AATIAN17 Datasheet, PDF (1/6 Pages) SiGe Semiconductor, Inc. – I2C/S2Cwire™ Controller

EV-125
I²C/S²Cwire™ Controller
with AAT1142 Demo Board
Introduction
This document describes how to connect the I²C/S²Cwire controller board to the AAT1142 dynamically program-
mable DC/DC buck converter. The schematic and PCB drawing of the controller board, as well as the function
of each button, is described. The I²C/S²Cwire controller board contains a microcontroller which provides the I²C
and S²Cwire interface via a five-wire ribbon cable. This controller board works as a master device in either the
I²C or S²Cwire system, while the AAT1142 slave device receives data and varies the AAT1142 output voltage in
response to push-button commands. The microcontroller is programmed with one I²C slave address.
Getting Started
Figure 1 shows how to connect the I²C/S²Cwire controller board to the AAT1142 demo board. ESD protection
(ground cable) is recommended to prevent unwanted ESD events.
GND
EN
VCC
SCL
SDA
Slave
Master
Figure 1: Connection of AAT1142 Demo Board and I²C/S²Cwire Controller Board.
There are three (3) buttons on the controller board. Selecting the 'Up' or 'Down' button blinks the green LED,
indicating that the I²C or S²Cwire signal was successfully transmitted from the microcontroller. The output volt-
age level of the AAT1142 responds by adjusting the AAT1142 demo board output voltage in ±50mV incre-
ments. By holding the 'Up' or 'Down' button, the voltage level is auto-incremented and auto-decremented with-
in the AAT1142 specified operating voltage range (please refer to the AAT1142 datasheet). Selecting the 'Up'
or 'Down' button at the voltage extremes returns the output to the lowest or highest voltage level, respective-
ly. The 'Reset' button sets the output voltage level to the lowest setting.
There is a toggle switch on the controller board that switches between the I²C and S²Cwire communication pro-
tocols. When the switch is in the left position, the S²Cwire protocol is implemented via the EN pin. When the
switch is in the right position, the I²C protocol is implemented via the SCL and SDA pins. It can be switched at
any time, as the microcontroller has auto-detection capability.
Upon initial power-up and prior to I²C or S²Cwire programming, the default output voltage of the AAT1142 is
set at 1.8V. The input DC voltage range of the I²C/S²Cwire controller board and AAT1142 demo board is 2.7V
to 5.5V. On/Off control of the AAT1142 demo board using I²C interface is accomplished by applying or remov-
ing DC input voltage.
EV-125.2006.08.1.1
1