MAX1586A Datasheet, PDF (22/32 Pages) Maxim Integrated Products – High-Efficiency, Low-IQ PMICs with Dynamic Core for PDAs and Smart Phones

High-Efficiency, Low-I_Q PMICs with
Dynamic Core for PDAs and Smart Phones
A
B
C
D
EF
G
t_LOW t_HIGH
SCL
SDA
t_SU:STA tHD:STA
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMB DATA LINE LOW
t_SU:DAT
t_HD:DAT
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE (OP/SUS BIT)
H = LSB OF DATA CLOCKED INTO SLAVE
I = SLAVE PULLS SMB DATA LINE LOW
Figure 4. I²C-Compatible Serial-Interface Timing Diagram
H
IJ
K
LM
t_SU:STO t_BUF
J = ACKNOWLEDGE CLOCKED INTO MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
Bit Transfer
One data bit is transferred during each SCL clock
cycle. The data on SDA must remain stable during the
high period of the SCL clock pulse. Changes in SDA
while SCL is high are control signals (see the START
and STOP Conditions section). Both SDA and SCL idle
high when the bus is not busy.
START and STOP Conditions
When the serial interface is inactive, SDA and SCL idle
high. A master device initiates communication by issu-
ing a START condition. A START condition is a high-to-
low transition on SDA with SCL high. A STOP condition
is a low-to-high transition on SDA while SCL is high
(Figure 4). A START condition from the master signals
the beginning of a transmission to the MAX1586/
MAX1587. The master terminates transmission by issu-
ing a not acknowledge followed by a STOP condition
(see the Acknowledge Bit section). The STOP condition
frees the bus.
When a STOP condition or incorrect address is detect-
ed, the MAX1586/MAX1587 internally disconnect SCL
from the serial interface until the next START condition,
minimizing digital noise and feedthrough.
Acknowledge Bit (ACK)
The acknowledge bit (ACK) is the ninth bit attached to
every 8-bit data word. The receiving device always
generates ACK. The MAX1586/MAX1587 generate an
ACK when receiving an address or data by pulling SDA
low during the ninth clock period. Monitoring ACK
allows for detection of unsuccessful data transfers. An
unsuccessful data transfer occurs if a receiving device
is busy or if a system fault has occurred. In the event of
an unsuccessful data transfer, the bus master should
reattempt communication at a later time.
Serial Address
A bus master initiates communication with a slave
device by issuing a START condition followed by the
7-bit slave address (Table 3). When idle, the
MAX1586/MAX1587 wait for a START condition fol-
lowed by its slave address. The serial interface com-
pares each address value bit by bit, allowing the
interface to power down immediately if an incorrect
address is detected.
The LSB of the address word is the read/write (R/W) bit.
R/W indicates whether the master is writing or reading
(RD/W 0 = write, RD/W 1 = read). The MAX1586/
MAX1587 only support the SEND BYTE format; there-
fore, RD/W is required to be 0.
After receiving the proper address, the MAX1586/
MAX1587 issue an ACK by pulling SDA low for one
clock cycle. The MAX1586/MAX1587 have two user-
programmed addresses (Table 3). Address bits A6
through A1 are fixed, while A1 is controlled by SRAD.
Connecting SRAD to GND sets A1 = 0. Connecting
ADD to IN sets A1 = 1.
V3 Output Ramp-Rate Control
When V3 is dynamically changed with the serial inter-
face, the output voltage changes at a rate controlled by
a capacitor (C_RAMP) connected from RAMP to ground.
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