PRODUCT DATASHEET
AAT2550178
SystemPowerTM
Total Power Solution for Portable Applications
The DATA pin function is active low and should normally
be pulled high to VADP. 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:
VPULL-UP
3mA
RPULL-UP
≤
Data Timing
The system microcontroller should assert an active low
data request pulse for minimum duration of 200ns; this is
specified by the SQPULSE. 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 TDATA(RPT). The period of the following group of
data pulses will be defined by the TDATA specification.
1.8V to 5.0V
IN
RPULL_UP
IN
AAT2550
Status
DATA Pin
Control
GPIO
OUT
OUT
μP GPIO
Port
Figure 3: Data Pin Application Circuit.
Timing Diagram
SQPULSE
PDATA
SQ
System Reset
System Start
CK
TSYNC
TLAT
TOFF
Data
TDATA(RPT) = TSYNC + TLAT < 2.5 PDATA
TOFF > 2 PDATA
N=3
N=1
N=2
w w w . a n a l o g i c t e c h . c o m
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2550.2008.02.1.3
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
