MAX6902ETA-T MAXIM [Maxim Integrated Products], MAX6902ETA-T Datasheet - Page 4

• Manufacturer Part Number: MAX6902ETA-T
• Description: SPI-Compatible RTC in a TDFN
• Manufacturer: MAXIM [Maxim Integrated Products]

The MAX6902 is a real-time clock/calendar with an SPI-
compatible interface and 31 x 8 bits of SRAM. It pro-
vides seconds, minutes, hours, day of the week, date of
the month, month, and year information, held in seven 8-
bit timekeeping registers (Functional Diagram). An on-
chip 32.768kHz oscillator circuit requires only a single
external crystal to operate. Table 1 specifies the para-
meters for the external crystal, and Figure 1 shows a
functional schematic of the oscillator circuit. The
MAX6902’s register addresses and definitions are
described in Figure 2 and in Table 2. Time and calendar
data are stored in the registers in binary-coded decimal
(BCD) format. A polled alarm function is included for
scheduled timing of user-defined times or intervals.
SPI-Compatible RTC in a TDFN
4
(T
PIN
A
1
2
3
4
5
6
7
8
= +25°C, unless otherwise noted.)
_______________________________________________________________________________________
NAME
DOUT
SCLK
GND
V
DIN
CS
X2
X1
CC
Serial Clock Input. SPI clock for DIN and
DOUT data transfers.
SPI Data Output
SPI Data Input
Ground
Chip Select Input. Active low for valid data
transfers.
Power-Supply Pin. Bypass V
with a 0.1µF capacitor.
External 32.768kHz Crystal
External 32.768kHz Crystal
Detailed Description
Pin Description
FUNCTION
CC
10.0
1.0
0.1
to GND
2.0
2.5
TIMEKEEPING CURRENT
vs. SUPPLY VOLTAGE
3.0
SUPPLY VOLTAGE (V)
3.5
Table 1. Acceptable Quartz Crystal
Parameters
Figure 1. Crystal Oscillator Circuit Schematic
4.0
PARAMETER
Frequency
Equivalent
Series
Resistance
(ESR)
Parallel Load
Capacitance
Q Factor
Typical Operating Characteristics
4.5
5.0
5.5
25pF
MAX6902
SYMBOL
R
C
Q
f
S
L
X1
EXTERNAL
CRYSTAL
40,000
11.2
MIN
40
32.768
X2
TYP
12.5
60,000
25pF
MAX
13.7
60
UNITS
kHz
kΩ
pF