Operation M41T56
10/27 Doc ID 6104 Rev 9
2.2 Read mode
In this mode, the master reads the M41T56 slave after setting the slave address (see
Figure 7 on page 11 and Figure 8 on page 11). Following the WRITE mode control bit
(R/W
= 0) and the acknowledge bit, the word address A
n
is written to the on-chip address
pointer. Next the START condition and slave address are repeated, followed by the READ
mode control bit (R/W
= 1). At this point, the master transmitter becomes the master
receiver. The data byte which was addressed will be transmitted and the master receiver will
send an acknowledge bit to the slave transmitter. The address pointer is only incremented
on reception of an acknowledge bit. The M41T56 slave transmitter will now place the data
byte at address A
n
+ 1 on the bus. The master receiver reads and acknowledges the new
byte and the address pointer is incremented to A
n
+ 2. This cycle of reading consecutive
addresses will continue until the master receiver sends a STOP condition to the slave
transmitter.
An alternate READ mode may also be implemented, whereby the master reads the M41T56
slave without first writing to the (volatile) address pointer. The first address that is read is the
last one stored in the pointer, see Figure 9 on page 11.
Table 2. AC characteristics
Symbol Parameter
(1)
1. Valid for ambient operating temperature: T
A
= –40 to 85 °C; V
CC
= 4.5 to 5.5 V (except where noted).
Min Max Unit
f
SCL
SCL clock frequency 0 100 kHz
t
LOW
Clock low period 4.7 µs
t
HIGH
Clock high period 4 µs
t
R
SDA and SCL rise time 1 µs
t
F
SDA and SCL fall time 300 ns
t
HD:STA
START condition hold time
(after this period the first clock pulse is generated)
4µs
t
SU:STA
START condition setup time
(only relevant for a repeated start condition)
4.7 µs
t
SU:DAT
Data setup time 250 ns
t
HD:DAT
(2)
2. Transmitter must internally provide a hold time to bridge the undefined region (300 ns max.) of the falling
edge of SCL.
Data hold time 0 µs
t
SU:STO
STOP condition setup time 4.7 µs
t
BUF
Time the bus must be free before a new
transmission can start
4.7 µs
