LTC2944
4
2944f
For more information www.linear.com/LTC2944
TiMing DiagraM
elecTrical characTerisTics
Note 1. Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2. All currents into pins are positive, all voltages are referenced to
GND unless otherwise specified.
Note 3. I
SUPPLY
= I
SENSE
+
+ I
SENSE
–
. In most operating modes I
SUPPLY
is
flowing in SENSE
+
pin. Only during ADC conversions current is flowing in
SENSE
–
pin as well. Typically, I
SENSE
–
= V
SENSE
–
/150k during ADC voltage
conversion and I
SENSE
–
= 20µA during ADC current conversion.
Note 4. The equivalent charge of an LSB in the accumulated charge
register depends on the value of R
SENSE
and the setting of the internal
prescaling factor M:
q
LSB
= 0.340mAh • (50mΩ/R
SENSE
) • (M/4096):
See Choosing R
SENSE
and Choosing Coulomb Counter Prescaler M section
for more information. 1mAh = 3.6C (Coulombs)
Note 5. Deviation of q
LSB
from its nominal value.
Note 6. The quantization step of the 14-bit ADC in voltage mode, 12-bit
ADC in current mode and 11-bit ADC in temperature mode is not the same
as the LSB of the respective combined 16-bit registers. See the Voltage,
Current
and Temperature Registers section for more information.
Note 7. C
B
= Capacitance of one bus line in pF (10pF ≤ C
B
≤ 400pF).
Note 8. Guaranteed by design, not subject to test.
Note 9. See "Effect of Differential Offset Voltage on Total Charge Error”
section.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
2
C Timing Characteristics
f
SCL(MAX)
Maximum SCL Clock Frequency
l
400 900 kHz
t
BUF(MAX)
Bus Free Time Between Stop/Start
l
1.3 µs
t
SU(STA(MIN))
Minimum Repeated Start Set-Up
Time
l
600 ns
t
HD(STA(MIN))
Minimum Hold Time (Repeated)
Start Condition
l
600 ns
t
SU(STO(MIN))
Minimum Set-Up Time for Stop
Condition
l
600 ns
t
SU(DAT(MIN))
Minimum Data Setup Time Input
l
100 ns
T
HD(DAT(MIN))
Minimum Data Hold Time Input
l
50 ns
T
HDDATO
Data Hold Time Input Output
l
0.3 0.9 µs
T
OF
Data Output Fall Time (Notes 7, 8)
l
20 + 0.1 • C
B
300 ns
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
SDA
SCL
2944 TD01
t
HD(STA)
START
CONDITION
t
SU(DAT)
t
HD(DAT0)
t
HD(DAT1)
t
HD(STA)
t
SU(STO)
t
SU(STA)
STOP
CONDITION
START
CONDITION
REPEATED START
CONDITION
t
OF
t
BUF
Figure 1. Definition of Timing on I
2
C Bus
