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LX7165 EVAL BOARD USER GUIDE
Copyright 2012
Rev. 0.2, 2013-10-23
LX7165 5 Amp Step Down Converter
LX7165 EVALUATION BOARD
USER GUIDE
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Microsemi
Analog Mixed Signal Group
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LX7165 EVAL BOARD USER GUIDE
Copyright 2012
Rev. 0.1, 2013-10-23
Table of Contents
Introduction to Product .............................................................................................. 1
Key Features .............................................................................................................. 2
Applications ............................................................................................................... 2
Part Specific Information ........................................................................................... 3
Evaluation Board Schematic ...................................................................................... 3
Basic Connection Instructions ................................................................................... 4
LX7165 I2C GUI ........................................................................................................ 5
Recommended Operating Conditions ........................................................................ 6
PCB Layout of Evaluation Board .............................................................................. 7
Bill of Material .........................................................................................................11
Efficiency Plot ..........................................................................................................12
Dynamic Load Response Scope Shots .....................................................................13
Start up Scope Shots ................................................................................................16
Dimax Sub20 Installation ........................................................................................20
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Introduction to Product
The LX7165 is a digitally controlled step-down regulator IC with an integrated 30mΩ high-side P-
channel MOSFET and a 10mΩ low-side N-channel MOSFET. It features Microsemi’s proprietary
constant-frequency hysteretic control engine for near-instantaneous correction to sudden line/load
transients. It does not require high-ESR output capacitors and incorporates energy-saving “PSM”
(Power Saving or Pulse Skip Mode) at light loads, to extend battery life in mobile applications.
The LX7165 has an I2C serial interface port for output voltage margining and monitoring if
required (it can operate in default mode too). It includes robust fault monitoring functions.
The LX7165 will operate from 3V to 5.5V, and is available in several fixed output voltage options
from 0.6V to 0.97V (no voltage divider is necessary). Each version’s output voltage can also be
made adjustable with use of an external voltage divider.
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Key Features
Constant Frequency Hysteretic Control
Extremely Fast Line/Load Transient Response
I2C for Output Adjustment (3.4Mbps)
1.875MHz Switching Frequency
Extremely Low-R
Input Voltage Rail 3.3V to 5V, Current 5A
Programmable Power Save Mode for Light-Load Efficiency
UVLO, OVP, OCP
0°C to +85°C Ambient Temperature
Available in WLCSP-20 (0.4mm pitch)
RoHS Compliant
MOSFETS
DSON
Applications
High Performance HDD
LCD TV’s
Notebook/ Netbook
Server and Workstations
Video Cards
PoE Powered Devices
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
IC Part Number
Description
LX7165-xyCSP
WLCSP 20Ball 0.4mm Pitch
Evaluation Board Part Number
Description
LX7165 EVAL BOARD
Evaluation PCB for LX7165
Part Specific Information
Note: “x” is the 2 LSB bits of the binary I
“y” is the set output voltage (0 is 0.6V, 1 is 0.9V, 2 is 0.95V, 3 is 0.97V)
2
C slave address (0 to 3);
Evaluation Board Schematic
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Figure 1 Schematic of Evaluation Board
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Analog Mixed Signal Group
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Basic Connection Instructions
Figure 2 Power Supply and Load Connection with I2C Implemented
Figure 3 Power Supply and Load Connection without I2C Implemented
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
LX7165 I2C GUI
Figure 4 LX7165 GUI
LX7165 I2C GUI is a graphic user interface that can read/write IC status or change default
settings via I2C serial portal. For example, it can used to enable/disable device, change output
voltage, or enable power saving mode, etc.
More information about register map and I2C function can be found in LX7165 datasheet.
Note: To use this GUI, a SUB-20 USB-I2C adaptor is needed. See Dimax SUB-20 and LX7165
GUI Installation for details.
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Description
Symbol
Min
Max
Unit
Input Voltage
VIN
3
5.5 V Output Current
I
OUT
0 5 A
Operating Ambient Temperature
TA 0 85
°C
Enable Chip
EN
VIN
Shut Down Chip
EN Pull to GND
Recommended Operating Conditions
Enabling Regulator from I2C Bus
In addition to the ENABLE pin, the regulator can be enabled and disabled via the I2C bus by
programming the control register. During disable, the regulator and most of the support circuitry
is turned off. However, the I2C bus circuitry is still active and maybe programmed.
Setting the Output Voltage
Only use I2C interface can adjust VOUT from 0.6V to 1.2V. When I2C interface is implemented,
the reference voltage is programmed with the I2C bus VSEL register value.
Where N
is the decimal value of the 7 VSEL bits.
SEL
In case a higher output voltage is needed, it must be programmed through an external resistor
divider connected from SW to VOUT then to GND. For noise immunity, the lower resistor R2
from VOUT to GND should be greater than 100kOhm. A feed-forward capacitor C9 in parallel
with upper resistor is needed to ensure loop stability. Recommend C9=33pF. The formula below
gives the value of VOUT.
V
is determined by the chip, for example, to set LX7165-03CSP VOUT = 1.83V, given
REF
V
= 0.97V. First pick the lower resistor R2=150k, calculate the upper resistor R1=133k, and
REF
C9=33pF.
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
PCB Layout of Evaluation Board
The LX7165 EVAL Board is a 4-layer board, the thickness of the board is 63mil in total. The
second layer to top layer is 7mil, the third layer to the bottom layer is 7mil. There’s no
microvias or blind vias needed, each signal can leave the LX7165 directly without using any
via under the device. And, it can lower the ESL with the bypass capacitors C2, C3 and C9
implemented. C4 is only needed when there’s long wires connected.
Figure 5 Layout Recommendation
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
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Figure 6 Top Silkscreen
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Figure 7 Layer 1: Top Layer
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Figure 8 Layer 2: Ground Layer
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LX7165 EVAL BOARD USER GUIDE
Page 10
Copyright 2012
Rev. 0.1, 2013-10-23
Figure 9 Layer 3: Sense Layer
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Figure 10 Layer 4: Bottom Layer
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
MISCELLANEOUS COMPONENTS
Item
Part Description
Reference
Qty
1
Microsemi IC – LX7165
U1
1
2
Test Point
SW, PGOOD, VIN_S, VO_S,
GND_S, GND_S
6
3
Terminal
VIN, VOUT, GND, GND
4 4 Jumper/3pin
JP2
1 5 Jumper/4pin
J2
1
CAPACITORS
Item
Part Description
Reference
Qty
6
1uF
C2 1 7
22uF/10V/X5R
C3, C8
2 8 47uF Electronic
C4 1 9
22uF/6.3V/X5R
C5, C6, C7
3
RESISTORS
Item
Part Description
Reference
Qty
10 0 R1, R4
2
11
100kOhm
R3 1 12
10kOhm
R5, R6
2
INDUCTOR
Item
Part Description
Reference
Qty
13
0.47uH -- IHLP-2020CZ-01series
L1
1
Bill of Material
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
10 100 1000
Efficiency %
Load Current mA
LX7165-03CSP Vout=0.97V Efficiency
PWM
PSM
+
Efficiency Plot
Figure 11 Efficiency Plot of LX7165-03CSP
Analog Mixed Signal Group
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Dynamic Load Response Scope Shots
Dynamic load response with 0.5↔2.5A load
Figure 12 Dynamic Load Response with 0.5↔2.5A Load
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CH2: VOUT, CH4: Load Current
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Dynamic load response with 0.5↔2.5A load Rising Edge
Figure 13 Dynamic Load Response Rising Edge with 0.5↔2.5A Load
CH2: VOUT, CH3: SW, CH4: Load Current
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LX7165 EVAL BOARD USER GUIDE
Page 15
Copyright 2012
Rev. 0.1, 2013-10-23
Dynamic load response with 0.5↔2.5A load Falling Edge
Figure 14 Dynamic Load Response Falling Edge with 0.5↔2.5A Load
CH2: VOUT, CH3: SW, CH4: Load Current
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LX7165 EVAL BOARD USER GUIDE
Page 16
Copyright 2012
Rev. 0.1, 2013-10-23
Start up Scope Shots
Start up with ENABLE toggled
Figure 15 Startup with ENABLE toggled
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CH2: EN, CH3, VOUT
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Soft Start with VIN tied to EN
Figure 16 Soft start VIN tied to ENABLE
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CH3, VOUT
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LX7165 EVAL BOARD USER GUIDE
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Copyright 2012
Rev. 0.1, 2013-10-23
Start up when VIN = 4.5V, Load = 0.5Ohm
Figure 17 Start Up When Vin=4.5V Load=0.5ohm
CH1: PG, CH3: VOUT, CH4: Inductor Current
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Copyright 2012
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Start up when VIN = 4.5V, Load = 0.5Ohm, Rising Edge
Figure 18 Zoomed in Rising Edge of Start Up When VIN = 4.5V Load = 0.5ohm
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CH3: VOUT, CH4: Inductor Current
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Copyright 2012
Rev. 0.1, 2013-10-23
Dimax SUB-20 and LX7165 GUI Installation
Figure 19 Dimax SUB-20 Adapter
1. Uninstall any previous version of the SUB-20 adapter if exist.
2. Download and install SUB-20 USB driver from
http://www.xdimax.net/download/SUB-20-120121-x32.exe
Note: Install the x64 driver file for 64-bit systems.
More downloads available at http://www.xdimax.com/sub20/sub20.html#DLD
3. Connect SUB-20 device to computer's USB,
If this is the first time you connect the specific device, wait for SUB-20 driver installation
to finish - Found new hardware, let computer auto search for driver.
4. Firmware update:
The SUB-20 firmware version should be 0.3.5.
Open “Firmware updater” tool. The Firmware updater tool has a shortcut on the
desktop. It may also be found at Start Programs SUB-20 Firmware
updater.
5. Follow the instructions in the following link: SUB-20 Firmware Update
6. Connect the adaptor according to the following connection:
4 PIN to 9PIN cable connects LX7165 EVB I2C port and SUB-20 ( Unused pin
on 4 PIN connecter aligns with V+ pin on I2C port )
USB to mini-USB cable connects SUB-20 and PC
SUB-20 DB-9 connector pin #5 = GND
SUB-20 DB-9 connector pin #6 = I2C_SDA
SUB-20 DB-9 connector pin #8 = I2C_SCL
7. Install LX7165 GUI
Click CD:/LX7165 GUI/I2C Register Access_1_0_8_x.exe to start the installation,
To open the GUI, go to Startup> All Programs> Microsemi> Register Access>
Choose "LX7165" when "production selects window “pops out.
8. LX7165 GUI and SUB-20 driver could be found in the Support CD
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