RT8008GB Evaluation Board Purpose

RT8008GB Evaluation Board  Purpose
RT8008GB
Evaluation Board
Purpose
The RT8008 is a high-efficiency 1.5MHz current mode synchronous step-down regulator that can deliver up to
600mA output current from an input voltage range of 2.5V to 5.5V. This document explains the function and use of
the RT8008 evaluation board (EVB) and provides information to enable operation and modification of the
evaluation board and circuit to suit individual requirements.
Table of Contents
Purpose ..................................................................................................................................................................1
Introduction .............................................................................................................................................................2
General Product Information ...................................................................................................................................2
Key Performance Summary Table...........................................................................................................................3
Bench Test Setup Conditions ..................................................................................................................................4
Headers Description and Placement .......................................................................................................................4
Test Points .............................................................................................................................................................4
Power-up & Measurement Procedure .....................................................................................................................5
Output Voltage Setting ............................................................................................................................................5
Schematic, Bill of Materials and Board Layout .........................................................................................................6
EVB Schematic Diagram.........................................................................................................................................6
Bill of Materials .......................................................................................................................................................6
EVB Layout ............................................................................................................................................................7
More Information................................................................................................................................................... 10
Important Notice for Richtek Evaluation Board ...................................................................................................... 10
UG8008GB-00
March
2014
www.richtek.com
RT8008GB
Evaluation Board
Introduction
General Product Information
General Description
The RT8008 is a high-efficiency pulse-width-modulated (PWM) step-down DC/DC converter. Capable of delivering
600mA output current over an input voltage range of 2.5V to 5.5V, the RT8008 is ideally suited for portable electronic
devices that are powered from 1-cell Li-ion battery (or from other power sources within that range) such as cellular
phones, PDAs and handy-terminals.
An internal synchronous rectifier with low RDS(ON) dramatically reduces conduction losses in PWM mode. No external
Schottky diode is required in practical applications. The RT8008 automatically turns off the synchronous rectifier
when the inductor current is low entering discontinuous PFM mode to increase efficiency at light loads.
The RT8008 enters Low-Dropout mode when normal PWM operation cannot regulate the output voltage, turning on
the upper P-MOSFET continuously. The RT8008 enters shutdown mode and consumes less than 0.1μA when EN
pin is pulled low.
The switching ripple is easily smoothed-out by small sized filtering elements due to a fixed operating frequency of
1.5MHz. This, along with its small SOT-23-5 and TSOT-23-5 packages provides a small PCB area. Other features
include soft start, low internal reference voltage with 2% accuracy, over temperature protection, and over current
protection.
Features
 2.5V to 5.5V Input Range
 Adjustable Output from 0.6V to VIN
 1.0V, 1.2V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/ Adjustable Output Voltage
 600mA Output Current, 1A Peak Current
 95% Efficiency
 No Schottky Diode Required
 1.5MHz Fixed Frequency at PWM Operation
 Small SOT-23-5 and TSOT-23-5 Package
 RoHS Compliant and 100% Lead (Pb)-Free
UG8008GB-00
March
2014
www.richtek.com
2
RT8008GB
Evaluation Board
Key Performance Summary Table
Key features
Evaluation board number: PCB003_V1
Default Input Voltage
5V
Max Output Current
600mA
Default Output Voltage
1.2V
Default Marking & Package Type
RT8008GB, SOT-23-5
Operation Frequency
Steady 1.5MHz at PWM
Other Key Features
PSM/ PWM Auto Switched.
Protection
Over Current Protection, Over Temperature Protection
UG8008GB-00
March
2014
www.richtek.com
3
RT8008GB
Evaluation Board
Bench Test Setup Conditions
Headers Description and Placement
Please carefully inspect the EVB IC and external components, comparing them to the
following Bill of Materials, to ensure that all components are installed and undamaged. If any
components are missing or damaged during transportation, please contact the distributor or
send e-mail to [email protected]
Test Points
The EVB is provided with the test points and pin names listed in the table below.
Test point/
Pin name
Signal
Comment (expected waveforms or voltage levels on
test points)
VIN
Input voltage
Input voltage range= 2.5V to 5.5V
VOUT
Output voltage
Default Output Voltage = 1.2V
Output voltage range= 0.6V to 5V
(see ‘’ Output Voltage Setting’’ section for changing output
voltage level)
LX
Switching node test point
LX waveform
J1
Chip Enable control
Drive EN or install a shorting block on Jumper J1 to enable
operation (shorting 1-2) or disable operation (shorting 2-3).
GND
UG8008GB-00
Ground
March
2014
Ground
www.richtek.com
4
RT8008GB
Evaluation Board
Power-up & Measurement Procedure
1. Apply a 5V nominal input power supply (2.5V < VIN < 5.5V) to the VIN and GND terminals.
2. Place a shorting block across pins 1 and 2 of the J1 jumper to connect EN to VIN (>1.5V), to turn on the
converter. Short pins 2-3, connecting EN to GND, to turn off the converter.
3. Verify the output voltage (approximately 1.2V) between VOUT and GND.
4. Connect an external load up to 600mA to the VOUT and GND terminals and verify the output voltage and
current.
Output Voltage Setting
Set the output voltage with the resistive divider (R1, R2) between VOUT and GND with the midpoint connected to
FB. The output is set by the following formula:
VOUT = 0.6 x (1 +
R1
)
R2
The installed VOUT capacitor (C4) is a 10μF, 6.3V X5R ceramic type. For higher output voltages, consider its
voltage coefficient (capacitance vs. bias voltage) and ensure that the capacitance is sufficient to maintain stability
and provide sufficient transient response for your application. This can be verified by checking the output transient
response as described in the RT8008 IC datasheet.
UG8008GB-00
March
2014
www.richtek.com
5
RT8008GB
Evaluation Board
Schematic, Bill of Materials and Board Layout
EVB Schematic Diagram
TP3
LX
SOT-23-5
4
VIN
L1
LX
3
2.2uH
J1
SIP-2P-POWER
1
2
3
C3
4.7uF
Vout
1
VIN
1
EN
C4
10uF
C1
22pF
R1
120k
SIP-2P-POWER
SIP-3P
2
TP2
1
GND
GND
FB
5
TP1
C2
1
GND
U1
R2
120k
NF
C3: 4.7μF/6.3V/X5R, 0603, TDK C2012X5R0J475M
C4: 10μF/6.3V/X5R, 0805, TDK C2012X5R0J106M
L1: 2.2μH TAIYO YUDEN NR3015T2R2M, DCR=60mΩ
Bill of Materials
Reference
Qty
Part number
Description
Package
Manufacture
U1
1
RT8008GB
DC-DC Converter
SOT-23-5
Richtek
C1
1
0603B220K500NT
0603
WALSIN
22pF/±10%50V/X7R
Ceramic Capacitor
C2
0
C3
1
Not Installed
0603
4.7μF/±20%/6.3V/X5R
C2012X5R0J475M
0603
TDK
0805
TDK
Ceramic Capacitor
C4
1
C2012X5R0J106M
10μF/±20%/6.3V/X5R
Ceramic Capacitor
L1
1
NR3015T2R2M
2.2μH/1.5A/±20%,
3mmx3mmx1.5mm TAIYO YUDEN
DCR=60mΩ, Inductor
UG8008GB-00
R1
1
120kΩ/±1%, Resistor
0603
R2
1
120kΩ/±1%, Resistor
0603
J1
1
3-Pin Header
TP
3
Test Pin
GP
4
Golden Pin
March
2014
www.richtek.com
6
RT8008GB
Evaluation Board
EVB Layout
Top View (1st layer)
Bottom View (2nd Layer)
UG8008GB-00
March
2014
www.richtek.com
7
RT8008GB
Evaluation Board
Component Placement Guide—Component Side (1st layer)
PCB Layout—Component Side (1st Layer)
UG8008GB-00
March
2014
www.richtek.com
8
RT8008GB
Evaluation Board
Component Placement Guide—Bottom Side (2nd Layer)
PCB Layout—Bottom Side (2nd layer)
UG8008GB-00
March
2014
www.richtek.com
9
RT8008GB
Evaluation Board
More Information
For more information, please find the related datasheet or application notes from Richtek website
http://www.richtek.com.
Important Notice for Richtek Evaluation Board
THIS DOCUMENT IS FOR REFERENCE ONLY, NOTHING CONTAINED IN THIS DOCUMENT SHALL BE CONSTRUED AS RICHTEK’S WARRANTY, EXPRESS
OR IMPLIED, UNDER CONTRACT, TORT OR STATUTORY, WITH RESPECT TO THE PRESENTATION HEREIN. IN NO EVENT SHALL RICHTEK BE LIABLE T O
BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL
DAMAGES.
UG8008GB-00
March
2014
www.richtek.com
10
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement