Datasheet

SMBC
SMBD
SMBC
SMBD
SMBC
SMBD
S
t
SU(STA)
SP
t
BUF
t
SU(STO)
t
R
t
F
SMBC
SMBD
t
TIMEOUT
t
HIGH
t
LOW
t
F
t
R
t
HD(DAT)
t
SU(DAT)
t
HD(STA)
Start and Stop condition Wait and Hold condition
Timeout condition Repeated Start condition
bq20z655
SLUSAH8A –APRIL 2011–REVISED MAY 2012 www.ti.com
SMBus TIMING CHARACTERISTICS (continued)
T
A
= –40°C to 85°C Typical Values at T
A
= 25°C and V
REG25
= 2.5 V (Unless Otherwise Noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Bus free time between start and stop
t
(BUF)
4.7 µs
(see Figure 3)
t
(HD:STA)
Hold time after (repeated) start (see Figure 3) 4 µs
t
(SU:STA)
Repeated start setup time (see Figure 3) 4.7 µs
t
(SU:STO)
Stop setup time (see Figure 3) 4 µs
t
(HD:DAT)
Receive mode 0 ns
Data hold time (see Figure 3)
Transmit mode 300
t
(SU:DAT)
Data setup time (see Figure 3) 250 ns
t
(TIMEOUT)
Error signal/detect (see Figure 3) See
(1)
25 35 µs
t
(LOW)
Clock low period (see Figure 3) 4.7 µs
t
(HIGH)
Clock high period (see Figure 3) See
(2)
4 50 µs
t
(LOW:SEXT)
Cumulative clock low slave extend time See
(3)
25 ms
Cumulative clock low master extend time
t
(LOW:MEXT)
See
(4)
10 ms
(see Figure 3)
t
f
Clock/data fall time See
(5)
300 ns
t
r
Clock/data rise time See
(6)
1000 ns
(1) The bq20z655 times out when any clock low exceeds t
(TIMEOUT)
.
(2) t
(HIGH)
, Max, is the minimum bus idle time. SMBC = SMBD = 1 for t > 50 ms causes reset of any transaction involving bq20z655 that is
in progress. This specification is valid when the NC_SMB control bit remains in the default cleared state (CLK[0]=0).
(3) t
(LOW:SEXT)
is the cumulative time a slave device is allowed to extend the clock cycles in one message from initial start to the stop.
(4) t
(LOW:MEXT)
is the cumulative time a master device is allowed to extend the clock cycles in one message from initial start to the stop.
(5) Rise time t
r
= VILMAX – 0.15) to (VIHMIN + 0.15)
(6) Fall time t
f
= 0.9 V
DD
to (VILMAX – 0.15)
A. SCLKACK is the acknowledge-related clock pulse generated by the master.
Figure 3. SMBus Timing Diagram
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