DS1216 SmartWatch RAM/SmartWatch ROM
WARNING:
Under no circumstances should negative undershoots of any amplitude be allowed when the device is in
battery-backup mode. Water washing for flux removal will discharge internal lithium source because
exposed voltage pins are present.
NOTES:
1) Pin locations are designated “U” when a parameter definition refers to the socket receptacle and “L”
when a parameter definition refers to the socket pin.
2) No memory inserted in the socket.
3) Pin 26L can be connected to VCC or left disconnected at the PC board.
4) SmartWatch sockets can be successfully processed through some conventional wave-soldering
techniques as long as temperature exposure to the lithium energy source contained within does not
exceed +85°C. However, post-solder cleaning with water-washing techniques is not permissible.
Discharge to the lithium energy source can result, even if deionized water is used. It is equally
imperative that ultrasonic vibration is not used in order to avert damage to the quartz crystal resonator
employed by the oscillator circuit.
5) tCE max must be met to ensure data integrity on power loss.
6) VCCO1 is the maximum voltage drop from VCC(L) to VCC(U) while Vcc(L) is supplying power. VCCO
is the maximum voltage drop from VBAT to VCC(U) while the part is in battery backup.
2
7) Input pulse rise and fall times equal 10ns.
8) Applies to pins RST L, A2 L, A0 L, CE L, OE L, and WE L.
9) tWR is a functions of the latter occurring edge of WE or CE.
10) tDH and tDS are a function of the first occurring edge of WE or CE.
11) tAS is a function of the first occurring edge of OE or CE.
12) tAH is a function of the latter occurring edge of OE or CE.
13) RST (Pin 1) has an internal pullup resistor.
14) Expected data retention is based on using an external SRAM with a data retention current of less than
0.5µA at +25°C. Expected data-retention time (time while on battery) for a given RAM battery
current can be calculated using the following formula:
0.045 / (current in amps) = data-retention time in hours
15) The DS1216 products are shipped with the battery-backup power off. First power-up switches backup
battery on to clock and RAM VCC pin upon power-down.
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