with its lithium energy source disconnected, ensuring full energy
capacity. When V
backup operation.
BYTE 0
BYTE 1
BYTE 2
BYTE 3
BYTE 4
BYTE 5
BYTE 6
BYTE 7
NOTE: THE PATTERN RECOGNITION IN HEX IS C5, 3A, 5C, C5, 3A, A3, 5C. THE ODDS OF THIS PATTERN
ACCIDENTALLY DUPLICATING AND CAUSING INADVERTENT ENTRY TO THE SMARTWATCH ARE LESS
THAN 1 IN 10
CC
is first applied at a level greater than the lithium energy source is enabled for battery-
19
. THIS PATTERN IS SENT TO THE SMARTWATCH LSB TO MSB.
0
7
1
0
1
0
1
0
1
1
1
0
0
1
1
0
0
0
0
1
1
0
0
1
1
TP
. The DS1216 constantly monitors the V
1
0
1
0
1
0
1
0
5 of 15
1
0
1
0
1
0
1
0
CC
1
supply, depending on which voltage is greater.
1
0
0
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
VALUE
HEX
C5
3A
A3
5C
C5
3A
A3
5C
CC
supply. When V
CC
CC
or