AATIAN19 Datasheet, PDF (1/6 Pages) SiGe Semiconductor, Inc. – AAT1145 EVAL:1.5 MHz, 1.2A Step-Down

EV136
AAT1145 EVAL:1.5 MHz, 1.2A Step-Down
DC/DC Converter with Low Quiescent Current
Introduction
The AAT1145 Evaluation Board contains a fully tested 1.2A, 1.5MHz step-down DC/DC regulator. The circuit
has an input voltage range of 2.5V to 5.5V and a 1.8V output capable of delivering up to 1.2A output current
with a 3.6V V_IN. The output is adjustable from 0.6V to V_IN. The circuit can provide up to 96% efficiency and it
consumes less than 1µA in shutdown mode. In light load mode operation there is very low output ripple volt-
age for noise-sensitive applications.
The AAT1145 comes in a small 10-pin DFN package, which has an exposed pad on the bottom-side of the IC
for better thermal performance. The board has a ground pad just below the exposed pad for reliable soldering
and better thermal dissipation. These features, plus the nominal operating frequency of 1.5MHz allowing the
use of low profile surface mount components, make the AAT1145 an ideal circuit for use in battery-powered,
hand-held applications.
Figure 1: AAT1145 Evaluation Board.
Layout Guidelines
The following guidelines should be followed to ensure proper operation of the AAT1145:
1. The Exposed Pad (EP) must be reliably soldered to GND. A large pad under the device is strongly rec-
ommended for heat sinking purposes.
2. The power traces, including the GND trace, the LX-to-L1-to-VOUT trace and the VIN-to-IN trace should be
kept short, direct and wide to allow large current flow. Put many multiple-layer VIA pads when connecting
traces change between layers.
3. Connect the input capacitor C1 to the IN and AIN pins as close as possible to get good power filtering.
4. Keep the switching node, LX pin 7 and 8, away from the sensitive FB/OUT node.
5. To avoid large GND noise affecting the accurate reference circuit, it is recommended that pin 4 and pin 6
AGND connect to the GND plane to a single point under the device.
EV-136.2007.08.1.1
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