Data Sheet

TIMEKEEPER products AN1012
12/33 Doc ID 6395 Rev 4
5 TIMEKEEPER products
TIMEKEEPER
®
products are very similar in construction and operation to ZEROPOWER
®
products. However, they must be evaluated separately. The current drawn is highly
dependent not only on the temperature, but also on whether the oscillator is active. The
main components of TIMEKEEPER devices are (see Figure 5):
● a CMOS RAM array;
● voltage sense and switching circuitry;
● an analog oscillator and clock chain;
● a lithium power cell; and
● a high-accuracy quartz crystal.
Figure 5. Block diagram of a TIMEKEEPER
®
device
AI01383D
LITHIUM
CELL
OSCILLATOR AND
CLOCK CHAIN
V
PFD
RSTV
CC
V
SS
32,768 Hz
CRYSTA L
VOLTAGE SENSE
AND
SWITCHING
CIRCUITRY
16 x 8 BiPORT
SRAM ARRAY
8176 x 8
SRAM ARRAY
A0-A12
DQ0-DQ7
E
W
G
POWER
IRQ/FT