Datasheet
V
IH
V
IL
SMBCLK
P
S
V
IH
V
I
L
SMBDAT
t
BUF
t
HD;STA
t
LOW
t
R
t
HD;DAT
t
HIGH
t
F
t
SU;DAT
t
SU;STA
t
SU;STO
PS
LM73
SNIS141D –OCTOBER 2005–REVISED MAY 2009
www.ti.com
LOGIC ELECTRICAL CHARACTERISTICS - SMBus DIGITAL SWITCHING CHARACTERISTICS
Unless otherwise noted, these specifications apply for V
DD
= +2.7 V to +5.5 V, C
L
(load capacitance) on output lines = 400 pF.
Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= +25°C, unless otherwise noted.
Symbol Parameter Conditions Typical
(1)
Limits
(2)
Units
(Limit)
f
SMB
SMBus Clock Frequency No minimum clock frequency 400 kHz (max)
if Time-Out feature is
disabled.
t
LOW
SMBus Clock Low Time 300 ns (min)
t
HIGH
SMBus Clock High Time 300 ns (min)
t
F;SMBO
Output Fall Time
(3)
C
L
= 400 pF 250 ns (max)
I
PULL-UP
≤ 3 mA
t
TIMEOUT
SMBDAT and SMBCLK Time Low for Reset of 15 ms (min)
Serial Interface
(4)
45 ms (max)
t
SU;DAT
Data In Setup Time to SMBCLK High 100 ns (min)
t
HD;DATI
Data Hold Time: Data In Stable after SMBCLK 0 ns (min)
Low
t
HD;DATO
Data Hold Time: Data Out Stable after SMBCLK 30 ns (min)
Low
t
HD;STA
Start Condition SMBDAT Low to SMBCLK Low 60 ns (min)
(Start condition hold before the first clock falling
edge)
t
SU;STO
Stop Condition SMBCLK High to SMBDAT Low 50 ns (min)
(Stop Condition Setup)
t
SU;STA
SMBus Repeated Start-Condition Setup Time, 50 ns (min)
SMBCLK High to SMBDAT Low
t
BUF
SMBus Free Time Between Stop and Start 1.2 µs (min)
Conditions
t
POR
Power-On Reset Time
(5)
1 ms (max)
(1) Typicals are at T
A
= 25°C and represent most likely parametric norm.
(2) Limits are ensured to TI's AOQL (Average Outgoing Quality Level).
(3) The output fall time is measured from (V
IH;MIN
+ 0.15V) to (V
IL;MAX
- 0.15V).
(4) Holding the SMBDAT and/or SMBCLK lines Low for a time interval greater than t
TIMEOUT
will reset the LM73's SMBus state machine,
setting SMBDAT and SMBCLK pins to a high impedance state.
(5) Represents the time from V
DD
reaching the power-on-reset level to the LM73 communications being functional. After an additional time
equal to one temperature conversion time, valid temperature will be available in the TEMPERATURE DATA REGISTER.
Figure 2. SMBus Communication
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