AAT2550_08 Datasheet, PDF (20/34 Pages) Advanced Analogic Technologies – Total Power Solution for Portable Applications

SystemPower^TM
PRODUCT DATASHEET
AAT2550178
Total Power Solution for Portable Applications
The DATA pin function is active low and should normally
be pulled high to V_ADP. This data line may also be pulled
high to the same level as the high state for the logic I/O
port on the system microcontroller. In order for the DATA
pin control circuit to generate clean, sharp edges for the
data output and to maintain the integrity of the data tim-
ing for the system, the pull-up resistor on the data line
should be low enough in value so that the DATA signal
returns to the high state without delay. If too small a
pull-up resistor is used, the strobe pulse from the system
microcontroller could exceed the maximum pulse time
and the DATA output control could issue false status
reports. A 1.5kΩ resistor is recommended when pulling
the DATA pin high to 5.0V. If the data line is pulled high
to a voltage level less than 5.0V, the pull-up resistor can
be calculated based on a recommended minimum pull-up
current of 3mA. Use the following formula:
R_PULL-UP ≤
V_PULL-UP
3mA
Data Timing
The system microcontroller should assert an active low
data request pulse for minimum duration of 200ns; this is
specified by the S_QPULSE. Upon sensing the rising edge of the
end of the data request pulse, the AAT2550 status data
control will reply the data word back to the system micro-
controller after a delay defined by the data report time
specification T_DATA(RPT). The period of the following group of
data pulses will be defined by the T_DATA specification.
1.8V to 5.0V
IN
AAT2550
Status
Control
OUT
DATA Pin
R_{P UL L _ UP}
GPIO
Figure 3: Data Pin Application Circuit.
Timing Diagram
SQ
CK
Data
S_QPULSE
System Reset
System Start
T_SYNC
T_LAT
T_DATA(RPT) = T_SYNC + T_LAT < 2.5 P_DATA
T_OFF > 2 P_DATA
P_DATA
N=1
N=2
T_OFF
N=3
IN
OUT
μP GPIO
Port
20
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2550.2008.02.1.3