AAT1142
800mA Voltage-Scaling Step-Down Converter
S2Cwire Serial Interface
S2Cwire Serial Interface Timing
AnalogicTech's S2Cwire serial interface is a propri-
etary high-speed single-wire interface. The S2Cwire
interface records rising edges of the EN/SET input
and decodes them into one of 32 registers which
determines the output voltage, as shown in Table 2.
Each state corresponds to an output voltage setting.
The S2Cwire serial interface has flexible timing.
Data can be clocked-in at speeds up to 1MHz.
After data has been submitted, EN/SET is held
high to latch the data for a period TLAT. The output
is subsequently changed to the predetermined volt-
age. When EN/SET is set low for a time greater
than TOFF, the AAT1142 is disabled. When dis-
abled, the data register is reset to the default value.
When using the S2Cwire interface, both I2C inputs
should be tied to the ground return. This disables
the I2C functionality.
S2Cwire Timing Diagram
THI
TOFF
TLO
TLAT
EN/SET
1
2
n-1
n ≤ 64
0
n-1
Data Reg
0
S2Cwire Output Voltage Programming
Rising
Clock
Rising
Clock
The AAT1142 is programmed through the S2Cwire
interface according to Table 2. The rising clock
edges received through the EN/SET pin corre-
sponding to a given data register determine the
output voltage set-point. Upon power-up and prior
to S2Cwire programming, the default output voltage
is set to 1.8V.
Edges/
Data
Output
Voltage
(V)
Edges/
Data
Output
Voltage
(V)
Register
Register
1
2
No change
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1.40
1.45
3
1.50
4
1.55
5
1.60
6
1.65
7
1.70
8
1.75
9
1.80 (default)
1.85
10
11
12
13
14
15
16
1.90
1.95
2.00
2.00
2.00
2.00
Table 2: AAT1142 S2Cwire Output Voltage
Programming Map.
16
1142.2006.07.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
