MAX6901 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX6901 Datasheet PDF : 18 Pages
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3-Wire Serial RTC in a TDFN
(a) 3-WIRE SINGLE BYTE READ:
CS
SCLK
I/O
A0
A1 A2
A3
A4 A5 A6 A7 D0 D1 D2
D3
D4
D5
D6 D7
1
A1 A2
A3
A4
A5
R
1
ADDRESS/COMMAND BYTE
R = RAM/ REGISTER SELECT BIT
RAM = 1, REGISTER = 0
I/O DATA BYTE
(b) 3-WIRE SINGLE BYTE WRITE:
CS
SCLK
A1
A2
A3
A4 A5
A6 A7
D0 D1 D2 D3 D4
D5 D6 D7
I/O
0 A1
A2
A3
A4
A5
R1
ADDRESS/COMMAND BYTE
R = RAM/ REGISTER SELECT BIT
RAM = 1, REGISTER = 0
I/O DATA BYTE
Figure 2. Single Byte Data Transfer
32.768kHz Output (32KHZ)
32KHZ is a push-pull 32.768kHz output for timing or
clocking of external devices. Bit D7 in the Clock
Seconds register is the active-low enable bit for 32KHZ.
When D7 is logic 0, 32KHZ is enabled. When logic 1,
32KHZ is disabled and set to high impedance. Power-
on reset enables the 32.768kHz output.
Applications Information
Crystal Selection
The MAX6901 is designed to use a standard 32.768kHz
watch crystal. Table 1 details the recommended crystal
requirements. Some suggested crystals are listed in
Table 4. In addition to the specified SMT devices, some
of the listed manufacturers also offer other package
options.
Frequency Stability and Temperature
Timekeeping accuracy of the MAX6901 is dependent
on the frequency stability of the external crystal. To
determine frequency stability, use the parabolic curve
in Figure 6 and the following equations:
∆f = fk (T0 - T)2
where:
∆f = change in frequency from +25°C
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