EV-104 - Skyworks Solutions, Inc.

EV-104
AAT1154EVAL
1MHz 3A Buck DC/DC Switch Mode Regulator
Introduction
The AAT1154 evaluation board demonstrates performance, along with the suggested size and placement of
external components, for the AAT1154 integrated buck regulator. The external components are selected for
minimum size and optimum operation up to 3.0A output current. Please refer to the AAT1154 datasheet for
more details about this product.
Component Summary
Capacitor C4 is a high equivalent series resistance (ESR) tantalum for damping the high Q input network associated with the inductance of the leads feeding the input power to the evaluation board and the low ESR 10µF
ceramic input capacitor (C1). R2 is a pull-up resistor to allow the enable pin to be used to enable and disable
the IC by either shorting the enable pin to GND or leaving the pin open. Both R2 and C4 are for demonstration purposes only and are not necessary in the final solution. Resistors R3 and R4 are used with the 1V model
to set the out voltage to any desired value from 1V to as high as 200mV below the minimum input voltage.
They are not required for the fixed output voltage versions of the AAT1154. For fixed output voltage versions,
R4 is omitted and R3 is replaced with a short.
Layout
As with all switching power supplies, the board layout for the AAT1154 is critical (see Figure 1). Special care
has been taken with the placement of the external components. The input capacitor (C1) placement is critical;
it must be placed immediately adjacent to the AAT1154. As can be seen in Figure 2, the LX node trace has
been routed under C1 in order to facilitate placement of C1 close to the IC. The output voltage feedback trace
has been routed on the portion of the back side of the board which has a ground plane on the top side (see
Figure 3). The trace is routed to avoid the LX node and associated noise. Please refer to Table 1 for AAT1154
evaluation board specifications.
VIN+
VO+
R1
100
U1
AAT1154
R3
C4
100µF
1
R2
100k
2
3
Enable
4
C1
10µF
C3
0.1µF
FB
VP
GND
LX
EN
LX
VCC
VP
8
7
L1
1.5uH
6
5
CR1
B340LA
R4
10.0k
C2
120µF
GND
Figure 1: AAT1154 Evaluation Board Schematic.
EV-104.2005.01.1.0
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EV-104
AAT1154EVAL
1MHz 3A Buck DC/DC Switch Mode Regulator
Specification
Test Conditions
Input Voltage
Output Error Voltage
Output Current
Min
Typ
Max
Units
2.7
3.6
±3
5.5
V
%
A
0
3.0
Table 1: AAT1154 Evaluation Board Specifications.
Figure 2: AAT1154 Evaluation
Board PCB Top Side.
Figure 3: AAT1154 Evaluation
Board PCB Bottom Side.
Test Equipment
1. 6.0V 10A laboratory power supply: HP33401A or equivalent.
2. DC 0A to 3.0A load capable of operation down to 1.0V: Keithley 2400 or equivalent.
When using the Keithley 2400, set the meter to zero volts in voltage source mode and set the load current by varying the current compliance (maximum current) of the meter.
3. DC voltmeter: HP34401A or equivalent.
4. Oscilloscope: Tektronix TDS744A or equivalent.
Setup and Test
A: Load and Line Regulation (see connection diagram in Figure 4)
1. Apply a DC power supply and DC voltmeter across input voltage terminals: VIN+ (positive terminal) and
GND (negative terminal or return).
2. Apply a DC load and DC voltmeter to output terminals. VO+ and GND.
3. Vary the load from 0 to 3.0A and the input voltage from 2.7V to 5.5V while monitoring the output voltage.
4. The output voltage as measured at the output terminals of the evaluation board should not vary by more
than ±3% of the nominal voltage.
B: Short-Circuit and Over-Temperature Protection
1. Raise the input voltage to 5.5V.
2. Apply a short from VO+ to GND at the evaluation board terminals.
3. Remove the short and verify that output returns to its initial value.
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EV-104.2005.01.1.0
EV-104
AAT1154EVAL
1MHz 3A Buck DC/DC Switch Mode Regulator
C: Enable Input and Power OK Output
1. Short the enable pin to GND. The output should decay to zero.
2. Remove the short applied to the enable pin. The output should recover to its initial value.
3.600V
Power Supply
3.650V
0.147A
Voltmeter
1.500V
Load
Voltmeter
0-3.0A
Figure 4: AAT1154 Connection Diagram.
Component
U1
U1
U1
U1
CR1
C2
C4
C1
C3
R1
R2
L1
Part Number
Description
AAT1154IKS-1.0-T1
AAT1154IKS-1.8-T1
AAT1154IKS-2.5-T1
AAT1154IKS-3.3-T1
B340LA
594D127X96R6R3C2T
565D107X0016C
GRM319R60J106KE01
GRM155R61A104KA01
Chip Resistor
Chip Resistor
CDRH6D28-1R5
1.0V, 1MHz, 3.0A Buck Converter
1.8V, 1MHz, 3.0A Buck Converter
2.5V, 1MHz, 3.0A Buck Converter
3.3V, 1MHz, 3.0A Buck Converter
Low VF, 3A, 40V Schottky Diode
120µF, 6.3V, Tantalum
100µF, 16V, Tantalum
10µF, 6.3V, X5R, 10%, 1206
0.1µF, 25V, X5R, 10%, 0603
100kΩ, 5%, 1/10W, 0603
100kΩ, 5%, 1/10W, 0603
1.5µH Shielded Inductor
AAT1154IKS-1.0-T1, Table 3, 1%, 1/10W, 0603
AAT1154IKS-1.8-T1 thru AAT1154IKS-3.3 -T1; 0Ω, 0603
AAT1154IKS-1.0-T1 (for output greater than 1.0V);
10kΩ, 1%, 1/10W; 0603
AAT1154IKS-1.8-T1 thru AAT1154IKS-3.3 -T1
R3
Chip Resistor
R4
Chip Resistor
Manufacturer
AnalogicTech
AnalogicTech
AnalogicTech
AnalogicTech
Diodes Inc.
Vishay
Vishay
MuRata
MuRata
Vishay
Vishay
Sumida
Vishay
Vishay
Vishay
n/a
Table 2: AAT1154 EVAL Bill of Materials.
EV-104.2005.01.1.0
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EV-104
AAT1154EVAL
1MHz 3A Buck DC/DC Switch Mode Regulator
Output Voltage
For an adjustable output, set R4 to 10kΩ and select R3 according to Table 3 using the AAT1154IKS-1.0-T1.
VO (V)
Ω)
R3 (kΩ
1.0
1.1
1.2
1.25
1.3
1.4
1.5
1.6
1.7
1.8
1.85
1.9
2.0
2.1
2.2
2.3
2.4
2.5
3.3
0.00 (short)
1.00
2.00
2.55
3.01
4.02
4.99
6.04
6.98
8.06
8.45
9.09
10.0
11.0
12.1
13.0
14.0
15.0
23.2
Ω).
Table 3: Resistor Selection for Adjustable Output Voltage (R4=10.0kΩ
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work
rights, or other intellectual property rights are implied.
AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice, and advise customers to obtain the latest
version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability.
AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and
other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
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EV-104.2005.01.1.0